Issue Description Cauda equina syndrome is a serious neurologic
condition in which there is acute loss of function of the neurologic
elements (nerve roots) of the spinal canal below the termination
(conus) of the spinal cord. Other Names Cauda Equina Syndrome, Degenerative
Lumbosacral Stenosis, Lumbosacral Stenosis, Lumbosacral Instability,
Lumbosacral Malarticulation, Lumbar Spinal Stenosis, Lumbosacral
Spondylolisthesis, Lumbosacral Nerve Root Compression
Causes Cauda Equina Syndrome is caused by compression
of the nerve roots (cauda equina) coursing through the lumbosacral
spinal canal in the lower back. Nerve root entrapment and pressure can
result from an arthritic process, infection, a degenerative disc
rupture, or tumors. Most dogs affected by lumbosacral degeneration are
middle aged or older large, athletic breeds.
Symptoms The most common symptom is progressive sharp
pain. However, this syndrome can manifest itself in a number of ways.
Intermittent lameness in one or both pelvic (rear) limbs or a stilted
gait is a common initial sign. The patient may progressively have more
difficulty rising from a prone position or may be unusually reluctant
to leap. The dog may act suddenly painful or lame immediately after
getting up or jumping. Strenuous activity may exacerbate the signs.
Vocal expression of pain may vary from moans or whimpers when the dog
tries to rise to sharp cries or howls when touched over the rear
quarters or when making a wrong move during exercise. Eventually even
the most pain tolerant individuals will react to the burning pain of
the nerve root entrapment caused by this syndrome. Chewing at the tail
or rear feet as well as bowel and bladder incontinence may be seen in
advanced cases where severe pressure on the nerve roots causes a
burning sensation. The most devastating cases can evolve to full
Diagnosis The veterinarian will ask the owner for a
history of when the symptoms developed. A physical exam will then be
performed. The hind limbs will be manipulated in various ways to
determine which positions are painful. The veterinarian will also do a
neurological exam, including testing the reflexes, to determine which
nerves may be injured.
Radiographs (x-rays) are taken to
evaluate the spine and pelvis. The findings can be very suggestive of
lumbosacral stenosis, but are not sufficient to make the diagnosis. To
achieve a diagnosis, special procedures must be performed by injecting
dye into the affected area and re-radiographing. Depending on where
the dye is placed, the procedure is called myelography, epidurography,
or diskography. These procedures must be done under anesthesia.
Displacement of the dye by the abnormalities in the bones and
intervertebral disc confirms the diagnosis of lumbosacral stenosis.
Treatment Medical therapy (consisting of rest and
anti-inflammatory/ analgesic medication) should be tried in patients
with the first episode when experiencing mild pain only.
Indications for surgical intervention include neurologic deficits,
pain unresponsive to proper conservative treatment, and frequent
recurrences to pain, even if the episodes respond well to medical
treatment. To relieve pressure on the entrapped roots a dorsal
laminectomy is performed. This involves removing portions of the bony
canal entombing the entrapped nerve roots. This conservative
laminectomy adequately exposes the nerve roots and allows the surgeon
to safely retract them for exposure of the disc space. The cauda
equina is gently retracted to one side with blunt nerve hooks,
exposing the herniated discs as a large dome on the floor of the
spinal canal. The herniated disc is excised, compressive osteophytes
removed, and formenotomies (opening the nerve root canals) performed
to relieve root entrapment. Once the pressure s relieved, the
neurologic function gradually returns as the nervous tissue heals in
its decompressed environment.
Prognosis The prognosis for complete recovery is
dependent upon many factors. The most important of these factors is
the severity and duration of compression upon the damaged nerve(s). As
a general rule the longer the interval of time before intervention to
remove the compression causing nerve damage the greater the damage
caused to the nerve(s).
Damage can be so severe and/or
prolonged that nerve regrowth is impossible. In such cases the nerve
damage will be permanent. In cases where the nerve(s) has been damaged
but is still capable of regrowth, recovery time is widely variable.
Quick surgical intervention can lead to complete recovery almost
immediately afterward. Delayed or severe nerve damage can mean up to
several years recovery time because nerve growth is exceptionally