NEUROPATHY ASSOCIATED WITH BENIGN ANTI-MYELIN-ASSOCIATED GLYCOPROTEINIGM GAMMOPATHY - CLINICAL, IMMUNOLOGICAL, NEUROPHYSIOLOGICAL PATHOLOGICAL FINDINGS AND RESPONSE TO TREATMENT IN 33 CASES

We studied 33 patients presenting with a peripheral neuropathy associa ted with non-malignant anti-myelin-associated glycoprotein (MAG) IgM m onoclonal gammopathy (MG) in an attempt to delineate their clinical, i mmunological, electrophysiological and pathological characteristics; w e also reviewed our experience concerning long-term follow-up and ther apy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46-81), A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progressio n was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a de myelinating process in 90% of cases, and electron microscopic examinat ion of nerve biopsy specimens demonstrated widening of the myelin lame llae in more than 95% of cases. Most of our patients showed a disappoi nting response to steroids and chemotherapy or plasma exchanges. Intra venous immune globulin, evaluated in 17 patients, had a transient, mos tly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antib ody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progress ion may greatly vary from patient to patient, the combination of clini cal, electrophysiological and pathological features delineates a chara cteristic pattern in peripheral neuropathy associated with non-maligna nt anti-MAG IgM MG.