Triple-stimulation technique improves the diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy

Abstract

Introduction: A difficult clinical situation occurs when a chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) patient does not fulfill any of the diagnostic criteria. Moreover, nerve conduction studies (NCS) can be consistent with axonal neuropathy and lead to misdiagnosis.

Methods: We aimed to assess the usefulness of the triple-stimulation technique (TST) for detection of proximal conduction blocks (CBs) in patients with axonal-like CIDP. Four patients with axonal-like CIDP were studied and compared with 10 typical CIDP patients. In the axonal-like group, NCS showed a decrease in compound muscle action potential amplitude without features of demyelination, but nerve biopsy showed features of demyelination in all 4.

Results: Twelve nerves were tested with TST, and 8 CBs were detected between the root emergence and the Erb point in the 4 patients, all of whom improved after treatment with intravenous immunoglobulin.

Conclusion: TST can identify very proximal CBs in CIDP. The sensitivity of nerve conduction studies may be improved by TST in CIDP.

Keywords: CIDP; conduction block; demyelinating neuropathy; transcranial magnetic stimulation; triple-stimulation technique.