Chorea describes a neurological symptom characterized by involuntary, unpredictable, and flowing movements affecting various body parts. These dance-like movements can significantly interfere with daily activities. While not a disease itself, chorea signals an underlying medical condition, with Huntington’s disease being a recognized genetic cause. Medication is a primary strategy to manage these disruptive movements and improve quality of life.
The Neurological Basis for Treatment
Understanding the brain’s role in movement helps clarify why certain medications are used for chorea. The basal ganglia, deep within the brain, regulate voluntary movement and inhibit unwanted movements. These structures rely on a delicate balance of chemical messengers, known as neurotransmitters.
Dopamine, a key neurotransmitter in the basal ganglia, transmits signals influencing movement. In many forms of chorea, an imbalance in dopamine pathways, often overactivity or heightened sensitivity, leads to uncontrolled movements. Medications for chorea frequently target this overactivity to restore neurological balance.
First-Line Chorea Medications
For chorea linked to Huntington’s disease, a specific class of medications known as vesicular monoamine transporter 2 (VMAT2) inhibitors represents the primary treatment approach. These drugs are approved to manage the involuntary movements associated with the condition.
Tetrabenazine was the first VMAT2 inhibitor approved for this purpose. A newer medication, deutetrabenazine, offers an alternative within this class. Both medications reduce dopamine available to nerve cells by inhibiting VMAT2, a protein that packages neurotransmitters like dopamine into vesicles for release. Limiting this packaging reduces dopamine release into the synaptic space, dampening excessive signaling that contributes to chorea.
Deutetrabenazine often has a more manageable side-effect profile and can be taken less frequently than tetrabenazine. Its modified chemical structure allows for slower metabolism. This extended presence contributes to reduced dosing frequency and potentially milder adverse effects.
Alternative and Off-Label Drug Options
When first-line VMAT2 inhibitors are not effective or well-tolerated, other medication classes may be considered. These options are often used in specific clinical situations or when chorea is due to other underlying causes.
Antipsychotics
Certain antipsychotic medications, such as haloperidol or olanzapine, can treat chorea. Unlike VMAT2 inhibitors, they primarily block dopamine receptors in the brain. By occupying these receptors, antipsychotics prevent dopamine from binding and transmitting signals, reducing the overactivity associated with chorea.
Benzodiazepines
Benzodiazepines, including clonazepam, may also be prescribed. These medications enhance the effects of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter. By boosting GABA’s activity, benzodiazepines help calm excessive neuronal firing and reduce hyperexcitability, alleviating choreic movements.
Anticonvulsants
In some cases, certain anti-seizure medications, also known as anticonvulsants, might be considered. While their exact mechanism for chorea is not fully understood, these drugs can help stabilize nerve cell activity. They may be used when other treatments have not provided sufficient relief or for specific types of chorea.
Monitoring Treatment and Side Effects
Managing chorea with medication requires a personalized approach, often starting with a low dose and gradually increasing it until an effective balance is found. This “start low, go slow” strategy allows the body to adjust and helps identify the lowest effective dose. Regular communication and follow-up with a neurologist are important to assess effectiveness and monitor for adverse reactions.
Primary chorea medications, VMAT2 inhibitors, have potential side effects requiring careful monitoring. Drowsiness or sedation is common and can affect daily functioning. Parkinsonism, characterized by stiffness, slow movement, and tremor, is another concern, resulting from reduced dopamine activity. There is also a risk of mood changes, including depression and worsening suicidal thoughts, necessitating close observation of a patient’s mental state.