ELECTROPHYSIOLOGICAL CHARACTERISTICS OF CENTRAL TREMOR SYNDROMES: A STUDY OF 360 PATIENTS
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Abstract
Background: Tremor is an involuntary, rhythmic, and repetitive movement disorder that may originate from either peripheral or central mechanisms. Parkinsonian tremor (PD), essential tremor (ET), and dystonic tremor (DT) are among the most common causes of central tremor syndromes. In clinical practice, differentiating these disorders can be challenging because of overlapping clinical features. Surface polymyography combined with frequency spectrum analysis has been recognized as a useful tool for the evaluation and classification of tremor.
Objective: To investigate the electrophysiological characteristics of tremor and evaluate the diagnostic value of electrophysiological parameters in differentiating Parkinson’s disease (PD), essential tremor (ET), and dystonic tremor (DT).
Methods: A cross-sectional descriptive and analytical study was conducted on 360 patients diagnosed with PD (n = 191), ET (n = 122), and DT (n = 47). All participants underwent surface polymyography and accelerometry. Electrophysiological parameters assessed included tremor occurrence state, peak frequency, peak frequency width, and muscle contraction pattern.
Results: The mean age of the study population was 60,87 ± 14.07 years. Age differed significantly among the three groups (p = 0.002). Rest tremor was predominantly observed in the PD group (96,9%), whereas postural tremor was present in all ET and DT patients. Peak frequency differed significantly among the groups (p < 0,001), being highest in ET (7,22 ± 1,62 Hz), followed by DT (5,99 ± 1,64 Hz), and lowest in PD (5,02 ± 0,92 Hz). Peak frequency width increased progressively from PD (0,78 ± 0,14) to ET (0,85 ± 0,17) and DT (1,29 ± 0,44) (p < 0,001). Alternating muscle contraction pattern predominated in PD (77,5%), whereas synchronous contraction pattern was more common in ET (81,1%) and DT (78,7%) (p < 0,001). Multinomial logistic regression analysis demonstrated that peak frequency, peak frequency width, and muscle contraction pattern were independent predictors for distinguishing among tremor syndromes.
Conclusions: Electrophysiological parameters, particularly peak frequency, peak frequency width, and muscle contraction pattern, are valuable in the differential diagnosis of PD, ET, and DT. Surface electromyography combined with frequency spectrum analysis may serve as a useful adjunctive tool in the evaluation of patients with tremor.
Keywords
Parkinson’s disease, essential tremor, dystonic tremor, surface electromyography, peak frequency, peak frequency width, muscle contraction pattern
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