Clinical features of drug-induced Parkinsonism

Drug-induced Parkinsonism is often reversible after withdrawal of the causative drug. Its clinical course, however, is not well understood, as the majority of cases are caused by drugs prescribed by departments outside of neurology. We reviewed 21 cases of drug-induced parkinsonism for several factors, including age, sex, causative drug and reason for prescription, department by which it was prescribed, and outcome. The age at onset ranged from 40 to 87 years, with an average Hoehn and Yahr Scale score of 4, indicating severe disability. Sulpiride was the most commonly observed causative drug (71.4%). All causative drugs were prescribed in non-neurological departments and over one half were prescribed in non-psychiatric departments; most were prescribed to treat depression or abdominal discomfort. Ten patients (48%) were previously diagnosed with a neuromuscular disease, including cerebrovascular diseases and Parkinson's disease. Recovery was observed in 15 cases (71%) after withdrawal of the causative drug, but lingering symptoms were observed in the remaining cases. It is suggested that physicians should be more cautious of Parkinsonian side effects when prescribing such drugs.

Tetrabenazine in treatment of hyperkinetic movement disorders: an observational study

BACKGROUND

Tetrabenazine (TBZ) is commonly used in hyperkinetic movement disorders. In this retrospective study, we aimed to assess the TBZ effectiveness and adverse events (AEs) in Huntington disease (HD), vascular chorea, tics, dystonia, tardive oromandibular (OM) dyskinesia and other tardive syndromes (TS).

METHODS

Qualitative analysis of clinical response was used to estimate TBZ effectiveness. TBZ-associated AE frequency and subsequent discontinuation rate were used to estimate tolerability; the tolerability profile was measured through the TBZ minimal dose and exposure time required to elicit AEs.

RESULTS

Of 108 included patients, 87% had a clinically meaningful improvement sustained over a period of 40 months. TBZ-responder rate ranged from 100% in HD to 62.5% and 77.1% in tic disorders and OM dyskinesia, respectively (p < 0.001). TBZ-associated AE frequency ranged from 40.9% in other TS and 41.7% in vascular chorea and HD, to 60% in OM dyskinesia (p < 0.001). The most common AEs were Parkinsonism (51.8%) and psychiatric disorders (25%). The 'other AEs' category (mainly somnolence) presented the shortest minimal exposure time (3 months). AE-eliciting dose differed from 18.8 mg and 25 mg in tics and tardive disorders, to 75 mg in HD (p = 0.003). Patients with AEs were tendentiously older at TBZ initiation (p = 0.022).

CONCLUSIONS

TBZ proved an effective and relatively well tolerated treatment in hyperkinetic disorders, with excellent results in HD. AEs were more common in OM dyskinesia, which may be related to higher age at TBZ initiation. TBZ-associated somnolence and Parkinsonism were more frequent during the titration and maintenance periods, respectively.