Plasma-exchange therapy in chronic inflammatory demyelinating polyneuropathy. A double-blind, sham-controlled, cross-over study. Plasma exchange in chronic inflammatory demyelinating polyradiculoneuropathy.
Eighteen patients with definite, untreated chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) of chronic progressive (nine patients) or relapsing course (nine patients) were randomized prospectively to receive 10 plasma-exchange (PE) or sham plasma-exchange (SPE) treatments over 4 weeks in a double-blind trial. After a wash-out period of 5 weeks or when they returned to baseline scores, patients were crossed over to the alternate treatments. Neurological function was assessed serially using a quantitative neurological disability score (NDS), a functional clinical grade (CG) and grip strength (GS) measurements. Electrophysiological studies were done at the beginning and end of each treatment. A primary 'intention to treat' analysis showed significant improvement with PE in all clinical outcome measures: NDS by 38 points, P < 0.001; CG by 1.6 points, P < 0.001; GS by +13 kg, P < 0.003 and in selected electrophysiological measurements, sigma proximal CMAP, P < 0.01; sigma motor conduction velocities, P < 0.006; sigma distal motor latencies, P < 0.01. Fifteen patients completed the trial and of those, 12 patients (80%) improved substantially with PE; i.e. five out of seven patients with chronic progressive course and seven out of eight patients with relapsing CIDP improved. There were three drop-outs; one patient lost venous access; one patient suffered a stroke and one patient left the trial to receive open treatment elsewhere. The improvement in motor functions correlated with the electrophysiological data, i.e. with improved motor conduction velocities and reversal of conduction block. Eight of 12 PE responders (66%) relapsed within 7-14 days after stopping PE. All improved with subsequent open label PE; all but two patients required long-term immunosuppressive drug therapy for stabilization. The PE non-responders improved with prednisone. We conclude that PE is a very effective adjuvant therapy for CIDP of both chronic progressive and relapsing course; concurrent immunosuppressive drug treatment is required. Exchange treatments should be given two to three times per week until improvement is established; the treatment frequency should then be tapered over several months. Plasma exchange has been reported to be efficacious in chronic inflammatory demyelinating polyradiculoneuropathy. We performed a prospective double-blind trial in which patients with static or worsening disease were randomly assigned to plasma exchange (n = 15) or to sham exchange (n = 14) for three weeks. After three weeks, we observed statistically significant differences in combined measurements of nerve conduction (total, motor, proximal, velocity, and amplitude) favoring patients who had received plasma exchange. Improvement to a greater degree than for any patient receiving sham exchange was detected in the neurologic-disability score in five patients (P = 0.025) and in subset scores for weakness and reflex in four patients (P less than 0.057). We conclude that for some patients with chronic inflammatory demyelinating polyradiculoneuropathy, plasma exchange has an ameliorating effect on neurologic dysfunction and nerve conduction, but in others no improvement is observed. Because plasma was replaced with normal serum albumin, a humoral factor or factors may have a role in the neurologic deficit of this disorder.
Moderate to high quality evidence from two small trials showed that plasma exchange provides significant short-term improvement in disability, clinical impairment and motor nerve conduction velocity in CIDP but rapid deterioration may occur afterwards. Adverse events related to difficulty with venous access, use of citrate and haemodynamic changes are not uncommon. More research is needed to identify agents which will prolong the beneficial action of plasma exchange.