Abstract

ROLE OF VOXEL-BASED MORPHOMETRIC ANALYSIS IN DEMONSTRATING ABNORMAL CEREBRAL STRUCTURE IN GENETIC GENERALIZED EPILEPSY: A SYSTEMATIC REVIEW

Balarabe S. A.* and Watila M. M.

ABSTRACT

Background: Quantitative Magnetic Resonance Imaging such as Voxel-Based Morphometry (VBM) has made important contributions to the evaluation and management of epilepsy over the last two decades. Although VBM techniques together with histopathological studies reveal focal cerebral abnormalities in patients with Genetic Generalized Epilepsy (GGE); results of published studies are sometimes contradictory thereby limiting reasonable conclusions for effective clinical practice. This review aims to provide quantitative summary estimates of studies on role of VBM in detecting focal cerebral abnormalities in patients with GGE. Method: Studies were included in the systematic review if they were full texts published in English, with at least two groups (cases and controls) and sample size of not less than 15 cases. Studies were identified through three electronic databases (Pubmed EMBASE and Google scholar) from January 1995 to July 2014. Studies were systematically searched using key words (‘‘epilepsy’’ or "Idiopathic Generalized Epilepsy" or "IGE" or ‘‘juvenile myoclonic epilepsy’’ or ‘‘JME’’ or "Absences Epilepsy" or "AE" or "Juvenile Absence Epilepsy" or "JAE" or "Childhood Absence Epilepsy" or "CAE" or "Generalized Tonic-clonic seizure" or "GTCS") and (‘‘voxel-based morphometry" or ‘‘VBM’’ or ‘‘voxelbased’’ or ‘‘voxel-wise’’ or ‘‘voxel’’). The references of relevant articles were also scrutinized for additional studies. For each eligible study, data were extracted for descriptive and diagnostic variables and summaries relating to outcome. Results: The systematic literature search yielded six hundred and sixteen (616) published studies according to the topic and abstracts. Eighty three (83) articles were identified as potentially eligible and were reviewed in full text. Fifteen studies (15) with a total of six hundred and forty one (641) patients with Genetic Generalized Epilepsy [Juvenile Myoclonic Epilepsy (JME) 393 (61.3%), Epilepsy with Generalized seizure on Awakening (EGA) 194 (30.3%) and Absence Epilepsy (AE)54 (8.4%)] and five hundred and five (505) healthy control subjects were selected. Some studies revealed anatomical changes such as increased Gray Matter Volume (GMV) in bilateral prefrontal cortex, while others showed decreased GMV in bilateral thalamus in patients with GGE. Conclusion: This systematic review reveals consistent subtle anatomical changes among patients with GGE; and support the concept of thalamocortical circuitry involvement in the pathogenesis of GGE, particularly in JME.

Keywords: Epilepsy, voxel-based morphometry, Genetic Generalized Epilepsy, Gray matter volume.