Hemispherectomy

Hemispherectomy
Intervention
ICD-9-CM	01.52
MeSH	D038421
[]

Hemispherectomy is a very rare surgical procedure in which one cerebral hemisphere (half of the brain) is removed, disconnected, or disabled. This procedure is used to treat a variety of seizure disorders where the source of the epilepsy is localized to a broad area of a single hemisphere of the brain, notably Rasmussen's encephalitis. About one in three patients with epilepsy will continue to have persistent seizures despite epileptic drug therapy. Hemispherectomy is reserved for the most extreme cases of this one-third in which the individual’s seizures are irresponsive to medications or other less invasive surgeries and significantly impair functioning or put the patient at risk of further complications. The procedure successfully cures seizures in about 85%-90% of patients. Additionally, it is also known to often markedly improve the cognitive functioning and development of the individual.

Hemispherectomy was first performed on a dog in 1888 by Friedrich Goltz. The first such operation on humans was done by Walter Dandy in 1928 for glioblastoma multiforme. Hemispherectomy was revitalized in children in the 1980s by John M. Freeman and Ben Carson at Johns Hopkins Hospital.

In the 1960s and early 1970s, hemispherectomy involved essentially removing an entire half of the brain. This procedure is known as anatomical hemispherectomy. Anatomical hemispherectomy decreases the likelihood that seizures will return, as there is no longer any part of the identified epileptic brain area left to cause seizures. A second type of hemispherectomy, known as functional hemispherectomy, has become more prevalent in recent years. In this procedure, only the epileptic portions of that side of the brain are removed, as opposed to the entire hemisphere. If a functional hemispherectomy is chosen over an anatomical hemispherectomy, it is likely because it allows for less blood loss and greater chance of resilience for the patient. Additionally, functional hemispherectomy is less likely to cause hydrocephalus, the “excessive accumulation of (cerebrospinal) fluid in the brain,” which leads to complications from harmful pressure on brain tissues.

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