22. Cauda Equina Syndrome Flashcards
A 50-year-old woman presents 4 weeks after receiving an epidural
steroid injection for chronic back pain.
She is now experiencing severe back pain and perineal numbness.
What is the differential diagnosis?
Chronic mechanical lower back pain
Lumbar disc pathology
Spinal cord compression from infection, neoplasm or haematoma
Guillain–Barre syndrome
Peripheral nerve disorder
Conus medullaris syndrome
Lumbosacral plexopathy
What are the causes of cauda equina syndrome?
- Vertebral disc herniation
Central disc prolapse – incidence of 1%–15% - Neoplasm
Metastatic prostate cancer, ependymomas, schwannomas - Inflammatory
Infective e.g. spinal abscess
Non-infective Diseases which predispose to developing
vertebral fractures or spinal stenosis, e.g. Paget’s disease - Lumbar spinal stenosis
- Trauma
Violent Injuries to the lower back (gunshots, falls and road traffic accidents) - Post-operative lumbar spine surgery complications
- Spinal and epidural anaesthesia resulting in an abscess or haematoma
- Epidural steroid injection
What further history would you seek from her?
A history of severe low back pain
Weakness of her legs
Pain in one or, more commonly, both legs
Saddle anaesthesia – Does wet toilet paper feel wet?
A recent onset of bladder dysfunction, which may manifest as an inability to
initiate or stop a stream of urine or as overflow incontinence
Recent onset of faecal incontinence
Sensory abnormalities in the bladder or rectum
Recent onset of sexual dysfunction
Severe recent trauma to her back
Recent lumbar spine surgery
A history of cancer
Recent severe infection
Spinal or epidural analgesia
What are the signs of the cauda equina syndrome
Saddle anaesthesia.
Residual urine on bladder catheterization indicative of a neurogenic bladder.
Lower motor neuron weakness is found in the plantar flexors and evertors.
Lower limb reflexes are absent or impaired.
Loss of anal tone.
What are the markers of infection?
ESR and CRP
What further investigations would you carry out?
- Haematology
FBC, INR, APTT - Biochemistry
Urea, electrolytes and LFT’s
Radiology
Plain X-ray may reveal vertebral fractures, tumour or infection
CT scan
An urgent MRI scan is probably the gold standard investigation
to confirm and localise the lesion.
Anatomy relating to the cauda equina
The anatomy of the distal spinal cord and
the cauda equina is responsible for the inconsistency
in presenting signs and symptoms.
The conus medullaris is narrower than the more cephalad
spinal cord and overlies the body of L1.
It represents the termination of the spinal cord in
the proximal lumbar spine.
The conus medullaris continues to taper to form the filum terminale.
The bridle of lumbar and sacral nerves descends
below the conus medullaris to form the cauda equina or horse’s tail.
Roots:
The lumbar and sacral nerve roots contain:
Sensory and motor function for the lower limbs
Sensation to the perineum and genitals
Voluntary and involuntary functions:
micturition, defaecation and sexual function.
Compression of the cauda equina may involve
all of the above functions,
sensory only,
motor only, or
only those roots responsible
for bowel and bladder function.
