Septo-optic dysplasia plus bilateral perisylvian polymicrogyria: a case report

Abstract

Septo-optic dysplasia (SOD) is a rare and highly heterogeneous disorder that is usually characterised by any combination of the classic triad of optic nerve hypoplasia, midline neuroradiological abnormalities and pituitary hypoplasia [1]. Furthermore back in 2000, Miller et al. [2] divided SOD into two subgroups, isolated SOD characterised by the absence of the septum pellucidum, hypoplasia of the optic nerves, and diffuse white matter hypoplasia and SOD plus characterised by the association with diverse brain malformations. Although SOD has been observed with several cortical abnormalities, the association with congenital bilateral perisylvian polymicrogyria has been reported only by few authors and exclusively in patients with refractory epilepsy, oropharyngoglossal dysfunction or delayed developmental milestones [1, 2]. Here, we describe a 22-year-old Romanian man was referred to our neurology clinic because of characterization of very rare complex partial seizures. He was born by caesarean section after a normal pregnancy at 38 weeks of gestation from a nonconsanguineous marriage. No problems have been encountered in the pre and perinatal period. There is no family history of epilepsy or neurological disorders. After the age of two it was noted that he had left hemiparesis. He began to have sporadic complex partialtype seizures described as staring and rare secondary generalization at 21 years of age, easily controlled with levetiracetam. His cranial nerves were intact and the neuroophthalmologic examination showed only a pale optic disk. He had no mental or cognitive impairment. Routine laboratory analyses were normal. He suffered of isolated high levels of prolactin. A cytogenetic analysis of his peripheral blood indicated a normal 46, XY karyotype. Screening for HESX1 and SOX2 mutations, rarely reported in patients with SOD, showed normal results [2]. As well TUBB2B mutation [3] often associated with neuronal migration was negative and the array-CGH analysis ruled out chromosomal re-arrangements. The electrocardiogram was normal. The patient underwent standard and sleep-deprived electroencephalography as well as a brain magnetic resonance imaging (MRI) (3-Tesla GE SIGNA NVI at the Neuroimaging research Unit, Institute of Neurologic Science of National Research Council, Germaneto, Catanzaro), based on our protocol routinely used for patients with epilepsy extensively described elsewhere [4, 5]. Electroencephalographic examinations showed only sporadic diffuse slowwaves without frank epileptiform discharges. Cranial MRI displayed absence of the septum pellucidum and a bilateral perisylvian polymicrogyria more pronounced over the left hemisphere (Fig. 1a, b). The current case represents an isolated report of a patient with SOD plus bilateral perisylvian polymicrogyria presenting only with very mild epilepsy. It might enlarge the heterogeneous spectrum of mild form of SOD plus although our patient suffered only from drug-responsive A. Labate A. Quattrone Institute of Neurology, University Magna Graecia, Catanzaro, Italy