Iatrogenic brainstem injury during cerebellomedullary cistern puncture.

Cerebrospinal fluid collection is fundamental to the investigation of central nervous system disorders although it carries potential risks. Herein we report the clinical signs and magnetic resonance (MR) imaging findings associated with needle injury to the brainstem during cerebellomedullary cistern puncture in four dogs. Three dogs were nonambulatory tetraparetic with cranial nerve deficits and one dog had unexplained left thoracic limb paresis. In MR images, there were conspicuous T2 hyperintensities in the myelencephalon in all dogs. In T2* gradient echo images, the lesions were hypointense in two dogs with multiple cranial nerve deficits, and hyperintense in another dog. One dog was euthanized due to sudden neurologic deterioration 12 days later, one died shortly after MR imaging, and a third was euthanized due to concurrent cervical spondylomyelopathy. The fourth dog recovered gradually. Diagnosis was confirmed histopathologically in one dog and was presumptive based on clinical signs and MR findings in three dogs. None of the dogs with cranial nerve deficits recovered, only the one dog with left thoracic limb paresis and concurrent syringomyelia.