Medline ® Abstracts for References 38-40

OBJECTIVE: To investigate the additional diagnostic value of sural nerve biopsy of 64 patients in whom chronic inflammatory demyelinating polyneuropathy (CIDP) was considered, as sural nerve biopsy is recommended in the research criteria of an ad hoc subcommittee to diagnose CIDP.

METHODS: Firstly, the additional diagnostic value of sural nerve biopsy was analysed with multivariate logistic regression. Six clinical features (remitting course, symmetric sensorimotor neuropathy in arms and legs, areflexia, raised CSF protein concentration, nerve conduction studies consistent with demyelination, and absence of comorbidity or relevant laboratory abnormalities) were entered into a logistic model. Afterwards, all significant features identified from this model, as well as the results of sural nerve biopsy were forced into a second logistic model. Secondly, the diagnostic performance of a neurologist experienced in diagnosis of peripheral nerve disorders was studied by receiver operating characteristics (ROC) curve analysis.

RESULTS: The results of the first logistic analysis showed that CSF protein concentration>1 g/l (odds ratio (OR)=38.5) and neurophysiological studies consistent with demyelination (OR=51.7) were strong predictors of CIDP. When forcing the significant features and the sural nerve biopsy data into the model, an independent predictive value of sural nerve biopsy could not be found. The neurologist was able to discriminate patients with and without CIDP (area under the curve (AUC)=0.95). His diagnostic performance did not improve significantly by offering him the results of sural nerve biopsy.

CONCLUSION: Any additional diagnostic value of sural nerve biopsy in the diagnosis of CIDP could not be shown.

The objective of the study was to determine the diagnostic value of features of demyelination and inflammation in sural nerve biopsy specimens of patients with chronic inflammatory demyelinating polyneuropathy (CIDP). The features of (i) demyelination, (ii) axonal de- and regeneration and (iii) inflammation were investigated by measuring the number of onion bulbs, g ratio (axon diameter/total nerve fibre diameter), myelinated nerve fibre density, number of clusters and endoneurial area in 21 patients with CIDP, as well as in 13 patients with chronic idiopathic axonal polyneuropathy (CIAP) and six autopsy controls. In addition, teased fibres were classified and lengths of internodes measured. We found no difference in demyelinating features between patients with CIDP and CIAP, as the percentage of fibres with segmental de- and remyelination and the number of onion bulbs were similar in both polyneuropathy groups. The g ratio, expected to be higher in a demyelinating disease due to thinner myelin sheaths, was significantly lower in CIDP than CIAP. Evidence for axonal degeneration was found in both CIDP and CIAP, as both showed a decrease in myelinated nerve fibre density. There was no evidence of endoneurial oedema in CIDP, as the endoneurial area did not differ between CIDP, CIAP and the autopsy controls. Although significant differences of features of demyelination, axonal degeneration and inflammation were found in sural nerve biopsy specimens, there was a considerable overlap between abnormalities in CIDP and CIAP patients. In the majority of patients, quantitative analysis of light microscopical abnormalities in sural nerves was similar in CIDP and CIAP. Therefore, a sural nerve biopsy is of limited diagnostic value in CIDP.

The diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) relies primarily on clinical and electrophysiologic examination, but the nerve biopsy findings may be supportive, especially in atypical cases. In order to define the usefulness of nerve biopsy in this disease, we retrospectively studied 44 consecutive patients whom we classified as having CIDP on pathological grounds. We found that 8 of these 44 patients had pathological findings indicative of CIDP but did not meet any of the usually accepted electrophysiological criteria for its diagnosis. Among these eight patients, five responded favorably to conventional therapy. All of these eight patients had an electrophysiological pattern of generalized axonopathy with additional subtle findings suggestive of demyelination that prompted us to perform a nerve biopsy. Our data suggest that a significant number of patients with unrecognized CIDP are erroneously classified as having chronic idiopathic axonal polyneuropathy. CIDP should be suspected if the electrophysiological examination displays subtle abnormalities suggestive of demyelination, even in the presence of a prominent axonal pattern. Nerve biopsy in these patients may reveal abnormalities suggestive of CIDP and guide therapeutic options.