Approach to medication-induced movement disorders: Clinical sciences

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Introduction0:00–0:48

Medication-induced movement disorders are a group of conditions characterized by abnormal movements resulting from exposure to certain medications.
These medications often include serotonergic medications, dopamine antagonists, and anticonvulsants, which are all commonly prescribed in psychiatric treatment.
Medication-induced movement disorders can range from mild to severe and from acute to chronic. Life-threatening ones requiring emergency intervention include serotonin syndrome and neuroleptic malignant syndrome.
Less severe ones include acute dystonia, postural tremor, extrapyramidal symptoms, akathisia, and tardive dyskinesia. If a patient presents with a chief concern suggesting a medication-induced movement disorder, first, perform an ABCDE assessment to determine if they are stable or unstable.

Unstable Patient0:48–1:24

If unstable, stabilize their airway, breathing, and circulation, which may require supplemental oxygen and even endotracheal intubation.
Next, obtain IV access, and consider starting IV fluids. Finally, begin continuous vital sign monitoring, including respiratory rate, pulse oximetry, and cardiac telemetry.

Focused H&P, Labs1:24–1:46

Once you have initiated the acute management, your next step is to obtain a focused history and physical exam, and order labs, including a CPK or creatine phosphokinase, CBC, and CMP.
In unstable patients, you should think about serotonin syndrome or neuroleptic malignant syndrome. Patients with serotonin syndrome typically report recent exposure to one or more serotonergic medications, such as serotonin reuptake inhibitors, tricyclic antidepressants, or monoamine oxidase inhibitors.

Serotonin Syndrome1:46–2:55

Additionally, there might be exposure to synthetic opioid tramadol, the muscle relaxer cyclobenzaprine, and the antibiotic linezolid, all of which have serotonergic properties as well.
As for the physical exam, look out for elevated temperature, hypertension, tachycardia, muscle rigidity, tremor or myoclonus, hyperreflexia, diaphoresis, and even confusion and seizures in severe cases.
If you see these findings, think of serotonin syndrome. Here is a clinical pearl!
The most important step in the acute management of serotonin syndrome is to discontinue the serotonergic medications immediately, followed by supportive care.
Additionally, consider adding anticonvulsants if seizures are present. Okay, let’s move on to neuroleptic malignant syndrome, which is a rare but life-threatening condition commonly associated with the use of first-generation antipsychotics.

Neuroleptic Malignant Syndrome2:55–4:22

It typically arises within the first four weeks of treatment or during dose adjustments. History usually reveals exposure to one or more antipsychotic medications.
On physical exam, you may notice generalized muscle rigidity, hyperthermia with diaphoresis, and altered mental status. Additionally, your patient might have low or high blood pressure and tachycardia.
When it comes to labs, CPK is usually greater than 10 times the upper normal limit. You might also find elevated white cell count, liver enzymes, and creatinine.
With these findings, you can diagnose neuroleptic malignant syndrome. Here’s another clinical pearl!
Acute treatment of neuroleptic malignant syndrome focuses on discontinuing the antipsychotic and providing supportive care.
Additionally, you may consider medications like a dopamine agonist such as bromocriptine; a muscle relaxant like dantrolene; and benzodiazepines if your patient has agitation.
In severe, treatment-resistant cases, electroconvulsive therapy might be necessary. Alright, now let’s go back to the ABCDE assessment and take a look at stable patients.

Stable Patient4:22–5:20

As before, obtain a focused history and physical exam. Patients usually report recently starting a new psychiatric medication; or increasing the dose of a psychiatric medication.
They might also report abnormal movements, such as tremors, or the feeling of restlessness. The physical exam can reveal a variety of abnormal movements depending on the underlying disorder.
These include chorea, characterized by brief, involuntary, and random, irregular contractions; myoclonus, which is a brief, involuntary, shock-like jerk; or dystonia, presenting as a sudden onset of sustained contraction in a muscle or muscle group.
If you see these findings, consider a medication-induced movement disorder. Now, a type of abnormal movement present during a physical exam can help determine which movement disorder you are dealing with.

Acute Dystonia5:20–7:51

Let’s start by assessing for dystonia. Logically, if your patient has dystonia, consider acute dystonia as the diagnosis.
In this case, patients may report recent use of antipsychotics, accompanied by an abrupt onset of muscle contractions. First-generation antipsychotics are associated with most cases of acute dystonia compared to second-generation ones.
Among patients treated with first-generation antipsychotics, approximately 10 percent will develop acute dystonia, while only 2 percent treated with second-generation antipsychotics are affected.
Moving on to the physical exam, you’ll notice dystonia, characterized by various abnormal movements such as torticollis, which is a contraction of the sternocleidomastoid muscle; trismus, meaning sustained clenching of the jaw; oculogyric crisis that presents as a fixed upward gaze due to contraction of the extraocular muscles; or opisthotonos, which refers to an extension of the back and neck due to contraction of the axial spinal muscles.
If these findings are present, you can diagnose acute dystonia. While acute dystonia is distressing, it is not usually life-threatening.
The one exception is when there’s glossopharyngeal muscle involvement, as this can cause airway compromise. When it comes to treatment, it involves intramuscular diphenhydramine or intramuscular benztropine.
Here’s a clinical pearl! Acute dystonia results in strange postures, similar to some presentations of catatonia.
However, postures in catatonia are characterized as waxy flexibility, meaning you can move the patient into a position, and they will remain frozen in that position.
In acute dystonia, abnormal postural changes result from sustained muscle contraction and cannot be repositioned. Also, patients with acute dystonia tend to be distressed from sustained muscle contraction, while catatonic patients are more withdrawn.
Now, let’s shift our focus to patients without dystonia. The next step here is to assess for tremor, characterized by rapid, repeated oscillating movement, typically involving the upper extremities, or the head and neck.

Postural tremor & Extrapyramidal symptoms7:51–8:14

If a tremor is present, consider either a postural tremor or a tremor associated with extrapyramidal symptoms, also known as parkinsonism.
Starting with postural tremor, patients usually report recent use of lithium, antidepressants, or stimulant medications, and less commonly anticonvulsants, dopaminergic medications, or even caffeine.

Postural tremor8:14–8:53

During the physical exam, look for fine tremor of the upper extremities, especially notable when the patient holds a posture, such as holding their arms outstretched.
Other movement problems, such as bradykinesia or cogwheel rigidity, are typically absent. With these findings, diagnose postural tremor.
Next up is tremor associated with extrapyramidal symptoms, or EPS for short. EPS commonly arise from exposure to first-generation antipsychotics, but can also occur with second-generation antipsychotics, antidepressants, mood stabilizers, calcium channel blockers, chemotherapeutic agents, and some immunosuppressant medications.

Extrapyramidal Symptoms8:53–10:13

If your patient reports a tremor that began after recent exposure to antipsychotic medication, and the physical exam reveals resting tremor of the upper extremities, face, head, or neck, along with cogwheel rigidity, bradykinesia, and shuffling gait, diagnose EPS, sometimes called parkinsonism, since they resemble the symptoms of Parkinson disease.
Time for a clinical pearl! The severity of EPS often correlates with the dose of the offending medication, while discontinuation of the medication typically resolves the symptoms.
If discontinuation is not possible, symptoms might be treated with anticholinergics such as benztropine or diphenhydramine.
Alternatively, EPS can be treated with benzodiazepines or amantadine. Now that we’ve evaluated for dystonia and tremor, let’s consider a patient who doesn't have either of these findings.

Akathisia10:13–11:23

In this case, you should consider akathisia or tardive dyskinesia. Patients with akathisia report a sensation of restlessness, often associated with behaviors like pacing or marching in place, fidgeting, rocking, or frequently changing positions.
Symptoms typically start after initiating or increasing the dose of an antipsychotic or antidepressant, or less commonly stimulants, calcium channel blockers, antiemetics, or dopaminergic medications such as carbidopa-levodopa.
These behaviors might be apparent on the physical exam, although patients might be able to suppress them for several minutes at a time.
If you see these findings, diagnose akathisia. Management typically involves either lowering the dosage of the medication or switching to a different medication.
Alternatively, benzodiazepines can be added to alleviate symptoms. Finally, let's discuss tardive dyskinesia.

Tardive Dyskinesia11:23–12:58

History typically reveals involuntary movements for more than 4 weeks in patients who have been on antipsychotic medication for more than 3 months, most commonly first-generation antipsychotics.
Alternatively, symptoms might develop within 4 weeks of stopping antipsychotics. During the physical exam, look for choreiform movements which are repeated, abnormal, involuntary, rapid jerky movements; athetoid movements which consist of slow sinuous movements; or semirhythmic movements, displaying repeated stereotypes.
You might also notice the involvement of the mouth or tongue, presenting as lip pursing, lip licking, tongue darting, grimacing, or lateral jaw movements.
Less commonly, the movements may involve the head, neck, trunk, or upper extremities. If these findings are present, you can diagnose tardive dyskinesia.
Here’s a high-yield fact! Clozapine is the only antipsychotic considered to have minimal risk of tardive dyskinesia.
Mild tardive dyskinesia cases usually remit with discontinuation of the medication, but symptoms are unlikely to resolve if the patient is elderly or if symptoms are severe.
Currently, there are two FDA-approved medications for treating tardive dyskinesia: valbenazine and deutetrabenazine. Alright, as a quick recap… The most severe and potentially life-threatening medication-induced movement disorders are serotonin syndrome and neuroleptic malignant syndrome.

Review12:58–13:31

In less severe cases, you can get to the diagnosis based on the specific abnormal movement. If there is dystonia, consider acute dystonia.
If you find a tremor, consider a postural tremor or EPS. However, if there is no dystonia or tremor,