Severe and unclassifiable tremor.

Background:  Patients often exhibit very severe or disabling forms of tremor that cannot be clearly characterized.

Objective:  To present a series of 37 cases of tremor considered unclassifiable. Patients diagnosed with essential tremor according to criteria of the International Parkinson Disease and Movement Disorder Society (IPDMDS), who had been previously studied, were included as controls. All patients underwent a battery of tests between 2019 and 2022, which enabled us to compare them.

Methods:  Relevant demographic and clinical information were collected. The following tools were applied: the Mini-Mental State Examination (MMSE); the Hospital Anxiety and Depression Scale (HADS); the Fahn-Tolosa-Marín Tremor Rating Scale (TRS); and the Quality of Life in Essential Tremor (QUEST). A simple brain magnetic resonance imaging (MRI) scan was performed for all patients. The categorical variables were compared using the Chi-squared test and the t-test with Fisher correction if appropriate, and the quantitative variables were compared through the two-tailed Student t-test. Values of p ≤ 0.01 were considered statistically significant.

Results:  The cases presented higher scores on the anxiety and depression subscales of the HADS than the controls (p ≤ 0.006 and 0.000 respectively). In all domains of the TRS, the cases scored significantly higher, as well as in the QUEST. History of enolism was higher among the controls, and history of orthostasis and rest tremor was higher among the cases (p ≤ 0.000). Cerebellar atrophy was present in every patient in the case group, and in 24 subjects in the control group. Dystonia was observed in 7 subjects in the case group, and in none of the patients in the control group.

Conclusion:  There are patients with unclassifiable and extremely disabling tremors who respond poorly to the pharmacological therapy options.