Early axonal loss predicts long-term disability in chronic inflammatory demyelinating polyneuropathy

To investigate early pre-treatment nerve fiber loss as a predictor of long-term clinical outcome in chronic inflammatory demyelinating polyneuropathy (CIDP).

In 14 patients, motor and sensory conduction studies of the median, fibular, and sural nerves were performed at pre-treatment and follow-up 11-28 years later. Z-scores of amplitudes were combined as biomarkers of axonal loss and Z-scores of conduction properties as demyelination scores. The axonal loss was further examined by electromyography (EMG) and motor unit number estimation. Axonal and demyelination scores were compared to clinical outcomes in the Inflammatory Rasch-built Overall Disability Scale, the Neuropathy Impairment Score, and dynamometry.

At follow-up 12 patients walked independently, one needed support and one could not walk. The initial and follow-up axonal and demyelination scores were markedly abnormal. The initial axonal loss but not demyelination was strongly associated with both the follow-up axonal loss and the clinical measures. Moreover, delay of treatment initiation negatively influenced the axonal scores and clinical outcomes.

In this hypothesis generating limited study, we found that axonal loss at early CIDP was highly predictive for long-term nerve fiber loss and disability.

The study indicates that prompt initiation of treatment to prevent nerve fiber loss is necessary for outcome in CIDP.