Teaching Case

A 48-year-old man with low intelligence, dysarthria, and long-standing epilepsy .

MRI revealed an abnormal, vertically oriented, right perisylvian fissure extending to the parietal convexity (Figure 1 a). An abnormally thickened and hyperintense grey matter around the sylvian fissure was found (Figure 1 b, c).

Perisylvian syndrome is a structural malformation of cortical development that consists of primitive Sylvian fissure and dysplastic operculum [1-5]. It was first reported by Shelvell in 1992 [3].

The aetiology is genetic and can be sporadic or familial. Perisylvian syndrome has also been associated with congenital cytomegalovirus infection or in patients with Aicardi syndrome.
Bilateral involvement is more common than unilateral [1-5]. When pathological findings are unilateral or there is a markedly asymmetric polymicrogyria, with local brain volume reduction, the pathology is in a majority of cases not genetic, and is due to a post-clastic event occurring before the 25th week of gestation [6].

Usual clinical symptoms are: cognitive deficit, seizures, paralysis of face-tongue-throat with typical inability to move the tongue from side to side, chewing problems, and dysarthria [1-5].

Essential criteria for diagnosis of this syndrome are oropharyngoglossal dysfunction, dysarthria and perisylvian malformations on imaging. Additional criteria include epilepsy, mental retardation and abnormal EEG, arthrogryposis multiplex, limb malformations, and infantile spasms [5].

MRI classical findings: The Sylvian fissures are vertically oriented, wide, deep and extend further back to the central/postcentral sulcus. The operculum is dysplastic due to polymicrogyria or pachygyria. Irregularity of the cortical-white matter junction is also found [1, 2, 4].