Multifocal Motor Neuropathy: Recovery After 107 Six-Weekly Infusions of High Dose Immunoglobulin

Figure 44-1 Cross-section of right sural nerve biopsied at ankle level. Nerve conduction studies of this nerve performed 1 week before biopsy were within normal limits. This methylene blue–stained semithin cross-section of a large fascicle appears entirely normal both by inspection and by systematic morphometric assessment. Teased nerve fiber preparations done from this biopsy specimen in 1987 (not illustrated; no longer available) by two observers independently revealed that a modest number of myelinated nerve fibers displayed demyelinated-remyelinated internodes. There was little or no evidence of recent or active demyelination. These findings are concordant with those of Corse and colleagues,⁵ who found modest demyelination-remyelination changes in teased nerve fiber preparations done in all 11 sural nerve biopsies from their patients with multifocal motor neuropathy. As a cautionary note, similar findings were noted in 14%, + or – 7%, of sural nerves from adults with no known neurological disorder (P.J. Dyck, personal communication, 2008).

(The photomicrograph and morphometric analysis were done recently on epoxy-embedded biopsy tissue from February 1987. This work was carried out through the courtesy of Ms. JaNean K. Engelstad and Peter J. Dyck, MD, 2008.)

In 1987 and 1988, he was first prescribed corticosteroids on the basis that he had a multifocal motor form of chronic inflammatory demyelinating polyneuropathy. Steroids were only briefly effective. Several trials of plasma exchange followed, which also helped only briefly. He then took matters into his own hands, and had all of his teeth extracted (he thought the mercury in the dental fillings were responsible for his disorder), and tried other remedies, all to no avail. In early 1991, he returned for further consultation, was found to be minimally better than when first examined, but was still too weak to return to work. He was given his first course of high-dose, intravenous pooled immunoglobulin. Unequivocal improvement began in days, plateaued for several weeks, and then weakening over a few days recurred. Because his insurance plan required in-hospital administration of the intravenous immunoglobulin (IVIg), retreatments thereafter were done on an overnight in-patient basis. Retreatment was required every 4 to 6 weeks. His strength was mostly restored after each infusion sequence, but some persistent weakness never responded to IVIg. The fixed deficit was mainly right footdrop, mild grip weakness of the right hand, and mild proximal left arm weakness. In the 11th year of continuous six-weekly infusions, he noted no loss of strength after 6 weeks. We waited, and he remained strong after several more weeks. He has never required further IVIg. The last IVIg infusion was administered in December, 2001 and the first took place in March, 1991 nearly eleven years earlier. Total hospital admissions numbered 108, of which 107 were for IVIg administration.

In 1991, shortly after his first IVIg infusion, the patient returned to work and remained gainfully employed until retirement at age 65 in 2005, 4 years after his last IVIg infusion. Since then, he has continued to lead a vigorous life with a daily weight lifting session and several hours of working in his garden. His only residual deficit is mild right footdrop. His hand and wrist strength have returned.

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