Original surgical treatment of thoracolumbar subarachnoid cysts in six chondrodystrophic dogs

Abstract

Background: Subarachnoid cysts are rare conditions in veterinary medicine, associated with spinal cord dysfunction. Most of the 100 cases of subarachnoid cysts described since the first report in 1968 were apparently not true cysts. Reported cysts are usually situated in the cervical area and occur in predisposed breeds such as the Rottweiler. The purpose of this retrospective study, from May 2003 to April 2012, was to describe the distinctive features of thoracolumbar spinal subarachnoid cysts, together with their surgical treatment and outcome in 6 chondrodystrophic dogs.

Results: Five Pugs and 1 French Bulldog were examined. Images suggestive of a subarachnoid cyst were obtained by myelography (2/6) and computed tomography myelography (4/6), and associated disc herniation was observed in 3/6 dogs. A hemilaminectomy was performed. The protruding disc eventually found in 5/6 dogs was treated by lateral corpectomy. The ventral leptomeningeal adhesions observed in all dogs after durotomy were dissected. No or only mild post-operative neurological degradation was observed. Follow-up studies (7 months to 4 years) indicated good outcome and no recurrence.

Conclusions: All the thoracolumbar subarachnoid cysts described in these 6 chondrodystrophic dogs were associated with leptomeningeal adhesions. Good results seemed to be obtained by dissecting and removing these adhesions. A protruding disc, found here in 5/6 dogs, needs to be ruled out and can be treated by lateral corpectomy.

Figure 1

Sagittal plane CT myelogram. CT image showing the focal accumulation of contrast medium with a “tear-drop” shape (sagittal plane) (Dog 3).

Figure 2

Transverse plane CT myelogram. CT image showing the focal accumulation of contrast medium in transverse plane. The spinal cord is ventrally deviated (Dog 6).

Figure 3

Lateral corpectomy (Dog 4).

Figure 4

Leptomeningeal adhesions. Visualisation of the ventral leptomeningeal adhesions between the pia mater and the arachnoid to pia mater (Dog 5).

Figure 5

Persistence of a dorsal mark. Persistence of a slight dorsal mark (tip of the forceps) at the level of the subarachnoid cyst after dissection of the ventral leptomeningeal adhesions (Dog 6).

Figure 6

Durectomy. Durectomy (3/4 of the diameter of the dura mater) (Dog 6).