USMLE Step 1 – Adverse effects of anti psychotics – Movement Disorders

Tyler York

Movement disorders are a common adverse effect of antipsychotic medications. They can be caused by all types of antipsychotics, but are more common with the typical or classical drugs. These disorders include dystonia, akathisia, drug-induced Parkinsonism and tardive dyskinesia.

If you’re looking for a comprehensive course to pass your USMLE Step 1 exam the first time, try Achievable’s USMLE Step 1 course. Our course is information rich, concise, and uses spaced repetition-backed practice questions to improve your memory retention.

Full USMLE Step 1 – Adverse effects of anti psychotics – Movement Disorders video transcript:

Hi, I am Sujata. In this video we will discuss adverse effects of antipsychotics, movement disorders. Antipsychotics are classified as atypical or typical antipsychotics. Movement disorders can occur as a side effect of any type of antipsychotics, but they are much more common with the typical first generation, also called as classical antipsychotics. Examples include.
Thyridazine, halloperidol, etc. These antipsychotics act primarily by blocking the dopamine receptor D2. There are four types of movement disorders. These are dystonia, akathisia, drug induced parkinsonism and tardive dyskinesia. To correctly diagnose these movement disorders, it is not only important to know the clinical features.
But it is also important to note the duration of onset of the movement disorder after starting the antipsychotic medication dystonia. Dystonia can happen within hours to days of starting an antipsychotic. It presents as sustained, involuntary, repetitive, spasmodic contractions of antagonistic muscle groups, which leads to abnormal postures and motion.
For example, ocalogyrate crisis torticollis which can be sustained, sustained laryngospasm which can be life threatening and need intubation, etc. Treatment is with anticholinergies like benztropine or in emergencies even intramuscular lorazepam. Diazepam derivatives can be used. Other medications that are helpful are bipyridin and diphenhydramine.
Akathisia It manifests as a feeling of restlessness and constant motion which starts days to weeks after starting therapy. Treatment includes Propranolol, mirtazapine, parenteral diazepam, derivatives like clonazepam or azepam, etc. Other therapies which may be useful include five HT2 antagonists.
5HD1 Egonist, Vitamin B6, etc. Drug induced Parkinsonism. It starts months after starting therapy and it presents like any other Parkinsonism with Barry Kinasia rigidity, mask, face tremors, etc.
Treatment of drug induced Parkinsonism includes reducing the dose of the medication, changing to another antipsychotic or medications like benztropine and Amantadine tardive dyskinesia. It is seen months or even years after starting therapy and unfortunately in some people it may be permanent and may not go away even after stopping the medication.
Clinical features include coriform or athetoid movements, which are involuntary movements involving the lower face, trunk, and extremities. Examples of such movements include persistent grimace or lip smacking, persistent eye blinking, etc. Treatment includes switching to another medication, monomine transport inhibitors like valbenazine or tetrabenazine.
In some cases, clonazepam and diazepam derivatives may help. In resistant or severe cases, stimulation of the Globus pallidus has been shown to be effective. Hope this video helps you how to differentiate between the movement disorders caused by antipsychotics and how to manage them. Thanks for watching.
USMLE Step 1 - $299
Achievable's USMLE Step 1 course makes it easy to efficiently learn and remember the material on test day, helping you reach your target score.
View USMLE prep course
Desktop and mobile screenshots of USMLE Step 1
All rights reserved ©2016 - 2023 Achievable, Inc.