A 24-year-old man survived for 8 years after a vascular lesion of the pons and midbrain. During these years a subresponsive comatose state with neurological signs extending from the oculomotor nuclei to the trigeminal and facial nuclei levels was present. A decorticated type of rigidity, with bilateral paralysis of the limbs accompanied by pyramidal signs, was also present. The EEG during the first months showed slow activity which afterwards gradually changed towards fast and alpha activities, maintained in the course of the years. The pathological diagnosis was a fibrous endarteritis, mainly in the territory of the basilar and vertebral arteries. The pons and midbrain, presenting a large cystic infarct, were serially studied to determine the anatomical extent of the lesion. After reviewing other examples from the literature, the clinical features of our case are discussed. The evolution of the EEG is related to different structures of the ponto-mesencephalic region with different functional activities.