Peduncular hallucinosis associated with pontine hemorrhage in an adult patient.

Peduncular hallucinosis refers to a rare neurophychiatric disorder presenting with vivid visual hallucinations, disturbances of sleep, and oculomotor dysfunction. It is typically caused by mesencephalic lesions. Nonetheless, a few cases have also been reported, in which the same syndrome was associated with thalamic and pontine lesions. We report the case of a 63-year-old male patient presenting to the Emergency Department of our hospital with irritability, gait difficulty, and diplopia of sudden onset two hours ago. Neurological examination revealed dysarthria, right facial palsy, bilateral gaze palsy, dysmetria of his left extremities, left-sided hemihypaethesia and extensory plantar response on the left. Brain computerized tomography (CT) showed a hemorrhagic lesion on the right lateral side of the pons. During his hospitalization at the Department of Neurology, he developed visual hallucinations, confusion, disorientation, insomnia, and strong emotional response. An extensive laboratory screening was performed and showed no abnormal findings. Suspecting peduncular hallucinosis due to the brainstem lesion, treatment with quetiapine and melatonin was administered to the patient and symptoms resolved completely within days. Subsequently, gradual neurological clinical improvement was also noted and two weeks after his admission, a repeated brain CT and a brain magnetic resonance imaging (MRI) showed partial absorption of the brainstem hemorrhage. The patient underwent rehabilitation for two months, showing further clinical improvement, and treatment with quetiapine and melatonin was discontinued without any further episodes being noted. A repeated brain MRI was performed two months after his admission to our hospital and showed no hemorrhage, but a mixed signal intensity core and a hypointense hemosiderin rim at the location of the absorbed hemorrhagic lesion, compatible with pontine carvenoma. Peduncular hallucinosis is most commonly associated with ischemic lesions of the posterior brain blood circulation, but different lesions have been reported, like vasospasm, brain tumors, encephalitis, hemorrhage associated with vascular malformations, such as a carvenoma, as seen in our case, representing a very rare form of peduncular hallucinosis.