Spinal cord disease of this type has been reported from the Caribbean islands, southeastern United States, southern Japan, South America, and Africa. The clinical picture is one of a slowly progressive paraparesis with increased tendon reflexes and Babinski signs; disorder of sphincteric control is usually an early feature but symmetric paresthesias, reduced vibratory and position senses, and ataxia follow over several months or years. A few patients have had an associated polyneuropathy, as in Cruickshank’s early cases. The upper extremities are usually spared (except for lively tendon reflexes), as are cerebral and brainstem functions.
The CSF contains small numbers of T-lymphocytes (10 to 50/mm3), normal concentrations of protein and glucose, and an increased content of immunoglobulin (Ig) G with antibodies to HTLV-I. The diagnosis is confirmed by the detection in the serum of the antibodies to the virus. Thinness of the spinal cord is evident on MRI and subcortical cerebral white matter lesions may be seen as well. Neuropathologic study has documented an inflammatory myelitis with focal spongiform, demyelinative, and necrotic lesions, perivascular and meningeal infiltrates of inflammatory cells, and focal destruction of gray matter. The posterior columns and corticospinal tracts are the main sites of disease, most evident in the thoracic cord.
Because of slow evolution, the clinical picture can easily be confused with that of progressive spastic paraplegia of the heredofamilial variety, sporadic motor neuron disease, or the chronic phase of multiple sclerosis. There are also similarities with the AIDS myelopathy described earlier, but the other features of HIV infection are absent. A single intravenous infusion of the anti-CCR4 T-cell antibody, mogamulizumab, has been shown in preliminary studies to reduce viral load and improve spasticity and motor function (Sato et al).
Myelitis Secondary to Bacterial, Fungal, Parasitic, and Granulomatous Diseases (See Also Chap. 31)
With few exceptions, this class of spinal cord disease seldom offers difficulty in diagnosis. The CSF usually holds the clue to causation. In most cases, the inflammatory reaction in the meninges is only one manifestation of a generalized (systemic) disease process. The spinal lesion may involve primarily the pia-arachnoid (leptomeningitis), the dura (pachymeningitis), or the epidural space, for example, taking the form of a compressive abscess or granuloma; or it may reside in the adjacent spinal bones. In some acute forms both the spinal cord and meninges are simultaneously affected, or the cord lesions may predominate. Chronic spinal meningitis may involve the pial arteries or veins; and as the inflamed vessels become thrombosed, infarction (myelomalacia) of the spinal cord results. Chronic meningeal inflammation may provoke a progressive constrictive pial fibrosis (spinal arachnoiditis) that virtually strangulates the spinal cord. In certain cases, spinal roots become progressively damaged, especially the lumbosacral ones, which have a long meningeal exposure. Posterior roots, which enter the subarachnoid space near arachnoidal villi (where CSF is resorbed) tend to suffer greater injury than anterior ones (as happens in tabes dorsalis). Interestingly, there are cases of chronic cerebrospinal meningitis that remain entirely without symptoms until the spinal cord or roots become involved.