Hemispherectomy: Difference between revisions
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{{Short description|Surgical |
{{Short description|Surgical removal of one hemisphere of the brain}} |
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'''Hemispherectomy''' is a neurosurgical procedure in which a [[cerebral hemisphere]] (half of the upper [[brain]], or [[cerebrum]]) is removed or disconnected that is used to treat a variety of refractory or drug-resistant seizure disorders ([[epilepsy]]).<ref name="pmid25380174">{{cite journal |last1=Griessenauer |first1=CJ |last2=Salam |first2=S |last3=Hendrix |first3=P |last4=Patel |first4=DM |last5=Tubbs |first5=RS |last6=Blount |first6=JP |last7=Winkler |first7=PA |title=Hemispherectomy for treatment of refractory epilepsy in the pediatric age group: a systematic review. |journal=Journal of Neurosurgery. Pediatrics |date=January 2015 |volume=15 |issue=1 |pages=34–44 |doi=10.3171/2014.10.PEDS14155 |pmid=25380174|doi-access=free }}</ref> Refractory or drug-resistant epilepsy is defined as seizures that fail to be controlled using 2 or more appropriate anti-seizure medications.<ref name=":pmid10660394">{{cite journal |last1=Kwan |first1=P |last2=Brodie |first2=MJ |title=Early identification of refractory epilepsy. |journal=The New England Journal of Medicine |date=3 February 2000 |volume=342 |issue=5 |pages=314–9 |doi=10.1056/NEJM200002033420503 |pmid=10660394}}</ref> About one in three patients with epilepsy have drug-resistant epilepsy and of those, about half of them have focal epilepsy that can potentially be treated with epilepsy surgery.<ref name="pmid29279892">{{cite journal |last1=Chen |first1=Z |last2=Brodie |first2=MJ |last3=Liew |first3=D |last4=Kwan |first4=P |title=Treatment Outcomes in Patients With Newly Diagnosed Epilepsy Treated With Established and New Antiepileptic Drugs: A 30-Year Longitudinal Cohort Study. |journal=JAMA Neurology |date=1 March 2018 |volume=75 |issue=3 |pages=279–286 |doi=10.1001/jamaneurol.2017.3949 |pmid=29279892|pmc=5885858 }}</ref> In drug-resistant epilepsy where all or most seizures arise from one hemisphere, hemispherectomy is a highly effective procedure producing seizure freedom in about 80-90% of patients.<ref name="pmid27281073">{{cite journal |last1=Cao |first1=K |last2=Liu |first2=M |last3=Wang |first3=C |last4=Liu |first4=Q |last5=Yang |first5=K |last6=Tao |first6=L |last7=Guo |first7=X |title=Five-Year Long-Term Prognosis of Epileptic Children After Hemispheric Surgery: A Systematic Review and Meta-analysis. |journal=Medicine |date=June 2016 |volume=95 |issue=23 |pages=e3743 |doi=10.1097/MD.0000000000003743 |pmid=27281073|pmc=4907651 }}</ref> In addition to controlling seizures and as a result of that, improved development and cognition is also very frequently achieved after hemispherectomy.<ref name="pmid34537627">{{cite journal |last1=Shurtleff |first1=HA |last2=Roberts |first2=EA |last3=Young |first3=CC |last4=Barry |first4=D |last5=Warner |first5=MH |last6=Saneto |first6=RP |last7=Buckley |first7=R |last8=Firman |first8=T |last9=Poliakov |first9=AV |last10=Ellenbogen |first10=RG |last11=Hauptman |first11=JS |last12=Ojemann |first12=JG |last13=Marashly |first13=A |title=Pediatric hemispherectomy outcome: Adaptive functioning, intelligence, and memory. |journal=Epilepsy & Behavior |date=16 September 2021 |volume=124 |pages=108298 |doi=10.1016/j.yebeh.2021.108298 |pmid=34537627|s2cid=237541132 }}</ref> Most patients who qualify for hemispherectomy already have neurological deficits such as hemibody weakness or loss of vision in one visual field that is opposite to the side of the affected hemisphere.<ref name="pmid23980759">{{cite journal |last1=Moosa |first1=AN |last2=Jehi |first2=L |last3=Marashly |first3=A |last4=Cosmo |first4=G |last5=Lachhwani |first5=D |last6=Wyllie |first6=E |last7=Kotagal |first7=P |last8=Bingaman |first8=W |last9=Gupta |first9=A |title=Long-term functional outcomes and their predictors after hemispherectomy in 115 children. |journal=Epilepsia |date=October 2013 |volume=54 |issue=10 |pages=1771–9 |doi=10.1111/epi.12342 |pmid=23980759|s2cid=37942603 }}</ref> This means that performing hemispherectomy does not add deficits to a new hemisphere in these patients.<ref name="pmid23980759" /> However, detailed testing is always performed prior to epilepsy surgery in general (including hemispherectomy) to ensure that such procedures would achieve two goals: 1) eliminating or greatly reducing seizures and 2) causing no or minimal deficits that could impair the patient’s functionality.<ref name="pmid29671293">{{cite journal |last1=Herta |first1=J |last2=Dorfer |first2=C |title=Surgical treatment for refractory epilepsy. |journal=Journal of Neurosurgical Sciences |date=February 2019 |volume=63 |issue=1 |pages=50–60 |doi=10.23736/S0390-5616.18.04448-X |pmid=29671293|s2cid=4995620 }}</ref> |
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'''Hemispherectomy''' is a surgery that is performed by a [[Neurosurgery|neurosurgeon]] where an unhealthy [[Cerebral hemisphere|hemisphere]] of the [[brain]] is disconnected or removed. There are two types of hemispherectomy. ''Functional'' ''hemispherectomy'' refers to when the diseased brain is simply disconnected so that it can no longer send signals to the rest of the brain and body. ''Anatomical hemispherectomy'' refers to when not only is there disconnection, but also the diseased brain is physically removed from the skull. This surgery is mostly used as a treatment for medically intractable [[epilepsy]], which is the term used when [[Anticonvulsant|anti-seizure medications]] are unable to control [[Seizure|seizures]]. |
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A hemispherectomy was first performed by the pioneering neurosurgeon [[Walter Dandy]] while at The Johns Hopkins Hospital in 1923 for [[glioblastoma multiforme]].<ref name="10.1001/jama.1928.02690380007003">{{cite journal |last1=Dandy |first1=Walter E. |title=Removal of Right Cerebral Hemisphere for Certain Tumors with Hemiplegia: Preliminary Report |journal=Journal of the American Medical Association |date=17 March 1928 |volume=90 |issue=11 |pages=823 |doi=10.1001/jama.1928.02690380007003}}</ref> The first account of hemispherectomy used to treat epilepsy was in 1938 by McKenzie in Toronto, Canada.<ref name="pmid24348108">{{cite journal |last1=Koubeissi |first1=M |title=Hemispherectomy: the full half of the glass. |journal=Epilepsy Currents |date=September 2013 |volume=13 |issue=5 |pages=213–4 |doi=10.5698/1535-7597-13.5.213 |pmid=24348108|pmc=3854724 }}</ref> The procedure gained further popularity in the 1950s following a successful series of hemispherectomies in 12 children by South African neurosurgeon Rowland Krynauw<ref name="pmid14795238">{{cite journal |last1=KRYNAUW |first1=RA |title=Infantile hemiplegia treated by removing one cerebral hemisphere. |journal=Journal of Neurology, Neurosurgery, and Psychiatry |date=November 1950 |volume=13 |issue=4 |pages=243–67 |doi=10.1136/jnnp.13.4.243 |pmid=14795238|pmc=498647 }}</ref> and its adoption by the world-renowned Canadian neurosurgeons Wilder Penfield and Theodor Rasmussen at the Montreal Neurological Institute.<ref name="pmid6861011">{{cite journal |last1=Rasmussen |first1=T |title=Hemispherectomy for seizures revisited. |journal=The Canadian Journal of Neurological Sciences |date=May 1983 |volume=10 |issue=2 |pages=71–8 |doi=10.1017/s0317167100044668 |pmid=6861011|s2cid=29792761 |doi-access=free }}</ref> Up until that point, hemispherectomy was done by completely removing one hemisphere, which is now known as anatomical hemispherectomy.<ref name="pmid14795238" /> |
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In the following decades, complications in patients who underwent anatomical hemispherectomy began to be recognized including cerebral hemosiderosis (accumulation of blood in cerebral cortex) and hydrocephalus (excessive cerebrospinal fluid accumulation), which led to a decline in its usage.<ref name="pmid22480976">{{cite journal |last1=Bahuleyan |first1=B |last2=Robinson |first2=S |last3=Nair |first3=AR |last4=Sivanandapanicker |first4=JL |last5=Cohen |first5=AR |title=Anatomic hemispherectomy: historical perspective. |journal=World Neurosurgery |date=September 2013 |volume=80 |issue=3–4 |pages=396–8 |doi=10.1016/j.wneu.2012.03.020 |pmid=22480976}}</ref> These complications were believed to be related to the significant amount of brain removed during surgery; therefore, to reduce the risk of complication, Rasmussen developed a modified technique termed “subtotal hemispherectomy” in 1968 that include removing two-thirds to three-quarters of the hemisphere and disconnecting the rest.<ref name="pmid6861011" /> This resulted in a much lower rate of complications but less effective seizure control, which led Rasmussen to further modify the technique by removing only the central part of the brain and disconnecting the frontal and occipital parts.<ref name="pmid6861011" /> He called this approach “functionally complete-anatomically total” hemispherectomy. The seizure control results were comparable to anatomical hemispherectomy whereas the complication rate was very low.<ref name="pmid6861011" /> |
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The first anatomical hemispherectomy was performed and described in 1928 by [[Walter Dandy]]. This was done as an attempt to treat [[glioma]], a brain tumor.<ref>{{Cite journal |last=Dandy |first=Walter E. |date=1928-03-17 |title=REMOVAL OF RIGHT CEREBRAL HEMISPHERE FOR CERTAIN TUMORS WITH HEMIPLEGIA: PRELIMINARY REPORT |url=http://jama.jamanetwork.com/article.aspx?doi=10.1001/jama.1928.02690380007003 |journal=Journal of the American Medical Association |language=en |volume=90 |issue=11 |pages=823 |doi=10.1001/jama.1928.02690380007003 |issn=0002-9955}}</ref> The first known anatomical hemispherectomy performed as a treatment for intractable epilepsy was in 1938 by Kenneth McKenzie, a Canadian neurosurgeon.<ref>{{Cite journal |last=McKenzie |first=KG |date=1938 |title=The present status of a patient who had the right cerebral hemisphere removed |journal=JAMA |volume=111 |pages=168–183}}</ref> Krynaw, a neurosurgeon from South Africa, was one of the first to perform and report a case series on hemispherectomies in 1950. He performed the surgery on pediatric patients with infantile hemiplegia, specifically as a treatment for their seizures and [[cognitive impairment]].<ref name=":0">{{Cite journal |last=Krynauw |first=R. A. |date=1950-11-01 |title=Infantile Hemiplegia Treated by Removing One Cerebral Hemisphere |journal=Journal of Neurology, Neurosurgery & Psychiatry |language=en |volume=13 |issue=4 |pages=243–267 |doi=10.1136/jnnp.13.4.243 |issn=0022-3050 |pmc=498647 |pmid=14795238}}</ref> His hemispherectomy technique removed the damaged hemisphere except the [[thalamus]] and [[Caudate nucleus|caudate]] structures. Krynaw reported good outcomes overall, although there was one post-operative death. Specifically, there was an overall theme of improvement in weakness, [[spasticity]] and cognition.<ref name=":0" /> Amazingly, ten out of the twelve patients had seizures prior to the operation and none of the patients had seizures afterwards.<ref name=":0" /> Other neurosurgeons began performing hemispherectomies as well, primarily for the treatment of seizures. For the most part, the surgeries would go well initially, but there was a general theme of subsequent deterioration and even death years after the surgery. As a result of the complication risk and the introduction of new anti-seizure medications, the popularity of the procedure began to decline in the 1950s.<ref name=":1">{{Cite journal |last=Rasmussen |first=Theodore |date=May 1983 |title=Hemispherectomy for Seizures Revisited |url=https://www.cambridge.org/core/product/identifier/S0317167100044668/type/journal_article |journal=Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques |language=en |volume=10 |issue=2 |pages=71–78 |doi=10.1017/S0317167100044668 |pmid=6861011 |issn=0317-1671}}</ref> Oppenheimer and Griffith were one of the first to describe the potential complications, and they reported their findings in 1966, describing superficial hemosiderosis, granular ependymitis and [[Hydrocephalus|obstructive hydrocephalus]].<ref name=":2">{{Cite journal |last1=Oppenheimer |first1=D R |last2=Griffith |first2=H B |date=1966-06-01 |title=Persistent intracranial bleeding as a complication of hemispherectomy. |journal=Journal of Neurology, Neurosurgery & Psychiatry |language=en |volume=29 |issue=3 |pages=229–240 |doi=10.1136/jnnp.29.3.229 |issn=0022-3050 |pmc=496024 |pmid=5937637}}</ref> They posited a theoretical solution to this problem, a surgery that is now known as a functional hemispherectomy.<ref name=":2" /> Rasmussen was one of the first neurosurgeons to develop and apply a functional hemispherectomy in practice. He initially made modifications to the original hemispherectomy by preserving the least epileptogenic quarter or third of the hemisphere, hoping this would ameliorate the known complications of the original anatomic hemispherectomy. Although this modification seemed to solve this issue, patients undergoing the modified hemispherectomy continued to have seizures, which was problematic. Therefore, he further modified his surgery to functionally sever residual portions of the [[Frontal lobe|frontal]] and [[Parietal lobe|parieto]]-[[Occipital lobe|occipital]] lobes.<ref name=":1" /> This surgery, the functional hemispherectomy, has been further modified over the years by several different neurosurgeons, and to this day there is not a consensus as to which exact technique should be used. Hemispherotomy refers to some of the more recently developed approaches to disconnect the epileptic hemisphere while minimizing brain removal and the risk for complications.<ref name=":3">{{Cite journal |last=Lew |first=Sean M. |date=July 2014 |title=Hemispherectomy in the treatment of seizures: a review |url=https://tp.amegroups.org/article/view/3760 |journal=Translational Pediatrics |language=en |volume=3 |issue=3 |pages=20817–20217 |doi=10.3978/j.issn.2224-4336.2014.04.01 |issn=2224-4344 |pmc=4729844 |pmid=26835338}}</ref> |
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== Nomenclature == |
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Later, further modifications were implemented, all aiming at minimizing the amount of brain tissue removed and instead disconnecting it, including central parasagittal hemispherectomy by Delalande in 1992,<ref name="pmid17297362">{{cite journal |last1=Delalande |first1=O |last2=Bulteau |first2=C |last3=Dellatolas |first3=G |last4=Fohlen |first4=M |last5=Jalin |first5=C |last6=Buret |first6=V |last7=Viguier |first7=D |last8=Dorfmüller |first8=G |last9=Jambaqué |first9=I |title=Vertical parasagittal hemispherotomy: surgical procedures and clinical long-term outcomes in a population of 83 children. |journal=Neurosurgery |date=February 2007 |volume=60 |issue=2 Suppl 1 |pages=ONS19-32; discussion ONS32 |doi=10.1227/01.NEU.0000249246.48299.12 |pmid=17297362|s2cid=9055072 }}</ref> periinsular hemispherectomy by Villemure,<ref name="pmid8559348">{{cite journal |last1=Villemure |first1=JG |last2=Mascott |first2=CR |title=Peri-insular hemispherotomy: surgical principles and anatomy. |journal=Neurosurgery |date=November 1995 |volume=37 |issue=5 |pages=975–81 |doi=10.1227/00006123-199511000-00018 |pmid=8559348}}</ref> and transylvian hemispherectomy by Schramm<ref name="pmid11564251">{{cite journal |last1=Schramm |first1=J |last2=Kral |first2=T |last3=Clusmann |first3=H |title=Transsylvian keyhole functional hemispherectomy. |journal=Neurosurgery |date=October 2001 |volume=49 |issue=4 |pages=891-900; discussion 900-1 |doi=10.1097/00006123-200110000-00021 |pmid=11564251|s2cid=31971370 }}</ref> The differences between these techniques was the surgical window used to perform the disconnection, but they all shared excellent seizure outcomes of 80-90% of patient becoming seizure free and minimal complications.<ref name="pmid17297362" /><ref name="pmid8559348" /><ref name="pmid11564251" /> These mostly disconnective techniques are now collectively referred to as functional hemispherectomy or hemispherotomy.<ref name="pmid25380174" /> |
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There are two main types of hemispherectomy: Anatomical and Functional. |
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''Anatomical hemispherectomy'' refers to the resection and removal of an entire hemisphere of the brain, which includes all four [[Lobes of the brain|lobes]], with or without the removal of basal ganglia and thalamus.<ref name=":3" /> |
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The surgical access that is typically used to perform a hemispherectomy is through a craniotomy, which involves making a window in the skull.<ref name="pmid30497135">{{cite journal |last1=Chandra |first1=PS |last2=Subianto |first2=H |last3=Bajaj |first3=J |last4=Girishan |first4=S |last5=Doddamani |first5=R |last6=Ramanujam |first6=B |last7=Chouhan |first7=MS |last8=Garg |first8=A |last9=Tripathi |first9=M |last10=Bal |first10=CS |last11=Sarkar |first11=C |last12=Dwivedi |first12=R |last13=Sapra |first13=S |last14=Tripathi |first14=M |title=Endoscope-assisted (with robotic guidance and using a hybrid technique) interhemispheric transcallosal hemispherotomy: a comparative study with open hemispherotomy to evaluate efficacy, complications, and outcome. |journal=Journal of Neurosurgery. Pediatrics |date=9 November 2018 |volume=23 |issue=2 |pages=187–197 |doi=10.3171/2018.8.PEDS18131 |pmid=30497135|s2cid=54167036 |doi-access=free }}</ref> More recently introduced techniques aim at minimizing tis surgical access by utilizing small burr holes to perform “endoscopic hemispherectomy” using either special endoscopic tools.<ref name="pmid30497135" /> or laser probes to perform the disconnection.<ref name="pmid33096521">{{cite journal |last1=Chua |first1=MMJ |last2=Bushlin |first2=I |last3=Stredny |first3=CM |last4=Madsen |first4=JR |last5=Patel |first5=AA |last6=Stone |first6=S |title=Magnetic resonance imaging-guided laser-induced thermal therapy for functional hemispherotomy in a child with refractory epilepsy and multiple medical comorbidities. |journal=Journal of Neurosurgery. Pediatrics |date=23 October 2020 |volume=27 |issue=1 |pages=30–35 |doi=10.3171/2020.6.PEDS20455 |pmid=33096521|s2cid=225057608 }}</ref> |
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''Functional hemispherectomy'' refers to surgeries that disable the function of one hemisphere, while maintaining its blood supply and without physically removing the entire hemisphere from the skull.<ref name=":3" /> Functional hemispherectomies are performed more frequently than anatomical hemispherectomies due to their lower complication rates.<ref name=":4">{{Cite journal |last1=Griessenauer |first1=Christoph J. |last2=Salam |first2=Smeer |last3=Hendrix |first3=Philipp |last4=Patel |first4=Daxa M. |last5=Tubbs |first5=R. Shane |last6=Blount |first6=Jeffrey P. |last7=Winkler |first7=Peter A. |date=January 2015 |title=Hemispherectomy for treatment of refractory epilepsy in the pediatric age group: a systematic review |url=https://thejns.org/view/journals/j-neurosurg-pediatr/15/1/article-p34.xml |journal=Journal of Neurosurgery: Pediatrics |volume=15 |issue=1 |pages=34–44 |doi=10.3171/2014.10.PEDS14155 |pmid=25380174 |issn=1933-0707}}</ref> However, they do carry a risk of incomplete disconnection, which refers to when the surgeon inadvertently leaves remnants of fibers that continue to connect the hemisphere to the brain and body. These remaining fibers can be problematic, as they may lead to seizure recurrence. |
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==Causes of hemispheric epilepsy== |
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There is a heterogeneous group of pathologies that could cause hemispheric epilepsy and these are typically divided into 3 groups.<ref name="pmid25380174" /> The first group is congenital pathologies which means that the patient is born with hemisphere that is malformed with abnormal cortex that is capable of seizing.<ref name="pmid23223541">{{cite journal |last1=Moosa |first1=AN |last2=Gupta |first2=A |last3=Jehi |first3=L |last4=Marashly |first4=A |last5=Cosmo |first5=G |last6=Lachhwani |first6=D |last7=Wyllie |first7=E |last8=Kotagal |first8=P |last9=Bingaman |first9=W |title=Longitudinal seizure outcome and prognostic predictors after hemispherectomy in 170 children. |journal=Neurology |date=15 January 2013 |volume=80 |issue=3 |pages=253–60 |doi=10.1212/WNL.0b013e31827dead9 |pmid=23223541|s2cid=12968652 }}</ref> Examples of such pathologies include focal cortical dysplasia, pending megaloencephaly, package area among others.<ref name="pmid23223541" /> The second group of etiologies is called acquired where an insult or an injury to one half of the brain is sustained early in life, usually around birth.<ref name="pmid23223541" /> Such etiologies include strokes that affect 1 hemisphere of the brain, hemorrhage (bleeding) or trauma.<ref name="pmid23223541" /> The third group is termed progressive etiologies and this group includes diseases that develop later in life with a protracted and progressive course.<ref name="pmid23223541" /> Such etiologies include Rasmussen's encephalitis, Sturge-Weber syndrome and hemispheric brain tumors.<ref name="pmid23223541" /> All these causes of hemispheric epilepsy have the common feature of a widespread pathology that is strictly or mostly restricted to one hemisphere.<ref name="pmid23223541" /> |
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Another term that falls under the hemispherectomy umbrella includes ''hemidecortication'', which is the removal of the cortex from one half of the cerebrum, while attempting to preserve the ventricular system by maintaining the surrounding white matter. Hemidecortication was originally developed as a possible strategy to mitigate some of the complications seen with complete anatomical hemispherectomy.<ref name=":3" /> |
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==Hemispherectomy workup and patient selection== |
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Patients who have drug-resistant focal epilepsy defined as failing 2 or more medications with seizures arising from 1 hemisphere of the brain qualify to be candidate for hemispherectomy.<ref name=":pmid10660394"/> To confirm this candidacy, a set of tests is required that usually includes electroencephalograph (EEG ), brain imaging in the form of brain magnetic resonance imaging (MRI ) and in certain cases further testing such as positron emission tomography (PET) and functional MRI (fMRI) are also required.<ref name="pmid31700611">{{cite journal |last1=Baumgartner |first1=C |last2=Koren |first2=JP |last3=Britto-Arias |first3=M |last4=Zoche |first4=L |last5=Pirker |first5=S |title=Presurgical epilepsy evaluation and epilepsy surgery. |journal=F1000Research |date=2019 |volume=8 |page=1818 |doi=10.12688/f1000research.17714.1 |pmid=31700611|pmc=6820825 }}</ref> The EEG shows the electrical signature of seizures. Brain MRI helps determine the presence of lesions and their exact location.<ref name="pmid23223541" /> PET scans help determine the level of metabolism of the brain where areas of the brain that produce seizures typically show a low level of metabolism.<ref name="pmid23223541" /> Functional MRI helps determine the presence of any functions based on alteration in the blood flow and response to certain tasks.<ref name="pmid23223541" /> It should be noted, however, that not all tests are required in order to make the determination whether hemispherectomy is applicable or not, rather there is a degree of variation between different patients.<ref name="pmid23223541" /> The determination of which kind of hemispherectomy procedure is most suitable for a patient depends on multiple factors including the kind of pathology that caused epilepsy, the anatomy of the brain, and the experience of the neurosurgeon.<ref name="pmid22480976" /><ref name="pmid28386922">{{cite journal |last1=Baumgartner |first1=JE |last2=Blount |first2=JP |last3=Blauwblomme |first3=T |last4=Chandra |first4=PS |title=Technical descriptions of four hemispherectomy approaches: From the Pediatric Epilepsy Surgery Meeting at Gothenburg 2014. |journal=Epilepsia |date=April 2017 |volume=58 Suppl 1 |pages=46–55 |doi=10.1111/epi.13679 |pmid=28386922|s2cid=275883 |doi-access=free }}</ref> However, anatomical hemispherectomy is almost never utilized anymore given the high rate of complications, rather variations of functional hemispherectomy are the mainstay of treatment.<ref name="pmid22480976" /><ref name="pmid28386922" /> |
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The term ''hemispherotomy'' refers to a surgery that is akin to a functional hemispherectomy in that it functionally severs the damaged hemisphere from the other and leaves some of the severed hemisphere within the skull, but the difference is that it removes even less tissue from the skull.<ref name=":3" /> The term hemispherotomy is now used as an umbrella term to describe the group of modern techniques and procedures that predominate at most contemporary epilepsy centers.<ref name=":4" /> |
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Hemispherectomy is arguably the most successful surgical procedure among all procedures used to treat epilepsy.<ref name="pmid25380174" /><ref name="pmid23223541" /> Regardless of the kind of hemispherectomy whether his anatomical or functional seizure freedom is achieved in 80-90% of patients.<ref name="pmid30780077">{{cite journal |last1=de Palma |first1=L |last2=Pietrafusa |first2=N |last3=Gozzo |first3=F |last4=Barba |first4=C |last5=Carfi-Pavia |first5=G |last6=Cossu |first6=M |last7=De Benedictis |first7=A |last8=Genitori |first8=L |last9=Giordano |first9=F |last10=Russo |first10=GL |last11=Marras |first11=CE |last12=Pelliccia |first12=V |last13=Rizzi |first13=S |last14=Rossi-Espagnet |first14=C |last15=Vigevano |first15=F |last16=Guerrini |first16=R |last17=Tassi |first17=L |last18=Specchio |first18=N |title=Outcome after hemispherotomy in patients with intractable epilepsy: Comparison of techniques in the Italian experience. |journal=Epilepsy & Behavior |date=April 2019 |volume=93 |pages=22–28 |doi=10.1016/j.yebeh.2019.01.006 |pmid=30780077|s2cid=73505960 }}</ref> A recent study compared to the different subtypes of functional hemispherectomy and found that they were all equally successful in treating seizures.<ref name="pmid28386922" /> |
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Furthermore, with advancements in surgical techniques, anesthesia and perioperative care, the risk of severe complications such as cerebral hemosiderosis and death have greatly diminished.<ref name="pmid33988937">{{cite journal |last1=Weil |first1=AG |last2=Fallah |first2=A |last3=Wang |first3=S |last4=Ibrahim |first4=GM |last5=Elkaim |first5=LM |last6=Jayakar |first6=P |last7=Miller |first7=I |last8=Bhatia |first8=S |last9=Niazi |first9=TN |last10=Ragheb |first10=J |title=Functional hemispherectomy: can preoperative imaging predict outcome? |journal=Journal of Neurosurgery. Pediatrics |date=1 June 2020 |volume=25 |issue=6 |pages=567–573 |doi=10.3171/2019.12.PEDS19370 |pmid=33988937|s2cid=216470321 |doi-access=free }}</ref> |
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The improvement after hemispherectomy is not limited to seizure control, as there is a comprehensive body of literature showing that early seizure control results in developmental and cognitive gains in most patients undergoing hemispherectomy.<ref name="pmid34537627"/> This is thought to be a result of removing the negative impact of seizures on the good hemisphere allowing it to "reorganize" its functions due to the plasticity of the brain.<ref name="pmid34537627" /> |
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The plasticity is most evident in young children where hemispherectomy is mostly utilized. In fact, it has been shown that the brain in the first few years of life is able to significantly recover major functions such as memory and language after hemispherectomy further supporting the notion that early surgery is strongly recommended when indicated and that it is not a last resort as frequently portrayed to be.<ref name="pmid28414105">{{cite journal |last1=Sebastianelli |first1=L |last2=Versace |first2=V |last3=Taylor |first3=A |last4=Brigo |first4=F |last5=Nothdurfter |first5=W |last6=Saltuari |first6=L |last7=Trinka |first7=E |last8=Nardone |first8=R |title=Functional reorganization after hemispherectomy in humans and animal models: What can we learn about the brain's resilience to extensive unilateral lesions? |journal=Brain Research Bulletin |date=May 2017 |volume=131 |pages=156–167 |doi=10.1016/j.brainresbull.2017.04.005 |pmid=28414105|s2cid=4728947 }}</ref> However, hemispherectomy can be used in virtually any age including adults with excellent outcomes.<ref name="pmid31677151">{{cite journal |last1=McGovern |first1=RA |last2=N V Moosa |first2=A |last3=Jehi |first3=L |last4=Busch |first4=R |last5=Ferguson |first5=L |last6=Gupta |first6=A |last7=Gonzalez-Martinez |first7=J |last8=Wyllie |first8=E |last9=Najm |first9=I |last10=Bingaman |first10=WE |title=Hemispherectomy in adults and adolescents: Seizure and functional outcomes in 47 patients. |journal=Epilepsia |date=December 2019 |volume=60 |issue=12 |pages=2416–2427 |doi=10.1111/epi.16378 |pmid=31677151|pmc=6911022 }}</ref> A recent study showed that even adults with hemispheric epilepsy can have excellent seizure and cognitive outcomes following hemispherectomy with seizure freedom in 77% of patients.<ref name="pmid31677151" /> |
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There is no statistically significant difference in seizure-free rates between the four different types of surgeries: Hemispherotomy, functional hemispherectomy, anatomical hemispherectomy and hemidecortication. The overall rate of seizure freedom is estimated to be 73.4%.<ref name=":4" /> However, hemispherotomy procedures may be associated with a more favorable complication profile.<ref name=":4" /> |
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== Results == |
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Overall, hemispherectomy is a successful procedure. A 1996 study of 52 individuals who underwent the surgery found that 96% of patients experienced reduced or completely ceased occurrence of seizures post-surgery.<ref>Carson, Benjamin S., MD, Sam Javedan P., John Freeman M., MD, Eileen Vining P.G., MD, Aaron Zuckerberg L., MD, Jeremy Lauer A., MS, and Michael Guarnieri, PhD. "Hemispherectomy: A Hemidecortication Approach And Review of 52 Cases." Journal of Neurosurgery 1996th ser. 84.June (n.d.): 903-11. Print.</ref> Studies have found no significant long-term effects on [[memory]], [[Personality psychology|personality]], or [[humor]],<ref>{{cite journal |doi=10.1542/peds.100.2.163 |title=Why Would You Remove Half a Brain? The Outcome of 58 Children After Hemispherectomy—The Johns Hopkins Experience: 1968 to 1996 |year=1997 |last1=Vining |first1=Eileen P. G. |last2=Freeman |first2=John M. |last3=Pillas |first3=Diana J. |last4=Uematsu |first4=Sumio |last5=Carson |first5=Benjamin S. |last6=Brandt |first6=Jason |last7=Boatman |first7=Dana |last8=Pulsifer |first8=Margaret B. |last9=Zuckerberg |first9=Aaron |journal=Pediatrics |volume=100 |issue=2 |pages=163–71 |pmid=9240794 |s2cid=6703956 |url=https://semanticscholar.org/paper/acfb80e68010a01fb2e841b00c4d9487344515ba }}</ref> and minimal changes in [[cognitive function]] overall.<ref>{{cite journal |doi=10.1111/j.0013-9580.2004.15303.x |title=The Cognitive Outcome of Hemispherectomy in 71 Children |year=2004 |last1=Pulsifer |first1=Margaret B. |last2=Brandt |first2=Jason |last3=Salorio |first3=Cynthia F. |last4=Vining |first4=Eileen P. G. |last5=Carson |first5=Benjamin S. |last6=Freeman |first6=John M. |journal=Epilepsia |volume=45 |issue=3 |pages=243–54 |pmid=15009226|s2cid=15894321 |doi-access=free }}</ref> For example, one case followed a patient who had completed college, attended graduate school and scored above average on intelligence tests after undergoing this procedure at age 5. This patient eventually developed "superior language and intellectual abilities" despite the removal of the left hemisphere, which contains the classical language zones.<ref>Smith, A and Sugar O. ''Development of above normal language and intelligence 21 years after left hemispherectomy''. [https://www.ncbi.nlm.nih.gov/pubmed/1172204] Neurology, 1975 September; 25(9):813-8.</ref> |
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== Candidates == |
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When resecting the left hemisphere, evidence indicates that some advanced language functions (''e.g.,'' higher order grammar) cannot be entirely assumed by the right side. The extent of advanced language loss is often dependent on the patient's age at the time of surgery.<ref>{{cite book |first1=Sophie |last1=Bayard |first2=Maryse |last2=Lassonde |chapter=Cognitive Sensory and Motor Adjustment to Hemispherectomy |chapter-url=https://books.google.com/books?id=PQDRThq4UeMC&pg=PA229 |pages=229–44 |year=2001 |editor1-first=Isabelle |editor1-last=Jambaqué |editor2-first=Maryse |editor2-last=Lassonde |editor3-first=Olivier |editor3-last=Dulac |title=Neuropsychology of Childhood Epilepsy |series=Advances in Behavioral Biology |volume=50 |issue=3 |isbn=978-0-306-47612-9}}</ref> One study following the cognitive development of two adolescent boys who had undergone hemispherectomy found that "brain plasticity and development arise, in part, from the brain's adaption of behavioral needs to fit available strengths and biases…The boy adapts the task to fit his brain more than he adapts his brain to fit the task."<ref>Coch, Donna, Kurt Fischer W., and Geraldine Dawson. "Dynamic Development of the Hemispheric Biases in Three Cases: Cognitive/Hemispheric Cycles, Music, and Hemispherectomy." Human Behavior, Learning, and the Developing Brain. New York: Guilford, 2007. 94–97. Print.</ref> Neuroplasticity after hemispherectomy does not imply complete regain of previous functioning, but rather the ability to adapt to the current abilities of the brain in such a way that the individual may still function, however different the new way of functioning may be.{{citation needed|date=July 2021}} |
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The typical candidates for hemispherectomy are pediatric patients who have intractable epilepsy due to extensive cerebral unilateral hemispheric injuries.<ref name=":5">{{Cite journal |last1=Fountas |first1=K. N. |last2=Smith |first2=J. R. |last3=Robinson |first3=J. S. |last4=Tamburrini |first4=G. |last5=Pietrini |first5=D. |last6=Di Rocco |first6=C. |date=August 2006 |title=Anatomical hemispherectomy |url=http://link.springer.com/10.1007/s00381-006-0135-2 |journal=Child's Nervous System |language=en |volume=22 |issue=8 |pages=982–991 |doi=10.1007/s00381-006-0135-2 |pmid=16810492 |s2cid=24948589 |issn=0256-7040}}</ref><ref name=":3" /> In addition, the seizures should ideally be emanating from that same hemisphere. In some situations, a hemispherectomy may still be performed if there are seizures from both hemispheres, as long as the majority come from one side. In order to assess the patient’s epilepsy completely, patients undergo extensive testing, including [[Electroencephalography|EEG]] and [[Magnetic resonance imaging|MRI]]. Most patients also undergo other studies including [[Functional magnetic resonance imaging|functional MRI (fMRI)]], [[Positron emission tomography|positron emission tomography (PET)]] or [[Magnetoencephalography|magnetoencephalography (MEG)]]. |
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Today, hemispherectomy is performed as a treatment for severe and intractable epilepsy, including for young children whose epilepsy has been found to be drug-resistant.<ref>{{Cite journal |last1=Tsou |first1=Amy Y. |last2=Kessler |first2=Sudha Kilaru |last3=Wu |first3=Mingche |last4=Abend |first4=Nicholas S. |last5=Massey |first5=Shavonne L. |last6=Treadwell |first6=Jonathan R. |date=2023-01-03 |title=Surgical Treatments for Epilepsies in Children Aged 1–36 Months: A Systematic Review |journal=Neurology |language=en |volume=100 |issue=1 |pages=e1–e15 |doi=10.1212/WNL.0000000000201012 |issn=0028-3878 |pmc=9827129 |pmid=36270898}}</ref> The most common underlying etiologies include malformations of cortical development (MCD), [[perinatal stroke]] and [[Rasmussen's encephalitis|Rasmussen’s encephalitis]].<ref name=":3" /> MCD is an umbrella term for a wide variety of developmental brain anomalies, including [[hemimegalencephaly]] and [[Focal cortical dysplasia|cortical dysplasia]]. Other less common underlying etiologies include hemiconvulsion-hemiplegia epilepsy syndrome and [[Sturge–Weber syndrome|Sturge-Weber syndrome]].<ref name=":4" /> |
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Christina Santhouse (now Paravecchia) underwent a Hemispherectomy on February 13, 1996, performed by [[Ben Carson]] when she was eight years old. Previously, she had had Rasmussen's encephalitis, which caused her to experience around 150 seizures a day. After the surgery, her family was told that she would never be able to do many normal activities, such as driving a car or holding a normal job. However, she far surpassed everyone's expectations by going on to earn a master's degree in speech pathology and by getting married and having children of her own.<ref>{{Cite web|url=https://www.inquirer.com/philly/news/local/20160214_20_years_after_surgery__a_full_life_with_half_a_brain.html|title = 20 years after surgery, a full life with half a brain}}</ref><ref>{{Cite web|url=https://apnews.com/d81263a495714dce90c15f1a13d9dafd|title=For brain surgery patient, greatest challenge is motherhood|website=[[Associated Press]]|date=18 May 2019}}</ref> |
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== Procedure == |
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==Traumatic hemispherectomy== |
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Patients often shave the area of the scalp that will be involved with the surgery. Patients undergo general [[anesthesia]] and are unconscious for the procedure. The surgical site is sterilized, after which the skin is incised. A substantial portion of the bone is removed, followed by incision of the [[Dura mater|dura]], which is the outer covering of the brain. There are several blood vessels that have connections with both sides of the brain, and these are carefully identified and clipped in such a way that spares the healthy hemisphere. Ultimately, a bundle of fibers that connect both of the cerebral hemispheres, the [[corpus callosum]], is removed which results in the functional separation of one hemisphere from the other. Portions of the cerebral lobes from the damaged side of the brain are removed, depending on the specific procedure being performed. The surgeon may leave some brain tissue, such as the [[thalamus]] or [[choroid plexus]]. After completing the resection, the surgical site is irrigated with saline, the brain covering called the dura is sutured back together, the bone that was removed is replaced and the skin is sutured. This surgery often takes four to five hours.<ref name=":5" /> Patients often spend a few nights in the hospital post-operatively, and they undergo physical and occupational therapy soon after the surgery.<ref name=":5" /> |
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There are cases where a person that received major trauma to one side of the brain, such as a gunshot wound, and has required a hemispherectomy and survived. The most notable case is that of [[Ahad Israfil]], who lost the right side of his cerebrum in 1987 in a gun-related work accident. He eventually regained most of his faculties, though he still required a wheelchair. It was noted that reconstructive surgery was difficult due to the gunshot shattering his skull, and he lived with a large indentation on that side of his head.{{citation needed|date=July 2021}} |
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== Potential complications == |
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The most common complication from surgery is [[hydrocephalus]], a condition in which fluid accumulates within the brain, and this is often treated with a shunt to divert the fluid away. The rate of shunts following surgery ranges from 14–23%.<ref name=":3" /> Other complications include wound complications, [[Epidural hematoma|epidural hemorrhages]], [[Subdural hematoma|subdural hemorrhages]], [[Intraparenchymal hemorrhage|intraparenchymal hemorrhages]], intracranial abscesses, [[meningitis]], [[ventriculitis]] and [[venous thrombosis]].<ref name=":4" /> Additional epilepsy surgery following hemispherectomy is rare (4.5%),<ref name=":4" /> but may be recommended if there is a residual connection between the two hemispheres that is causing frequent seizures. Mortality rates are low and estimated to be <1% to 2.2%.<ref name=":3" /><ref name=":4" /> Most patients do not experience changes in [[cognition]], but some individuals may be at risk.<ref name=":4" /> A visual deficit called contralateral homonymous hemianopsia is expected to occur in most patients, where the entire visual field contralateral to the removed hemisphere is lost.<ref name=":3" /> There is a risk of motor deficits, and this is variable.<ref name=":3" /> Other possible complications include [[infection]], [[aseptic meningitis]], [[hearing loss]], endocrine problems and transient neurologic deficits such as limb weakness.<ref name=":3" /> |
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| ⚫ | |||
Since seizures are the most common indication for hemispherectomy surgery, most research on hemispherectomy analyzes how the surgery affects seizures. Many patients undergoing surgery obtain good surgical outcomes, some obtaining complete seizure freedom (54–90%) and others having some degree of improvement in seizure burden.<ref name=":3" /><ref name=":4" /><ref name=":6">{{Cite journal |last1=Peacock |first1=Warwick J. |last2=Wehby-Grant |first2=Monica C. |last3=Shields |first3=W. Donald |last4=Shewmon |first4=D. Alan |last5=Chugani |first5=Harry T. |last6=Sankar |first6=Raman |last7=Vinters |first7=Harry V. |date=July 1996 |title=Hemispherectomy for intractable seizures in children: a report of 58 cases |url=http://link.springer.com/10.1007/BF00395089 |journal=Child's Nervous System |language=en |volume=12 |issue=7 |pages=376–384 |doi=10.1007/BF00395089 |pmid=8869773 |s2cid=16491901 |issn=0256-7040}}</ref><ref name=":7">{{Cite journal |last1=Weil |first1=Alexander G. |last2=Lewis |first2=Evan C. |last3=Ibrahim |first3=George M. |last4=Kola |first4=Olivia |last5=Tseng |first5=Chi-Hong |last6=Zhou |first6=Xinkai |last7=Lin |first7=Kao-Min |last8=Cai |first8=Li-Xin |last9=Liu |first9=Qing-Zhu |last10=Lin |first10=Jiu-Luan |last11=Zhou |first11=Wen-Jing |last12=Mathern |first12=Gary W. |last13=Smyth |first13=Matthew D. |last14=O'Neill |first14=Brent R. |last15=Dudley |first15=Roy |date=May 2021 |title=Hemispherectomy Outcome Prediction Scale: Development and validation of a seizure freedom prediction tool |url=https://onlinelibrary.wiley.com/doi/10.1111/epi.16861 |journal=Epilepsia |language=en |volume=62 |issue=5 |pages=1064–1073 |doi=10.1111/epi.16861 |pmid=33713438 |s2cid=232222766 |issn=0013-9580}}</ref> A recently developed scoring system has been proposed to help predict the probability of seizure freedom with more accuracy: HOPS (Hemispherectomy Outcome Prediction Scale).<ref name=":7" /> Although it cannot definitively predict surgical outcome with exact precision, some physicians may use it as a guide. The scoring system takes certain variables into consideration including age at seizure onset, history of prior brain surgery, seizure semiology and imaging findings. |
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There is also data pertaining to how hemispherectomy affects the body in other ways. After surgery, the remaining cerebral hemisphere is often able to take over some cognitive, sensory and motor functions. The degree to which the remaining hemisphere takes on this additional workload often depends on several factors, including the underlying etiology, which hemisphere is removed and the age at which the surgery occurs.<ref name=":8">{{Cite journal |last1=Ivanova |first1=Anna |last2=Zaidel |first2=Eran |last3=Salamon |first3=Noriko |last4=Bookheimer |first4=Susan |last5=Uddin |first5=Lucina Q. |last6=de Bode |first6=Stella |date=November 2017 |title=Intrinsic functional organization of putative language networks in the brain following left cerebral hemispherectomy |journal=Brain Structure and Function |language=en |volume=222 |issue=8 |pages=3795–3805 |doi=10.1007/s00429-017-1434-y |issn=1863-2653 |pmc=6032986 |pmid=28470553}}</ref> |
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In terms of postoperative motor function, some patients may have improvement or no change of their weaker extremity,<ref name=":6" /> and many can walk independently.<ref name=":8" /> Most patients postoperatively have minimal to no behavioral problems, satisfactory language skills, good reading capability,<ref name=":8" /> and only a minority of patients have a decline in [[Intelligence quotient|IQ]].<ref>{{Cite journal |last1=Pulsifer |first1=Margaret B. |last2=Brandt |first2=Jason |last3=Salorio |first3=Cynthia F. |last4=Vining |first4=Eileen P. G. |last5=Carson |first5=Benjamin S. |last6=Freeman |first6=John M. |date=March 2004 |title=The Cognitive Outcome of Hemispherectomy in 71 Children |url=https://onlinelibrary.wiley.com/doi/10.1111/j.0013-9580.2004.15303.x |journal=Epilepsia |language=en |volume=45 |issue=3 |pages=243–254 |doi=10.1111/j.0013-9580.2004.15303.x |pmid=15009226 |s2cid=15894321 |issn=0013-9580}}</ref> Predictors of poor outcome may include seizure recurrence and structural abnormalities in the intact hemisphere.<ref name=":8" /> |
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Ultimately, risks and benefits should be weighed on an individual basis and discussed in detail with the neurosurgeon. Many patients have excellent outcomes, and the International League Against Epilepsy (ILAE) reports that “about one-fifth of hemispherectomy patients are gainfully employed and even fewer live independently.”<ref name=":9">{{Cite web |title=The Brain Recovery Project Focuses On Research And Resources After Pediatric Epilepsy Surgery // International League Against Epilepsy |url=https://www.ilae.org/journals/epigraph/epigraph-vol-18-issue-2-fall-2016/the-brain-recovery-project-focuses-on-research-and-resources-after-pediatric-epilepsy-surgery |access-date=2024-02-08 |website=www.ilae.org}}</ref> |
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== The Brain Recovery Project == |
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The Brain Recovery Project is a non-profit corporation which funds new research and is based in the [[United States]]. This corporation hosts an annual two-day conference for patients who have had hemispherectomies and their families. There are several purposes to this reunion. The main goal is to educate patients and their families on the surgery and its necessary subsequent rehabilitation. It also serves as a way for patients and families to connect with one another, learn from specialists in the field and often offers research enrollment.<ref name=":9" /> |
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== See also == |
== See also == |
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Latest revision as of 00:37, 31 August 2024
| Hemispherectomy | |
|---|---|
| ICD-9-CM | 01.52 |
| MeSH | D038421 |
Hemispherectomy is a surgery that is performed by a neurosurgeon where an unhealthy hemisphere of the brain is disconnected or removed. There are two types of hemispherectomy. Functional hemispherectomy refers to when the diseased brain is simply disconnected so that it can no longer send signals to the rest of the brain and body. Anatomical hemispherectomy refers to when not only is there disconnection, but also the diseased brain is physically removed from the skull. This surgery is mostly used as a treatment for medically intractable epilepsy, which is the term used when anti-seizure medications are unable to control seizures.
History
[edit]The first anatomical hemispherectomy was performed and described in 1928 by Walter Dandy. This was done as an attempt to treat glioma, a brain tumor.[1] The first known anatomical hemispherectomy performed as a treatment for intractable epilepsy was in 1938 by Kenneth McKenzie, a Canadian neurosurgeon.[2] Krynaw, a neurosurgeon from South Africa, was one of the first to perform and report a case series on hemispherectomies in 1950. He performed the surgery on pediatric patients with infantile hemiplegia, specifically as a treatment for their seizures and cognitive impairment.[3] His hemispherectomy technique removed the damaged hemisphere except the thalamus and caudate structures. Krynaw reported good outcomes overall, although there was one post-operative death. Specifically, there was an overall theme of improvement in weakness, spasticity and cognition.[3] Amazingly, ten out of the twelve patients had seizures prior to the operation and none of the patients had seizures afterwards.[3] Other neurosurgeons began performing hemispherectomies as well, primarily for the treatment of seizures. For the most part, the surgeries would go well initially, but there was a general theme of subsequent deterioration and even death years after the surgery. As a result of the complication risk and the introduction of new anti-seizure medications, the popularity of the procedure began to decline in the 1950s.[4] Oppenheimer and Griffith were one of the first to describe the potential complications, and they reported their findings in 1966, describing superficial hemosiderosis, granular ependymitis and obstructive hydrocephalus.[5] They posited a theoretical solution to this problem, a surgery that is now known as a functional hemispherectomy.[5] Rasmussen was one of the first neurosurgeons to develop and apply a functional hemispherectomy in practice. He initially made modifications to the original hemispherectomy by preserving the least epileptogenic quarter or third of the hemisphere, hoping this would ameliorate the known complications of the original anatomic hemispherectomy. Although this modification seemed to solve this issue, patients undergoing the modified hemispherectomy continued to have seizures, which was problematic. Therefore, he further modified his surgery to functionally sever residual portions of the frontal and parieto-occipital lobes.[4] This surgery, the functional hemispherectomy, has been further modified over the years by several different neurosurgeons, and to this day there is not a consensus as to which exact technique should be used. Hemispherotomy refers to some of the more recently developed approaches to disconnect the epileptic hemisphere while minimizing brain removal and the risk for complications.[6]
Nomenclature
[edit]There are two main types of hemispherectomy: Anatomical and Functional.
Anatomical hemispherectomy refers to the resection and removal of an entire hemisphere of the brain, which includes all four lobes, with or without the removal of basal ganglia and thalamus.[6]
Functional hemispherectomy refers to surgeries that disable the function of one hemisphere, while maintaining its blood supply and without physically removing the entire hemisphere from the skull.[6] Functional hemispherectomies are performed more frequently than anatomical hemispherectomies due to their lower complication rates.[7] However, they do carry a risk of incomplete disconnection, which refers to when the surgeon inadvertently leaves remnants of fibers that continue to connect the hemisphere to the brain and body. These remaining fibers can be problematic, as they may lead to seizure recurrence.
Another term that falls under the hemispherectomy umbrella includes hemidecortication, which is the removal of the cortex from one half of the cerebrum, while attempting to preserve the ventricular system by maintaining the surrounding white matter. Hemidecortication was originally developed as a possible strategy to mitigate some of the complications seen with complete anatomical hemispherectomy.[6]
The term hemispherotomy refers to a surgery that is akin to a functional hemispherectomy in that it functionally severs the damaged hemisphere from the other and leaves some of the severed hemisphere within the skull, but the difference is that it removes even less tissue from the skull.[6] The term hemispherotomy is now used as an umbrella term to describe the group of modern techniques and procedures that predominate at most contemporary epilepsy centers.[7]
There is no statistically significant difference in seizure-free rates between the four different types of surgeries: Hemispherotomy, functional hemispherectomy, anatomical hemispherectomy and hemidecortication. The overall rate of seizure freedom is estimated to be 73.4%.[7] However, hemispherotomy procedures may be associated with a more favorable complication profile.[7]
Candidates
[edit]The typical candidates for hemispherectomy are pediatric patients who have intractable epilepsy due to extensive cerebral unilateral hemispheric injuries.[8][6] In addition, the seizures should ideally be emanating from that same hemisphere. In some situations, a hemispherectomy may still be performed if there are seizures from both hemispheres, as long as the majority come from one side. In order to assess the patient’s epilepsy completely, patients undergo extensive testing, including EEG and MRI. Most patients also undergo other studies including functional MRI (fMRI), positron emission tomography (PET) or magnetoencephalography (MEG).
Today, hemispherectomy is performed as a treatment for severe and intractable epilepsy, including for young children whose epilepsy has been found to be drug-resistant.[9] The most common underlying etiologies include malformations of cortical development (MCD), perinatal stroke and Rasmussen’s encephalitis.[6] MCD is an umbrella term for a wide variety of developmental brain anomalies, including hemimegalencephaly and cortical dysplasia. Other less common underlying etiologies include hemiconvulsion-hemiplegia epilepsy syndrome and Sturge-Weber syndrome.[7]
Procedure
[edit]Patients often shave the area of the scalp that will be involved with the surgery. Patients undergo general anesthesia and are unconscious for the procedure. The surgical site is sterilized, after which the skin is incised. A substantial portion of the bone is removed, followed by incision of the dura, which is the outer covering of the brain. There are several blood vessels that have connections with both sides of the brain, and these are carefully identified and clipped in such a way that spares the healthy hemisphere. Ultimately, a bundle of fibers that connect both of the cerebral hemispheres, the corpus callosum, is removed which results in the functional separation of one hemisphere from the other. Portions of the cerebral lobes from the damaged side of the brain are removed, depending on the specific procedure being performed. The surgeon may leave some brain tissue, such as the thalamus or choroid plexus. After completing the resection, the surgical site is irrigated with saline, the brain covering called the dura is sutured back together, the bone that was removed is replaced and the skin is sutured. This surgery often takes four to five hours.[8] Patients often spend a few nights in the hospital post-operatively, and they undergo physical and occupational therapy soon after the surgery.[8]
Potential complications
[edit]The most common complication from surgery is hydrocephalus, a condition in which fluid accumulates within the brain, and this is often treated with a shunt to divert the fluid away. The rate of shunts following surgery ranges from 14–23%.[6] Other complications include wound complications, epidural hemorrhages, subdural hemorrhages, intraparenchymal hemorrhages, intracranial abscesses, meningitis, ventriculitis and venous thrombosis.[7] Additional epilepsy surgery following hemispherectomy is rare (4.5%),[7] but may be recommended if there is a residual connection between the two hemispheres that is causing frequent seizures. Mortality rates are low and estimated to be <1% to 2.2%.[6][7] Most patients do not experience changes in cognition, but some individuals may be at risk.[7] A visual deficit called contralateral homonymous hemianopsia is expected to occur in most patients, where the entire visual field contralateral to the removed hemisphere is lost.[6] There is a risk of motor deficits, and this is variable.[6] Other possible complications include infection, aseptic meningitis, hearing loss, endocrine problems and transient neurologic deficits such as limb weakness.[6]
Outcomes
[edit]Since seizures are the most common indication for hemispherectomy surgery, most research on hemispherectomy analyzes how the surgery affects seizures. Many patients undergoing surgery obtain good surgical outcomes, some obtaining complete seizure freedom (54–90%) and others having some degree of improvement in seizure burden.[6][7][10][11] A recently developed scoring system has been proposed to help predict the probability of seizure freedom with more accuracy: HOPS (Hemispherectomy Outcome Prediction Scale).[11] Although it cannot definitively predict surgical outcome with exact precision, some physicians may use it as a guide. The scoring system takes certain variables into consideration including age at seizure onset, history of prior brain surgery, seizure semiology and imaging findings.
There is also data pertaining to how hemispherectomy affects the body in other ways. After surgery, the remaining cerebral hemisphere is often able to take over some cognitive, sensory and motor functions. The degree to which the remaining hemisphere takes on this additional workload often depends on several factors, including the underlying etiology, which hemisphere is removed and the age at which the surgery occurs.[12]
In terms of postoperative motor function, some patients may have improvement or no change of their weaker extremity,[10] and many can walk independently.[12] Most patients postoperatively have minimal to no behavioral problems, satisfactory language skills, good reading capability,[12] and only a minority of patients have a decline in IQ.[13] Predictors of poor outcome may include seizure recurrence and structural abnormalities in the intact hemisphere.[12]
Ultimately, risks and benefits should be weighed on an individual basis and discussed in detail with the neurosurgeon. Many patients have excellent outcomes, and the International League Against Epilepsy (ILAE) reports that “about one-fifth of hemispherectomy patients are gainfully employed and even fewer live independently.”[14]
The Brain Recovery Project
[edit]The Brain Recovery Project is a non-profit corporation which funds new research and is based in the United States. This corporation hosts an annual two-day conference for patients who have had hemispherectomies and their families. There are several purposes to this reunion. The main goal is to educate patients and their families on the surgery and its necessary subsequent rehabilitation. It also serves as a way for patients and families to connect with one another, learn from specialists in the field and often offers research enrollment.[14]
See also
[edit]References
[edit]- ^ Dandy, Walter E. (1928-03-17). "REMOVAL OF RIGHT CEREBRAL HEMISPHERE FOR CERTAIN TUMORS WITH HEMIPLEGIA: PRELIMINARY REPORT". Journal of the American Medical Association. 90 (11): 823. doi:10.1001/jama.1928.02690380007003. ISSN 0002-9955.
- ^ McKenzie, KG (1938). "The present status of a patient who had the right cerebral hemisphere removed". JAMA. 111: 168–183.
- ^ a b c Krynauw, R. A. (1950-11-01). "Infantile Hemiplegia Treated by Removing One Cerebral Hemisphere". Journal of Neurology, Neurosurgery & Psychiatry. 13 (4): 243–267. doi:10.1136/jnnp.13.4.243. ISSN 0022-3050. PMC 498647. PMID 14795238.
- ^ a b Rasmussen, Theodore (May 1983). "Hemispherectomy for Seizures Revisited". Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques. 10 (2): 71–78. doi:10.1017/S0317167100044668. ISSN 0317-1671. PMID 6861011.
- ^ a b Oppenheimer, D R; Griffith, H B (1966-06-01). "Persistent intracranial bleeding as a complication of hemispherectomy". Journal of Neurology, Neurosurgery & Psychiatry. 29 (3): 229–240. doi:10.1136/jnnp.29.3.229. ISSN 0022-3050. PMC 496024. PMID 5937637.
- ^ a b c d e f g h i j k l m Lew, Sean M. (July 2014). "Hemispherectomy in the treatment of seizures: a review". Translational Pediatrics. 3 (3): 20817–20217. doi:10.3978/j.issn.2224-4336.2014.04.01. ISSN 2224-4344. PMC 4729844. PMID 26835338.
- ^ a b c d e f g h i j Griessenauer, Christoph J.; Salam, Smeer; Hendrix, Philipp; Patel, Daxa M.; Tubbs, R. Shane; Blount, Jeffrey P.; Winkler, Peter A. (January 2015). "Hemispherectomy for treatment of refractory epilepsy in the pediatric age group: a systematic review". Journal of Neurosurgery: Pediatrics. 15 (1): 34–44. doi:10.3171/2014.10.PEDS14155. ISSN 1933-0707. PMID 25380174.
- ^ a b c Fountas, K. N.; Smith, J. R.; Robinson, J. S.; Tamburrini, G.; Pietrini, D.; Di Rocco, C. (August 2006). "Anatomical hemispherectomy". Child's Nervous System. 22 (8): 982–991. doi:10.1007/s00381-006-0135-2. ISSN 0256-7040. PMID 16810492. S2CID 24948589.
- ^ Tsou, Amy Y.; Kessler, Sudha Kilaru; Wu, Mingche; Abend, Nicholas S.; Massey, Shavonne L.; Treadwell, Jonathan R. (2023-01-03). "Surgical Treatments for Epilepsies in Children Aged 1–36 Months: A Systematic Review". Neurology. 100 (1): e1–e15. doi:10.1212/WNL.0000000000201012. ISSN 0028-3878. PMC 9827129. PMID 36270898.
- ^ a b Peacock, Warwick J.; Wehby-Grant, Monica C.; Shields, W. Donald; Shewmon, D. Alan; Chugani, Harry T.; Sankar, Raman; Vinters, Harry V. (July 1996). "Hemispherectomy for intractable seizures in children: a report of 58 cases". Child's Nervous System. 12 (7): 376–384. doi:10.1007/BF00395089. ISSN 0256-7040. PMID 8869773. S2CID 16491901.
- ^ a b Weil, Alexander G.; Lewis, Evan C.; Ibrahim, George M.; Kola, Olivia; Tseng, Chi-Hong; Zhou, Xinkai; Lin, Kao-Min; Cai, Li-Xin; Liu, Qing-Zhu; Lin, Jiu-Luan; Zhou, Wen-Jing; Mathern, Gary W.; Smyth, Matthew D.; O'Neill, Brent R.; Dudley, Roy (May 2021). "Hemispherectomy Outcome Prediction Scale: Development and validation of a seizure freedom prediction tool". Epilepsia. 62 (5): 1064–1073. doi:10.1111/epi.16861. ISSN 0013-9580. PMID 33713438. S2CID 232222766.
- ^ a b c d Ivanova, Anna; Zaidel, Eran; Salamon, Noriko; Bookheimer, Susan; Uddin, Lucina Q.; de Bode, Stella (November 2017). "Intrinsic functional organization of putative language networks in the brain following left cerebral hemispherectomy". Brain Structure and Function. 222 (8): 3795–3805. doi:10.1007/s00429-017-1434-y. ISSN 1863-2653. PMC 6032986. PMID 28470553.
- ^ Pulsifer, Margaret B.; Brandt, Jason; Salorio, Cynthia F.; Vining, Eileen P. G.; Carson, Benjamin S.; Freeman, John M. (March 2004). "The Cognitive Outcome of Hemispherectomy in 71 Children". Epilepsia. 45 (3): 243–254. doi:10.1111/j.0013-9580.2004.15303.x. ISSN 0013-9580. PMID 15009226. S2CID 15894321.
- ^ a b "The Brain Recovery Project Focuses On Research And Resources After Pediatric Epilepsy Surgery // International League Against Epilepsy". www.ilae.org. Retrieved 2024-02-08.
Further reading
[edit]- Battro, Antonio M. (2001). Half a Brain is Enough: The Story of Nico. Cambridge University Press. ISBN 978-0-521-78307-1.
- Kenneally, Christine (July 3, 2006). "The Deepest Cut". The New Yorker. pp. 36–42.
- Choi, Charles Q. (March 2008). "Do You Need Only Half Your Brain?". Scientific American. 298 (3): 104. Bibcode:2008SciAm.298c.104C. doi:10.1038/scientificamerican0308-104.
External links
[edit]- The Deepest Cut by Christine Kenneally, The New Yorker