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  • Updated 08.16.2020
  • Released 07.16.1993
  • Expires For CME 08.16.2023

Acute drug-induced movement disorders



Acute drug-induced movement disorders are primarily due to neuroleptics, but other psychoactive medications may produce them as well, selective serotonin reuptake inhibitors (SSRIs) being the most common. Although it is generally believed that drug-induced movement disorders are much less common in the era of atypical antipsychotic drugs, there are few data to support this contention. Both acute and nonacute drug-induced movement disorders still do occur; therefore, neurologists and psychiatrists should be able to recognize and treat them. Developments in diagnosis and prevention of drug-induced movement disorders, such as the use of dopamine transporter scan (DaTscan) and treatment with vesicular monoamine type 2 inhibitors (VMAT2) have improved outcomes for many patients with these movement disorders (23). Akathisia may be mistaken for other conditions, including restless legs, increased psychosis, or anxiety and should be included on the differential diagnostic list for agitation. These problems are occasionally seen with antiemetics and, more commonly, with antipsychotics (eg, chlorpromazine) used for migraines or depression (eg, aripiprazole and brexpiprazole). Akathisia may also be seen with VMAT2 inhibitors used to treat hyperkinetic movement disorders, such as chorea or a tardive syndromes. Although these drugs do not cause tardive syndromes, they have been associated with acute dystonic reaction and akathisia. Acute dystonic reactions occur with some, but not all, of the newer antipsychotic medications. Acute akathisia is harder to characterize because of the subjective nature of the symptoms. Neuroleptic malignant syndrome occurs with all antipsychotics, including clozapine and the other atypicals. The SSRIs may cause akathisia, or, with overdose, serotonin syndrome, which can be difficult to distinguish from neuroleptic malignant syndrome.

Key points

• Extrapyramidal side effects are seen with all first generation, and most second generation, antipsychotic drugs.

• Acute akathisia and acute dystonic reactions are usually the first extrapyramidal side effects to develop, primarily shortly after initiation of an antipsychotic or a dose increase, and generally before parkinsonism develops.

• Akathisia may be difficult to diagnose because of its subjective nature and overlap with anxiety and psychosis but is a very important cause for noncompliance. It may also account for agitation in patients who have impaired communication.

• VMAT2 inhibitors may cause akathisia and, rarely, acute dystonic reactions, such as demented patients.

Historical note and terminology

The term “acute drug-induced movement disorders” refers primarily to acute dystonic reactions and akathisia. These syndromes were first described as adverse drug effects in the mid-1950s (75; 17) and were recognized as being similar to the dystonic and akathisic syndromes seen in postencephalitic parkinsonism. Akathisia had been recognized even before the encephalitis epidemic, the term having been coined at the turn of the century to describe psychiatric patients unable to remain seated and thought to suffer from a form of hysteria (33). The syndrome we currently call akathisia had been described in the 19th century in idiopathic Parkinson disease (09). The term “akathisia” was taken up by neurologists after the epidemic of postencephalitic parkinsonism, which was frequently associated with akathisia (84).

These syndromes are thought to have become considerably less common in the current era of atypical antipsychotic drugs but have not been well studied. Non-acute drug-induced movement disorders have been widely thought to have been reduced with the introduction of the atypical antipsychotics, but data on this are conflicting (16; 57).

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