Clinically, the illness is characterized by a rapidly evolving (several hours or days) symmetrical or asymmetrical paraparesis or paraplegia, ascending paresthesia, loss of deep sensibility in the feet, a sensory level on the trunk, sphincteric dysfunction, and bilateral Babinski signs. The CSF shows a modest number of lymphocytes and increase in total protein but both may be normal early in the illness. As many as one-third of patients report an infectious illness in the weeks preceding the onset of neurologic symptoms, in which case a monophasic postinfectious demyelinating disease rather than MS is the likely cause of the myelitis. The MRI usually shows indications of focal demyelination in the spinal cord at the appropriate level and there may be enhancement with gadolinium infusion, but neither of these findings is invariable. The lesions, as shown in
Fig. 35-1 (lower right panel), are almost indistinguishable from those of postinfectious myelitis. In instances of myelitis associated that are a component of MS, even if not previously symptomatic, MRI of the cerebral hemispheres will show lesions consistent with demyelination; the absence of such lesions, however, does not ensure that the myelitic illness is monophasic and will not evolve to MS. Some cases progress to a necrotic myelopathy, with or without optic neuropathy, that is an expression of neuromyelitis optica (NMO), as discussed in a later section.
Fewer than half the patients have evidence of an asymptomatic demyelinating lesion elsewhere in the nervous system or develop clinical evidence of dissemination within 5 years of the initial attack of acute myelitis (Ropper and Poskanzer). Not entirely in accord with our experience is the analysis of subgroups in a trial of interferon therapy conducted by Beck and colleagues (2002), in which the cumulative probability of developing MS after 2 years was similar after either optic neuritis or transverse myelitis. Our sense has been that acute transverse myelitis is somewhat less often an initial expression of MS than is optic neuritis.
A special problem is presented by patients with recurrent myelitis at one level of the spinal cord but in whom no other signs of demyelinating disease can be found by careful clinical examination or MRI. Some of them may even have oligoclonal bands in the CSF, which are commonly associated with MS (see further on). Enough cases of this limited nature have come to our attention to permit the tentative conclusion that there is a recurrent form of spinal cord MS in which cerebral dissemination is infrequent (Tippett et al). Isolated recurrent myelitis or myelopathy occurs also with lupus erythematosus, sarcoidosis, Sjögren syndrome, mixed connective tissue disease, and the antiphospholipid antibody syndrome or in the presence of other autoantibodies, as well as with dural and cord vascular fistulas and arteriovenous malformations. An analogous situation pertains in respect to some instances of optic neuritis—repeated attacks that remain confined to the optic nerve. Another relatively isolated syndrome, occurring mainly in older women, is a slowly progressive cervical myelopathy with weakness and ataxia. This is particularly difficult to differentiate from cervical spondylosis.
Other aspects of transverse myelitis are discussed in Chap. 42, and later in this chapter.
Other Clinical Features of Acute Attacks