Acute Dystonic Reaction

What Is It, Causes, and More

Author:Corinne Tarantino, MPH

Editors:Alyssa Haag,Emily Miao, PharmD,Kelsey LaFayette, DNP, RN

Illustrator:Jessica Reynolds, MS

Copyeditor:Sadia Zaman, MBBS, BSc

What is an acute dystonic reaction?

An acute dystonic reaction is an acute medication-induced dystonia. Dystonic reactions, in general, are movement disorders characterized by involuntary contractions of muscles, and typically develop within minutes or hours following a trigger, such as a medication. Different muscle groups can be affected and the reaction may be further categorized based on the specific muscles involved. For example, an oculogyric crisis involves the ocular muscles while laryngeal dystonia involves the larynx. An acute dystonic reaction can be potentially life threatening, so seeking emergent care at an emergency department is advisable.

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What causes an acute dystonic reaction?

The primary cause of an acute dystonic reaction is the body’s reaction to a medication. Acute dystonic reactions form one of the most commonly experienced extrapyramidal side effects, which are medication-induced movement disorders that range from dystonia to parkinsonism

Most commonly, it occurs in response to antidopaminergic agents and dopamine receptor antagonists, such as antiemetics (i.e., metoclopramide) and antipsychotics (i.e., haloperidol and chlorpromazine). Dopamine is a neurotransmitter that commonly binds to its D1 and D2 receptors in the brain. Both receptors have a role in memory, attention, and movement. Since the D2 receptors are the typical target of the antidopaminergic agents, these medications can block dopamine’s function at the D2 receptor, thereby causing involuntary muscle contraction of muscle groups, commonly in the face and neck.  

Sometimes, serotonergic agents can also induce the reaction. 

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What are the signs and symptoms of an acute dystonic reaction?

muscles positioned in an atypical position, along with accompanying pain. This often develops within minutes to days of initially starting a medication. The ocular muscles, jaw, tongue, face, neck, and trunk of the body are most often affected. An acute dystonic reaction may also cause a characteristic appearance, such as backwards tilting of the head, rotation of the head, or an eye looking in one direction. 

How is an acute dystonic reaction diagnosed?

An acute dystonic reaction is typically diagnosed through a medical evaluation, including a review of medical history and a physical examination. This exam often involves neuromuscular testing to examine range of motion of the affected area, breathing ability, swallowing, and speech. In order to rule out other potential causes of dystonia (e.g., tetanus, hyperventilation, hypocalcemia, hypomagnesemia, and primary neurological causes like Wilson disease), a thorough vaccination history may be conducted and blood tests performed to assess for various nutrients, electrolytes, and proteins in the blood (e.g., calcium, magnesium and ceruloplasmin). 

How is an acute dystonic reaction treated?

An acute dystonic reaction is usually treated with anticholinergic agents (e.g., benztropine) or benzodiazepines (e.g., diazepam). Most often these medications are administered intravenously since individuals may have difficulty swallowing. It is also typically advised to terminate or reduce any medication that is responsible for the reaction.

What are the most important facts to know about acute dystonic reactions?

An acute dystonic reaction is a movement disorder characterized by involuntary muscle contractions. The reaction is one of the adverse effects of certain medications, such as antidopaminergic agents. The signs and symptoms include an onset of atypical posture or position of muscles within a few days of taking these medications. The diagnosis is made after a medical evaluation and it is promptly treated with intravenous medication as well as stopping the causative agent.

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Related links

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