Here, as in multiple sclerosis, the degree of ataxia and spastic weakness is variable. A few patients have an almost pure state of spastic weakness of the legs, requiring differentiation from motor system disease and familial spastic paraplegia. Such a syndrome, formerly called Erb spastic paraplegia and attributed to meningovascular syphilis, is now recognized as being nonspecific and more often caused by demyelinating disease. In a minority of chronic syphilitic patients, sensory ataxia and other posterior column signs predominate. Ventral roots are involved in the chronic meningeal inflammation, giving rise to signs of segmental amyotrophy—hence the term syphilitic amyotrophy of the upper extremities with spastic paraplegia. Confirmation of this now infrequent diagnosis depends on finding a lymphocytic pleocytosis, an elevated protein and gamma globulin, and a positive serologic reaction in the CSF. Other aspects of this disease and treatment are discussed under “Spinal Syphilis” in Chap. 31. Tabes dorsalis is, of course, another important form of syphilitic myelitis.
Subacute Combined Degeneration of the Spinal Cord (See Chap. 40)
This form of nutritional spinal cord disease is caused by vitamin B12 deficiency and is fully described in
Chap. 40. Almost invariably it begins with bilateral symptoms and signs of posterior column involvement in the hands (paresthesias and reduced touch, pressure, and joint sensibility), which, if untreated, is followed within a matter of several weeks or months by progressive spastic paraparesis because of involvement of the corticospinal tracts to which a vague sensory level on the trunk may be added. Particular importance attaches to the fact that this is a treatable disease and that the degree of reversibility is dependent upon the duration of symptoms before specific treatment is begun.
Copper Deficiency Myelopathy (Combined System Disease of Nonpernicious Anemia Type)
This refers to a metabolic disease of the spinal cord caused by low copper, affecting the posterior and lateral columns, in this sense, also a combined system degeneration. The clinical syndrome and potential causes were elegantly elaborated by Kumar and colleagues. A homologous disease exists as “swayback” in lambs. A deficiency of vitamin B12 is not causative, but may coexist in some cases, probably on the basis of a shared inadequacy of dietary intake. Women are more often affected than men. Imbalance is the most common presenting complaint. Posterior column signs and gait ataxia tend to predominate but a degree of spasticity is usually conjoined and there may be Babinski signs and reduced ankle reflexes. The problem is typically one of impaired absorption of copper, for example, after gastric bypass or bowel surgery, which together account for half of cases. Of importance in causation in some patients is excess zinc intake in the form of health supplements, coin swallowing, and denture creams (see Nations et al).
There is an associated hypocupremic anemia with ringed sideroblasts and leukopenia with vacuolated myeloid precursors in the marrow that may be mistaken for a myelodysplastic process. The idiopathic variety has certain similarities to the disorder of copper mobilization in Menkes disease, but the disordered enzyme responsible in the latter has been normal. As reported by others, in a recent case on our service without explanation for the discovered copper deficiency, MRI of the cervical cord revealed distinctive signal changes in both the posterior and lateral columns identical to those of B12 deficiency, and these were no longer present after copper treatment. The majority of affected patients have abnormal somatosensory evoked potentials with delays in central conduction.