Prevalence, clinical characteristics and treatment response of tremor in chronic inflammatory demyelinating polyneuropathy.

BACKGROUND: Tremor can be a disabling symptom of chronic inflammatory demyelinating polyneuropathy (CIDP). Studies on tremor in CIDP are limited and generally include small populations. We aim to determine the prevalence, clinical characteristics and treatment response of tremor in a large cohort of patients with CIDP. METHODS: We conducted a multicentre cross-sectional study in patients with CIDP. Tremor was assessed using the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (FTM-TRS) and electromyography tremor recording. CIDP and additional tremor characteristics were assessed with validated scales and specific questionnaires. RESULTS: Of the 124 included CIDP patients, 86 patients (69%, 95% CI 61 to 77%) currently had clinically tremulous movements (CTM), mainly consisting of tremor but also of myoclonus or both. Lifetime prevalence was 76% (95% CI 68 to 83%). CTM were present in the upper extremities in all (median FTM-TRS part A (FTM-TRS-A) upper extremity score 4, range 1-16), and in the lower extremities in 20% (median FTM-TRS-A lower extremity score 0, range 0-9). Tremor and myoclonus were most prevalent during action/intention. CTM were associated with CIDP-related and tremor-related disability and upper arm sensory impairment. Complete or partial improvement of CTM following immune therapy was reported by 22 out of 48 patients (46%; 95% CI 31 to 61%), while 8 out of 10 patients (80%, 95% CI 44 to 98%) reported partial improvement with beta-blocker use. CONCLUSIONS: CTM are common in CIDP. They are generally mild, although it does impact disability. Immune therapy reportedly improved CTM in a proportion of patients, while beta-blockers seemed effective in a small subgroup of patients.