Cauda equina syndrome: mitigating risk for a high-litigation profile condition

Cauda equina syndrome (CES) is a devastating spinal condition. A 2019 UK report highlighted that 23% of litigation claims for spinal disease in England related to CES. Between 2008 and 2018, NHS Resolution received 827 claims for CES related incidents – 340 were settled with damages. This has cost the UK NHS just over £186 million. Further impact manifests in clinicians practising defensive medicine in the face of such conditions with high-litigation profiles. The UK National Institute of Health and Care Excellence (NICE), working with the UK Medical Protection Society (MPS) recently made changes to guidelines in 2018 in an effort to promote earlier diagnosis and reduce the number of patients left with permanent disability.

CES is the compression of the nerve roots at the lower end of the spinal cord, called the cauda equina (the ‘horse’s tail’). These nerves control movement and sensation in the legs and allow normal bladder and bowel function. Damaged cauda equina roots can lead to pain, incontinence and paralysis, if untreated. Surgical decompression is the mainstay of treatment. Definitions have been highly contentious and variable. CES is currently broadly considered as two types:

Incomplete CES (CES-I): loss of urgency or sensation in the bladder and bowel. This affects 40% of people with CES.

Complete CES (CES-R): urinary and/or bowel retention or incontinence. This affects about 60% of people with CES.

The most common cause is a herniated lumbar disc. It happens in an estimated 3% of all disc herniations and affects 1 in 30,000 to 100,000 people per year worldwide.

Other causes include infection, lower back injuries, spinal stenosis, complications of spine surgery, epidural hematoma, spinal tumours. Permanent damage may ensue if left untreated or treatment is delayed. Studies have attempted to demonstrate the optimal time window for surgery – within 24–48 hours is important for maximising the chances of functional improvement.

Symptoms of CES may include low back pain and/or leg pain (sciatica), leg weakness, numbness or sensations (burning, prickling, tingling) in the backs of the legs, buttocks, hips and inner thighs (paraesthesia), urinary and/or faecal incontinence, urinary retention.

Delays in diagnosis are common in the UK, deficiencies in out of hours MRI scanning being a key issue. Inadequate history taking is also a problem. What does this mean for remote management of travellers with worrying symptoms?

Knowledge of red flags of serious spinal pathology is pivotal. Clear communication with patients overseas and maintaining a low index of suspicion for CES are also vital in reducing the risks of a missed diagnosis. In cases where red flags appear, there should be no hesitation in organising MRI of the lumbo-sacral spine. If this means an air ambulance transfer to a regional centre it must be done swiftly, undertaking the transfer with spinal precautions, and to a centre where cauda equina compression appears confirmed on imaging, it can also then be surgically managed by an orthopaedic or neuro-spinal surgeon.

Bladder ultrasound scan to assess function and evaluate likelihood of CES is a useful adjunct. For our case in Indonesia, we were able to ascertain red flags early via direct history taking, and source MRI scanning and a local neurosurgeon for timely decompressive surgery followed by commercial repatriation to the UK for check imaging and neurorehabilitation.

NICE included new, more explicit symptoms for practitioners to check:

• Bilateral sciatica

• Severe or progressive bilateral neurological deficit of the legs • Loss of feeling/pins and needles between inner thighs or genitals

• Numbness in or around the back passage or buttocks

• Altered feeling when using toilet paper

• Increasing difficulty when trying to urinate

• Increasing difficulty when trying to stop or control urine flow

• Inability to sense when passing urine/ could not feel catheter being passed

• Leaking urine or recent need to use pads

• Not knowing when the bladder is either full or empty

• Inability to stop a bowel movement or leaking

• Loss of sensation when passing a bowel motion

• Changes in sexual function

Bladder scans should not be used in isolation or as a discriminator in deciding to request an MRI or undertake surgery – 60% of patients who underwent emergency decompressive surgery for CES have a post void residual (PVR) of 600ml, request catheterisation of the patient and document if sensate and perform a catheter tug.

If a patient is able to void, document the following:

• Pre-void urine volume

• Post-void residual volume (PVR)

• If PVR 200ml in a patient with suspected CES, then CES is 20 times more likely • If PVR >600ml catheterise and document if sensate and catheter tug (this avoids damage to the bladder muscles – bladder distension injury).