Improvement of peduncular hallucinosis by surgical resection and carbamazepin administration in a young patient with pineocytoma]

Peduncular hallucinosis is a rare phenomenon characterized by visual hallucination consisting of vivid, colored image of people, animals, scenes or geometric patterns. In most of the cases the hallucination is accompanied by sleeping disorder, and is by the patient recognized as not being real. It can be observed mainly in patients with thalamic/midbrain vascular disease, and is less frequently seen in brain stem tumor. The damage of the ascending reticular activating system by brain stem compression causing dream activity releasing what is normally suppressed during wakefulness is thought to be the mechanism of peduncular hallucinosis. The authors report a 13-years old female presenting peduncular hallucinosis due to brainstem compression by a pineocytoma. The patient had a 3-month history of complex visual hallucination and slight somnolence. The hallucination mainly consisted of TV game characters, animals, and vegetables which were colorful and vivid. She was well oriented and realized that the hallucination was not real. MRI showed a pineal mass compressing the quadrigeminal plate inferiorly. There was mild obstructive hydrocephalus due to aqueduct stenosis. The tumor was totally removed and was pathologically diagnosed as pineocytoma. After the surgery, the hallucination ameliorated remarkably. Although the administration of benzodiazepine exacerbated the hallucination and sleep disorder, oral carbamazepine was clearly effective and produced nearly complete disappearance of hallucination. To the best of our knowledge, this is the first report of peduncular hallucinosis caused by quadrigeminal plate compression by a pineal tumor.