In the first of a new series into diagnoses that could easily be missed, Dr Sharon Viner recalls when she spotted a case of cauda equina
Clinical history
A 30-year-old man was seen by the musculoskeletal team for acute on chronic low back pain radiating down his right leg to his foot. The back pain was spontaneous in onset with no history of trauma. The practitioner diagnosed right-sided sciatica; no neural deficit and the patient was managed with self-care exercises.
The man was seen again by the musculoskeletal team five months later with the same but worsening lower back pain radiating to his right leg and foot. He was diagnosed with right sciatica with no neural deficit and referred for a routine MRI scan.
He presented once again to his GP four weeks later with worsening low back pain radiating down the back of his right leg. On further questioning by the GP, he reported occasional pain radiating to his left leg.
He attended the emergency department with the same symptoms four days earlier where he was assessed and discharged home with naproxen.
He denied any lower limb numbness, pins and needles or weakness. There was no saddle anaesthesia or any bladder or bowel dysfunction. However, when specifically asked about incontinence, he recalled an episode of urinary incontinence but had not been alarmed by this.
Examination was unremarkable. There was no spinal tenderness and no lower limb focal neurology. Perianal sensation was intact and anal tone was normal.
Despite a normal examination, the GP had diagnosed developing cauda equina. This diagnosis was based on concerns relating to the history alone, more specifically; the patient’s response to direct questions about urinary flow and continence and questions which probed for any shift from unilateral to bilateral symptoms.
The GP referred the patient the same day to hospital and an MRI showed acute cauda equina compression at L5/S1 due to large central/right paracentral disc extrusion. Urgent discussion with the neurosurgical team was advised. The following day the patient underwent an L5/S1 decompression and discectomy and the procedure was performed without any complications. Prior to the surgery, the neurosurgical team found the patient to have normal peri-anal sensation, intact lower limb dermatomes and myotomes bilaterally and a post void bladder scan volume of 24 mls.
The GP followed up the patient four weeks post-surgery and was pleased to see the man walking normally without any pain or discomfort and no focal neurology.
Learning points for primary care physicians
This case highlights how a normal examination does not rule out cauda equina syndrome and that signs such as saddle anaesthesia and loss of anal tone may be absent. Subtle changes in the history and very specific questioning associated with bladder and bowel control and other red flag symptoms, is vitally important for primary care physicians as may be the only clue that raises suspicion of the condition.
Dr Sharon Viner is a GP in Warrington
this is a good case, which highlights important point in management. which is that history alone should be sufficient to warrant urgent referral. I had similar cases over years, and with very interesting pathology that had caused cauda equina syndrome, history, if properly taken is enough. Refer and if hospital juniors are trying to be obstructive, politely ask for spelling of their names or try to speak to the on call Consultant.