Antipsychotic-Induced Movement Disorders: Evaluation and Treatment

For routine evaluation, thyroid function tests are performed in most or all patients with tremor to exclude hyperthyroidism. In patients under 55 years, serum and urine tests for Wilson’s disease may be indicated. A temporary reduction of lithium dosage resulted in a clear improvement of the tremor, but unfortunately induced a relapse into a depression unresponsive to other treatments, and hence lithium was reinstituted. Tetrabenazine and propranolol were contraindicated because of depressive symptoms and the use of fluoxetine. The video shows a 48-year-old woman diagnosed with multiple sclerosis with lesions involving the cerebellum and the brainstem; she presented with tremors of bilateral arms and head. The tremor in her left arm is seen during resting, postural elevation, and kinetic tasks.

Tardive disorders

Diagnosis of your drug-induced tremors will start with your doctor asking you about your symptoms and medical history. A complete list of the medications you’re taking will be extremely helpful during diagnosis. Telling your doctor how often you’re having tremors can help aid in your diagnosis. The speed of your tremors can also help your doctor determine their cause.

Interview and Clinical Examination of Patients with Tremor

Features consistent with psychogenic tremor are abrupt onset, spontaneous remission, changing tremor characteristics, and extinction with distraction. Other types of tremor include cerebellar, dystonic, and drug- or metabolic-induced. The first step in evaluating a patient with tremor is to categorize the tremor based on its activation condition, topographic distribution, and frequency. Resting tremors occur in a body part that is relaxed and completely supported against gravity. Action tremors occur with voluntary contraction of a muscle and can be further subdivided into postural, isometric, and kinetic tremors. The most common pathologic tremor is essential tremor, which affects 0.4% to 6% of the population.

Intramuscular benztropine or diphenhydramine will generally produce complete resolution in 20 to 30 minutes. The dose can be repeated after 30 minutes if complete recovery does not occur. Involvement of the laryngeal and pharyngeal muscles may lead to respiratory distress, asphyxia, and choking.

Additional and Relevant Useful Information for Drug-Induced Tremors:

We believe that the slowness of hand movements was caused by the presence of tremor as previous studies have shown that tremor leads to drug-induced tremor: symptoms, diagnosis treatments prolonged reaction times due to incomplete muscle contractions, leading to a perception of bradykinesia (31, 32). Additionally, tremors can cause pacing effects as a result of voluntary movements (33, 34). Furthermore, slowness in left-hand movement was resolved after right VIM MRgFUS, supporting this hypothesis since VIM is not a target for bradykinesia. As a result of these factors, we concluded that the patient did not have Parkinsonism and thus we did not order a DaT scan.

• MRI provides detailed images of the brain, particularly of cerebellar dysfunction, showing evidence of atrophy, tumors, and stroke.
• Discontinuation of the causative drug is advised when feasible while maintaining the risk of relapse in mind.1 For patients in whom their symptoms are stabilized, neuroleptic dose reduction would be a viable option.
• Although some devices follow the principles of increasing weights around the wrist to stabilize the arm mechanically, some use tuned mass damper technology to dampen vibrations and a gyroscope to reduce the angular momentum.

MRgFUS VIM thalamotomy offers a non-invasive, safe, and effective treatment option for medication induced tremor; however, larger studies with a longer follow-up are needed to validate the result. Several hyperkinetic movement disorders can mimic tremor, including action myoclonus and dystonia of the upper limbs. Once these are ruled out, determine whether the tremor is isolated or accompanied by other neurologic abnormalities.

Tardive Dystonia

Despite the lack of high‐quality evidence, our data clearly identify at least 3 medications that appear to have good‐to‐excellent effectiveness (propranolol) or a trend toward good‐to‐excellent effectiveness (tetrabenazine and metoprolol). Moreover, we identified other medications that are mostly proven not useful and could be avoided in clinical practice. Based on this knowledge, we created a treatment algorithm that may serve as a starting point to aid clinical decision making.

Literature Review

Trunk rolling and fidgeting movements of the upper limbs may also be seen. Imaging (MRI, CT) can sometimes be helpful if a structural cause is suspected. MRI provides detailed images of the brain, particularly of cerebellar dysfunction, showing evidence of atrophy, tumors, and stroke. It can also reveal the demyelination caused by MS leading to action tremors.

The pathophysiology of the more common forms of tremor is outlined, and treatment options are discussed. Essential tremor is characterized primarily by postural and action tremors, may be a neurodegenerative disorder with pathologic changes in the cerebellum, and can be treated with a wide range of pharmacologic and nonpharmacologic methods. Tremor at rest is typical for Parkinson’s disease, but may arise independently of a dopaminergic deficit. Enhanced physiologic tremor, intention tremor, and dystonic tremor are discussed.

But it can cause cognitive or mental health symptoms too, and though not generally considered a parkinsonian condition, the diagnosis remains controversial. The surface electromyography (EMG) recordings of a 67-year-old man with PD reveal a rhythmic activity with a frequency of ~5 Hz in all muscles studied. The antagonists, anterior tibial and gastrocnemius muscles, are activated in shifted phases, and a slight electrical activity was detected in the quadriceps musculature on the same side. The frequency in the electrophysiologic activity on the left and on the right side differs slightly, with 13 activations in the left anterior tibial muscle, but only 12 in the right side during the period represented in the figure.

The healthcare provider will also assess for signs of other neurological conditions that could be causing the tremors. Bronchodilators, which are commonly prescribed for asthma and chronic obstructive pulmonary disease (COPD), can also trigger tremors. This is especially true for medications containing stimulants like albuterol. Additionally, some drugs used to treat neurological conditions, such as those for Parkinson’s disease, may paradoxically cause or exacerbate tremors in certain individuals.

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• Although there is ample experience with thalamotomy to treat tremor of other origins, we did not mention this explicitly in the flowchart because of the lack of reported cases with medication‐induced tremor.
• It develops after chronic exposure to antipsychotics for about six months.
• Stop the offending drug, and give an intravenous or intramuscular anticholinergic drug (such as benzatropine or trihexyphenidyl (benzhexol) hydrochloride).
• While medication-induced tremors are primarily diagnosed based on medical history and physical examination, additional tests may be recommended to rule out other potential causes.
• There is a paucity of literature that deals with the mechanisms of MIT, with most manuscripts only describing the frequency and clinical settings where MIT is observed.
• Cessation of the offending drug can be difficult, and many medical treatments for drug-induced tremor are ineffective.

Slow and irregular speech with increased separation of syllables or explosive sounds may indicate cerebellar dysarthria. Dystonia can manifest as spasmodic dysphonia, with effortful, jerky, strained sounds in the adductor type of spasmodic dysphonia, or a breathy, whispering voice with sudden breaks in the abductor type of spasmodic dysphonia. Typical parkinsonian or cerebellar gait may be noted, and muscular rigidity in combination with a tremor at rest is typical for PD, whereas spasticity may develop in multiple sclerosis. The frequency of a tremor can be approximated by observation with the naked eye, and more accurately measured with surface electromyography.