Safety of care
Cauda equina syndrome: A case for timely recognition and treatment
An article for physicians by physicians
Originally published June 2007
Cauda equina syndrome is not common, but has the potential for serious and long-lasting disability. Knowing the symptoms and signs, examining the patient adequately, and obtaining timely and appropriate investigations and consultations may help to avoid the risk of disability.
Of interest to physicians ordering and interpreting tests
Physicians frequently assess and treat patients with low back pain, sometimes related to disc herniation. Cauda equina is a relatively rare but important syndrome that may occur when a protruding disc, usually a large one, presses on the lumbar and sacral nerve roots more centrally, impairing the function of multiple roots. Motor and sensory function may be impaired, particularly of the bladder and bowel. Timely recognition and treatment may avoid significant sequelae for the patient, and may prevent medico-legal difficulties for the physicians involved. The following is a case of cauda equina syndrome from the CMPA files.
The patient was 40 years of age and was working as a cabinet maker. He injured his back while he was in a crouched position and performing a rotary type movement of the upper body. The patient attended the local emergency department complaining of acute onset of pain. There was no neurological deficit. The emergency physician diagnosed lumbar strain and sent the patient home with a prescription for antiinflammatories and analgesics.
Approximately one week later the patient was seen again in a local clinic. As the clinical examination was reassuring, the clinic physician suggested the patient return to work on a progressive work schedule.
However, the pain worsened and two days later the patient attended the local emergency department. The clinical examination showed hypoesthesia of the lateral aspect of the right foot with decreased power of dorsiflexion (grade 4/5) of the great toe and absence of the Achilles reflex. The emergency physician diagnosed a herniated lumbar disc at L4/5 and arrangements were made for outpatient diagnostic imaging studies. The patient was discharged and prescribed an appropriate potent narcotic.
Two days later, the patient went again to the emergency department because the pain continued to worsen and was not relieved by the narcotic. Recognizing the significance of the progressive neurological signs, severe pain and repeated emergency visits, the physician admitted the patient for pain management and further diagnostic testing.
A plain X-ray was done and arrangements were made for an urgent CT scan; however, it could not be done in the supine position due to pain and was done in the prone position. The scan was not helpful in confirming the diagnosis of a herniated lumbar disc at L4/5. Another CT scan was ordered, but not urgently. While in hospital, the patient developed urinary retention requiring a catheter. The following day, he developed fecal incontinence. There was no referral or discussion of the case by the physician with any specialists or any attempt to make an appointment for an earlier repeat CT scan.
It was only when the patient was reassessed two days later by a new on-call physician that the diagnosis of cauda equina syndrome was made on the basis of the patient's signs and symptoms. A CT scan of the lumbosacral spine done urgently confirmed a large centrolateral disc herniation impinging on the nerve roots; the patient was transferred to a tertiary care centre where he underwent immediate surgery. Unfortunately, the patient was left with permanent urinary, rectal and sexual sequelae.
The patient began a legal action and the admitting physician was the only one ultimately named.
In the legal action, medical experts were critical of this physician because:
- the history did not include inquiries about bowel or urinary tract difficulties,
- the physical examination did not include checking for rectal tone or a sensory examination of the perineal area,
- urinary retention, fecal incontinence and numbness of the perineal area were important findings not pursued, and
- there was no consultation with an appropriate specialist.
Supporting medical expert opinions could not be obtained for the physician named. The case was therefore settled in favour of the patient and compensation was paid by the CMPA on behalf of the member.
Although it is true that cauda equina syndrome is a relatively rare condition and can be difficult to diagnose, this case demonstrates that physicians should consider this diagnosis in some patients with low back pain and appropriate neurological symptoms and signs.