ORIGINAL PAPER Cognitive changes following surgery in intractable hemispheric and sub-hemispheric pediatric epilepsy Santhosh George Thomas & Roy Thomas Daniel & Ari George Chacko & Maya Thomas & Paul Swamidhas Sudhakhar Russell Received: 14 January 2010 / Accepted: 29 January 2010 # Springer-Verlag 2010 Abstract Objectives The objectives were to study the short and longitudinal changes in the cognitive skills of children with intractable epilepsy after hemispheric/sub-hemispheric epi- lepsy surgery. Methods Sixteen patients underwent surgery from September 2005 until March 2009. They underwent detailed presurgical evaluation of their cognitive skills and were repeated annually for 3 years. Results Their mean age was 6.6 years. Epilepsy was due to Rasmussen’ s encephalitis (n =9), Infantile hemiplegia seizure syndrome (n =2), hemimegalencephaly (n =2), and Sturge Weber syndrome (n =3). Fourteen (87.5%) patients underwent peri-insular hemispherotomy and two (12.5%) underwent peri-insular posterior quadrantectomy. The mental and social age, gross motor, fine motor, adaptive, and personal social skills showed a steady increase after surgery (p <0.05). Language showed positive gains irre- spective of the side and etiology of the lesion (p =0.003). However, intelligence quotient (IQ) remained static on follow-up. Patients with acquired pathology gained more in their mental age, language, and conceptual thinking. Age of seizure onset and duration of seizures prior to surgery were predictive variables of postoperative cogni- tive skills. Conclusions There are short- and long-term gains in the cognitive skills of children with intractable epilepsy after hemispherotomy and posterior quadrantectomy that was better in those patients with acquired diseases. Age of seizure onset and duration of seizures prior to surgery were independent variables that predicted the postoperative outcome. Keywords Intractable epilepsy . Epilepsy surgery . Cognitive decline . Cognitive outcome . Children Introduction “Intractable epilepsy” in adults was previously defined as a failure to respond to at least two antiepileptic drugs (AEDs) given over at least a 2-year period [1]. A single definition for “intractable” epilepsy cannot suit all situations as definitions of intractability are individualized to the patient. Of these patients deemed to be intractable, approximately 50% are estimated to have surgically remediable epilepsy [2, 3]. “Hemispheric epilepsy” refers to epileptiform activity in all four lobes of one hemisphere, and when it involves more than two lobes of the brain, it is termed “sub- hemispheric epilepsy” [2, 4]. Children with refractory epilepsy are at considerable risk for cognitive impairment [5–10] as well as school failure [11], behavioral and mental health problems [6, 12–14], and overall compromised quality of life [15]. The numerous risk factors for epilepsy-related cognitive decline discussed in literature are the mere presence of seizures [10], seizure- related variables such as age of onset, frequency and/or severity, duration [15], underlying pathology [15], AEDs [6, 10, 11, 14], and various psychosocial factors [13] often called the “burden of epilepsy” [15]. S. G. Thomas : R. T. Daniel (*) : A. G. Chacko : M. Thomas Department of Neurological Sciences, Christian Medical College, Vellore, Tamil Nadu, India e-mail: roy.daniel@chuv.ch P. S. S. Russell Department of Child and Adolescent Psychiatry, Christian Medical College, Vellore, India Childs Nerv Syst DOI 10.1007/s00381-010-1102-5