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Failure to act on cauda equina

13 April 2018
By Dr Ellen Welch, GP

Mr X, a 25-year-old fit and active man, was reviewed by his GP, Dr A, with a recurrence of lower back pain. He had noticed lumbar back pain intermittently throughout his 20s, but played a lot of sports to which he attributed his symptoms. On this occasion, he described lumbar back pain radiating into both thighs, along with cramping in both feet. He had no other worrying features, so a repeat prescription for his usual analgesia was given.

Six months later, he returned to see Dr A, this time complaining of difficulty passing urine. Mr X recalled telling Dr A about his ongoing back problems, but this was not documented and Dr A did not recollect any back pain being mentioned. A urinalysis was negative and Mr X was given antibiotics for a presumed urinary tract infection. 

Two months later, Mr X collapsed whilst playing football, complaining of a sudden onset headache. He was admitted under the care of Mr B’s neurosurgical team and assessed by the locum doctor on duty. His head CT was unremarkable so a lumbar puncture was carried out, which showed blood in his CSF. The locum diagnosed a migraine. While in hospital, Mr X went into urinary retention and required catheterisation. The patient decided to discharge himself and left the hospital with the catheter still in situ, removing it himself at home the following day.

His symptoms persisted and, a week later, Mr X returned to the GP surgery to consult again with Dr A. He complained this time of both lumbar back pain and difficulty passing urine, which prompted Dr A to arrange an urgent MRI scan of his lumbar spine. This was carried out two weeks later and revealed an arterio-venous malformation (AVM) in the lumbar region, with a normal spinal cord and no evidence of nerve root compression. 

Dr A wrote to Mr B to advise him of the MRI result, and Mr X was seen in the outpatient clinic three weeks later, by which time he had saddle anaesthesia and numb, weak legs, and was incontinent of urine and faeces. He underwent embolisation of his AVM, but unfortunately his symptoms did not resolve. 

Mr X made a claim against both Dr A and the hospital.
 
Expert opinion
Expert opinion was critical of all involved in the case. The hospital breached their duty of care by failing to suspect, detect and treat the spinal pathology during the hospital admission. The GP experts agreed that Dr A had failed to diagnose bilateral sciatica when Mr X first presented. They agreed that bilateral sciatica is a red flag symptom that warrants urgent referral to the back clinic. They criticised Dr A’s failure to document a physical examination, including straight leg raise and neurological testing.

Dr A and Mr X had different recollections of what was discussed during the second presentation at the surgery. The GP experts agreed that regardless of whether or not Mr X mentioned his back pain, Dr A should have explored potential neurological causes for Mr X’s urinary symptoms, including specific enquiries regarding the back pain he mentioned in the previous consultation. Furthermore, they agreed that it is unusual for a UTI to be present with a negative urine dip test, and they criticised Dr A’s  failure to recognise urinary retention with back pain, and admit Mr X to hospital that same day to exclude cauda equina syndrome. 

Once the AVM had been discovered on the MRI ordered by Dr A, the consensus among the experts was that the GP should have urgently sought the advice of a neurosurgeon, rather than leaving Mr X a further three weeks to have an outpatient appointment.

The experts conceded that on the balance of probability, there would have been no neurological findings the first two occasions Mr X consulted Dr A. It was also agreed that, had the AVM been detected and treated before Mr X collapsed, or even during his hospital admission, it is likely that he would not have been left with persisting neurological deficits.
 
Outcome
The case was settled for a high sum, with a 25% contribution from Medical Protection on behalf of Dr A.
 
Learning points
  • Missed cauda equina syndrome comes up again and again in Casebook. The presence of red flag symptoms in back pain indicates the need for further investigations and specialist referral. 

  • Think twice before attributing urinary symptoms to infection where presentation is atypical. Even when there is urine dip evidence of infection, consider that infection can co-exist with retention and specifically enquire about the presence of other neurological symptoms.

  • When tests reveal unfamiliar pathology outside your scope of knowledge, it is prudent to seek advice from the relevant specialist sooner rather than later.

  • Unfortunately, we can’t always rely on our colleagues to have done the right thing. If a patient presents with concerning symptoms that persist after specialist investigations, take any action necessary to ensure the patient is reassessed with the appropriate degree of urgency.