Recognition and Management of Antipsychotic-Induced Parkinsonism in Older Adults: A Narrative Review

Symptomatic Treatment of Extrapyramidal Hyperkinetic Movement Disorders

Extrapyramidal hyperkinetic movement disorders comprise a broad range of phenotypic phenomena, including chorea, dystonia, and tics. Treatment is generally challenging and individualized, given the overlapping phenomenology, limited evidence regarding efficacy, and concerns regarding the tolerability and safety of most treatments. Over the past decade, the treatment has become even more intricate due to advancements in the field of deep brain stimulation as well as optimized dopamine- depleting agents. Here, we review the current evidence for treatment modalities of extrapyramidal hyperkinetic movement disorders and provide a comprehensive and practical overview to aid the choice of therapy. Mechanism of action and practical intricacies of each treatment modality are discussed, focusing on dosing and adverse effect management. Finally, future therapeutic developments are also discussed.

Prevention of Parkinson's Disease: From Risk Factors to Early Interventions

Parkinson's disease (PD) is a debilitating neurological disorder characterized by progressively worsening motor dysfunction. Currently, available therapies merely alleviate symptoms, and there are no cures. Consequently, some researchers have now shifted their attention to identifying the modifiable risk factors of PD, with the intention of possibly implementing early interventions to prevent the development of PD. Four primary risk factors for PD are discussed including environmental factors (pesticides and heavy metals), lifestyle (physical activity and dietary intake), drug abuse, and individual comorbidities. Additionally, clinical biomarkers, neuroimaging, biochemical biomarkers, and genetic biomarkers could also help to detect prodromal PD. This review compiled available evidence that illustrates the relationship between modifiable risk factors, biomarkers, and PD. In summary, we raise the distinct possibility of preventing PD via early interventions of the modifiable risk factors and early diagnosis.

Treatment Changes and Prognoses in Patients with Incident Drug-Induced Parkinsonism Using a Korean Nationwide Healthcare Claims Database

This retrospective cohort study assessed treatment changes and prognoses after incident drug-induced parkinsonism (DIP). We used the National Health Insurance Service's National Sample Cohort database in South Korea. We selected patients diagnosed with incident DIP and given prescriptions to take offending drugs (antipsychotics, gastrointestinal (GI) motility drugs, or flunarizine) for a period of time that overlapped with the time of DIP diagnosis during 2004-2013. The proportion of patients experiencing each type of treatment change and prognosis was assessed for 2 years after DIP diagnosis. We identified 272 patients with incident DIP (51.9% of patients were aged ≥ 60 years and 62.5% of them were women). Switching (38.4%) and reinitiation (28.8%) were the most common modifications in GI motility drug users, whereas dose adjustment (39.8%) and switching (23.0%) were common in antipsychotic users. The proportion of persistent users was higher among antipsychotic users (7.1%) than that among GI motility drug users (2.1%). Regarding prognosis, 26.9% of patients experienced DIP recurrence or persistence, the rate being the highest in persistent users and the lowest in patients who discontinued the drug. Among patients with incident DIP diagnoses, the patterns of treatment change and prognosis differed across the types of offending drugs. Over 25% of patients experienced DIP recurrence or persistence, highlighting the need for an effective strategy to prevent DIP.

Permanent non-progressive cinnarizine and flunarizine-induced parkinsonism: An under-recognized tardive syndrome in the elderly?

Secondary parkinsonism induced by exposure to dopamine (DA) receptor antagonists as first and second generation antipsychotics, DA storage depleters, calcium channel blockers, benzamides substituted and other classes of drugs is traditionally believed to be completely reversible in most of patients following withdrawal of the offending drug even though after a variable time delay. The lack of recovery or initial full recovery with subsequent development of progressive parkinsonism has been regarded to result from an underlying subclinical degenerative process like PD unmasked by the inducing drug. These well-recognized clinical outcomes of drug-induced parkinsonism (DIP) have disregarded the existence of another outcome, characterized by permanent non-progressive parkinsonism. This syndrome may fullfil the criteria of tardive parkinsonism, a controversial entity currently referred to as a persistent condition without indication of its long-term course and clinical features. On reviewing the published literature on DIP, we have identified two prospective long-term follow-up of elderly patients in which parkinsonism induced by the calcium channel antagonists cinnarizine and flunarizine became permanent and non-progressive following drug discontinuation in a non-negligible proportion of patients, consistent with the clinical concept of a true tardive syndrome, according to currently accepted criteria. The authors hypothesize that the development of tardive parkinsonism might be due to a neurotoxic effect of the pharmacodynamic proprieties of the calcium channel blockers and their metabolites, exerted on post-synaptic striatal neurons and/or a neurotoxic damage on presynaptic DA neurons in patients without an underlying subclinical degenerative parkinsonism, so accounting for the stable and non-progressive course over time.

Phenytoin-associated movement disorder: A literature review

Phenytoin (PHT) was first synthesized as a barbiturate derivative and was approved in 1953 by the Food and Drug Administration. This work aimed to review the pathophysiology, epidemiology, clinical presentation, and treatment of PHT-associated movement disorders (MDs). Studies were searched in relevant databases (ScienceDirect, Google Scholar, Excerpta Medica, Latin American and Caribbean Health Sciences Literature, Medline, and Scientific Electronic Library Online) and were selected by two reviewers irrespective of language between 1963 and 2021. Papers of PHT-induced ataxia alone or tremor were excluded. In total, 127 reports with 219 individuals who developed MDs associated with PHT were encountered. MDs found: 126 dyskinesias, 49 myoclonus, 19 dystonia, 14 parkinsonism, 6 tics, 3 stuttering, and 2 restless legs syndrome. The mean age was 35 years (standard deviation [SD]: 23.5) and the predominant sex was male (53.4%). The mean PHT dose when the MD took place was 370.4 mg (SD: 117.5). A serum PHT concentration was reported in 103 cases, ranging from 4 to 110 μg/mL (median: 27.7 μg/mL). No significant relationship was found between PHT dose and age or PHT level. The mean onset time of PHT-associated MD was 23.4 months (SD: 4.4). The mean recovery time after MD management was 3.7 weeks (SD: 1.1). Regarding management, the most common form was PHT withdrawal in 90.4%. 86.3% of the individuals recovered fully. PHT-induced MD was extensively reported in the literature. Only general terms were used in the majority of the reports. The mechanisms underlying the adverse events caused by PHT probably depend on the presence of predisposing factors.