Intraventricular tension pneumocephalus and cervical subarachnoid pneumorrhachis in a bull mastiff dog after craniotomy.

An eight-year-old bull mastiff dog underwent a craniotomy for surgical excision of an olfactory lobe meningioma. Rapidly progressive neurological deficits with cervical pain developed within the early postoperative period. Intraventricular and cervical subarachnoid space air accumulation (pneumorrhachis) was identified through magnetic resonance imaging and computed tomography. Repair of a dural defect using synthetic dura substitute resulted in gradual resolution of neurological signs attributable to the tension pneumocephalus and subarachnoid space pneumorrhachis. Regrowth of the meningioma was not observed. Postoperative intraventricular tension pneumocephalus and air accumulation within subarachnoid space are uncommon but life-threatening complications of intracranial surgery. Early diagnosis and treatment can result in a satisfactory outcome.