A plasma exchange versus immune globulin infusion trial in chronic inflammatory demyelinating polyradiculoneuropathy

Abstract

Chronic inflammatory demyelinating polyradiculoneuropathy is a paralytic syndrome, causing considerable disability and even death. In controlled clinical trials, plasma exchange prevented or ameliorated neurological deficits, but the efficacy of immune globulin infusion remains unproved. Also unknown is whether immune globulin infusion is as effective, or more effective, than plasma exchange and what dosages and frequencies are best. In this observer‐blinded study, using some objective end points not subject to bias (e.g., summated compound muscle action potential), 20 patients with progressive or static polyneuropathy were randomly assigned to receive either of the two treatments for 6 weeks, followed by a washout period, and then were assigned to receive the other treatment. Plasma exchange (twice a week for 3 weeks then once a week for 3 weeks) and immune globulin infusion (0.4 gm/kg once a week for 3 weeks, then 0.2 gm/kg once a week for the next 3 weeks) were used. End points assessed before and after treatment schedules were neurological disability score; muscle weakness of the neurological disability score; summated compound muscle action potentials of ulnar, median, and peroneal nerves; summated sensory nerve action potentials of ulnar and sural nerves; and vibratory detection threshold of the great toe using CASE IV. Observers were masked as to treatment used. Of 20 patients, 13 received both treatments whereas 4 did not worsen sufficiently to receive the second treatment—1 patient left the study during and 2 after the first treatment to receive unscheduled treatment elsewhere. Of the 17 patients who received plasma exchange in either treatment period, statistically significant improvement occurred in the neurological disability score (38.3 ± 34.6 points, mean±standard deviation, p < 0.001), weakness subset of the score (33.4 ±29.5 points, p < 0.001), and summated compound muscle action potentials (3.7 ±3.5 mV, p < 0.001). This improvement is large and unequivocal, being equivalent to a change from a 50% bilateral weakness of pelvic and lower limb muscles to no weakness. Of the 15 patients who received immune globulin infusion in either schedule, the comparable changes were as follows: the nerological score, 36.1± 32.0 points (p = 0.006); the weakness subset of the neurological score, 31.4 ±31.5 points (p < 0.002); and summated muscle action potentials, 3.3 ±2.8 mV (p < 0.001). In a comparison of the change in neuropathic end points between the two treatments, statistically significant differences were not found for any end point. In an open trial of 8 patients, to determine the frequency and dosage of immune globulin infusion needed to maintain good function, we found that frequency could be titrated by assessing the neurological disability score and the summated muscle action potentials at 6‐week intervals. The dosage and frequency required to achieve a high functional level were quite variable among patients. Both treatments are efficacious in ameliorating neurological deficit in chronic inflammatory demyelinating polyradiculoneuropathy. The effect is large, but for most patients is short‐lived, requiring continued intermittent treatment for maximal or sustained improvement. For schedules of treatment that cost approximately the same, a clear difference in efficacy was not shown between plasma exchange and immune globulin infusion. Since immune globulin can be infused without expensive devices and can be given in the home, it may be the preferable treatment. The frequency and dosage of infused globulin needed to maintain improvement was quite variable (from as little as 0.025 gm/kg once every 10 days to 0.4 gm/kg [seldom more] every 2–4 days).