DISORDERS OF THE SPINE AND SPINAL CORD

DISORDERS OF THE SPINAL NERVES AND SPINAL CORD

DR. BASHAR SHAKER


The spinal cord and spinal roots may be affected by intrinsic disease or by disorders of the surrounding meninges and bones. The clinical presentation of these conditions depends on the anatomical level at which the cord or roots are affected, as well as the nature of the pathological process involved. It is important to recognise when emergency surgical intervention is necessary and to plan investigations to identify such patients.

COMPRESSION OF THE SPINAL CORD

Acute spinal cord compression is one of the most common neurological emergencies encountered in clinical practice. A space-occupying lesion within the spinal canal may damage nerve tissue either directly by pressure or indirectly by interfering with blood supply. Oedema from venous obstruction impairs neuronal function, and ischaemia from arterial obstruction may lead to necrosis of the spinal cord. The early stages of damage are reversible but severely damaged neurons do not recover; hence the importance of early diagnosis and treatment.

Tumours (e.g. glioma, ependymoma, metastasis)

5 %
Spinal cord (intradural intramedullary)
Tumours (e.g. meningioma, neurofibroma, ependymoma, metastasis, lymphoma, leukaemia)Epidural abscess
15 %
Meninges (intradural extramedullary)
Trauma (extradural) Intervertebral disc prolapse Metastatic carcinoma (e.g. breast, prostate, bronchus) MyelomaTuberculosis
80 %
Vertebral
Causes
Frequency
Site

CAUSES OF SPINAL CORD COMPRESSION

Clinical features


The onset of symptoms of spinal cord compression is usually slow (over weeks), but can be acute as a result of trauma or metastases, especially if there is associated arterial occlusion.

SYMPTOMS OF SPINAL CORD COMPRESSION

Pain Localised over the spine or in a root distribution, which may be aggravated by coughing, sneezing or straining Sensory Paraesthesia, numbness or cold sensations, especially in the lower limbs, which spread proximally, often to a level on the trunk Motor Weakness, heaviness or stiffness of the limbs, most commonly the legs Sphincters Urgency or hesitancy of micturition, leading eventually to urinary retention


Pain and sensory symptoms occur early, while weakness and sphincter dysfunction are usually late manifestations.  The signs vary according to the level of the cord compression and the structures involved.  There may be tenderness to percussion over the spine if there is vertebral disease, and this may be associated with a local kyphosis.  Involvement of the roots at the level of the compression may cause dermatomal sensory impairment and corresponding lower motor signs.  Interruption of fibres in the spinal cord causes sensory loss

SIGNS OF SPINAL CORD COMPRESSION

Cervical, above C5 Upper motor neuron signs and sensory loss in all four limbs Diaphragm weakness (phrenic nerve) Cervical, C5 to T1 Lower motor neuron signs and segmental sensory loss in the arms; upper motor neuron signs in the legs Respiratory (intercostal) muscle weakness Thoracic cord Spastic paraplegia with a sensory level on the trunk Conus medullaris Lesions at the end of the spinal cord cause sacral loss of sensation and extensor plantar responses Cauda equina Spinal cord ends at approximately the T12/L1 spinal level and spinal lesions below this level can only cause lower motor neuron signs by affecting the cauda equina

INVESTIGATION OF ACUTE SPINAL CORD SYNDROME

Plain X-rays of spine may show bony destruction and soft-tissue abnormalities and are an essential initial investigation Chest X-rays may provide evidence of systemic disease MRI of spine is the investigation of choice; myelography also localises the lesion and, with CT in suitable cases, defines the extent of compression and associated soft-tissue abnormality CSF should be taken for analysis at the time of myelography. In cases of complete spinal block this shows a normal cell count with a very elevated protein causing yellow discoloration of the fluid (Froin's syndrome). Acute deterioration may develop after myelography and the neurosurgeons should be alerted before it is undertaken. Serum B12 Needle biopsy is required prior to radiotherapy to establish the histological nature of the tumour.

Loss of vertebral pedicle (arrow) by bony erosion of an osteolytic metastasis

An osteosclerotic metastasis


A neurofibroma is compressing the spinal cord and emerging in a 'dumbbell' fashion through the vertebral foramen into the paraspinal space.

Management

Treatment and prognosis depend on the nature of the underlying lesion. Benign tumours should be surgically excised, and a good functional recovery can be expected unless a marked neurological deficit has developed before diagnosis. Extradural compression due to malignancy is the most common cause of spinal cord compression in developed countries and has a poor prognosis, although useful function can be regained if treatment is initiated within 24 hours of the onset of severe weakness or sphincter dysfunction. Surgical decompression may be appropriate in some patients, but has a similar outcome to radiotherapy. Spinal cord compression due to tuberculosis is common in some areas of the world, and requires surgical treatment if seen early. This should be followed by appropriate anti-tuberculous chemotherapy for an extended period. Traumatic lesions of the vertebral column require specialised neurosurgical treatment.

Vitamin B12 deficiency (subacute combined degeneration)

Metabolic

Glioma, ependymoma

Neoplastic

Diastematomyelia (spina bifida)

Hereditary spastic paraplegia
Congenital
Clinical features
Condition
Type of disorder

INTRINSIC DISEASES OF THE SPINAL CORD

Anterior spinal artery infarct Intervertebral disc embolus


Spinal AVM/dural fistula
Vascular
Weakness and sensory loss, often with pain, developing over hours to daysUMN features below lesionImpaired sphincter function
Transverse myelitis due to viruses (HZV), schistosomiasis, HIV, MS, sarcoidosis
Infective/inflammatory
Clinical features
Condition
Type of disorder

INTRINSIC DISEASES OF THE SPINAL CORD

Motor neuron disease

Syringomyelia

Degenerative
Clinical features
Condition
Type of disorder

INTRINSIC DISEASES OF THE SPINAL CORD

CERVICAL SPONDYLOSIS

In the cervical spine, some degree of osteoarthritic degenerative change is a normal radiological finding in the middle-aged and elderly. Degeneration of the intervertebral discs and secondary osteoarthrosis (cervical spondylosis) is often asymptomatic, but may be associated with neurological dysfunction. The C5/6, C6/7 and C4/5 vertebral levels and C6, C7 and C5 roots, respectively, are most commonly affected

CERVICAL SPONDYLOTIC RADICULOPATHY

Compression of a nerve root occurs when a disc prolapses laterally, which may develop acutely or more gradually due to osteophytic encroachment of the intervertebral foramina.

Clinical features

The patient complains of pain in the neck that may radiate in the distribution of the affected nerve root. The neck is held rigidly and neck movements may exacerbate pain. Paraesthesia and sensory loss may be found in the affected segment and there may be lower motor neuron signs, including weakness, wasting and reflex impairment

Triceps

Middle finger
Triceps, finger and wrist extensors
C7
Supinator
Lower lateral arm, thumb, index finger
Brachioradialis
C6
Biceps
Upper lateral arm
Biceps, deltoid, spinati
C5
Reflex loss
Sensory loss
Muscle weakness
Root

PHYSICAL SIGNS IN CERVICAL ROOT COMPRESSION

Investigations


Plain X-rays, including lateral and oblique views, should be obtained to confirm the presence of degenerative changes and to exclude other conditions, including destructive lesions. If surgery is contemplated, MRI is required. Electrophysiological studies rarely add to the clinical examination, but may be necessary if there is doubt about the differential diagnosis between root and peripheral nerve lesions.

Management

Conservative treatment with analgesics and physiotherapy results in resolution of symptoms in the great majority of patients, but a few require surgery in the form of foraminotomy or disc excision.

CERVICAL SPONDYLOTIC MYELOPATHY

Dorsomedial herniation of a disc and the development of transverse bony bars or posterior osteophytes may result in pressure on the spinal cord or the anterior spinal artery which supplies the anterior twothirds of the cord

Clinical features

The onset is usually insidious and painless, but acute deterioration may occur after trauma, especially hyperextension injury. Upper motor neuron signs develop in the limbs, with spasticity of the legs usually appearing before the arms are involved. Sensory loss in the upper limbs is common, producing tingling, numbness and proprioception loss in the hands, with progressive clumsiness. Sensory manifestations in the legs are much less common. The neurological deficit usually progresses gradually and disturbance of micturition is a very late feature.

Investigations

Plain X-rays confirm the presence of degenerative changes, and MRI or myelography may be indicated if surgical treatment is being considered. MRI may also show areas of high signal within the spinal cord at the level of compression. Imaging of the cervical spine should be considered if there is diagnostic doubt or if surgery is contemplated.

MRI showing cervical cord compression (arrow) in cervical spondylosis

Management


Surgical procedures, including laminectomy and anterior discectomy, may arrest progression of disability but may not result in neurological improvement. The judgement on whether surgery should be undertaken may be difficult. Manipulation of the cervical spine is of no proven benefit and may precipitate acute neurological deterioration.

Prognosis

The prognosis of cervical myelopathy is variable. In many patients the condition stabilises or even improves without intervention, but if progressive disability does develop, surgical decompression should be considered.

LUMBAR DISC HERNIATION

Acute lumbar disc herniation is often precipitated by trauma, usually by lifting heavy weights while the spine is flexed. The nucleus pulposus may bulge or rupture through the annulus fibrosus, giving rise to pressure on nerve endings in the spinal ligaments, changes in the vertebral joints or pressure on nerve roots.

Clinical features

Ankle
Plantar flexion
Sole and lateral foot
S1
L5/S1
Dorsiflexion of hallux/toes
Outer calf and dorsum of foot
L5
L4/L5
Knee
Inversion of foot
Inner calf
L4
L3/L4
Reflex loss
Weakness
Sensory loss
Root
Disc level

PHYSICAL SIGNS IN LUMBAR ROOT COMPRESSION

Investigations


Plain X-rays of the lumbar spine are of little value in the diagnosis of lumbar disc disease, although they may show other conditions such as malignant infiltration of a vertebral body. CT, especially using spiral scanning techniques, can provide helpful images of the disc protrusion and/or narrowing of the exit foramina. MRI is the investigation of choice if available, since soft tissues are well imaged.

L5–SI disc herniationto the left, displacing the SI nerve root

Management


Some 90% of patients with sciatica recover with conservative treatment with analgesia and early mobilisation; bed rest does not help recovery. The patient should be instructed in back-strengthening exercises and advised to avoid physical manoeuvres likely to strain the lumbar spine. Injections of local anaesthetic or corticosteroids may be useful adjunctive treatment if symptoms are due to ligamentous injury or joint dysfunction. Surgery may have to be considered if there is no response to conservative treatment or if progressive neurological deficits develop. Central disc prolapse with bilateral symptoms and signs and disturbance of sphincter function requires urgent surgical decompression.

LUMBAR CANAL STENOSIS

This is due to a congenital narrowing of the lumbar spinal canal exacerbated by thedegenerative changes that common l occur .with age

Clinical features

The patients, who are usually elderly, develop exercise-induced weakness and paraesthesia in the legs (cauda equina claudication). These symptoms progress with continued exertion, often to the point that the patient can no longer walk, but are quickly relieved by a short period of rest. Physical examination at rest shows preservation of peripheral pulses with absent ankle reflexes. Weakness or sensory loss may only be apparent if the patient is examined immediately after exercise.

Investigations Myelography, CT orMRI will demonstrate narrowing of the lumbar canal

Management Extensive lumbar laminectomy often results in complete relief of symptoms and recovery of normal exercise tolerance