RESUMO
Tremor is the most common movement disorder and there are numerous causes of tremor. In many individuals, tremor can be due to drugs. The most common drugs associated with tremor include amiodarone, selective serotonin (and norepinephrine) reuptake inhibitors (SSRIs/SNRIs), amitriptyline, lithium, valproate, ß-adrenoceptor agonists, dopamine receptor antagonists, VMAT2 inhibitors, or drugs of abuse: ethanol, cocaine, etc. Drug-induced tremor usually resembles essential or parkinsonian tremor, depending on the offending drug; however, features such as unilateral, task-specific, position-dependent tremor or sudden onset, distractibility, entrainment and arrest with contralateral movements suggest etiologies such as dystonic or functional (psychogenic) tremor. Risk factors for drug-induced tremor include polypharmacy, male gender, older age, high doses and immediate-release preparations or reaching toxic levels of the offending drugs. Drug-induced tremor usually resolves once the offending medication is discontinued, however, persistent tremor may be observed in some cases (tardive tremor). In this manuscript, we discuss the most common causes of drug-induced tremor. This article is part of the Special Issue "Tremor" edited by Daniel D. Truong, Mark Hallett, and Aasef Shaikh.
Assuntos
Inibidores da Recaptação de Serotonina e Norepinefrina , Tremor , Amitriptilina , Humanos , Masculino , Serotonina , Inibidores Seletivos de Recaptação de Serotonina/uso terapêutico , Tremor/induzido quimicamente , Tremor/diagnósticoRESUMO
Tremor and parkinsonism are recognized side effects of valproate; however, the relationship between rest tremor and other signs of parkinsonism has not been addressed in patients taking valproate. We studied a cohort of 125 consecutive patients treated with valproate due to epilepsy or migraine, evaluated with the Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS). A total of 14 (11.2%) patients had rest tremor (bilateral n = 10, unilateral n = 4). Patients with rest tremor had significant higher scores in the FTM-TRS (P < 0.001), but only one was diagnosed with parkinsonism. Patients may have valproate-induced parkinsonism or exacerbated motor features of Parkinson's disease by valproate. The frequency of parkinsonism was 1.6% in this cohort and of 3% in the pooled data of 717 patients from previous reports. Rest tremor is observed in 11.2% of patients treated with valproate and is related to the burden of valproate-induced tremor, rather than the presence of parkinsonism.
Assuntos
Anticonvulsivantes/efeitos adversos , Transtornos Parkinsonianos/induzido quimicamente , Tremor/induzido quimicamente , Ácido Valproico/efeitos adversos , Adolescente , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos Parkinsonianos/diagnóstico , Tremor/diagnóstico , Adulto JovemRESUMO
BACKGROUND: Tremor is a known side-effect of anticonvulsants, particularly of valproate. However, there is a dearth of information regarding detailed clinical features and functional impact of valproate-induced tremor. METHODS: We studied a cohort of patients treated with anticonvulsants for neurological disorders, through blinded evaluations using the Clinical Rating Scale for Tremor (CRST); we compared the frequency, severity and functional impact of drug-induced tremor between patients treated with valproate and those treated with other anticonvulsants. RESULTS: From a cohort of 218 consecutive patients, 171 were fully evaluated; 118 patients were taking valproate alone or combined with other anticonvulsants and 53 patients were taking other anticonvulsants. Mean age (±SD) at evaluation of the cohort was 32 ± 13 years, females represented 55.6% of cases. Tremor was more frequently observed in patients taking valproate particularly postural upper limb tremor: 49% vs. 15% (right-side) (P < 0.001) and 48.3% vs. 13.2% (left-side), (P < 0.001); had a higher total CRST score: 12.14 vs. 3.06 (P < 0.001), and required more frequently treatment for drug-induced tremor: 23.7% vs. 5.6% (P=0.005) compared with patients taking other anticonvulsants. Among 118 patients taking valproate, women had a higher total CRST score compared with men: 14.54 ± 14.9 vs. 9.56 ± 9.55 (P=0.034). A weak correlation between the total CRST score, dose per Kg of valproate and serum levels of valproate were observed. CONCLUSIONS: Tremor is frequently observed in patients taking valproate and is severe enough to require treatment in about 24% of cases.