Which of the following is the closest approximation for the prevalence of dystonia associated with the use of typical antipsychotics?
Extrapyramidal side-effects
The following table from the Maudsley Guidelines provides a good summary of EPSEs
| Dystonia | Pseudo-parkinsonism (e.g. tremor) | Akathisia | Tardive dyskinesia | |
|---|---|---|---|---|
| Prevalence (with older drugs) | Approximately 10% But more common in - young males - neuroleptic-naive - high potency drugs (e.g. haloperidol) | Approximately 20% But more common in - elderly females - those with pre-existing neuro damage (e.g. stroke) | Approximately 25% | 5% of patients per year of antipsychotic exposure But more common in - elderly women - those with affective illness - those who have had EPSE early on in treatment |
| Time taken to develop | Acute dystonia can develop within minutes or hours of starting antipsychotics | Days to weeks after antipsychotic started or dose increased | Hours to weeks | Months to years |
| Treatment |
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The extrapyramidal side effects (EPSE's) are a group of side effects that affect voluntary motor control. They are most commonly seen in patients taking antipsychotic drugs but have also been reported in the use of SSRI's and tricyclics (TCA).
EPSE's include:-
- Dystonias - prolonged and unintentional muscular contractions of voluntary or involuntary muscles
- Parkinsonism - characterized by the triad of tremor, rigidity (lead pipe or cogwheel), and bradykinesia
- Akathisia - a subjective sense of restlessness, along with such objective evidence of restlessness as pacing or rocking
- Tardive dyskinesia
EPSE's can be frightening, and uncomfortable leading to problems with non-compliance. More worrying they can be life threatening in the case of laryngeal dystonia.
EPSE's are normally associated with the use of antipsychotics drug but they can also occur when antipsychotics are discontinued (withdrawal dystonia).
EPSE's are thought to be due to antagonism of dopaminergic D2 receptors in the basal ganglia. The cells of the basal ganglia are referred to as extra pyramidal as they are separate from the axons of the pyramidal cells that connect the cortex to the spinal cord.
Symptoms generally occur within the first few days of treatment. Dystonias tend to appear quickly, within a few hours of administration of the first dose.
There are several types of Dystonia:-
- Torticollis - cervical muscles spasms, resulting in a twisted posturing of the neck.
- Trismus - contraction of the jaw musculature and can result in lockjaw.
- Opisthotonus - arched posturing of the head, trunk, and extremities.
- Laryngeal dystonia - difficulty in breathing
- Oculogyric crises - involuntary contraction of one or more of the extraocular muscles, which may result in a fixed gaze with diplopia
Newer antipsychotics tend to produce less EPSE's and clozapine carries the lowest risk. Haloperidol carries the highest risk.
Akathisia is the most resistant EPSE to treat.
Taken from: John Kamin. Extrapyramidal Side Effects in the Psychiatric Emergency Service. Psychiatr Serv 51:287-289, March 2000.
