Objective: The aim of this study was to give a detailed description of the clinical and neurophysiological characteristics of tremor in patients with Myotonic dystrophy type 2 (DM2) and we wanted to see if DM2 patients with tremor had any specifics in relation to the group of these patients who did not have tremor.

Background: DM2 is an inherited autosomal dominant, multisystemic disease manifested predominantly by proximal limb weakness, muscle cramps, and stiffness associated with other somatic abnormalities. Besides that, cognitive and extrapyramidal disorders in these patients have been described recently.

Method: For this study, 27 patients with DM2 and tremor were compared to 30 DM2 patient without tremor. Tremor was registered and measured by accelerometer in the postural position with and without load. Patients were clinically evaluated according to Tolosa-Fahn-Marin Tremor Rating Scale (TFMRS) and Clinical Rating Scale (CRS) for scoring tremor and Medical Research Council 0-5 point scale for muscle strength.

Results: Tremor was action tremor with postural and mild kinetic component. The average frequency of postural tremor was 6.4±1.23 Hz and varied from 4.9 Hz to 10.55 Hz. Most patients had frequency of 4.9Hz to 5.96Hz, while five patients had tremors above 7 Hz in which the load decreased frequency by more than 1 Hz.  Patients who had tremor were statistically significantly older and had higher MRC scores. No statistically significance was observed for higher frequency of polyneuropathy in DMT2 patients with tremor. There was no correlation between the total TFMRS score, the overall CRS score and MRC score. There was statistically significant correlation between tremor amplitude and the objective and total TFMRS score, also between total CRS score and the strength of the tremor activity.

Conclusion: Tremor is a relatively common symptom in patients with DM2 and represents heterogeneous phenomenon with a small number of patients having tremor that has the characteristics of increased physiological tremor, while a larger group of patients have tremor that has a frequency and response to stress similar to essential tremor indicating of its central origin.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tremor-in-patients-with-myotonic-dystrophy-type-2/