Hemispherectomy has been performed in the treatment of epilepsy in association with hemiplegia for over 50 years. However, the optimal timing of surgery with respect to age at presentation and the influence of underlying pathology on outcome is only slowly emerging.
This study reports on the clinical course and outcomes of 33 children who underwent hemispherectomy at Great Ormond Street Hospital, London, 1991–6199727ya. Age at surgery was 0.33–17 years (median 4.25) with 1–8 years follow-up (median 3.4). The underlying pathology was developmental in 16 (10 hemimegalencephaly, 2 polymicrogyria, 2 focal cortical dysplasia, one diffuse cortical dysplasia and one microdysgenesis), acquired in 11 (six middle cerebral artery infarct, 3 post encephalitis/trauma, and one each of hemiconvulsion-hemiplegia epilepsy and perinatal ischaemic insult) and progressive in 6 children (four Rasmussen encephalitis, 2 Sturge-Weber syndrome).
At follow-up, 52% were seizure free, 9% experienced rare seizures, 30% showed >75% reduction in seizures and 9% showed <75% seizure reduction or no improvement. Seizure freedom was highest in those with acquired pathology (82%), followed by those with progressive pathology (50%) and those with developmental pathology (31%). However, seizure freedom, rare seizures or >75% reduction in seizures occurred in 100% of those with progressive pathology, 91% of those with acquired and 88% of those with developmental pathology, indicating a worthwhile seizure outcome in all groups. Hemiplegia remained unchanged following surgery in 22⁄33 children, improved in 5 and was worse in 6. No large cognitive deterioration or loss of language occurred, and 4 children showed large cognitive improvement. behavioral improvement was reported in 92% of those who had behavior problems pre-operatively.
…The cognitive category of the patients pre-operatively assessed according to IQ or DQ is shown in Figure 1. Figure 1 shows that the majority of children (88%) with developmental pathology, including all 10 subjects with hemimegalencephaly, exhibited severe cognitive/developmental delay. The majority of patients with acquired pathology (64%) also showed severe delay and a further 27% showed moderate delay. Those with Rasmussen encephalitis were most likely to have normal levels of cognitive function (three out of 4) whilst the 2 children with Sturge-Weber syndrome were in the severe and moderate impairment groups. 12 children (36%) had shown evidence of developmental regression prior to surgery.
Particular difficulty with expressive language was noted in 6 subjects and was anticipated in 2 subjects with Rasmussen encephalitis of the left hemisphere who came to surgery at 3.8 and 4.2 years of age, respectively. One was developmentally normal and the other was only mildly developmentally delayed prior to surgery. One showed very slurred speech, which was reduced in quantity during formal assessment, but developed clear speech immediately prior to surgery and the other became aphasic 2 weeks prior to surgery. One further subject with left-sided pathology resulting from a congenital MCA infarction was 2.3 years at the time of surgery with severe developmental delay. The 3 remaining subjects showed abnormal pathology of the right hemisphere and when assessed at age 1.5, 2.6 and 12 years, respectively, were thought to be severely developmentally delayed thereby making language assessment difficult particularly in the 2 younger patients. In the opinion of experienced examiners, however, these children exhibited expressive language difficulties beyond those which would have been predicted from cognitive performance and comprehension. The pathology was developmental in one, acquired in one and the other child had Sturge-Weber syndrome.
Behaviour difficulties were present in 12 children (36%). The most common problem was difficulty with concentration (75%), followed by fluctuating mood with or without socially intrusive behavior (66%). 25% showed temper tantrums or aggression. The duration of seizures prior to surgery (median 7.38 years) and hence age at surgery was statistically-significantly greater in those with behavior problems compared with those without (median duration of seizures 2 years, Mann-Whitney U test p = 0.0033). The median duration of seizures prior to surgery in those with acquired pathology was statistically-significantly longer at 7.75 years compared with 2.6 years and 1.9 years in the developmental and progressive pathology groups, respectively (Kruskal-Wallis p = 0.0004). behavior problems were most common in the group with acquired pathology (73%), followed by the group with progressive pathology (33%) and least common in those with developmental pathology (12.5%). There was no apparent association between the category of cognitive performance and the presence or absence of behavior problems.
