Cervical and lumbar spondylosis, spinal cord compression and intrinsic cord disease

Overview

The spinal cord runs from the medulla at C1 to the lower border of L1, where it ends as the conus medullaris. Below that the canal holds the cauda equina (lumbar and sacral roots).

• A lesion of the cord gives upper motor neurone (UMN) signs below the level, a sensory level and bladder problems.
• A lesion of a root gives pain, lower motor neurone (LMN) signs and sensory loss in that root's territory.
• A lesion of the cauda equina gives LMN signs in both legs, saddle numbness and sphincter failure.

Spinal disorders are a major cause of disability, and two of them (acute cord compression and cauda equina syndrome) are surgical emergencies where hours matter.

Spondylosis: what degenerates

Spondylosis is age-related wear of the spine. The changes are very common on imaging after 40, often without symptoms, so scans must be read alongside the clinical picture.

• The intervertebral disc dries out, loses height and develops fissures; the inner nucleus pulposus may bulge or herniate through the outer annulus fibrosus, usually posterolaterally where the posterior longitudinal ligament is weakest.
• Osteophytes (bony spurs and bars) form on the vertebral margins.
• Facet joints develop osteoarthritis.
• The ligamentum flavum thickens and buckles.
• Result: narrowing of the spinal canal (cord or cauda equina compression) and of the intervertebral foramina (root compression).

Cervical spondylosis

Commonest at C5/6 and C6/7. The patient is usually over 40.

1. Neck pain and stiffness

Pain and stiffness, often worse on waking, radiating to the occiput, shoulders and between the scapulae; flare-ups with long quiet spells.

2. Cervical radiculopathy (root compression)

Caused by a lateral disc protrusion or osteophytes narrowing the root canal.

• Sharp, electric arm pain in a root distribution, tingling, numbness, weakness and loss of the reflex for that root.
• C7 is the commonest single root affected.

• Treatment: most settle with rest, analgesia, a soft collar for a short time and physiotherapy. Root decompression for persistent pain or progressive weakness.

3. Cervical spondylotic myelopathy (cord compression)

• Posterior disc bulges, osteophyte bars and a thick ligamentum flavum squeeze the cord, often in a congenitally narrow canal; ischaemia contributes.
• The commonest cause of spastic paraparesis in an elderly person.
• Often little neck pain. The patient notices slowly worsening stiff, clumsy legs and a spastic gait, clumsy numb hands, and later urinary urgency.
• Signs:
  • UMN signs in the legs: spasticity, brisk reflexes, extensor plantars.
  • LMN signs in the arms at the level of compression (wasting, lost reflex) with UMN signs below it. The classic "inverted supinator jerk" at C5/6: tapping brachioradialis produces finger flexion but no forearm flexion.
  • Lhermitte's sign: electric shock down the spine on bending the neck.
  • Loss of joint position and vibration in the hands and legs.
• Investigation: MRI shows the level, the degree of compression and signal change in the cord.
• Treatment: avoid neck manipulation. Surgical decompression (for example anterior cervical discectomy and fusion, or laminoplasty) if severe or progressing; surgery mainly halts progression rather than reversing damage.

Lumbar spondylosis

Commonest at L4/5 and L5/S1.

Mechanical low back pain

• Very common; disc or facet joint pain without root signs.
• Keep active, simple analgesia, physiotherapy and exercise; avoid prolonged bed rest. Most attacks settle whatever the treatment.

Acute lumbar disc prolapse (sciatica)

• Often starts suddenly with lifting, bending or twisting, but disc degeneration is the underlying cause.
• Low back pain plus sciatica: sharp pain shooting from the buttock below the knee into the leg and foot, with tingling and numbness; worse on coughing and sneezing.
• Scoliosis from muscle spasm.
• Straight leg raise is limited: lifting the straight leg past about 30 degrees reproduces pain shooting below the knee. Crossed straight leg raise (pain on lifting the good leg) suggests a large or central prolapse.
• A posterolateral disc compresses the root that exits one level below: L4/5 disc → L5 root; L5/S1 disc → S1 root.

• Management: analgesia and early mobilisation; most cases settle without surgery. MRI if symptoms persist, for red flags, or before surgery. Discectomy (microdiscectomy) for persistent disabling sciatica with a matching disc on MRI, progressive weakness, or cauda equina.

Lumbar spinal stenosis and neurogenic claudication

• Narrowing of the canal and lateral recesses by disc bulge, facet osteoarthritis, thick ligamentum flavum and degenerative spondylolisthesis, usually in people over 50.
• Neurogenic (spinal) claudication: aching, heaviness, numbness and tingling in both buttocks and legs after standing or walking a certain distance.
• Relieved by sitting, squatting or bending forward (flexion widens the canal), not by just standing still. Patients can often walk further uphill or pushing a trolley, and cycle comfortably.
• Foot pulses are normal; neurological signs may appear only after walking.
• MRI confirms the level. Treatment: physiotherapy, analgesia, weight loss; surgical decompression (laminectomy) for severe symptoms, which relieves leg pain better than back pain.

Spondylolisthesis

Forward slip of one vertebra on the one below: from pars interarticularis defects (spondylolysis) in adolescents, or degenerative in older people with facet arthritis (commonly L4 on L5). It can cause back pain, root pain or stenosis, rarely cauda equina syndrome.

Red flags in back pain

First onset in a child or an older adult, history of cancer, weight loss, fever or immunosuppression, IV drug use, TB contact, night pain or constant non-mechanical pain, thoracic pain, saddle anaesthesia, sphincter disturbance, progressive neurological deficit, and major trauma. These need urgent imaging.

Cauda equina syndrome

• Compression of the lumbosacral roots below the conus, most often by a large central L4/5 or L5/S1 disc prolapse; also tumour, abscess, haematoma, or stenosis.
• Features:
  • Bilateral sciatica and leg weakness (may be asymmetric).
  • Saddle (perineal) anaesthesia.
  • Urinary retention (painless, with overflow), loss of anal tone, faecal incontinence, erectile dysfunction.
  • Flaccid (LMN) weakness with reduced reflexes; plantars not extensor.
• Emergency: urgent MRI and surgical decompression within hours to save bladder function.

Spinal cord compression

Causes

Clinical features

• Back or root pain first, often a band-like pain around the chest at the level, worse on coughing, straining or lying flat; often at night.
• Spastic weakness of the legs (paraparesis) or all four limbs (tetraparesis) developing over hours, days or months. In a very acute lesion there may be spinal shock: flaccid, areflexic legs at first, with UMN signs appearing later.
• Sensory level: numbness rising from the feet up to a level on the trunk, usually a little below the true level of compression.
• Bladder and bowel: urinary retention, constipation (often later in slow compression).
• Below the level: brisk reflexes, extensor plantars. At the level: LMN signs and root pain.

Investigations

• MRI of the whole spine: the investigation of choice (metastases often occur at more than one level).
• CT if MRI is unavailable or contraindicated; CT-guided biopsy when the cause is unknown.
• Chest X-ray (primary lung cancer, TB), PSA, protein electrophoresis (myeloma), blood cultures, ESR/CRP, Mantoux/interferon-gamma test for TB.

Management

• Malignant compression: high-dose corticosteroids (dexamethasone) at once, analgesia, and urgent neurosurgical and oncology review. Surgical decompression and stabilisation for suitable patients (single level, good performance status, unstable spine); radiotherapy for others or after surgery.
• Spinal TB: anti-tuberculous treatment (often longer than for lung TB); surgery for cord compression not improving, instability or large abscess. Pott paraplegia can recover well with treatment.
• Epidural abscess: drainage plus antibiotics.
• Benign tumours and haematomas: early removal gives excellent results.
• General care of paraplegia: bladder catheterisation, bowel care, pressure area care, DVT prophylaxis, physiotherapy, and rehabilitation.

Intrinsic (intramedullary) cord disease

Syringomyelia

• A fluid-filled cavity (syrinx) in the centre of the cervical cord, usually linked to an Arnold–Chiari malformation; also after cord trauma or with intrinsic tumours. Syringobulbia = cavity extending into the brainstem.
• Symptoms often begin at 20–30 years.
• Pathophysiology: the syrinx first destroys the crossing spinothalamic fibres in the centre of the cord, then the anterior horn cells and corticospinal tracts.
• Features:
  • Dissociated sensory loss: lost pain and temperature with preserved light touch, vibration and joint position, in a "cape" (shawl) distribution over the shoulders and arms.
  • Painless burns and cuts on the hands; Charcot (neuropathic) joints of the shoulder and elbow.
  • Wasting of small hand muscles and lost arm reflexes (LMN at the level).
  • Spastic paraparesis (UMN below).
  • Horner syndrome; with syringobulbia: tongue wasting and fasciculation, bulbar palsy, facial sensory loss, nystagmus.
• MRI shows the cavity and descended cerebellar tonsils. Foramen magnum decompression often collapses the syrinx.

Transverse myelitis

• Acute inflammation across the whole width of one or two cord segments, evolving over hours to days: back pain, weakness, a sensory level and sphincter loss.
• Causes: post-infectious or post-vaccination (commonest), multiple sclerosis, neuromyelitis optica (long lesion over 3 or more segments, aquaporin-4 antibodies, with optic neuritis), SLE, sarcoidosis, infections (varicella zoster, HIV, HTLV-1, TB, syphilis, schistosomiasis).
• MRI shows cord swelling and enhancement; CSF may show lymphocytes.
• Treatment: high-dose steroids or other immunotherapy; treat infection. Recovery is often partial.

Anterior spinal artery occlusion

• The anterior spinal artery supplies the anterior two-thirds of the cord; the thoracic part depends on the artery of Adamkiewicz.
• Causes: aortic surgery or cross-clamping, aortic dissection, atherosclerosis, hypotension, vasculitis, emboli.
• Sudden paraplegia, loss of pain and temperature below the level, sphincter loss, but preserved joint position and vibration (dorsal columns, supplied by the posterior spinal arteries). Blocking the artery of Adamkiewicz gives a watershed infarct, typically around T8, where the cord's blood supply is poorest.
• Poor prognosis among incomplete cord syndromes.

Subacute combined degeneration of the cord (vitamin B12)

• The commonest metabolic cord disease. Dorsal columns and lateral corticospinal tracts degenerate, often with a peripheral neuropathy.
• Loss of vibration and joint position, sensory ataxia (Romberg positive), with extensor plantars but absent ankle jerks.
• Nitrous oxide abuse can precipitate it. Treat with hydroxocobalamin; do not give folate alone. (Covered in the B12 chapter.)

Other causes of spastic paraparesis

• Motor neurone disease (no sensory signs), multiple sclerosis, hereditary spastic paraparesis (stiffness more than weakness; baclofen helps), tropical spastic paraparesis (HTLV-1), lathyrism (eating grass pea, seen in parts of South Asia during famine), copper deficiency, radiation.
• Dural arteriovenous fistula: middle-aged men, slowly progressive myelopathy with back pain, worse with exercise; MRI cord swelling with dilated surface veins; treated by endovascular glue or surgery.
• A parasagittal meningioma pressing on both leg areas of the motor cortex can mimic a cord lesion.

Spinal cord syndromes at a glance

Quick revision

• Cord ends at L1 (conus); below is the cauda equina.
• Cervical spondylosis: C5/6, C6/7; radiculopathy (C7 commonest root) and myelopathy (UMN legs, LMN arms at level); MRI; decompress if progressive.
• Lumbar disc: L4/5 → L5 (big toe extension, dorsum of foot); L5/S1 → S1 (ankle jerk, plantar flexion, lateral foot).
• Spinal stenosis: leg pain on walking or standing, eased by sitting or bending forward, normal pulses.
• Cauda equina: saddle numbness, retention, bilateral LMN legs → urgent MRI and surgery.
• Cord compression: metastases, TB (Pott), abscess, disc, meningioma; band pain, spastic legs, sensory level; whole-spine MRI; steroids, surgery, radiotherapy within 24 hours.
• Syringomyelia: cape-like loss of pain and temperature, wasted hands, Charcot joints, Arnold–Chiari.
• Anterior spinal artery: paraplegia, lost pain and temperature, dorsal columns spared.
• Brown-Séquard: same-side weakness and proprioception loss; opposite-side pain and temperature loss.

Written by The House Job from standard references (Kumar and Clark's Clinical Medicine; Apley's System of Orthopaedics and Fractures; ATLS Student Course Manual).

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