Cauda Equina

Definition

 

Compression of some or all of the nerve roots in the cauda equina

- bladder dysfunction

- bowel dysfunction

- saddle anaesthesia

- variable motor and sensory loss

 

Aetiology

 

HNP

- most common

 

Epidural haematoma

- post surgical

- spinals and anticoagulation

 

Epidural abscess

 

Tumours

- metastatic prostate / lung / breats

 

Trauma

 

Chronic stenosis / spondylithesis

 

Post surgical

- seen post stenosis decompression

- cause unknown

 

Anatomy

 

Spinal cord ends at L1 / conus medullaris

- L3 in children

- spinal cord appears to migrate proximally with growth

- relative greater growth of the spinal column

 

Conus medullaris

- attached to coccyx

- filum terminale

 

Dural sac containing L2 - S5

 

Neurology

 

Lower motor neurone symptoms in leg

- weakness

- sensory loss

- decreased / absent reflexes

 

Bladder dysfunction

 

S2-4 disruption

- parasympathetic nerves

- promote bladder emptying

- contract detrusor & relax internal sphincter

 

Unable to feel bladder filling

 

Unable to void

- retention

- eventual overflow

 

Pathology

 

Nerve roots

- very susceptible to compression

- don't have 3 layers like peripheral nerve roots

- endoneurium only

- then CSF and dura

 

May develop ischaemia

- radicular arteries

- form of compartment syndrome

 

Issue

 

Injury to the sacral nerve roots can be permanent

- need early decompression < 24 hours

- otherwise permanent bladder and bowel dysfunction

 

Symptoms

 

Two groups

- acute presentation - severe pain

- insidious presentation - stenosis / spondylolithesis

 

Bladder dysfunction

- difficulty initiating / stopping stream

- progresses to retention

- progresses to overflow incontinence

 

Bowel

- unable to feel or control / incontinence

 

Other symptoms

- severe back pain

- severe sciatica

- lower leg weakness and parasthesia 

- saddle anaesthesia / can't feel toilet paper

 

Signs

 

Perianal sensation

- may have preserved light touch

- may need pin prick

- S 3,4,5

 

Rectal tone

- decreased

 

Bladder

- full

- increased volume on bladder scan

- cannot feel tug on catheter

 

MRI

 

Usually a disc will take up > 1/3 of canal diameter

 

Management

 

Urgent Decompression

 

Timing

- evidence of improved outcomes for decompression within 48 hours versus > 48 hours

- no evidence for < 24 hours

- reasonable to do so as soon as able

 

Outcomes

 

Buchner and Schiltenwolf Orthopedics 2002

- 17 / 22 regained full urinary function

 

Outcome likely related to

- duration of symptoms / timing of decompression

- severity of initial symptoms / signs / bladder dysfunction