Spinal cord compression (SCC) is simply compression of the spinal cord. Our spinal cord is an extension of our CNS and thus compression of it affects neurological function of the tracts within the compressed region. Spinal cord compression itself isn’t dangerous but when it progresses to irreversible spinal cord injury, then it is a much graver risk.
The spinal cord runs through the vertebrae C1 - L1. It tapers to an end (known as the conus medullaris), approximately at the first lumbar vertebra, with nerve roots L1-S5 and Cox1 leaving from at this region to pass down the spinal canal (as the cauda equina) to exit at their respective foramina.
Pathophysiology
SCC may be due to acute causes or it may be chronic:
Acute spinal cord compression
- Trauma - as seen in falls, RTAs, sports injuries, surgery etc.
- Vertebral fractures - usually in elderly with osteoporotic bone.
- Disc herniation
- Penetrating injuries
- Spinal subluxation
Chronic spinal cord compression
- Neoplasm - slow growing primary tumours can be present, however, it is more common to have metastatic tumours deriving from breast, lung, and prostate.
- Infection - it can be direct involvement or external pressure that then affects the spinal cord. For example, in Pott’s diseas (tuberculous spondylitis) when infection spreads from 2 adjacent vertebra into the intervertebral space.
- Degenerative bone disorders
- Inflammatory conditions - such as rheumatoid arthritis or Ankylosing spondylitis.
- Degenerative conditions - such as ligamentum flavum hypertrophy.
😷 Presentation
- Back pain - most common symptom. It may be worsened with coughing or lying down.
- Paresis - weakness or even atrophy of muscle with long-term compression.
- Sensory changes - numbness and paraesthesia.
- Neurological signs
- Above L1 - usually causes UMN signs (hyperreflexia and spasticity) in the legs.
- Below L1 - usually causes LMN signs (hyporeflexia and flaccidity) in the legs and perianal region.
- Neurogenic shock - bradycardia, hypotension, warm dry extremities, priapism.
- Spinal shock - paralysis, hyporeflexia/areflexia which may last a few weeks after resolution of the compression.
- Bladder/bowel dysfunction - if the lumbar cord is compressed.
- Cauda equina syndrome - presents with saddle anaesthesia, bladder retention/incontinence and leg weakness.
- Central cord syndrome - most common C-spine injury causing a loss of the spinothalamic tract (pain, itch and temperature) in a cape-like distribution.
🔍 Investigations
Imaging:
- MRI - gold-standard investigation. Needs to be done within 24 hours of presentation.
- If infection is the suspected underlying cause then a gadolinium enhanced MRI is more appropriate.
Spinal cord injury as a result of compression may occur without any findings on CT or X-ray. This is referred to as SCI without radiographic abnormality (SCIWORA) and it may warrant a MRI as 2/3rds of cases of SCIWORA have detectable abnormalities on MRI.
🧰 Management
Acute traumatic SCC:
- Immobilisation - with cervical collar or backboard/head strap
- Stabilisation
- VTE prophylaxis
- LMWH - i.e. enoxaparin
- BP and volume monitoring
- Gastric ulcer prophylaxis - as neurological injury coupled with severe physiological stress increases risk of stress-related GI bleeding. It is given for 4 weeks post-SCI.
- Omeprazole
- Cimetidine/famotidine - H2 antagonists.
- Decompressive surgery
Non-traumatic IVD compression (Cauda Equina Syndrome):
- Emergency decompressive laminectomy surgery
- VTE prophylaxis
- BP and volume monitoring
- Gastric ulcer prophylaxis
- Nutritional support
Malignant SCC:
- Corticosteroids
- IV dexamethasone
- Methylprednisolone
- ± Surgery
- ± Radiotherapy
- VTE prophylaxis
- BP and volume monitoring
- Gastric ulcer prophylaxis
- Nutritional support
Epidural abscess (infective SCC):
- Empirical IV antibiotics - S. aureus is the most common causative agent.
- Vancomycin + metronidazole + cefotaxime
- ± Surgery
- VTE prophylaxis
- BP and volume monitoring
- Gastric ulcer prophylaxis
- Nutritional support
Let’s now discuss cauda equina syndrome specifically:
CAUDA EQUINA SYNDROME (CES)
CES occurs when there is SCC at the level of the lumbosacral nerve roots. It is a surgical emergency that, if not treated promptly, can lead to permanent disability.
The most common cause of CES is a herniated disc but any of the aforementioned causes may result in CES.
🔢 Classification
We can classify CES into levels of severity based on the presenting symptoms:
- CES with retention (CESR) - dural sac compression with established neurogenic urinary retention.
- Incomplete CES (CESI) - dural sac compression with subjective symptoms (e.g., difficulty urinating or a loss of desire to urinate, but no retention) and objective signs of CES.
- CES suspected (CESS) - dural sac compression with bilateral radiculopathy and/or subjective sphincter problems and/or subjective perineal sensory changes with no objective evidence of CES.
😷 Presentation
Cauda equina syndrome results in lower motor neurone signs and symptoms:
- Pain:
- Severe back pain
- Radicular pain (pain along a specific dermatome)
- Sciatica - bilateral (50% of cases), unilateral, or absent
- Bowel & rectum:
- Bowel dysfunction and incontinence - due to loss of anal sphincter control, and due to affecting the nerves of the bowel.
- Loss of bulbocavernous reflex (Osinski reflex)
- Bladder:
- Bladder dysfunction (retention) - this is a key feature to assess. Confirmed retention or reduced ability to void (loss of desire, reduced urinary sensation) suggests complete or incomplete CES respectively.
- Urinary incontinence may resulte from overflow from retention.
- Motor:
- Lower limb muscle weakness - some patients never develop it, however.
- Sensory:
- Reduced lower limb sensation and reduced rectal tone - may be unilateral or bilateral.
- 🚩 Saddle anaesthesia/paraesthesia - this is the lack of sensitivity in the dermatomes S3–S5, affecting the areas around the anus, genitalia, and inner thighs (may be asymmetric). Saddle anaesthesia is typical of CES, and is a “red flag”. More subtle presentations of saddle sensation (e.g., numbness, 'pins and needles') should be sought, especially in patients with low back pain and bilateral sciatica.
- Sexual dysfunctions:
- Impotence
🔍 Investigations
- Clinical history and physical examination - assessing specifically for saddle anaesthesia, lower limb anaesthesia, lower limb weakness and hyporeflexia.
- Digital rectal examination - to assess anal tone (may be lost in CES)
- Post-void bladder scan - may indicate urinary retention.
- 🏆 Lumbosacral spine MRI - however, only a minority of patients suspected to have CES from clinical assessment have an abnormality found on MRI.
🧰 Management
CES is a surgical emergency:
- 🥇 🏆 Urgent decompressive surgery (laminectomy) - to prevent permanent sphincter and lower limb dysfunction, especially for those with incomplete CES as the prognosis is potentially more favourable. It is said that patients should be operated within 24-48 hours to prevent permanent motor and sensory deficits.
- Bladder catheterisation - if there is urinary retention.
- Bowel programme (laxatives and/or bowel evacuation) - may be required to help to prevent involuntary bowel movements, constipation, and impaction of the bowels.
The same measures as with all other SCC also apply:
- VTE prophylaxis
- BP and fluid level maintenance
- Nutritional support
- Prevention of gastric ulcers
- Radiotherapy and/or chemotherapy or IV steroids - in rare situations like malignancy.