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.

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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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Background To date, only a few clinical and neurophysiological studies have assessed the features of valproate‐induced tremor (VIT), and whether valproate (VPA) affects voluntary movements is underinvestigated. Objective To better characterize the clinical and neurophysiological features of VIT in patients with epilepsy and the effect of VPA on the execution of voluntary movement. Methods We tested 29 patients with VIT (13 taking VPA alone and 16 taking VPA plus other antiepileptics). Patients underwent a neurological examination, video recordings and kinematic assessments of postural, kinetic, and resting upper limb tremor using a motion analysis system. Movement execution was tested by kinematic assessment of finger tapping. Data of patients with VIT were compared with those of 13 patients with epilepsy taking VPA but without tremor, 13 patients with epilepsy who were not on VPA treatment, 20 patients with Parkinson's disease (PD), and 20 healthy controls (HCs). Results Clinical and kinematic evaluations showed that tremor in patients taking VPA alone was less severe than tremor in patients taking VPA plus other antiepileptics. All patients taking VPA, regardless of the presence of tremor, performed slower finger tapping compared with HCs, similar to what was observed in PD, although with no sequence effect. Patients with epilepsy without VPA showed a normal motor performance. Conclusions Tremor and movement slowness are motor signs induced by VPA. VIT severity is exacerbated when VPA is taken in combination with other antiepileptics. VPA‐induced slowness occurs regardless of tremor, may precede tremor development, and is not attributed to epilepsy.