Background and purpose Essential tremor (ET) is a movement disorder primarily characterized by upper limb postural and kinetic tremor. Although still under‐investigated, bradykinesia may be part of the phenotypic spectrum of ET. The aim was to evaluate bradykinesia features in ET through clinical examination and kinematic analysis of repetitive finger movements. Data collected in ET patients were compared with those recorded in Parkinson’s disease patients and healthy controls. Methods Overall, 258 subjects participated in the study (90 ET patients, 84 Parkinson’s disease patients and 84 healthy controls). Repetitive finger tapping was kinematically recorded using a motion analysis system. Movement velocity, amplitude and decrement (sequence effect) were measured. The three groups were first compared by one‐way analysis of variance. A cluster analysis was also performed to better address the data variability observed in ET patients. Possible relationships between kinematic and clinical data were assessed in ET patients. Results Essential tremor patients were slower than healthy controls. Movement slowness in ET did not correlate with postural or kinetic tremor severity. It was also found that movement slowness in ET was not associated with a sequence effect, which instead is a common feature in Parkinson’s disease. Cluster analysis showed that a proportion of ET patients may have movement abnormalities similar to those observed in Parkinson’s disease. Conclusions Movement slowness without sequence effect is a common feature in ET patients. The present findings are relevant when interpreted in the context of the new tremor classification system and in the development of a more accurate bradykinesia definition.
Tremor is a common movement disorder that can be induced by medications, including valproate, which is used for the treatment of epilepsy. However, the clinical and neurophysiological features of valproate-induced tremor are still under-investigated. We performed a clinical and kinematic assessment of valproate-induced tremor by considering tremor body distribution and activation conditions. We investigated possible correlations between demographic and clinical data and kinematic features. Valproate-induced tremor results were also compared with those collected in a large sample of patients with essential tremor. Sixteen valproate-induced tremor patients and 93 essential tremor patients were enrolled. All participants underwent a standardised neurological examination and video recording. Patients also underwent an objective assessment of postural, kinetic and rest tremor of the upper limbs and head tremor through kinematic analysis. Nonparametric tests were used for statistical comparisons between the two groups. Clinical evaluation showed a higher occurrence of rest tremor as well as head or voice, and lower limb involvement in patients with valproate-induced tremor. Kinematic analysis showed a substantial variability in the tremor features of patients with valproate-induced tremor. Compared to essential tremor, we found a higher occurrence of rest tremor of the upper limbs and the involvement of more body segments in valproate-induced tremor patients. Valproate-induced tremor has distinctive clinical and kinematic features, which may suggest that valproate interferes with the cerebellar functions.
Background and purpose Essential tremor (ET) is a common and heterogeneous disorder characterized by postural/kinetic tremor of the upper limbs and other body segments and by non‐motor symptoms, including cognitive and psychiatric abnormalities. Only a limited number of longitudinal studies have comprehensively and simultaneously investigated motor and non‐motor symptom progression in ET. Possible soft signs that configure the ET‐plus diagnosis are also under‐investigated in follow‐up studies. We aimed to longitudinally investigate the progression of ET manifestations by means of clinical and neurophysiological evaluation. Methods Thirty‐seven ET patients underwent evaluation at baseline (T0) and at follow‐up (T1; mean interval ± SD = 39.89 ± 9.83 months). The assessment included the clinical and kinematic evaluation of tremor and voluntary movement execution, as well as the investigation of cognitive and psychiatric disorders. Results A higher percentage of patients showed tremor in multiple body segments and rest tremor at T1 as compared to T0 (all p‐values < 0.01). At T1, the kinematic analysis revealed reduced finger‐tapping movement amplitude and velocity as compared to T0 (both p‐values < 0.001). The prevalence of cognitive and psychiatric disorders did not change between T0 and T1. Female sex, absence of family history, and rest tremor at baseline were identified as predictive factors of worse disease progression. Conclusions ET progression is characterized by the spread of tremor in multiple body segments and by the emergence of soft signs. We also identified possible predictors of disease worsening. The results contribute to a better understanding of ET classification and pathophysiology.
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