Epilepsy: polymicrogyria and grey matter heterotopia

Case contributed by Dr Gabrielle Matta

Presentation

Admitted for investigation of a 6 month history of focal and generalized seizures. These begin with altered sensation in his fingers with unusual percetual disturbances (olfactory, auditory and visual hallucinations) with progression to generalized tonic-clonic seizures. He has a number of developmental problems, including bilateral ureteric obstruction and undescended testes. He has dysmorphic facies and borderline intellectual abilities.

Patient Data

Age: 15 years
Gender: Male

There is a developmental anomaly involving both cerebral hemispheres, worse on the right. There is grey matter heterotopia on the right with multiple islands of grey matter seen adjacent to the lateral ventricle, particularly anteriorly. There is polymicrogyria centered on the sylvian fissure with moderate thickening of the insular and extending into the operculum.

On the left hand side there are some subtle small areas of grey matter heterotopia.

Case Discussion

There is extensive polymicrogyria with perisylvian distribution on the right side. There is also periventricular grey matter heterotopia. The eyes appear small in proportion to the head, although both are normal in diameter, presumably representing enlargement of the skull vault. The ventricles are not strikingly abnormal however they are asymmetrical and there is migrational disorder on right. The posterior fossa is not abnormal. The septum pellucidum is intact.

The patient was admitted for video EEG monitoring which confirmed refractory, right-sided focal seizures. He was treated with two anti-epileptic medications.

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