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.