A 12-year-old male Shi-Tsu dog was presented with chronic progressive quadriparesis for 3 months. Tl-weighted transversal MR images revealed hypointense cystic lesion at the quadrigeminal cistern (supracollicular of the mesencephalon) . The signal intensity of the cystic content was equivalent to that of cerebrospinal fluid. Fenestration was performed, and the cerebrospinal fluid of the cyst was communicated with the subarachnoid space. Clinical signs were markedly improved immediately after surgery. The size of the cyst clearly reduced on MR images which were taken 1 month after surgery.
A 12-year-old castrated male Japanese domestic cat was presented for evaluation of frequent seizures accompanied by tonic convulsion. MRI examination revealed a space-occupying lesion with a clear boundary in the area from the temporal to occipital region of the left cerebral hemisphere. The intracranial mass was surgically removed, and was histologically diagnosed as meningioma. Although neurological abnormalities such as lowered consciousness level, circling, and visual disturbance with loss of pupillary light reflex and menace reflex were temporally observed after surgery, the cat was improved with time by intensive postoperative care. Seizure disappeared after surgical removal of the intracranial menigioma in this case.