The Mayo Clinic experience with plasma exchange in chronic inflammatory-demyelinating polyneuropathy (CIDP)

Fourteen patients with static or progressive CIDP with a neurologic disability score (NDS) greater than or equal to 50 were entered into a double-blind, stratified, 3-week trial of twice-weekly plasma exchange or sham plasma exchange. The end-points evaluated included the NDS, computer assisted sensory examination of the foot, and various attributes of nerve conduction of motor and sensory fibers of limb nerves. Of the 7 patients receiving plasma exchange, 4 improved by more than 10 points on the NDS (45, 32, 11, and 24 points) while 3 remained unchanged (2, -2, and -3 points). One patient, who did not appear to respond to either sham or plasma exchange, improved (100 points) with a 3 month alternate day course of prednisone. Of the 7 patients on sham exchange, 3 improved by more than 10 points (26, 15, and 16), 3 remained unchanged (-5, 4, and 8) and 1 was not able to complete the study due to cardiac tamponade. This preliminary trial will end with acquisition of 30 patients. It is too early to draw any conclusion from these studies other than that the double-blind study employed here is feasible and should provide information on the efficacy of plasma exchange in CIDP if its effect is prompt and large. The improvement which may be seen in the sham group appears to suggest that studies of efficacy require a double-blind design.