A Canine Case of Gliosis with Cyst Formation in the Posterior Fossa.

Abstract

ABSTRACT. A 5-month-old male Great Pyrenees with symptoms of convulsions, circling, and a head tilt was referred to the Animal Medical Center of Nihon University. On a magnetic resonance image (MRI), a cyst in the posterior fossa was noted and a part of the cyst enhanced by gadoteridol. Based on MRI and clinical findings, the patient was tentatively diagnosed with a cyst formation tumor, and an operation to open the cyst and remove the part enhanced by contrast was performed. Postoperatively, the clinical course was good. Pathologically, the removed tissue was diagnosed as a gliosis with cyst formation. KEY WORDS: canine, MRI, posterior fossa cyst.J. Vet. Med. Sci. 64(7): 611-614, 2002 In humans subjects, cyst formating diseases occurring in the posterior fossa include hemangioblastoma, astrocytoma, arachnoid cysts, Dandy-Walker malformation (DWM) and mega cisterna magna [2]. The differential diagnosis of these diseases is difficult because the clinical signs and age at onset are very similar. In veterinary medicine, the same cystic diseases in the posterior fossa have been reported. The diagnosis of meningioma, arachnoid cysts and DWM by means of magnetic resonance imaging (MRI) and computed tomography (CT) have also been reported [1,[3][4][5][6]. Authors report here a case of gliosis with a cyst in the posterior fossa in a dog that was diagnosed on the basis of MRI, gross and histological findings.The dog was a 5-month-old male Great Pyrenees. It suddenly developed lameness 1 month prior to the initial presentation followed by right circling and a head tilt two days later. At the first examination the temperature was 39.4°C, the heart rate was 96/min and respiration was panting. The first blood biochemical examination showed high serum alanine aminotransferase and high cholesterol, but no abnormalities were noted on other examinations. Twelve days later the dog showed signs of dropping of the right labialis, nystagmus, convulsion of the right thoracic limb and right hemiparesis. Corticosteroid, non-steroidal anti-inflammatory drugs and vitamin E were administered at another hospital but the symptoms did not improve. The patient was referred to the Animal Medical Center of Nihon University Upon neurological examination on the day of surgery, left hypermetria and a depression of menace reflex were noted. Since the cyst was located in the right cerebellum, the authors suspected hypermetria caused by compression of the cerebellum. We also speculated that vestibular signs in the head tilt and circling were due to compression of the right brain stem. Right facial convulsions of the dog were considered to be due to irritation of the facial nerves.An MRI examination was performed with an MRI (FlexArt ® , Toshiba), which had a magnetic field intensity of 0.5 T. A coil for the geniculum was used. The T1-weighted image was obtained by means of the spin-echo method (TR 350 msec, TE 15 msec) and the T2-weighted image by the fast spin echo method (TR 4,000 msec, TE 120 msec). A cyst which showed hypo-intensity on the T1-...

Unilateral Facial Paresis Secondary to a Suspected Brainstem Arachnoid Cyst in a Maltese Dog

“…Intracranial cysts are likely developmental in origin and can develop in cerebrum, cerebellum, and brainstem thus may cause cranial nerve dysfunction in human and dogs as well [5,21,29,31]. However, intracranial cysts located in the brainstem are extremely rare in both human and dogs [8,18,21,23,28,31,32]. We described a case of unilateral facial paresis concurrent with lacrimal loss, which was strongly suspected to be caused by a pontomedullary cystic lesion.…”