What is Dystonic Reactions?
An acute dystonic reaction is a condition where certain muscles in the body contract involuntarily. These contractions can affect various parts, including the arms, legs, face, neck, stomach, pelvic area, or voice box. The contractions are ongoing or intermittent, leading to unusual movements or postures. These symptoms may go away or become permanent, often arising after taking certain medications that block dopamine receptors in the brain.
Researchers believe that the cause of acute dystonic reactions may be an imbalance between two brain chemicals, dopamine and cholinergic, in an area of the brain known as the basal ganglia. These reactions usually happen soon after starting a new medication or increasing the dose of an existing one.
Most commonly, doctors use anticholinergic drugs and benzodiazepines to lessen or reverse the symptoms of an acute dystonic reaction. While these reactions are usually temporary and may cause significant discomfort to the patient, they can, in rare cases, be life-threatening. For instance, dystonia affecting the voice box can block the airway, posing a serious risk.
What Causes Dystonic Reactions?
Medications used to treat psychosis and nausea are often the main culprits behind acute dystonic reactions, which are sudden, involuntary muscle contractions. Other medications known to cause these reactions include those used to treat malaria, depression, allergies, and seizures.
Generally speaking, drugs used to treat severe mental disturbances like acute psychosis and bipolar mania, known as antipsychotic agents, can cause acute dystonic reactions. Every antipsychotic medication we currently know about has this risk.
Some forms of these antipsychotics, though, carry a greater risk than others. The first-generation versions, including those called haloperidol and thioridazine, have a higher risk of causing acute dystonic reactions. The second-generation ones, such as olanzapine, risperidone, and quetiapine, have a less risk. This is believed to be because these drugs do not stick to the brain’s D2 receptor sites as strongly.
Anti-nausea drugs like metoclopramide and prochlorperazine, also termed as antiemetic agents, are also often the reason behind acute dystonic reactions. So much so that some doctors give an additional medicine, diphenhydramine, to reduce their side effects. There have also been some cases where drugs like methylphenidate, albendazole, chloroquine, rivastigmine, and foscarnet have led to these reactions.
Risk Factors and Frequency for Dystonic Reactions
Acute dystonic reactions are side effects that we don’t know how often they occur in general. However, when these reactions are triggered by a drug called metoclopramide, we estimate that 1 in 500 people might experience them. Certain factors can increase the risk of these reactions, such as being male, young, already having an episode of acute dystonia, or using cocaine recently. In fact, one study found that almost 7% of adults taking antipsychotic drugs experienced acute dystonic reactions.
- The general frequency of acute dystonic reactions is still unknown.
- If induced by the drug metoclopramide, 1 out of 500 people may experience these symptoms.
- Risk factors for these reactions include male gender, young age, a previous episode, or recent cocaine use.
- Nearly 7% of adults treated with antipsychotics may experience acute dystonic reactions.
Signs and Symptoms of Dystonic Reactions
Acute dystonic reactions have specific appearances or presentations. Here are some of them:
- Buccolingual Crisis – Trismus (lockjaw), risus sardonicus (forced grin), difficulties in speaking and swallowing, face contorting, the tongue sticking out.
- Oculogyric Crisis – Extraocular muscles (muscles outside of the eyeball) spasm, often causing the eyes to deviate upward.
- Torticolic Crisis – An unusual, asymmetrical position of the head or neck.
- Tortipelvic Crisis – Unusual contractions in the abdominal wall, hip, and pelvic muscles.
- Opisthotonic Crisis – A specific flexion posture where the back arches.
- Laryngeal Dystonia – Voice disorders, and a harsh, noisy breathing (stridor).
- Pseudomacroglossia – The patient feels like their tongue is swelling and sticking out.
Testing for Dystonic Reactions
If someone is experiencing an acute dystonic reaction, which is a sudden involuntary muscle contraction, they should be evaluated just as you would during any emergency. This includes checking their airway, breathing, and blood flow. If they have a rasp or croak in their voice, or they complain about discomfort in their throat after they have taken certain medications, this could indicate a muscle spasm in their throat. In these cases, they may need help to breathe, such as the insertion of a tube into their windpipe.
A detailed medical history should be taken, and a thorough physical exam performed. This will help to rule out other emergencies like stroke or seizure. Any recent medications should be assessed as some can cause muscle spasms due to their impact on dopamine, a substance in the brain that helps control muscle movement.
If drug paraphernalia is present, or if the patient has used illegal substances, it could indicate that their drugs have been tampered with by being mixed with a dangerous medication.
In an acute dystonic reaction, the person will usually be fully alert and their vital signs like heart rate, blood pressure, and body temperature should stay within a normal range.
Treatment Options for Dystonic Reactions
Treatment of acute dystonic reaction, a movement disorder, focuses on restoring the balance between two chemicals in a part of the brain called the basal ganglia and stopping the use of the medication that caused the reaction. The most common medications used for this treatment in emergency situations are diphenhydramine and benztropine. After being given these medications, the symptoms usually improve or completely disappear in about 10 to 30 minutes. However, as most antipsychotic drugs stay in the body longer than these two medications, they may need to be given again.
Supportive treatments such as giving oxygen or assisting with breathing should be provided straight away when needed.
Diphenhydramine is used due to its ability to affect the activity of a certain chemical in the nervous system and its ability to get into the central nervous system efficiently. It is most effective when given intravenously (through a vein) rather than intramuscularly (into a muscle), as it works faster. Generally, adults are given 50 milligrams intravenously, and children are given 1 milligram per kilogram of their weight, up to a limit of 50 milligrams. After the reactions are treated and symptoms get better, individuals should continue to take diphenhydramine by mouth every six hours for 1 to 2 days to prevent the symptoms from coming back.
Benztropine is another medication that can get into the central nervous system effectively and is used to manage this condition. However, it may not always be immediately available in an emergency. This medication is equally effective when given intravenously or intramuscularly. The regular dose of Benztropine is a single dose of 1 to 2 milligrams given intravenously followed by the same dose given orally twice a day for up to 7 days to prevent a recurrence. Its use in children is considered “off-label,” which means it’s not formally approved for this use.
If the symptoms of the dystonic reaction do not fully resolve with these treatments, other medications such as IV benzodiazepines may be considered. These can be lorazepam, given intravenously or intramuscularly, or IV diazepam.
Patients who had breathing difficulties or needed additional oxygen should be observed for 12 to 24 hours after their symptoms have resolved to check for a recurrence.
Patients who had this reaction while taking an antipsychotic medication should have a follow-up appointment with their psychiatrist. If they need to continue taking the problematic medication, they should also be given a medication to manage the dystonic reaction until they can start on a different medication that’s less likely to cause this side effect.
What else can Dystonic Reactions be?
The following health conditions might seem a lot like an acute dystonic reaction:
- Conversion disorder (a mental condition that causes physical symptoms)
- Tetanus (a serious bacterial infection)
- Focal Seizure (a partial seizure)
- Strychnine poisoning (a type of poisoning from a certain chemical)
- Hypocalcemia (low levels of calcium in the blood)
- Anticholinergic toxicity (a poison control emergency due to certain drugs or substances)
- Meningitis (an infection of the protective membranes of the brain and spinal cord)
- Neuroleptic Malignant Syndrome (a rare reaction to certain medications)
- Stroke (damage to the brain due to interrupted blood supply)
- Temporomandibular joint dislocation (disruption of the jaw and skull joint)
- Mandibular fracture (a break in the jawbone)
- Orbital fracture (a break in the bones around the eye)
- Clonus (a type of muscle spasm)
Therefore, it’s important for doctors to correctly identify the symptoms and make an accurate diagnosis to provide the proper care.
