Extrapyramidal symptoms (EPS) are a group of movement disorders that can be side effects of certain medications, particularly antipsychotics. These symptoms affect the motor system and can include involuntary movements, muscle stiffness, and tremors. The term “extrapyramidal” refers to the part of the motor system that doesn’t involve the pyramidal tracts, which are responsible for direct voluntary control of muscles.
Involuntary Movements and Motor Control:
Involuntary Movements:
EPS can cause a range of involuntary movements, including dyskinesia (involuntary, repetitive movements), dystonia (sustained muscle contractions causing abnormal postures), and akathisia (restlessness and inability to sit still).
Motor Control Impairment:
EPS can significantly impair motor control and coordination, making daily activities difficult.
Causes and Medications:
Antipsychotics:
EPS are most commonly associated with the use of typical antipsychotics (e.g., haloperidol and fluphenazine), which block dopamine D2 receptors in the brain. Atypical antipsychotics have lower D2 receptor affinity and are less likely to cause EPS.
Other Medications:
Some antidepressants, antiemetics, and other medications can also induce EPS.
Dopamine Imbalance:
EPS are thought to be caused by a dopamine-cholinergic imbalance in the brain, particularly in the basal ganglia.
Types of Extrapyramidal Symptoms:
Acute Dystonia:
Sudden, severe muscle contractions, often affecting the neck, face, or limbs.
Parkinsonism:
Symptoms similar to Parkinson’s disease, including tremors, rigidity, and slow movements.
Akathisia:
Intense restlessness and an inability to sit or stand still.
Tardive Dyskinesia:
Late-onset movement disorder involving repetitive, involuntary movements of the face, mouth, and limbs.
Importance of Recognition and Treatment:
Early Recognition:
Recognizing EPS is crucial, as some symptoms (like acute dystonia) can be serious and require prompt treatment.