Movement disorders caused by atypical antipsychotics include EPS, neuroleptic malignant syndrome (NMS), seizures, and serotonin syndrome (Juurlink, 2019; Khoury & Ghosshoub, 2019; Mostel et al., 2022; Miyamatsu et al., 2021). Neuroleptic malignant syndrome and seizures are discussed separately. Serotonin syndrome is unlikely to occur unless an atypical antipsychotic and a serotonergic drug are used concurrently (Miyamatsu et al., 2021; Mostel et al., 2022).
Atypical antipsychotic-induced EPS includes akathisia, dystonias, parkinsonism, and tardive dyskinesia (Juurlink, 2019). It has been estimated that EPS occurs in up to 30% of patients taking an atypical antipsychotic, and these adverse effects can have a significant negative effect on a patient’s emotional, physical, and psychological functioning and well-being (Bjarke et al., 2022; Jouini et al., 2022; Kadakia et al, 2022).
Akathisia is characterized by intense, subjective feelings of restlessness and observable repetitive movements (Jouini et al., 2022; Juurlink, 2019; Pringsheim et al., 2018). The onset of akathisia is usually within days or weeks of starting the drug, and akathisia has been reported to occur in up to 27% of patients taking an atypical antipsychotic (Bjarke et al., 2022; Pringsheim et al., 2018). Akathisia can be treated by stopping the use of the drug, switching to another antipsychotic, lowering the dose, or giving the patient an anticholinergic drug, a beta-blocker, or a benzodiazepine (D’Souza & Hooten, 2022; Juurlink, 2019; Keepers et al., 2020).
Dystonias are involuntary contractions of agonist/antagonist muscles that cause abnormal, rhythmic, and repetitive movements and abnormal postures that are intermittent or sustained (Juurlink, 2019; Olanow & Klein, 2022). Dystonias often are seen in the head, face, neck, tongue, and ocular muscles, but they can affect the extremities, as well (Juurlink, 2019). Examples of dystonia include oromandibular dystonia, which is characterized by abnormal movements of the jaw, lips, lower face, and tongue (Olanow & Klein, 2022).
The onset of dystonia is usually within hours of taking the first dose, but it can be delayed for several days (Juurlink, 2019). Because of individual susceptibility to dystonias, different patient populations, and the number (15) of atypical antipsychotics, it is difficult to determine the incidence of dystonia associated with these drugs.Except for laryngeal dystonia, which can comprise airway integrity, atypical antipsychotic-induced dystonias are uncomfortable and frightening, but they are not dangerous, and they can be effectively treated with an anticholinergic drug like benztropine or diphenhydramine or a benzodiazepine (D’Souza & Hooten, 2022; Juurlink, 2019; Keepers et al., 2020; Stroup & Gray, 2018).
Parkinsonism is characterized by signs and symptoms that mimic Parkinson’s disease, including (but not limited to) bradykinesia, postural instability, muscular rigidity, and tremor (Juurlink, 2019; d’Errico et al., 2022). The incidence of parkinsonism has been estimated to be 20% to 40% (Pieters, 2018). Treatment includes (but is not limited to) discontinuing use, lowering the dose, amantadine, dopamine agonists, or an anticholinergic drug (D’Souza & Hooten, 2022; Juurlink, 2019; Keepers et al., 2020). Most cases of parkinsonism will resolve if the use of the antipsychotic is discontinued (Feldman et al., 2022).
Tardive dyskinesia (TD) is characterized by involuntary, repetitive, and choreiform movements of the jaw, mouth, and tongue, e.g., rhythmic and repetitive puckering of the lips, rhythmic and repetitive protruding of the tongue (Jain & Correll, 2018; Takeuchi et al, 2022). Occasionally TD affects the extremities and other body areas (Jain & Correll, 2018). Tardive refers to the delayed onset of this adverse effect; TD usually begins three months after beginning therapy with an antipsychotic, but TD can begin after years of use, and it can begin after a patient has stopped taking an antipsychotic (Jain & Correll, 2018). The prevalence of TD associated with atypical antipsychotics has been estimated to be ~ 20% (Stegmayer et al., 2018). Tardive dyskinesia is difficult to treat, and it can be, and often is, irreversible (Jain & Correll, 2018; Takeuchi et al, 2022; Juurlink, 2019).