Approach to involuntary movements: Clinical sciences

Involuntary movements are unintentional body movements that can occur due to various conditions, including metabolic derangements, medication effects, and neurodegenerative conditions. There are several distinct types of involuntary movements, such as tremors, dystonia, myoclonus, and chorea, and the underlying pathology is different for each condition.

Important conditions associated with involuntary movements include those secondary to anti-dopaminergic medications, and neurologic conditions, such as Parkinson disease, Creutzfeldt-Jakob disease, Tourette syndrome, and Huntington disease.

Now, if a patient presents with involuntary movements, first obtain a focused history and physical examination, and order a complete metabolic panel. History reveals body movements that the patient cannot control. The physical exam shows abnormal movements that persist even if you distract the patient, while the complete metabolic panel is normal. These findings are suggestive of movement disorder.

Here’s a clinical pearl! Metabolic derangements can cause different abnormal movements. For example, hypocalcemia can increase membrane excitability of peripheral nerves and cause muscle fasciculations and tetany. Less commonly, hypomagnesemia and hypokalemia can also cause fasciculations and tetany. Lastly, renal or hepatic failure might lead to asterixis, which is flapping of the hands when the arms are outstretched.

Your next step is to assess the use of anti-dopaminergic medications, including antipsychotics, especially first-generation antipsychotics, and anti-emetics, such as metoclopramide. If your patient is taking an anti-dopaminergic medication, diagnose medication-induced movement disorder and determine the type of medication reaction the patient is having.

Let’s start with medication-induced dystonia. These patients report sustained muscle tightening, twisting of the body that typically involves the face and neck, and recent use of an anti-dopaminergic agent within the last few hours to days. On the physical exam, you’ll find sustained muscle contractions, such as torticollis; twisting of the tongue; trismus, which is contraction of the muscles of mastication resulting in lockjaw; or opisthotonus, which refers to an extreme arching of the neck and back. With these findings, diagnose medication-induced dystonia.

Okay, let’s discuss medication-induced Parkinsonism. In this case, patients report slowness, stiffness of movement, and possibly shaky hands at rest and frequent falls. Additionally, they have used an anti-dopaminergic agent in the last few weeks to months. On the physical exam, you’ll observe bradykinesia, rigidity, and, sometimes, rest tremor. In this case, diagnose medication-induced parkinsonism. Remember, patients with medication-induced parkinsonism are less likely to have a tremor than patients with idiopathic Parkinson disease, and the symptoms are more likely to be symmetric.

Finally, let’s look at tardive dyskinesia. Here, history reveals frequent grimacing, lip-smacking, eye blinking, or tongue protrusion and twisting. Patients might also report abnormal twisting or posturing of the limbs or body. This type of involuntary movement occurs when anti-dopaminergic medications have been used for months to years. Next, the physical exam reveals repetitive stereotyped movements of the perioral region, extremities, and/or trunk. In this situation, you can diagnose tardive dyskinesia.

Here’s a clinical pearl! Treatment for medication-induced movement disorders involves cessation of the offending agent and benzodiazepine. Keep in mind that unlike medication-induced dystonia and Parkinsonism, tardive dyskinesia may not resolve after stopping the medication.

Alright, let’s switch gears and discuss situations in which an anti-dopaminergic agent was not used. In this case, your next step is to assess if the main involuntary movement is a tremor. If it is, detailed history and physical exam will give you clues about the underlying cause, which most commonly includes Parkinson disease and essential tremor.

Patients with Parkinson disease report shaky hands at rest, slowness of movement, sometimes in combination with frequent falls, and a loss of smell. The physical exam reveals bradykinesia, which is slowness of movement and a decrease in amplitude or speed with continued movement. Additionally, you’ll notice a pill-rolling tremor at rest and rigidity.

Moreover, if you passively move the patient’s limb, you might feel a series of stops or stalls, which is known as cogwheeling or cog-wheel rigidity. Some patients could also present with facial masking, which refers to an impaired facial expression in response to emotion, shorter stride length, and a stooped posture. At this point, consider Parkinson disease, and start a trial of dopaminergic therapy with levodopa and carbidopa.

Next, assess the supportive criteria for Parkinson disease, which include adequate response to dopaminergic therapy, levodopa-induced dyskinesia, the presence of a rest tremor of a limb, and olfactory loss or cardiac sympathetic denervation. If you find at least two of the four supportive criteria, diagnose Parkinson disease.