Objective: To describe tremor characteristics in patients with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP).

Background: Tremor is an underrecognized symptom of CIDP. There is limited data regarding characteristics of tremor in CIDP patients, and results vary.

Method: Patients were recruited at the outpatient clinic of the Amsterdam UMC, an expertise center for both CIDP and movement disorders. All patients with CIDP (EFNS/PNS 2010 criteria and/or EAN/PNS 2021 criteria) with clinically suspected tremor were invited to participate.

Whether or not to perform a tremor analysis was based on willingness to undergo a tremor analysis and the severity of tremor. These EMG-EEG recordings were used to classify movements as 1) tremor, 2) myoclonus, 3) tremor and myoclonus, and 4) enhanced physiological tremor. Characteristics, including activating conditions and frequency, and corticomuscular and intermuscular (right – left) coupling using coherence analyses, were investigated per group. These characteristics were additionally investigated after exclusion of patients with a possible other etiology of tremor (positive family history and/or possible medication induced tremor).

Results: We recruited 66 CIDP patients with clinically suspected tremor (76% men, median age 62). In 37 patients (70% men, median age 59), a tremor analysis was performed. In four patients, findings were inconsistent with tremor or myoclonus. Preliminary results of the other 33 patients are shown in Table 1. Postural and/or intentional tremor around 7 Hz was most prevalent. An irregular EMG bursts pattern, consistent with myoclonus, was seen in 16% of all patients (n=6). In three of them there was corticomuscular coherence with a cortical drive. Characteristics of enhanced physiological tremor were found in 27% of all patients (n=10). Myoclonus was found in 17% of the patients (n=5) after exclusion of 8 patients with a possible other etiology of the tremor than the neuropathy (Table 2).

Conclusion: In patients with CIDP with clinically suspected tremor, not only tremor but also cortical myoclonus was found. Further research is needed to gain more insight in the etiology of involuntary movements in patients with CIDP.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tremor-characteristics-in-patients-with-chronic-inflammatory-demyelinating-polyneuropathy/