Sural nerve biopsy in chronic inflammatory demyelinating polyneuropathy: Are supportive pathologic criteria useful in diagnosis?

Background : According to American Academy of Neurology (AAN) criteria, demonstration of demyelination in the sural nerve by teased fiber or ultrastructure is considered mandatory for diagnosis of chronic inflammatory demyelinating polyneuropathies (CIDP). In resource-restricted settings where these techniques are not freely available, it is useful to determine the utility of ′supportive′ pathologic criteria (subperineurial edema, inflammation, onion bulb formation, and demyelination) proposed by AAN for diagnosis of CIDP.
Settings and Design : Tertiary care hospital, retrospective study.
Patients and Methods : Forty-six patients with idiopathic CIDP (32 with progressive course and 14 with relapsing-remitting course) satisfying AAN clinical and electrophysiologic criteria evaluated between January 1991 and August 2004 were reviewed. Frequency of specific pathological alterations such as demyelination, inflammation, onion bulb formation, and axonal changes in sural nerve biopsies was evaluated.
Statistical Analysis : SPSS statistical package was used to calculate mean, range, and standard deviation. Student′s t test, chi-square test, and ANOVA were used for determining statistical significance.
Results and Conclusion : Reduction in myelinated fiber density was most frequent (93.5%), followed by demyelination (82.8%), inflammation (58.7%), and onion bulb formation (28.3%). Endoneurial inflammation was frequent in the relapsing-remitting form and epineurial inflammation and axonal changes in those with progressive course. Greater disability at presentation, poor response to immunomodulation, and lower CSF protein levels was seen in those with axonal pathology. Pathological abnormalities were demonstrable in all (100%), whereas electrophysiological abnormalities were detected in 90.8%, suggesting that supportive histologic AAN criteria are helpful in diagnosis of CIDP.

Keywords
American Academy of Neurology, chronic inflammatory demyelinating polyneuropathies, diagnosis, neuropathology, supportive pathologic criteria, sural nerve biopsy