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PubMed1988

Functional hemispherectomy for treatment of epilepsy associated with hemiplegia: rationale, indications, results, and comparison with callosotomy.

Hemispherectomy is effective in arresting seizures associated with maximal or near maximal hemiparesis. This procedure, however, carries an unacceptable 33% risk of late complications due to cerebral hemosiderosis. Anatomically partial but functionally complete hemispherectomy was devised to avoid these complications. The frontal or occipital lobes, or both, were left in place with the blood supply intact but with connections to commissures and brainstem divided. The central strip and parietal and temporal lobes were removed. Twenty patients were so treated with a follow-up of 4 to 13 years (average, 7.3 years) in 14. Ten of these are seizure free, 1 had a single nocturnal seizure, 1 had occasional focal twitching, and 2 had a worthwhile but lesser reduction in the seizure tendency. None has developed cerebral hemosiderosis, to date. In appropriately selected patients, functional hemispherectomy is an effective procedure preferable to callosotomy or to partial hemispherectomy. When there is no independent ictal discharge from the opposite hemisphere, arrest of seizures may be expected, leading to improvement in cognitive functioning (mean increase, 10 IQ points), social behavior, and a reduction in or discontinuation of anticonvulsant medication. In these patients, gait and hand use remain unchanged.

Adolescent↗
PubMed1995

EEG prior to hemispherectomy: correlation with outcome and pathology.

Hemispherectomy, for the treatment of seizures, is highly successful but has a significant morbidity rate. The procedure is usually restricted to patients with an intractable seizure disorder and hemiparesis. Because of the inherent risk of surgery, patient selection is a critical issue. This report describes the evaluation of background activity and ictal patterns on surface and invasive EEG in 12 children who underwent both anatomical (7) and functional (5) hemispherectomy in order to determine the role of electroencephalography in the selection of patients for hemispherectomy, and to correlate EEG findings with underlying pathology and outcome. A favorable outcome was predicted by an interictal EEG with two or more of the following: suppression over the abnormal hemisphere, absence of contralateral slowing, absence of generalized discharges and absence of bilateral independent spiking; or by unilateral onset of ictal discharges on invasive intracerebral EEG recording. Outcome did not correlate with the underlying pathology. Hemispherectomy can be successful in patients with a variety of predominantly unilateral pathologic entities.

Brain↗
PubMed1996

Phonological dyslexia and phonological dysgraphia following left and right hemispherectomy.

Four adults who had hemispherectomies because of severe epilepsy following infantile of childhood damage to one hemisphere of the brain, are assessed on their reading and spelling abilities in an attempt to see if the two hemispheres are equipotential for these abilities in infancy. The psycholinguistic assessments of language processing in aphasia (PALPA) are used, and the results are interpreted from the viewpoint of hypotheses of "normal" right and left hemisphere reading abilities. Overall, the results suggest that the two hemispheres are equipotential at infancy for developing the skills underlying reading, but the left hemisphere is more specialized for the skills underlying spelling. All participants could read learnt regular and irregular words, and abstract and concrete words, suggesting that the reading lexicon develops in line with a normal left hemisphere lexicon, whichever hemisphere remains intact following hemispherectomy. However, poor reading of non-words suggests that the phonological reading route is severely impaired following left hemispherectomy (phonological dyslexia), and somewhat impaired following right hemispherectomy. The right-hemispherectomized participant is only mildly impaired on spelling real words, in contrast to the left-hemispherectomized participants who are markedly impaired. None of the participants could spell non-words, suggesting that the phonological spelling route is impaired following removal of either hemisphere (phonological dysgraphia).

Adult↗
PubMed1999

The significance of bilateral EEG abnormalities before and after hemispherectomy in children with unilateral major hemisphere lesions.

The rate of seizure relief following hemispherectomy varies between 50 and more than 80%. There has been particular debate concerning the significance of bilateral electroencephalography (EEG) abnormalities in influencing prognosis. This study was set out to determine the frequency of bilateral EEG abnormalities and their relationship to underlying pathology and outcome. We investigated 28 children with unilateral hemisphere lesions, who underwent hemispherectomy. Interictal and ictal EEGs before and after hemispherectomy were reviewed. Post-operative outcome with respect to seizures was noted. Bilateral EEG abnormalities were seen in 75%, but were more common in children with malformations of cortical development than in patients with acquired cerebral lesions, and were found more often in interictal than in ictal records. Post-operative EEG abnormalities were variable and did not consistently predict outcome. Short-term outcome was similar, irrespective of aetiology. With longer term follow-up, only 47% of children with developmental abnormalities were still seizure-free in contrast to 77% of children with acquired abnormalities. Although the incidence of bilateral EEG abnormalities in patients with major unilateral hemisphere lesions is high, these findings alone should not preclude further consideration for hemispherectomy. Our findings emphasise that the aetiology of the lesion plays a major role in determining outcome.

Adolescent↗
PubMed1999

Histopathologic findings in 37 cases of functional hemispherectomy.

Hemispherectomy procedures are performed in patients for whom focal cortical resection would be predicted to produce a significant reduction in seizures. The functional hemispherectomy procedure consists of disconnecting the hemispheres while attempting, in some cases, to preserve parenchyma. This study retrospectively reviews the histopathologic findings in 37 cases of functional hemispherectomy performed between 1990 and 1998 at a major epilepsy center. Procedures were performed in 20 males and 17 females who ranged in age from 3 months to 37 years (mean age, 9.6 years). In all but two cases, more than half or all the material submitted for pathologic testing was examined histologically. Cortical dysplasias or hemimegalencephaly were identified in 14 patients. The most common patterns of dysplasia observed included architectural disorganization (n = 13), increased molecular layer neurons (n = 11), and neuronal cytomegaly (n = 11). One patient was known to have epidermal nevus syndrome. Six patients had Sturge-Weber syndrome. Remote infarct/ischemic damage was identified as the etiology of seizures in six patients; four of these patients had mild associated secondary cortical architectural abnormalities. Three patients demonstrated pathology consistent with Rasmussen's encephalitis; one additional patient had chronic encephalitis changes, not otherwise specified. In two cases, changes consistent with hippocampal sclerosis were identified; additionally, hippocampal neuronal loss and gliosis was focally identified in three patients. Most of these patients had coexistent cortical dysplasia or radiographic evidence of remote infarct. One specimen demonstrated areas of infarct following resection of an arteriovenous malformation. In two specimens, significant histopathologic findings were not identified; both of these patients had radiographic evidence of remote infarct. The spectrum of pathologic conditions that may be encountered in the setting of a functional hemispherectomy is varied and in this study most frequently included cortical dysplasia, Sturge-Weber syndrome remote infarct, and Rasmussen's encephalitis.

Adolescent↗
PubMed2001

Pattern electroretinograms after cerebral hemispherectomy.

Cortically blind patients with brain damage restricted to the optic radiations or primary visual cortex may be able to detect and discriminate visual stimuli presented in their field defects, even though they deny seeing them. In contrast, patients who are hemianopic as a result of cerebral hemispherectomy cannot explicitly discriminate visual stimuli in their field defects, even when forced choice procedures are used. A possible explanation for this difference is that retrograde, transneuronal degeneration of the retina, which affects approximately 85% of wavelength-sensitive ganglion cells (approximately 70% of the total) after damage restricted to striate cortex, could be far more extensive after hemispherectomy, rendering the retina incapable of processing and conveying visual information to the brain. To test this, we assessed retinal ganglion cell function by means of electroretinography in three patients with cerebral hemispherectomy who were functionally blind. Steady-state pattern electroretinograms elicited by achromatic and isoluminant-chromatic (red-green) sinusoidal gratings, whose contrast was temporally modulated, were recorded from both blind and sighted hemiretinae. The electroretinograms were qualitatively indistinguishable from those of a control patient with a unilateral striate cortical lesion with documented visual capacity in his field defect. Within-subject analysis of variance revealed significant differences in the amplitude of the second harmonic (2f(0)) component of the averaged signal (diagnostic of retinal ganglion cell function) with respect to stimulus, but no significant differences between blind and sighted hemiretinae. This indicates that many retinal ganglion cells must have survived in the hemispherectomized patients. Isoluminant chromatic stimuli tended to elicit stronger signals than achromatic stimuli, which was unexpected given that wavelength-opponent Pbeta ganglion cells are far more susceptible than broad-band Palpha ganglion cells to transneuronal degeneration after cortical damage. It suggests that the 2f(0) component of the response to isoluminant chromatic stimuli might not reflect the activity of chromatic processes. Overall, the results show that the absence of residual vision in the blind fields of patients with cerebral hemispherectomy cannot be due to complete degeneration of retinal ganglion cells and, by extension, complete degeneration of their subcortical targets. This supports an alternative explanation, which is that intact extrastriate cortex is required for mediating voluntary responses to visual stimuli presented in the scotoma.

Adult↗
PubMed1996

Delayed complications thirty-six years after hemispherectomy: a case report.

PURPOSE: To describe a late complication of hemispherectomy in a patient in whom symptoms of hydrocephalus developed 36 years after her left-sided hemispherectomy, the longest delay on record. METHODS: Hemispherectomy has been successfully used in the treatment of intractable epilepsy associated with infantile-type hemiplegia for a half century. Of the patients, however, up to 33% have late increased cerebrospinal fluid pressure complications attributed to superficial cerebral hemosiderosis. Through a retrospective case analysis, we describe such complications in a 52-year-old woman with cognitive impairment, gait instability, urinary incontinence, and right hemineglect 36 years after her initial procedure. RESULTS: Quantitative, objective measures of cognition and gait-laboratory testing confirmed the patient's favorable clinical response to ventriculoperitoneal shunting, as well as the complete resolution of her symptoms, including the atypical occurrence of right-sided hemineglect. CONCLUSIONS: This case uniquely demonstrates the clinical features of a late complication of hemispherectomy while documenting the longest reported delay for developing such adverse sequelae. We also emphasize the need for more extensive follow-up studies to assess the extent of posthemispherectomy complications.

Brain↗
PubMed1998

Continuous unilateral epileptiform discharge and language delay: effect of functional hemispherectomy on language acquisition.

PURPOSE: To assess the efficacy of functional hemispherectomy in promoting language acquisition in a child with severe language delay and continuous left hemispheric epileptiform discharge in the absence of clinical seizures. We report a 6-month-old girl who initially presented with a right hemiparesis secondary to a lesion of probable prenatal origin in the distribution of the left middle cerebral artery. Weeks later, she developed infantile spasms. At 1.5 years of age, because of intractable seizures, the patient had fenestration of the left porencephalic cyst and anterior temporal lobectomy. The seizures ceased; however, language development remained limited to 35 words at 3.5 years of age. The EEG showed almost continuous epileptiform activity over the left hemisphere with no independent epileptiform potentials contralaterally. She underwent a functional left hemispherectomy. METHODS: Imaging, electroencephalographic investigation, pre- and postoperative psychological and speech assessment were carried out. RESULTS: Considerable language, speech, and behavior improvement was noted within 2 months of surgery. CONCLUSIONS: Interictal epileptiform discharges can interfere with the development of contralateral hemispheric function in the absence of clinical seizures. Early functional hemispherectomy may have a role in promoting optimal language development in appropriately selected patients. Although the primary indication for functional hemispherectomy is to control intractable seizures, a secondary proposed indication is to reduce functional impairment of the other hemisphere by electrical interference.

Brain↗
PubMed2001

Disconnective hemispherectomy.

Hemispherectomy is a valuable procedure in the management of seizure disorders caused by unilateral hemispheric disease. Modifications to anatomical hemispherectomy have been proposed to reduce the incidence of superficial cerebral hemosiderosis and hydrocephalus while still achieving seizure control. We report on the modification of a previously described disconnective form of hemispherectomy. We used this procedure on 2 children, with the aid of stereotactic navigation in 1 of the 2 cases. This disconnection was achieved via a transventricular route with minimal cortical resection or disruption of the blood supply. Over the 20 months of follow-up, 1 patient achieved complete seizure control, and 1 patient achieved control of previously incapacitating seizures with few minor seizures persisting. Motor function and speech significantly improved in both patients. Blood loss during the two procedures was significantly less than that reported for anatomical hemispherectomy, and so far there have been no signs of postoperative complications. The hospital stay was limited to 7-14 days after surgery.

Cerebral Cortex↗
PubMed2002

Recovery of language after left hemispherectomy in a sixteen-year-old girl with late-onset seizures.

Hemispherectomy is a very effective surgical treatment for intractable seizures that occur in the setting of Rasmussen's syndrome. The decision of when to perform a dominant hemispherectomy depends greatly on how late the surgeon believes some shift in language to the nondominant hemisphere can occur. We report a right-handed patient with Rasmussen's syndrome who underwent a left hemispherectomy at the age of 16 and has had excellent control of her seizures and remarkable language recovery. Our results indicate that dominant hemispherectomy in adolescence in the setting of late-onset seizures and Rasmussen's syndrome in the profoundly aphasic patient does not commit the patient to the prognosis of a fixed language deficit.

Adolescent↗
PubMed1997

Why would you remove half a brain? The outcome of 58 children after hemispherectomy-the Johns Hopkins experience: 1968 to 1996.

PURPOSE: To report the outcomes of the 58 hemispherectomies performed at Johns Hopkins between 1968 and January 1996. METHODS: Charts were reviewed of the 58 hemispherectomies performed at Johns Hopkins Medical Institutions by the Pediatric Epilepsy Group during the years 1968 to 1996. Twenty-seven operations were done for Rasmussen's syndrome, 24 operations for cortical dysplasias/hemimegalencephalies, and 7 for Sturge-Weber syndrome or other congenital vascular problems. Seizure control alone did not seem to adequately describe the outcomes of the procedure. Therefore, a score was constructed that included seizure frequency, motor disability, and intellectual handicap. This burden of illness score better described the child's handicap before and after surgery. RESULTS: Perioperative death occurred in 4 out of 58 children. Of the 54 surviving children, 54% (29/54) are seizure-free, 24% (13/54) have nonhandicapping seizures, and 23% (12/54) have residual seizures that interfere to some extent with function. Reduction in seizures was related to the etiology of the unilateral epilepsy. Eighty-nine percent of children with Rasmussen's, 67% of those with dysplasias, and 67% of the vascular group are seizure-free, or have occasional, nonhandicapping seizures. All operations were considered by the parents and the physicians to have been successful in decreasing the burden of illness. In 44 the procedure was very successful, in 7 it was moderately successful, and in 3 it was minimally successful. Success was related to the etiology, and early surgery was preferable. CONCLUSION: Hemispherectomy can be a valuable procedure for relieving the burden of seizures, the burden of medication, and the general dysfunction in children with severe or progressive unilateral cortical disease. Early hemispherectomy, although increasing the hemiparesis in children with Rasmussen's syndrome, relieves the burden of constant seizures and allows the child to return to a more normal life. In children with dysplasias, early surgery can allow the resumption of more normal development.

Adolescent↗
PubMed1992

Functional hemispherectomy.

Complete hemispherectomies were performed throughout the 1950's and early 1960's for the treatment of medically refractory seizures associated with hemiplegia. In 1964 a study published by Laine, Pruvet and Ossen reported a late post operative complication; superficial cerebral hemosiderosis. This, with its associated neurological deterioration, hydrocephalus, and at times death, led to disfavor with the procedure. It was replaced by the subtotal hemispherectomy which effectively eliminated the late complication of superficial cerebral hemosiderosis but was less successful in controlling seizures. Results decreased from 85% showing improved seizure tendency to 68%. Dissatisfied with these results, a hybrid operation was designed by Dr. Rasmussen and Dr. Villemure known as functional hemispherectomy. Removing less cortical tissue but disconnecting the remaining tissue provided a functionally complete but anatomically incomplete removal. Patients, having undergone this surgery, have obtained the same degree of seizure reduction without any of the late complications of the complete hemispherectomy. Our presentation will discuss the preoperative, operative and post-operative course of these patients. Criteria for surgery will be reviewed. A description of the surgical procedure will be included so that one can understand why the complications of aseptic meningitis, hydrocephalus, cerebral hemosiderosis and altered motor function will or will not occur postoperatively. Concerns of family and patient will be addressed throughout the presentation.

Cerebral Cortex↗
PubMedDate not supplied

[Case of severe epilepsy treated by 2-stage hemispherectomy].

The authors describe a 7-year-old boy with severe epilepsy cured by means of two-stage hemispherectomy. Epileptic seizures occurred in the left extremities and recurred several tens of times daily despite intensive pharmacological treatment. EEG investigations demonstrated seizure activity in the right motor-parietal-temporal area. Stereotaxic destruction of Forel's field and thalamus on the right side gave only brief improvement lasting several days. In view of this the frontal, temporal and a part of the parietal lobe were removed according to electrocorticographic investigations. During 6 months after the operation epileptic attacks were absent, than they recurred with increasing frequency. After 10 months full hemispherectomy was done. The child tolerated the operation very well, and control examination after 2 years showed disappearance of epileptic attacks and considerable compensation of motor power loss and sensory disturbances in the left extremities. The authors believe that hemispherectomy carried out in two stages at an interval of several months is better tolerated by the patients and makes possible better compensation of functional disturbances than classic hemispherectomy. In the discussion the authors stress the importance of extrapyramidal pathways for compensation of motor disturbances.

Child↗
PubMed2005

Long-term follow-up in children with functional hemispherectomy for Rasmussen's encephalitis.

INTRODUCTION: Cerebral hemispherectomy has been performed for over 60 years. Multiple variations of functional hemispherectomy have been performed since its inception by Rasmussen. Long-term follow-up for these variations is lacking in the medical literature. METHODS: We review the long-term follow-up for five children with Rasmussen's encephalitis who underwent a modification of functional hemispherectomy. RESULTS: The length of follow-up for this cohort ranged from 13 to 23 years (mean 15.6 years). All patients experienced immediate and complete elimination of seizures. Only one patient underwent ventriculoperitoneal shunt placement. All patients are capable of ambulating on their own. Many years following their procedures, this cohort of patients remains seizure free.

Adolescent↗
PubMed2005

Syntactic development in children with hemispherectomy: the I-, D-, and C-systems.

This study reports on functional morpheme (I, D, and C) production in the spontaneous speech of five pairs of children who have undergone hemispherectomy, matching each pair for etiology and age at symptom onset, surgery, and testing. Our results show that following left hemispherectomy (LH), children evidence a greater error rate in the use of functional category elements than their right hemispherectomy (RH) counterparts. Nevertheless, error rates are surprisingly low and comparable across groups. We interpret these results as (a) weak empirical evidence for a left hemisphere advantage in acquisition of functional structure, (b) strong support that functional structure is a property of all human grammars, and (c) strong support that each isolated developing hemisphere has the potential to acquire a grammar embodying and constrained by highly specific structural principles defining human language.

Adolescent↗
PubMed2006

Unilateral hemispherectomy at adulthood asymmetrically affects immobile behavior of male Swiss mice.

In order to test the hypothesis that behavioral coping with stressful situations is asymmetrically modulated by the hemispheres, we used the unilateral hemispherectomy procedure to assess the relative importance of each hemisphere in the determination of the immobility time during the forced swimming test. Under anesthesia, adult Swiss male mice were submitted to unilateral (right or left) hemispherectomy or sham surgery. Fifteen days after surgery, the immobile and turning behaviors of each mouse were measured during a 5-min forced swimming testing session. In general, while turning activity decreased significantly as the test progressed, an increase in immobility was observed. The unilateral hemispherectomy asymmetrically affected the immobility time in the forced swimming test. Particularly, the increase in immobility time of right-hemispherectomized mice was greater than that observed for sham-operated ones. In contrast, there were no differences in turning activity between the groups. The higher immobility time in males that had their right hemisphere removed supports the hypothesis that the two hemispheres contribute differentially to the behavioral response to stress.

Animals↗
PubMed2005

Sound lateralization in subjects with callosotomy, callosal agenesis, or hemispherectomy.

The question of whether there is a right-hemisphere dominance in the processing of auditory spatial information in human cortex as well as the role of the corpus callosum in spatial hearing functions is still a matter of debate. Here, we approached this issue by investigating two late-callosotomized subjects and one subject with agenesis of the corpus callosum, using a task of sound lateralization with variable interaural time differences. For comparison, three subjects with left or right hemispherectomy were also tested by employing identical methods. Besides a significant reduction in their acuity, subjects with total or partial section of the corpus callosum exhibited a considerable leftward bias of sound lateralization compared to normal controls. No such bias was found in the subject with callosal agenesis, but merely a marginal reduction of general acuity. Also, one subject with complete resection of the left cerebral cortex showed virtually normal performance, whereas another subject with left hemispherectomy and one subject with right hemispherectomy exhibited severe deficits, with almost total loss of sound-lateralization ability. The results obtained in subjects with callosotomy indicate that the integrity of the corpus callosum is not indispensable for preservation of sound-lateralization ability. On the other hand, transcallosal interhemispheric transfer of auditory information obviously plays a significant role in spatial hearing functions that depend on binaural cues. Moreover, these data are compatible with the general view of a dominance of the right cortical hemisphere in auditory space perception.

Acoustic Stimulation↗
PubMed2004

Treatment of refractory status epilepticus with hemispherectomy.

A 7-year-old boy with left hemiparesis secondary to right hemispheric cortical dysplasia was admitted to the hospital with increasing numbers of seizures. Magnetic resonance imaging showed a small dysplastic right hemisphere with abnormally thickened gyri and an apparently normal left hemisphere. Previous video-electroencephalogram (EEG) monitoring showed bilateral independent spikes and generalized slow spike-and-wave episodes on EEG and [18F]fluorodeoxyglucose (FDG) positron emission tomography scan demonstrated scattered areas of regional hypometabolism bilaterally; therefore hemispherectomy was not undertaken at that time. During this hospital stay, nonconvulsive status epilepticus developed and was refractory to multiple medical therapies including pentobarbital (PTB) coma. Burst-suppression pattern during PTB coma appeared to be generalized spike and wave, but when EEG was reviewed with increased time resolution spikes suggested a right hemisphere origin. The patient underwent bilateral intracarotid amobarbital spike-suppression test that showed only minimal suppression of epileptiform discharges with injection of the left carotid, but complete suppression of spike activity after right-sided carotid injection. A right hemispherectomy was performed with complete cessation of status epilepticus. Postoperative EEG showed no epileptiform discharges. Patient follow-up was limited to 12 months after surgery. The patient had regained the ability to walk unaided and was seizure free with a single antiepileptic medication. This case illustrates a potentially life-saving procedure for refractory status epilepticus and several techniques including a spike-suppression test to aid in prediction of cessation of seizures after hemispherectomy.

Amobarbital↗