IVIG Effective in Diabetic-Related Inflammatory Neuropathy

Laurie Barclay, MD

June 04, 2002

June 5, 2002 -- Intravenous immunoglobulin (IVIG) is effective in treating some forms of diabetic-related neuropathy, according to results of a study published in the May issue of the Archives of Neurology. A separate study by the same group shows that chronic inflammatory demyelinating polyneuropathy (CIDP) is equally common in type 1 and type 2 diabetes patients, and much more common than in the general population.

"We have the impression that clinically significant CIDP is a sufficiently common occurrence in patients with diabetes mellitus (DM) that it should be considered in the differential diagnosis of any diabetic patient with a worsening, relatively severe neuropathy, particularly where there is major motor involvement," write Khema R. Sharma, MD, and colleagues from the University of Miami School of Medicine in Florida. "There is growing evidence that idiopathic CIDP and polyneuropathy in patients with DM that meets the electrophysiological criteria for CIDP (DM-CIDP) have many similarities."

In a prospective design, Sharma's group studied the frequency of electrophysiological testing results meeting criteria for CIDP in patients with DM, the frequency of DM in patients with other neuromuscular diseases and the frequency of idiopathic CIDP in their clinic.

During a 51-month period, 120 patients with DM met the electrophysiologic criteria for CIDP (DM-CIDP), with a predominantly large-fiber sensorimotor neuropathy, recent motor deterioration and moderately increased cerebrospinal fluid protein concentration. DM-CIDP occurred equally in type 1 and type 2 DM.

During a subsequent 14-month period in which 1127 patients were seen, 189 (16.8%) had DM with various neurologic disorders, including 32 patients (16.9%) with DM-CIDP. Among the remaining 938 patients without DM, 17 (1.8%) had idiopathic CIDP. The incidence of DM-CIDP was 11 times higher in diabetic than in nondiabetic patients (P<.001).

In a prospective, open-label pilot study, 26 patients with DM-CIDP received IVIG, 400 mg/kg per day for 5 days. Clinically significant improvement in neurologic deficit, measured using the Neuropathy Impairment Score at baseline and at the end of 4 weeks from the initiation of IVIG therapy, occurred in 21 patients (80.8%). Improvement in the Neuropathy Impairment Score occurred in all 11 patients who had a conduction block but in only 10 (66.7%) of 15 patients who did not (P=.03). Adverse reactions to IVIG included reversible renal dysfunction in three patients, flu-like symptoms in five, headache in five, and chest pain and shortness of breath in one patient.

"The potential risks of IVIG therapy have to be considered carefully in diabetic patients," the authors write, citing possible aggravation of abnormal renal function and precipitation of cardiovascular, cerebrovascular, and thromboembolic events. Another consideration is the total cost of each course of IVIG therapy, which is about $10,000-$15,000 per patient.

"For these reasons we believe it is important that the frequency of CIDP in DM be clarified, that the diagnosis of DM-CIDP by electrophysiological investigations be based on the strict criteria outlined above, and that a controlled trial of IVIG therapy for DM-CIDP be undertaken," they conclude.

Arch Neurol. 2002;59(5):751-757, 758-765

Reviewed by Gary D. Vogin, MD

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