Neurology: Levodopa and Restless Legs Syndrome

A neurotransmitter that plays a crucial role in movement, motivation, and reward.

A brain structure involved in motor control, learning, and habit formation. It is particularly important for smooth, coordinated movements.

A disorder characterized by a lack of dopamine in the striatum, leading to tremors, rigidity, and slow movements.

The process of breaking down dopamine by the enzyme Monoamine Oxidase B (MAO-B).

Harmful molecules that can damage cells and contribute to the degeneration of neurons in Parkinson's Disease.

A drug used to treat Parkinson's disease by increasing dopamine levels in the brain. It is a precursor to dopamine and can cross the blood-brain barrier.

Drugs that enhance the effects of levodopa by preventing its breakdown in the periphery, allowing more levodopa to reach the brain.

Drugs that directly stimulate dopamine receptors in the brain, providing an alternative way to increase dopamine signaling.

A side effect of levodopa therapy that involves involuntary movements like grimacing, tongue thrusting, and limb movements.

These movements develop within a few months of starting levodopa therapy at the optimal dose.

Dyskinesias worsen over time and most patients experience them after a few years.

The intensity of dyskinesias is directly related to the level of levodopa in the body.

Medications like phenothiazines, butyrophenones, and metoclopramide can block dopamine receptors, counteracting the positive effects of levodopa.

Levodopa is absorbed into the brain through specialized carriers that transport amino acids, but only a small percentage of the administered dose reaches the brain.

A state of low blood pressure upon standing, often seen in patients taking levodopa.

Postural hypotension is common in levodopa patients, but usually asymptomatic. Dizziness and fainting are less common.

A side effect of long-term levodopa treatment where the effectiveness of the medication fluctuates significantly, leading to periods of good motor control followed by periods of severe disability.

A type of levodopa fluctuation marked by abrupt transitions between periods of good and poor motor control. This can make daily activities unpredictable and difficult.

This refers to the period of time when a patient with Parkinson's Disease experiences the most intense symptoms and has limited movement. It typically occurs at the end of the levodopa dosage cycle.

A type of levodopa fluctuation characterized by a reduction in motor control that occurs toward the end of the dosage interval, before the next dose is taken.

Abnormal involuntary movements are an adverse effect of levodopa treatment that can significantly limit a patient's quality of life. These movements are often severe and unpredictable.

This antipsychotic drug is used to block the effects of levodopa-induced nausea and vomiting. It works by antagonizing dopamine receptors in the chemoreceptor trigger zone (CTZ), a brain area involved in triggering nausea.

This drug prevents the storage of dopamine in synaptic vesicles, effectively blocking the action of levodopa. It is a potent antipsychotic but can cause serious side effects.

These drugs prevent the breakdown of dopamine and norepinephrine, potentially causing a hypertensive crisis when combined with levodopa. They are used to treat depression.

A drug that converts to dopamine (a neurotransmitter) in the brain. It helps treat Parkinson's disease by increasing dopamine levels.

Drugs like carbidopa and benserazide that prevent levodopa from breaking down in the body before it reaches the brain. This makes levodopa more effective.

A side effect of levodopa treatment for Parkinson's disease where the body experiences alternating periods of good and bad motor control.

An enzyme that breaks down levodopa before it can reach the brain. It's the reason why pyridoxine (vitamin B6) can decrease levodopa's effectiveness.

A drug that inhibits peripheral decarboxylase, preventing levodopa from being broken down in the periphery. This allows more levodopa to reach the brain and be converted to dopamine.

A neurotransmitter that plays a vital role in movement, mood, and rewards. Its deficiency in the brain is a major cause of Parkinson's disease.

A brain region responsible for planning, executing, and controlling movements. It's heavily involved in Parkinson's disease.

A process that occurs in the brain where dopamine, after being released, is broken down. This can lead to a decrease in dopamine levels and contribute to Parkinson's symptoms.

Anticholinergics can improve Parkinson's symptoms, especially tremor, for a few hours after a single dose. However, their overall effectiveness is lower than levodopa, and they have less severe side effects.

Anticholinergics are the only drugs that effectively treat Parkinsonism induced by medications like phenothiazines.

Older patients, especially males, often experience side effects like memory impairment, confusion, blurred vision, and urinary retention when using anticholinergics.

Trihexyphenidyl is the most commonly used anticholinergic drug in treating Parkinson's disease.

When Parkinson's disease is mild, anticholinergics or selegiline might be sufficient to manage symptoms.

Monotherapy with newer DA agonists like ropinirole or pramipexole is increasingly used for early Parkinson's, especially in younger patients, due to fewer motor complications.

Levodopa combined with a decarboxylase inhibitor is considered the standard therapy for Parkinson's disease, and has replaced levodopa alone.

Selegiline can be combined with levodopa during the deterioration phase of Parkinson's therapy to help overcome the 'wearing off' effect of levodopa.

Restless Legs Syndrome (RLS) is a condition that causes an irresistible urge to move the legs, often accompanied by unpleasant sensations like tingling, itching, or aching. It typically worsens during periods of rest, especially at night.

RLS can be primary (idiopathic), meaning its cause is unknown, or secondary, meaning it is caused by other conditions like iron deficiency, pregnancy, or nerve damage.

Non-ergot dopamine agonists, such as ropinirole and pramipexole, are considered the most effective drugs for treating RLS. Low doses taken before bedtime can often provide significant relief.

MAO-B inhibitors, like selegiline, are medications that block the enzyme responsible for breaking down dopamine. However, their effectiveness in treating RLS is controversial, and they are not typically used for this purpose.

Selegiline can sometimes cause insomnia and agitation because it's metabolized into amphetamine, a stimulant. This side effect is more common at higher doses.

Although selegiline isn't typically used for RLS, there's some evidence that rasagiline, another MAO-B inhibitor, might have neuroprotective effects in Parkinson's disease.

Common side effects of selegiline include postural hypotension (low blood pressure upon standing), nausea, confusion, and worsening of levodopa-induced involuntary movements. It can also worsen psychosis in some cases.

Selegiline might be used to reduce the 'wearing-off' effect of levodopa and to increase its effectiveness. However, it's important to note that selegiline is not typically used for RLS.