Hamartomas and epilepsy: clinical and imaging characteristics.

Purpose: Cerebral hamartomas are lesions marked by a disorganized arrangement of mature neural elements and represent a rare cause of medically intractable focal epilepsy. We present the clinical presentation and imaging findings of this rare entity.

Methods: History and neurophysiological studies of 14 patients with pathologically confirmed hamartomas who had surgery for intractable focal epilepsy were reviewed. MRIs were available for review in 10 patients.

Results: The lesions were most commonly located in the temporal and frontal lobes. Seizure semiology was concordant with the anatomic location of the hamartoma in all patients. Nine of the thirteen patients (69%) with the hamartoma confined to one lobe had interictal spikes and sharp waves at the corresponding electrodes. The ictal pattern was confined to the same lobe of the hamartoma in five of nine patients with ictal recordings. Although imaging characteristics were variable, all patients had signal increase on T2-weighted images and 50% of them had mild mass effect. Neocortical involvement was present in the majority of patients (7/10), blurring of the gray/white matter interface was seen in seven patients. Five of those seven patients were found to have associated cortical dysplasia by pathology.

Conclusion: Hamartomas represent a rare entity and may cause devastating epilepsy. Imaging characteristics are difficult to distinguish from those of some other developmental tumors. Hamartomas are frequently associated with microscopic cortical dysplasia (CD), thus underlining their malformative etiology.