In the past, administration of pooled serum for the treatment of various infections led to brachial plexus neuritis or to an immune mononeuropathy multiplex, presumably from deposition of antibody–antigen complexes in the walls of the vasa nervorum. A similar “serum sickness” reaction occurred after certain viral infections associated with arthritis, rash, and fever. The neuropathy that arises with hepatitis C infection may be of this type, perhaps mediated by the frequently associated cryoglobulinemia as mentioned earlier. Interferon, which has been effective in treating the hepatitis, may also ameliorate the neuropathy, but greater success has been achieved with cyclophosphamide. Pooled immunoglobulin for the treatment of diverse neuromuscular diseases such as Guillain-Barré syndrome and myasthenia gravis has not, to our knowledge, led to a serum-sickness neuropathy, but one of our patients with Churg-Strauss disease developed a fulminating vasculitic skin eruption while being treated with IVIg.
In 2 cases of severe systemic vasculitis related to administration of hydralazine, we observed no neuropathic features; whether this applies to other drug-induced vasculitides is not known. Minocycline is another drug that has been associated in rare instances with a vasculitis, including mononeuropathies. The increasing appearance of vasculitic neuropathy with HIV infection, including a type that is independent of CMV infection, has already been mentioned; such cases have tended to improve spontaneously or with corticosteroid therapy. In about half of these cases the CSF contains polymorphonuclear cells. From time to time a patient with a lymphoproliferative disorder such as Hodgkin disease will develop mononeuritis multiplex that is found by biopsy to be caused by vasculitis. (A chronic demyelinating, nonvasculitic polyneuropathy is more common with lymphomas of any type as discussed earlier.)
A rare paraneoplastic variety of vasculitic neuropathy has also been described. Oh reported 2 of his patients and reviewed 13 previous ones. The most common underlying cancer was of the small oat cell lung type. Anti-Hu antibodies that are typical of paraneoplastic neurologic diseases from this cancer are generally not detected (see Chap. 31). Other solid tumors (renal, gastric, gynecologic) have been associated with a similar neuropathy but only in a few instances. Almost all have had slightly elevated protein concentration in the CSF but few showed a pleocytosis. At autopsy, the vasculitis was limited to nerve and muscle.
The role of an obscure small-vessel vasculitis in otherwise idiopathic axonal polyneuropathies of elderly patients has been reported, but is in our view, controversial. We have not found, as did Chia and colleagues, an unexpected vasculitis in the nerve biopsies of such patients. The vasoocclusive and infiltrative condition of intravascular lymphoma often includes a syndrome of multiple painless mononeuropathies as part of a larger multifocal illness of the central and peripheral nervous system.
Neuropathy of Critical Limb Ischemia