Antipsychotic medications are used to treat a wide array of mental health conditions including mood disorders and psychotic disorders. Extrapyramidal symptoms (EPS), or drug-induced movement disorders, are common adverse side effects of antipsychotic medications. EPS are important to recognize and address as they can cause patients significant distress and impairment and lead to self-discontinuation of pharmacologic therapy. EPS can result from the use of any antipsychotic but are more likely to occur with first generation antipsychotics, such as haloperidol and fluphenazine, and less likely to occur with second generation antipsychotics, such as aripiprazole and quetiapine. Those with a history of prior EPS and on higher medication doses are at particular risk. The spectrum of EPS includes dystonia, akathisia, parkinsonism, and tardive dyskinesia. Generally, strategies for managing EPS include reducing the antipsychotic dose, switching to an alternative antipsychotic that is less likely to cause EPS, and adding a medication to treat the EPS.
Dystonia
Dystonia is an involuntary, sustained muscle contraction that results in abnormal posturing or repetitive movements. This can occur within the first few days of antipsychotic initiation or dose increase. Rarely, acute dystonia can be life-threatening, e.g., laryngeal spasms can lead to respiratory arrest. Risk factors include young age, male sex, prior dystonic reactions, and the use of high-potency antipsychotics. The treatment of acute dystonia includes anticholinergic medications including oral or intramuscular benztropine or diphenhydramine.
Akathisia
Akathisia is an uncomfortable, internal sensation of restlessness that presents as repetitive movements or pacing. It typically presents days to weeks after antipsychotic initiation or dose increase. Akathisia can be formally assessed using the Barnes Rating Scale. Treatment options include adding a beta-blocker, such as propranolol, or a benzodiazepine, such as lorazepam.
Parkinsonism
Drug-induced parkinsonism typically presents week to months after antipsychotic initiation or dose increase. Its presentation is similar to idiopathic Parkinson’s Disease and is characterized by rigidity, tremor, bradykinesia, stooped posture, shuffling gait, and masked facies. Treatment options include adding an anticholinergic agent, such as benztropine, or amantadine.
Tardive Dyskinesia
Tardive dyskinesia is a potentially irreversible choreiform movement disorder often involving the mouth, tongue or upper extremities. Tardive dyskinesia presents in patients with long term (i.e., months to years) antipsychotic use. Risk factors for tardive dyskinesia include old age, affective illness, female sex, antipsychotic exposure for more than six months, high dose antipsychotic exposure, history of parkinsonian side effects, and diabetes. The best treatment of tardive dyskinesia is to prevent its development by using the lowest possible effective doses of antipsychotics and limiting the length of treatment, if possible. If tardive dyskinesia does develop, one can consider starting a vesicular monoamine transporter 2 inhibitor, such as valbenazine or deutetrabenazine. Withdrawal emergent dyskinesia, a subtype of tardive dyskinesia, occurs shortly after the rapid discontinuation of an antipsychotic. Most cases of withdrawal emergent dyskinesia spontaneously improve in 1-2 months.
Clinical Pearls:
– To prevent EPS, consider using second generation over first generation antipsychotics, use the lowest effective dose and limit the length of treatment, if possible.
– Actively monitor for EPS using the Abnormal Involuntary Movement Scale (AIMS), a standardized tool for assessing for EPS, every 3-6 months for patients on antipsychotics.
– If EPS develops, options for management include: (1) reducing the antipsychotic dose, (2) switching to a lower potency, second generation antipsychotic or (3) adding a medication to treat the EPS.
Resources:
– Abnormal Involuntary Movement Scale (AIMS): https://www.aacap.org/App_Themes/AACAP/docs/member_resources/toolbox_for_clinical_practice_and_outcomes/monitoring/AIMS.pdf
– Barnes Akathisia Rating Scale (BARS): https://simpleandpractical.com/wp-content/uploads/2014/09/Barnes-Akathisia-Rating-Scale-BARS.pdf
AUTHOR:
Dr. Kristen Kim, MD, Psychiatrist
Vista Hill Foundation