Hemispherectomy

Hemispherectomy; GA 1.7
Topic Started: Aug 9 2008, 12:00 PM (88 Views)
Carter	Aug 9 2008, 12:00 PM Post #1
O'Malley Forever Posts: 5,361 Group: Admin Member #1 Joined: August 2, 2008 Favorite Character George O'Malley Favorite Couple Callie & Arizona	Now I'm not exactly sure of this one but its from the episode where the anetheisest is drunk and george calls him out on it. I think its the case of the case of the little girl who's leg wont stop twitching. Hemispherectomy is the surgical removal or disconnection of one side of the brain from the other. This procedure is performed on a subset of epilepsy patients - those with medically intractable epilepsy arising from one side of the brain that lacks normal function. Typically they have long-standing hemiparesis of the contralateral body, which causes them to walk by circumducting the hip rather than with a normal leg swing. If the injury to one side of the brain occurs during infancy, patients can develop infantile hemiplegia-hemiatrophy with the contralateral side being smaller and weaker than the normal side. Hemispherectomy also is performed on patients who have hemimegalencephaly, Sturge-Weber or Rasmussen's encephalitis. The physical examination and magnetic resonance imaging scan of the brain are virtually diagnostic of patients who are eligible for hemispherectomy. It is usually quite difficult to localize the seizure onset to a specific area of the bad hemisphere on scalp EEG. It is important to make sure the patient is having true epilepsy rather than pseudoseizures, and to make sure that the seizures do arise from somewhere in the bad hemisphere. The seizure patterns (semiology) in these patients usually are not well localizable. Focal motor seizures, hemiconvulsions, drop attacks, generalized seizures or complex partial seizures may be present alone or in combination. Hemispherectomy leads to seizure control in about 80 percent of patients. Half need to remain on their medications indefinitely; the other half can slowly be tapered off of their seizure drugs after being seizure-free for 12 months. Twenty to 30 years ago, hemispherectomy involved removing half of the brain completely. However, early enthusiasm for this operation was replaced by skepticism due to progressive neurologic deficits caused by superficial cerebral hemosiderosis. This complication most likely was due to small recurrent hemorrhages into the large surgical cavity associated with minor trauma and from lack of support for the remaining hemisphere. To limit the area of removal, multi-lobar resections, subtotal hemispherectomies and hemisphercortisectomies were performed instead. Although these procedures reduced the superficial hemosiderosis, they resulted in less seizure control, probably because seizures continue to arise from residual portions of the damaged hemisphere. To duplicate the good results of the complete hemispherectomy while avoiding cerebral hemosiderosis, several modifications have been devised. Currently the most common operation performed is the functional hemispherectomy. In this operation, the temporal lobe is removed, corpus callosotomy is performed, and the frontal and occipital lobes are disconnected. The blood supply to the remaining brain is left intact; hence, the skull remains filled on the side of the operation rather than being left with a large cavity. The risks of this type of operation include persistent seizures, hemorrhage, anesthesia, infection and damage to the functioning cerebral hemisphere. Because a large area of the brain is exposed and large disconnections are made through the gray and white matter over the frontal occipital lobes, as well as during the temporal lobectomy and corpus callosotomy, these patients are at increased risk of intraoperative DIC (disseminated intravascular coagulation). Because of this, coagulation parameters must be watched carefully throughout the operative procedure. Typically, patients remain in the intensive care unit for one to two days postoperatively and are then transferred to the floor for two to three days before discharge. Many patients experience a transient decrease in contralateral muscle tone (i.e. they are less spastic) after the operation. This typically lasts two to four weeks. When this occurs, patients report that their bad side is "weaker" because they are less able to use functioning proximal musculature to swing a hypotonic extremity. As spasticity returns, the patient feels "stronger" again. In summary, functional hemispherectomy provides a relatively safe surgical procedure for patients who have a damaged cerebral hemisphere producing medically intractable epilepsy. Modifications of the original hemispherectomy procedure have led to lower morbidity while also maintaining a high chance of becoming seizure-free. for more information visit http://www.epilepsy.com/epilepsy/hemispherectomy.html Credit: Sara (mcobsessed)



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