The cerebellum is known to have an inhibitory effect on seizures. Neverthel
ess, cerebellar dysplastic lesions can be epileptogenic. A 4-month-old infa
nt had paroxysmal facial contractions; tachypnea and nystagmoid eyeball and
tremulous movements were occasionally combined. These evolved to stereotyp
ic clinical patterns and frequencies, which increased despite administratio
n of antiepileptic drugs (AEDs). Magnetic resonance imaging (MRI) demonstra
ted a mass arising from the superior cerebellar peduncle, although video-sc
alp EEG monitoring revealed no abnormal findings. Positron emission tomogra
phy with [F-18]fluorodeoxyglucose revealed focal hypermetabolism in the sam
e area identified by MRI. A depth electrode implanted in the mass revealed
focal spike-and-wave discharges. The lesion was partly removed, pathologic
diagnosis was ganglioglioma. Because of incomplete seizure control and resi
dual tumor visible on MRI, a second operation was performed. After complete
excision of the tumor, the patient became seizure free without AEDs. This
case confirms the presence of seizure originating from the cerebellum and e
mphasizes the need for the complete removal of an epileptogenic lesion.