Cauda Equina Syndrome Flashcards
What is the cauda equina?
Bundle of nerves situated inferior to the spinal cord.
The spinal cord tapers to an end (conus medularis) at L1.
Nerve roots L1-S5 leave from this region to pass down the spinal canal as the caudal equina to exit at their respective formaina - (below the respective vertebra)
Cauda equina if formed by lower motor neurones, containing motor, sensory to the lower limbs, motor innervation to the anal sphincters and parasympathetic innervation to the bladder.
Describe the innervation of the bladder
Sympathitic nervous system comminicates with the bladder via the hypogastric nerve (T12-L2). It causes relaxation of the detrusor muscle promoting urinary retention.
The parasympathetic nervous system communicates weight the bladder via the pelvic nerve (S2-S4) causing contraction of the detrusor muscle simulating micturition.
Somatic nervous supply gives voluntary control over micturition - innervates external urethral sphincter via the pudendal nerve (S2-S4) - can cause it to constrict in storage or relax in micturition - somatic control of urinary continence.
Describe the innervation of the anal canal and sphincter
Anal canal is divided into upper and lower parts by the pectinate line.
Above is derived from the hindgut - visceral innervation via inferior hypogastric plexus - sensitive to stretch
Below is derived form the ectoderm - somatic innervation from inferior anal nerves (branches of pudendal), sensitive to pain, temperature, touch and pressure
Inferior rectal nerve (from pudendal nerve (S2-S4)) provides motor supply to the external anal sphincter providing the somatic control of faecal continence.
S2-S4 keeps poo off the floor!
What causes cauda equina syndrome?
Compression of the cauda equina due to:
Disc herniation
Trauma - vertebral fracture/sublaxation - incomplete/partial dislocation
Neoplasm - cancer from thyroid, breast, lung, renal, prostate spread to vertebrae
Infection - discitis/Pott’s disease - TB of the spine
Ankylosing spondylitis - inflammation
Iatrogenic - haematoma secondary to spinal anaesthesia
What are the most common sites of disc herniation?
L5/S1 (younger pts) L4/L5
What are the symptoms and signs of cauda equina syndrome?
Reduced lower limb sensation
Perianal anaesthesia (saddle anaesthesia)
Urinary retention with secondary overflow incontinence
Faecal incontinence due to loss of anal tone
LL motor weakness and hyporeflexia
Severe back pain
Impotence
What suggests complete s incomplete CES?
Confirmed urinary retention suggests complete CES
Reduced ability to void (loss of desire, reduced urinary sensation ) suggests incomplete CES
What examination will a pt require?
PR exam for anal tone
Post-void bladder scan
What are differential diagnoses for back pain?
Radiculopathy (pinched nerve secondary to some other factor causing neuropathy)- radiating back pain but no faecal, urinary, sexual dysfunction
Cord compression - Upper motor neurone signs
What investigation are required for CES
Whole spine MRI is gold standard
What is the management of CES?
Neurosurgical review for urgent decompression
High dose steroids (dexamethasone) reduce any localised swelling
Immobilisation if there is trauma
Radiotherpay/chemo for malignancy
