This is an unusual process but we have reported cases that presented with excruciating thoracic back pain of such severity as to cause a bizarre, almost psychotic, reaction (Swann et al). The neck becomes slightly stiff and there may be a headache, suggesting subarachnoid hemorrhage. However, signs of a myelopathy do not appear, indicating that the bleeding is confined to the pliable subdural spaces surrounding the cord, thereby allowing the blood to spread over several segments.
Lumbar puncture yields a distinctive dark yellow-brown spinal fluid that resembles, to us, used motor oil. The color is imparted by methemoglobin and reflects the presence of an adjacent, decomposing walled-off clot. Usually there are also red blood cells in the CSF, suggesting seepage into the subarachnoid space from the adjacent collection. MRI or CT myelography shows a subdural collection, with characteristically smooth borders. When drained operatively, this is found to be clotted blood. Usually, no vascular malformation is demonstrable and the cause remains obscure. Trauma or anticoagulation underlies a few cases but many are spontaneous. The symptoms resolve in 1 or 2 weeks after removal of the subdural hematoma. Small collections may be managed without surgery, in which case corticosteroids may be helpful in reducing the pain.
The syndrome of spinal subarachnoid hemorrhage has been mentioned earlier and is also covered in Chap. 33 under “Other Causes of Intracranial Bleeding and Multiple Cerebral Hemorrhages.”
The gradual development of weakness of the legs is the common manifestation of many diseases of the spinal cord. A syndrome of this type, including ataxia of gait beginning insidiously in late childhood or adolescence and progressing steadily, is usually indicative of hereditary spinocerebellar degeneration (Friedreich ataxia) or one of its variants (see Chap. 38). In early adult life, MS is the most frequent cause and HIV myelopathy is being increasingly recognized; syphilitic meningomyelitis, formerly of great importance, is now quite uncommon. In middle and late adult life, cervical spondylosis, subacute combined degeneration of the cord (vitamin B12 deficiency), combined system degeneration of the nonpernicious anemia type, some associated with low levels of serum copper, radiation myelopathy, tropical spastic paraplegia, spinal arachnoiditis, and thoracic spinal tumor, particularly meningioma, are the important diagnostic considerations for the slowly progressive cord syndrome. In most forms of subacute and chronic spinal cord disease, spastic paraparesis is more prominent than posterior column ataxia, Friedreich ataxia and the myelopathy caused by vitamin B12 deficiency being notable exceptions.
(See earlier under “Acute Demyelinating Myelitis of Multiple Sclerosis” and also Chap. 35 for a discussion of multiple sclerosis.)
Ataxic paraparesis is among the most common manifestations of MS. Asymmetrical involvement of the limbs and signs of cerebral, optic nerve, brainstem, and cerebellar involvement usually provide confirmatory diagnostic evidence. Nevertheless, purely spinal involvement may occur, no lesions being found outside the spinal cord even at autopsy. A frequent problem in diagnosis is posed by the older woman who was not known to have had MS in earlier life, previous episodes having been absent, asymptomatic, or forgotten. A secondary progressive stage of spinal multiple sclerosis is the consequence of recurrent demyelinating attacks. There is another group, however, in which slowly advancing neurologic deterioration represents the primary manifestation of the disease. The National Hospital Research Group examined 20 cases of the secondary progressive type of spinal MS and 20 of the primary type by gadolinium-enhanced MRI of the spinal cord and brain and found new lesions in only 3 of each group (Kidd et al). They suggest that the progression correlates better with progressive atrophy of the spinal cord than with recurrent demyelinative lesions.