Thirty patients with definite or probable
chronic inflammatory demyelinating polyradiculoneuropathy (
CIDP) of chronic progressive (16 patients) or relapsing (14 patients) course were randomly assigned to receive
intravenous immunoglobulin (
IvIg) 0.4 g per kg
body weight or a placebo treatment on 5 consecutive days in a double-blind, cross-over trial. Neurological function was monitored by serial quantitative assessments [neurological disability score (
NDS); clinical grade (CG) and grip strength (GS) measurements] and by electrophysiological studies before and after each treatment period. Twenty-five patients completed both treatment periods. A comparison of the observed changes in clinical outcome measures revealed statistically significant differences in favour of
IvIg, with (mean +/- SD) improvements in
NDS by 24.4 +/- 5.4 points (P < 0.002) in CG by 1 +/- 0.3 points (P < 0.001) in GS by +6.3 +/- 1.7 kg (P < 0.005), whereas scores were unchanged or worse with placebo. A secondary two-groups analysis of the first trial period included all 30 patients; 16 patients had been randomly assigned to
IvIg and 14 to placebo treatments. Again significant differences in favour of
IvIg were observed in all the clinical end-points: improvement in
NDS was 35.6 +/- 25 points (P < 0.0001), in CG it was 1.3 +/- 1.9 points (P < 0.002) and in GS +9.8 +/- 7.7 kg (P < 0.001), whereas all scores worsened with placebo. Of the 30 patients, 19 (63%) improved with
IvIg treatments; nine out of 16 patients (56%) with chronic progressive
CIDP, and 10 out of 14 patients (71%) with relapsing
CIDP (differences were not statistically significant). A placebo response was seen in five patients. Comparison of paired electrophysiological measurements before and 4 weeks after
IvIg treatments revealed statistically significant improvements in the summed motor conduction velocities (sigma MCV; P < -0.0001) and in the summed compound muscle action potentials (CMAP) evoked with proximal stimulation (sigma proximal CMAP, P < 0.03) of median, ulnar, peroneal and tibial nerves. Eight of nine
IvIg responders with chronic progressive
CIDP improved gradually to normal function with a single 5 day course of
IvIg; in five of these, small doses of
prednisone were prescribed during follow-up. In 10
IvIg responders with relapsing
CIDP, improvements lasted a median 6 weeks (range 3-22 weeks) and was reproducible with open label treatments. All 10 patients have been maintained and stabilized with
IvIg pulse
therapy of 1 g per kg
body weight or less, given as a single infusion prior to the expected relapse. A beneficial response to
IvIg was found to be most likely in patients with acute relapse or with disease of one year or less. Patients with predominantly sensory signs did not improve.