Spinal Cord Compression and Cauda Equina Syndrome
Spinal cord compression is a neurological emergency caused by compression of the spinal cord, commonly due to trauma, metastatic disease, epidural abscess or epidural haematoma. Cauda equina syndrome affects the lumbosacral nerve roots rather than the spinal cord.
Relevant Anatomy
In adults, the spinal cord usually ends at around the L1-L2 vertebral level, forming the conus medullaris.
Below this, the spinal canal contains the descending lumbosacral nerve roots, known as the cauda equina (Latin for “horse’s tail”).
Causes
There are 4 main causes of spinal cord compression: [Ref]
| Cause category | Description |
|---|---|
| Traumatic injury | Acute spinal trauma can cause compression due to disc herniation, vertebral fracture with bone fragments pushed posteriorly into the spinal canal, or vertebral subluxation/dislocation narrowing the spinal canal. |
| Metastatic spinal cord compression | Metastases to the vertebral column can extend into the epidural space, producing a mass effect on the spinal cord or cauda equina. |
| Epidural abscess | Bacterial infection in the spinal epidural space can form an abscess, causing compression by mass effect.
Neurological injury may also occur due to inflammation, oedema and vascular compromise. |
| Epidural haematoma | Bleeding into the spinal epidural space can form an expanding haematoma, causing acute compression of the spinal cord or cauda equina. |
Clinical Features
Note: Cauda equina syndrome is not true spinal cord compression anatomically, as it affects the lumbosacral nerve roots rather than the spinal cord.
Importantly, cauda equina syndrome causes LMN signs because it affects the lumbosacral peripheral nerve roots rather than the spinal cord. In contrast, “true” spinal cord compression usually causes UMN signs below the level of the lesion.
| Upper motor neuron (UMN) signs | Lower motor neuron (LMN) signs |
|---|---|
|
|
Cauda Equina Syndrome
Key red flag features for cauda equina syndrome:
- Sudden onset bilateral sciatica (or unilateral sciatica progressing to bilateral)
- Severe or progressive bilateral lower limb neurological deficit (e.g. major motor weakness with knee extension, ankle eversion, foot dorsiflexion)
- Difficulty walking / gait disturbance
- Saddle anaesthesia / paraesthesia (sensory loss in the perianal, perineal, genital regions)
- Reduced anal sphincter tone (laxity)
- Erectile dysfunction
- Urinary dysfunction: impaired sensation of urinary flow / difficulty initiating micturition
- Bowel dysfunction: loss of sensation of rectal fullness
Late, advanced features include:
- Urinary retention with overflow urinary incontinence
- Faecal incontinence
Spinal Cord Compression
General features of spinal cord compression: [Ref]
- Localised neck or back pain
- Symmetrical limb paralysis
- Sensory level – a clear level on the trunk below which sensation is reduced or altered
- UMN signs below the level of the lesion +/- LMN signs at the level of the lesion
- Urinary retention or incontinence
In acute spinal cord compression (e.g. traumatic spinal cord compression), patients may develop spinal shock, with temporary loss of spinal cord function below the level of the lesion.
This can initially cause LMN-like features (e.g. hypotonia, areflexia) and reduced autonomic function (e.g. hypotension). As spinal shock resolves, UMN signs may become evident, such as spasticity, hyperreflexia and an extensor plantar response.
Clinical features as per cord syndromes (the affected anatomical areas of the spinal cord):
| Syndrome | Clinical presentation |
|---|---|
| Complete transverse myelopathy | Everything below the lesion is affected:
|
| Brown-Séquard syndrome (hemisection syndrome) |
The classic ‘crossed findings’ in Brown-Séquard are closely related to the spinal tract decussation concept |
| Anterior cord syndrome |
Dorsal columns (situated posteriorly) are spared, thus vibration / proprioception |
| Posterior cord syndrome |
Corticospinal and spinothalamic tract (situated anteriorly) are spared, thus motor function, pain and temperature sensation. |
| Central cord syndrome | Primarily affects the medial corticospinal tract fibres supplying the upper limbs
|
Conus medullaris syndrome
- Caused by compression of the terminal spinal cord (called: conus medullaris) at ~L1-L2 vertebral level
- The conus medullaris sits at the transition between the spinal cord and cauda equina, thus causing mixed UMN and LMN signs
- Typical presentation
- Mixed UMN and LMN signs
- Early bladder / bowel / sexual dysfunction
- Saddle anaesthesia / paraesthesia
Cause-Specific Clinical Features
| Cause of spinal cord compression | Clinical clues |
|---|---|
| Traumatic injury |
|
| Metastatic spinal cord compression |
|
| Epidural abscess |
|
| Epidural haematoma |
|
Investigation and Diagnosis
Gold standard / 1st line imaging: MRI [Ref]
- For suspected metastatic spinal cord compression, MRI of the entire spine should be performed to ensure additional lesions are not missed
Exception: in trauma (i.e. suspected traumatic spinal cord compression), CT is the preferred initial imaging study as it is highly sensitive [Ref]
Additional investigations depending on underlying cause:
- Epidural abscess → blood cultures and inflammatory markers (WBC, CRP, ESR)
- Epidural haematoma → clotting profile (including platelet count, INR, aPTT)
Management
Management depends on the specific underlying cause identified during the diagnostic work-up.
Traumatic Spinal Cord Compression
- Initial medical management
- Primary focus: BP control (hypotension is associated with poor neurological outcomes)
- Bladder catheterisation
- Definitive management: surgery
- Decompression and reduction
- Fixation and fusion for long-term stability
Corticosteroids are NOT routinely recommended in traumatic spinal cord compression.
Metastatic Spinal Cord Compression
Immediate Management
| Corticosteroid therapy | Immediately give oral dexamethasone 16 mg
If metastatic spinal cord compression is suspected clinically, give corticosteroids immediately without waiting for MRI confirmation. If subsequent MRI excludes the diagnosis, the corticosteroid can be discontinued. |
| Pain management | Provide prompt analgesia
If conventional analgesia fails in breast cancer / prostate cancer / myeloma → offer bisphosphonates for pain relief and fracture risk reduction |
If patients have suspected or confirmed metastatic spinal cord compression and neurological signs of spinal instability → immobilise them in a supine position to minimise weight-bearing on the spine
Definitive Management
1st line: surgical decompression
- Surgery should be offered ASAP after neurological signs or symptoms appear
- Also offer surgical stabilisation for those with spinal instability
If the patient is NOT suitable for spinal surgery → urgent radiotherapy
Compression from Epidural Abscess
- Immediate management: IV antibiotics
- Definitive management: surgery (surgical evacuation combined with irrigation, biopsy, and culture)
Compression from Epidural Haematoma
- Immediate management: reverse any anticoagulation or platelet dysfunction
- Definitive management: surgical evacuation of the blood clot if the haematoma is actively compressing the spinal cord