Cauda Equina Syndrome
What is Cauda Equina Syndrome?
Cauda Equina Syndrome (CES) is a compression of the nerve roots as they pass from the lower back toward the tail at the level of the lumbosacral junction. The most common cause of CES is a narrowing of the vertebral canal at the level of the lumbosacral joint. This condition is also called lumbosacral stenosis.
Lumbosacral stenosis is most commonly caused by degenerative changes to the intervertebral disc, arthritis of the joints, or abnormal proliferation of the ligaments. Dogs with misshapen lumbar or sacral vertebrae and German shepherd dogs are predisposed to developing lumbosacral stenosis. CES symptoms can also manifest with neoplasia (cancer) or discospondylitis, infection at the level of the lumbosacral disc.
What are symptoms of Cauda Equina Syndrome?
The most common neurologic sign associated with CES is lower back pain. Other signs may include decreased willingness to jump up or climb stairs, low tail carriage or reduced tail wagging, difficulty posturing to defecate, and whimpering or crying upon palpation of the lower back. In some cases dogs will have weakness or lameness in one or both hind limbs, which occurs secondarily to compression of the nerve root supplying the sciatic nerve as it exits at the lumbosacral joint. If the compression of the nerve root causes significant pain, dogs may hold up a limb or cry out after exercise. In more severe cases, compression of the nerve roots can lead to fecal and urinary incontinence, which is sometimes irreversible.
How is Cauda Equina Syndrome diagnosed?
The first step in diagnosing CES is a neurologic examination. The doctor will observe the dog’s gait for any lameness or stiffness. A pain response is elicited in palpation over the spine, tail, or hips in most dogs suffering from CES. Reflexes, proprioception (foot placement), and anal tone will also be checked in the exam. Radiographs are taken to look for abnormal shape of the lumbosacral joint, spinal arthritis at the lumbosacral joint, infection of the disc space, or tumors. Computed Tomography (CT scan) is used to better visualize the spinal vertebra in dogs with lumbosacral disease.
How is Cauda Equina Syndrome treated?
Treatment of CES is directly related to the symptoms presented by each individual patient. Dogs with no history of back pain that are now exhibiting mild pain are typically treated with strict rest and pain medications. In situations where the dog is not responding to conservative medical therapy, or exhibiting progressive neurologic symptoms, surgical intervention is necessary. The procedure is called a dorsal laminectomy. It involves removing the top bony layer of the spinal canal, releasing the entrapped nerve roots and removing the associated ruptured intervertebral disc if present. If necessary, a foraminotomy is performed to open the nerve root canals and relieve the entrapped nerve roots. If there is significant instability at the lumbosacral joint, the joint is surgically stabilized with pins and bone cement.
What is the post-operative prognosis?
Prognosis is very good in dogs with mild neurologic signs (i.e. pain only, mild weakness). Dogs with severe nerve root compression and subsequent urinary or fecal incontinence have a worse prognosis. Surgery, however, can work to alleviate pain in these dogs.
Many dogs with lumbosacral disease have other back problems (i.e. chronic intervertebral disc disease) and hip or other orthopedic disease, which can affect their recovery after surgery. Recovery is also slower in overweight dogs, and obese patients must be put on a strict diet to reduce their weight.
Strict cage rest is critical to a good surgical recovery. Specific complications that can occur after surgery include formation of a fluid pocket or scar tissue that compresses the nerve roots or fracture of the bones at the surgery site. Dogs which are overly active after surgery are much more likely to develop complications.