Antipsychotic-induced movement disorders

ANTIPSYCHOTIC drugs are the mainstay of treatment of schizophrenia and other psychotic disorders. The therapeutic efficacy of these drugs is well established. However, these drugs are associated with a wide range of side effects, including a variety of movement disorders.

The newer antipsychotics have a lower propensity to cause side effects.

The movement disorders associated with antipsychotics are disabling and distressing often resulting in behavioural disturbances (violence and aggression), non-adherence, and exacerbation of psychosis. Some of the motor signs may be misinterpreted as psychotic symptoms.

The commonly seen extra-pyramidal side effects causing movement disorders are summarised below:

Akathisia: Consists of motor restlessness accompanied by subjective feelings of inner tension and discomfort, mainly in the limbs and wanting to move the limbs. It usually appears within the first few days of treatment and sometimes it may develop only as higher doses are achieved.

In the lower-limbs movements, rocking from foot to foot, shuffling of legs, or swinging one leg over the other while sitting. In severe Akathisia, patients may pace up and down or they may be unable to feel comfortable in any position, such as sitting, lying, or standing, for more than a few minutes. Trunk rolling and fidgeting movements of the upper limbs may also be seen.

Acute Dystonia: Are involuntary movements characterised by intermittent or sustained muscle action. Movements vary from fleeting disturbance to maintained abnormal postures. It may occur in 25 to 40 percent of patients receiving conventional antipsychotics, with younger adults and children more commonly affected.

The muscle stiffness and postural distortion are both painful and uncomfortable and can make patients agitated and frightened. The muscles of the head and neck are most commonly affected. Involvement of the laryngeal and pharyngeal muscles may lead to respiratory distress, asphyxia, and choking.

Parkinsonism: Symptoms develop insidiously within days of starting antipsychotic treatment. The development of symptoms is dose dependent and emerges in about 20 to 40 percent of patients.

With continuation of medication, the Parkinsonian symptoms may gradually subside and tolerance may develop. The main features of drug-induced Parkinsonism are rigidity of the limbs resistant to passive movement is the most obvious feature of drug-induced Parkinsonism. Tremor and brady-kinesia are seen as well.

Tardive Dyskinesia: Is the main late onset condition among the EPSEs. These are involuntary movements, mainly of the tongue and mouth with twisting of the tongue, chewing, and grimacing movements of the face. It develops after chronic exposure to antipsychotics for about six months.

Antipsychotic drugs continue to be used in a substantial number of patients for a variety of reasons. These are associated with a number of movement disorders, some of which can be distressing and irreversible.

It is hence essential that clinicians regularly evaluate patients for these conditions to prevent their emergence and progression.

Those who are developing these movement disorders, it is paramount to let your doctor to know so that preventative action can be taken. It is also important to note that not all people, who use these medications develop problems.

DISCLAIMER: This column contains information about mental health related issues. However, the information is not advice, and should not be treated as such. No liability is accepted for any consequences arising from this article. ◆ Dr S. M. Chirisa is a passionate mental health specialist, who holds an undergraduate medical degree and Master’s degree in Psychiatry both from the University of Zimbabwe. He is currently working as a Senior Registrar in the Department of Psychiatry at Parirenyatwa Group of Hospitals and is also the current national treasurer of the Zimbabwe Medical Association (ZiMA). He can be reached at drsmchirisa@yahoo.com