Objective: To study the prevalence and clinical characteristics of malformation of cortical development (MCD) and incomplete hippocampal inversion (IHI) in adults with intractable seizures.
Materials and methods: In this prospective study of 3220 epileptic patients in our epilepsy clinic between 2012 and 2014, 416 had intractable seizures. In all patients, a detailed clinical history, neurological examination, electroencephalography (EEG), computed tomography (CT) scan, magnetic resonance imaging (MRI) brain, and neuropsychological assessment was conducted to identify MCD and IHI.
Results: Out of 416 patients with intractable seizures, MCD and IHI were confirmed in 85 patients (48 males, 37 females). MCD was observed in 46 (11.05%) patients and IHI were observed in 39 (9.37%) patients. Chi square test revealed no signi cant difference between the MCD and IHI groups across the patients in different age groups, gender, type of seizure, duration and onset of seizure, seizure frequency, clustering, status epilepticus, EEG, febrile seizures, and family history. Statistically significant differences (P < 0.05) were observed between the MCD and IHI groups for change in seizure semiology and in intelligence quotient (IQ) and memory quotient (MQ) scores obtained using Wechsler's adult intelligence scale III and Wechsler's memory scale. The IHI group showed higher IQ and MQ scores when compared to the MCD group. Furthermore, IHI occurred along with MCD in 6.52% (N = 3) of the population.
Conclusion: MCD and IHI patients are often associated with intractable complex partial seizures. Intractable epilepsy patients with normal intelligence and normal MRI should be investigated with hippocampal volumetric studies to identify the presence of IHI. Isolated IHI can be considered as a form of MCD because it mimics the clinical features of MCDs.
Keywords: Focal cortical dysplasia; hippocampal volumetric study; incomplete hippocampal inversion; intractable epilepsy; malformation of cortical development.