Craniotomy with cystoperitoneal shunting for treatment of intracranial arachnoid cysts in dogs

Objective - To describe a technique of decompressive craniotomy with cystoperitoneal shunt (CPS) placement for treatment of canine intracranial arachnoid cyst (IAC), and to evaluate outcome in 4 dogs. Study Design - Retrospective study. Animals - Dogs (n = 4) with IAC. Methods - Medical records of dogs diagnosed with IAC by magnetic resonance imaging (MRI; 3 dogs) or computed tomography (CT; 1 dog) were evaluated. All dogs had varying degrees of neurologic dysfunction before surgery. A combined lateral (rostrotentorial)/suboccipital craniotomy was performed sacrificing the transverse sinus on the operated side. The rostral ( ventricular) end of a low-pressure valve shunt (3.0 mm outer diameter, 7.0 cm length) was placed transversely into the cyst cavity; the distal end was placed in the peritoneal cavity. All dogs were rechecked at various intervals by >= 1 of the authors either directly, by telephone consultation with owners, or both. Three dogs were imaged postoperatively (CT-1 dog; MRI-1; ultrasonography-1). Results - Intraoperative complications were limited to excessive transverse sinus hemorrhage requiring blood transfusion in 1 dog. There were no postoperative complications. Clinical signs of neurologic dysfunction resolved in 3 dogs and improved substantially in 1 dog. The latter dog required long-term, low-dose corticosteroid therapy. No dogs required repeat surgery. Mean follow-up time was 23.8 months (range, 12 - 43 months). Collapse of the intracranial cyst was verified in 3 dogs with repeat imaging. In 2 dogs, there was no evidence of the cyst on CT or MRI; in the third dog, a small amount of fluid was demonstrated rostral to the cerebellum on ultrasonography, but there was no identifiable cyst. In 1 dog, the rostral aspect of the shunt had shifted; however, this was not associated with any clinical deterioration. Conclusion - Craniotomy with CPS placement was well tolerated and resulted in sustained improvement or resolution of dysfunction. Cyst decompression was verified in 3 dogs that were re-imaged. None of the patients required re-operation. Excessive transverse sinus hemorrhage is a potential danger that may necessitate blood transfusion. Other IAC patients treated with this method will need to be evaluated to fully evaluate its effectiveness. Clinical Significance-Craniotomy with CPS placement may be an effective treatment method for dogs clinically affected with IAC. (c) Copyright 2007 by The American College of Veterinary Surgeons.