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194 SPINAL CORD DISEASES

194 SPINAL CORD DISEASES
Harrison’s Manual of Medicine

194

SPINAL CORD DISEASES

Symptoms and Signs
Specific Signs by Spinal Cord Level
Intramedullary and Extramedullary Syndromes
Acute and Subacute Spinal Cord Diseases
Chronic Myelopathies
Complications
Bibliography

Diseases of the spinal cord can be devastating, but many are treatable if recognized early (Table 194-1). A working knowledge of relevant spinal cord anatomy is often the key to correct diagnosis (Fig. 194-1).

Table 194-1 Some Treatable Spinal Cord Disorders

FIGURE 194-1. Transverse section through the spinal cord, composite representation, illustrating the principal ascending (left) and descending (right) pathways. The lateral and ventral spinothalamic tracts (dark blue) ascend contralateral to the side of the body that is innervated. C, cervical; T, thoracic; L, lumbar; S, sacral, P, proximal; D, distal; F, flexors, E, extensors.

Symptoms and Signs
Principal signs are loss of sensation below a horizontal meridian on the trunk (“sensory level”), accompanied by weakness and spasticity.
Sensory Symptoms   Often paresthesia; may begin in one or both feet and ascend. Sensory level to pin sensation or vibration often correlates well with location of transverse lesions. May have isolated pain/temperature sensation loss over the shoulders (“cape” or “syringomyelic” pattern) or loss of sensation to vibration/position on one side of the body and pain/temperature loss on the other (Brown-Séquard hemicord syndrome).
Motor Impairment   Disruption of corticospinal tracts causes quadriplegia or paraplegia with increased muscle tone, hyperactive deep tendon reflexes, and extensor plantar responses. With acute severe lesions there may be initial flaccidity and areflexia (spinal shock).
Segmental Signs   These are approximate indicators of level of lesion, e.g., band of hyperalgesia/hyperpathia, isolated flaccidity, atrophy, or single lost tendon reflex.
Autonomic Dysfunction   Primarily urinary retention; should raise suspicion of spinal cord disease when associated with back or neck pain, weakness, and/or a sensory level.
Pain   Midline back pain is of localizing value; interscapular pain may be first sign of midthoracic cord compression; radicular pain may mark site of more laterally placed spinal lesion; pain from lower cord (conus medullaris) lesion may be referred to low back.
Specific Signs by Spinal Cord Level
Lesions Near the Foramen Magnum   Weakness of the ipsilateral shoulder and arm, followed by weakness of ipsilateral leg, then contralateral leg, then contralateral arm, with respiratory paralysis.
Cervical Cord   Best localized by noting pattern of motor weakness and areflexia; shoulder (C5), biceps (C5-6), brachioradialis (C6), triceps/finger and wrist extensors (C7), finger flexors (C8).
Thoracic Cord   Localized by identification of a sensory level on the trunk.
Lumbar Cord   Upper lumbar cord lesions paralyze hip flexion and knee extension, whereas lower lumbar lesions affect foot and ankle movements, knee flexion, and thigh extension.
Sacral Cord (Conus Medullaris)   Saddle anesthesia and early bladder/ bowel/sexual dysfunction.
Cauda Equina   Lesions below spinal cord termination at the L1 vertebral level produce a flaccid, areflexic, asymmetric paraparesis with bladder/bowel dysfunction and sensory loss below L1; pain is common and projected to perineum or thighs.
Intramedullary and Extramedullary Syndromes
Spinal cord disorders may be intramedullary (arising from within the substance of the cord) or extramedullary (compressing the cord or its blood supply). Extramedullary lesions often produce radicular pain, early corticospinal signs, and sacral sensory loss. Intramedullary lesions produce poorly localized burning pain, less prominent corticospinal signs, and often spare perineal/sacral sensation.
Acute and Subacute Spinal Cord Diseases
Commonly due to spinal cord compression (by tumor, infection, spondylosis, or trauma), infarction or hemorrhage, inflammation, or infection. Evaluation consists of MRI scans that provide excellent resolution of the spinal cord and identify most compressive lesions. Plain x-rays or CT of spine may be useful to assess presence of fractures and alignment of vertebral column. CSF analysis useful for infectious and inflammatory processes.

1.
Tumors of spinal cord: May be metastatic or primary, epidural or intradural; most are epidural metastases from adjacent vertebra. Malignancies commonly responsible: breast, lung, prostate, lymphoma, and plasma cell dyscrasias. Initial symptom is commonly back pain, worse when recumbent, with local tenderness preceding other symptoms by many weeks. Spinal cord compression due to metastases is a medical emergency; in general, therapy will not reverse paralysis of >48 h duration. Treatment consists of glucocorticoids (dexamethasone 40 mg daily) to reduce interstitial edema, local radiotherapy initiated as early as possible to the symptomatic lesion, and specific therapy for the underlying tumor type. Intradural tumors are generally benign—meningiomas or neurofibromas; treatment is surgical resection.

2.
Spinal epidural abscess: Triad of fever, localized spinal pain, and myelopathy (progressive weakness and bladder symptoms); once neurologic signs appear, cord compression rapidly progresses. Treatment is emergency decompressive laminectomy with debridement combined with long-term antibiotic therapy.

3.
Spinal epidural hemorrhage and hematomyelia: Presents as acute transverse myelopathy evolving over minutes or hours with severe pain. Causes: minor trauma, LP, anticoagulation, hematologic disorder, AV malformation, hemorrhage into tumor—most are idiopathic. Treatment is surgical evacuation and correction of any underlying bleeding disorder.

4.
Acute disk protrusion: Cervical and thoracic disk herniations are less common than lumbar.

5.
Acute trauma with spinal fracture/dislocation: May not produce myelopathy until mechanical stress further displaces destabilized spinal column.

6.
Inflammatory myelopathies: Acute transverse myelitis presents as sensory and motor symptoms, often with bladder involvement, evolving over hours to days. May follow infection, vaccination, or be the first sign of multiple sclerosis. Glucocorticoids, consisting of IV methylprednisolone followed by oral prednisone (Chap. 187), are indicated for moderate to severe symptoms. Rarely, a rapidly ascending necrotic myelopathy may occur as a paraneoplastic syndrome.

7.
Infectious myelopathies: Herpes zoster is the most common viral agent; schistosomiasis is an important cause worldwide.

8.
Spinal cord infarction: Anterior spinal artery infarction produces paraplegia or quadriplegia, dissociated sensory loss affecting pain/temperature and sparing vibration/position sensations (supplied by posterior spinal arteries), and loss of sphincter control. Associated conditions: aortic atherosclerosis, dissecting aortic aneurysm, hypotension. Treatment is symptomatic.
Chronic Myelopathies

1.
Spondylitic myelopathies: Presents as neck and shoulder pain, radicular arm pain, and progressive spastic paraparesis with paresthesia and loss of vibration sense; in advanced cases, urinary incontinence may occur. Results from combinations of disk bulging, osteophytic spur formation, partial subluxation, and hypertrophy of the dorsal spinal ligament. Treatment is surgical (Chap. 5).

2.
Vascular malformations: An important treatable cause of progressive myelopathy. May occur at any level; diagnosis is made by contrast-enhanced MRI, confirmed by selective spinal angiography. Treatment is embolization with occlusion of the major feeding vessels.

3.
Retrovirus-associated myelopathies: Infection with HTLV-I or HTLV- II may produce a slowly progressive spastic paraparesis with variable pain, sensory loss, and bladder disturbance; diagnosis is made by demonstration of specific serum antibody. Treatment is symptomatic. A progressive vacuolar myelopathy may also occur in AIDS.

4.
Syringomyelia: Cavitary expansion of the spinal cord resulting in progressive myelopathy; may be an isolated finding or associated with protrusion of cerebellar tonsils into cervical spinal canal (Chiari type 1) or with incomplete closure of spinal canal (Chiari type 2). Classic presentation is loss of pain/ temperature sensation in the neck, shoulders, forearms, or hands with areflexic weakness in the upper limbs and progressive spastic paraparesis; cough headache, facial numbness, or thoracic kyphoscoliosis may occur. Diagnosis is made by MRI; treatment is surgical.

5.
Multiple sclerosis: See Chap. 187.

6.
Subacute combined degeneration (vitamin B12 deficiency): Paresthesia in hands and feet, early loss of vibration/position sense, progressive spastic/ ataxic weakness, and areflexia due to associated peripheral neuropathy; mental changes (“megaloblastic madness”) may be present. Diagnosis is confirmed by a low serum B12 level and a positive Schilling test. Treatment is vitamin replacement.

7.
Tabes dorsalis: May present as lancinating pains, gait ataxia, bladder disturbances, and visceral crises. Cardinal signs are areflexia in the legs, impaired vibration/position sense, Romberg’s sign, and Argyll Robertson pupils, which fail to constrict to light but react to accommodation.

8.
Familial spastic paraplegia: Progressive spasticity and weakness in the legs occurring on a familial basis; may be autosomal dominant, recessive, or X-linked.
Complications
Damage to urinary tract due to urinary retention with bladder distention and injury to detrusor muscle; UTI; paroxysmal hypertension or hypotension with volume changes; ileus and gastritis; in high cervical cord lesions, mechanical respiratory failure; severe hypertension and bradycardia in response to noxious stimuli or bladder or bowel distention; pressure sores; venous thrombosis and pulmonary embolism.
Bibliography

For a more detailed discussion, see Hauser SL: Diseases of the Spinal Cord, Chap. 368, p. 2425, in HPIM-15.

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