Drug-induced parkinsonism

Drug-induced parkinsonism (DIP) is a condition characterized by Parkinson's disease-like symptoms such as tremors, rigidity, bradykinesia (slowness of movement), and postural instability. These symptoms are caused by the intake of certain medications. DIP is the second most common cause of parkinsonism after Parkinson's disease itself. Understanding the medications that can lead to DIP, its symptoms, diagnosis, and management is crucial for healthcare providers and patients alike.

Causes

Drug-induced parkinsonism is primarily caused by medications that affect the dopamine pathways in the brain. Dopamine is a neurotransmitter that plays a key role in controlling movement. The most common culprits include:

• Antipsychotic drugs, especially the older, "typical" antipsychotics such as haloperidol and chlorpromazine. Newer "atypical" antipsychotics can also cause DIP but at a lower rate.
• Anti-emetic drugs, such as metoclopramide, which are used to prevent nausea and vomiting.
• Certain medications used to treat high blood pressure, such as reserpine and tetrabenazine, which deplete dopamine stores.

Symptoms

The symptoms of drug-induced parkinsonism closely mimic those of Parkinson's disease and include:

• Tremor: A shaking that typically occurs at rest.
• Rigidity: Muscle stiffness that can limit movement.
• Bradykinesia: Slowness of movement, making everyday tasks difficult.
• Postural instability: Impaired balance and coordination, leading to a higher risk of falls.

Unlike Parkinson's disease, DIP usually presents with symmetrical symptoms (affecting both sides of the body equally) and lacks the characteristic Parkinson's tremor.

Diagnosis

Diagnosis of drug-induced parkinsonism involves a careful review of the patient's medication history, clinical examination, and sometimes, discontinuation of the suspected drug to see if symptoms improve. There are no specific tests for DIP, but imaging studies like MRI or DaTSCAN may be used to rule out other causes of parkinsonism.

Management

The primary treatment for drug-induced parkinsonism is the discontinuation or reduction of the offending medication, if possible. In cases where the medication cannot be stopped or symptoms persist, treatment may include:

• Levodopa: Although less effective in DIP than in Parkinson's disease, it may improve symptoms in some patients.
• Anticholinergic drugs: These can help reduce tremor and rigidity but are often limited by their side effects.

Prevention

Preventing drug-induced parkinsonism involves careful use of medications known to cause the condition, especially in individuals at higher risk, such as the elderly or those with a family history of Parkinson's disease. Regular monitoring and assessment by healthcare providers are essential for early detection and management of DIP.

Conclusion

Drug-induced parkinsonism is a significant condition that mimics Parkinson's disease but is caused by certain medications. Awareness of the drugs that can lead to DIP, along with prompt diagnosis and management, can greatly improve the quality of life for affected individuals.