The Electrophysiology of Disease Remission in Chronic Inflammatory Demyelinating Polyneuropathy.

BACKGROUND

Whether serial electrophysiology may be useful in chronic inflammatory demyelinating polyneuropathy (CIDP), in remission off treatment, is unknown.

METHODS

We retrospectively studied electrophysiological findings during active disease and post-remission, in subjects with CIDP, at 2 UK neuropathy centres.

RESULTS

We included 24 consecutive subjects. Eighteen (75%) had typical CIDP, 3 (12.5%) motor CIDP and 3 (12.5%) distal CIDP. Mean age was 61.3 years (SD: 15.8). Mean interval between electrophysiological study during active disease and post-remission was 63.25 months (SD: 52.0). Mean distal motor latency improved for median (p < 0.001), ulnar (p < 0.001), fibular (p = 0.01) and tibial (p = 0.002) nerves. Mean motor conduction velocity improved for median (p < 0.001), ulnar (p < 0.001) and fibular (p = 0.012) nerves. Mean minimum F-wave latency improved for median (p = 0.003), ulnar (p = 0.002), and tibial (p = 0.027) nerves. The proportion of nerves showing conduction block was greater during active disease than post-remission (26/66 vs. 10/67; p = 0.002). Criteria for demyelination were initially fulfilled by all subjects, but not post-remission (24/24 vs. 14/24; p = 0.006). Electrophysiological quasi-normalisation correlated with shorter pre-treatment disease duration (p = 0.002). Amplitude of functional improvement correlated with fibular nerve motor amplitude at first study (p = 0.024).

CONCLUSIONS

Electrophysiological quasi-normalisation may occur in a third of subjects with typical CIDP in clinical remission off treatment and may be more likely with prompt diagnosis/treatment. Amelioration may be observed in all tested nerves. Initial fibular nerve motor amplitude may predict clinical improvement amplitude. The value of electrophysiology for prognostication/disease monitoring/management may merit further study in CIDP. Further research is warranted for subjects with variant and possible CIDP.