Extrapyramidal Motor System and Tremors

• The extrapyramidal motor system controls involuntary movements, posture, and muscle tone through brain structures like the basal ganglia, substantia nigra, red nucleus, and cerebellum.
• It helps fine-tune movements to ensure they are smooth and coordinated, differing from the pyramidal system that controls voluntary movements.

Parkinson's Disease Pathophysiology

• Parkinson's disease (PD) involves the degeneration of dopaminergic neurons in the substantia nigra, leading to dopamine deficiency.
• This deficiency disrupts the balance of signals in the basal ganglia, impairing motor control and causing tremors, rigidity, bradykinesia, and postural instability.

Essential Tremor

• Essential Tremor (ET) is a kinetic tremor that occurs during voluntary movement, affecting the hands, head, or voice.
• Essential Tremor is typically symmetric and improves with alcohol consumption in some individuals.

Intentional Tremor

• Intentional Tremor occurs during purposeful movement toward a target and is commonly seen in cerebellar disorders.
• Intentional Tremor is associated with a loss of cerebellar function.

Cogwheel Rigidity

• Cogwheel rigidity is a muscle stiffness specific to Parkinson's disease, characterized by interruptions or jerks during passive limb movement.
• It results from abnormal muscle tone caused by disruptions in the basal ganglia's motor control.

Pyramidal Tract

• The pyramidal tract is involved in voluntary movements, especially fine motor control.
• Its main pathway is the corticospinal tract, which originates in the cortex and projects to the spinal cord.

Extrapyramidal Tract

• The extrapyramidal tract deals with involuntary motor control, such as posture, balance, and muscle tone, involving the basal ganglia and cerebellum.
• The extrapyramidal tract regulates and smooths movement.

Alpha-Synuclein in Parkinson's

• Alpha-synuclein accumulates to form Lewy bodies, which are hallmark features of Parkinson's disease.
• Lewy bodies are abnormal protein deposits found in neurons.

Tau Proteins in Parkinson's

• Tau protein accumulation is associated with neurodegenerative diseases, but in Parkinson's, alpha-synuclein plays a more prominent role.

Lewy Bodies, and Lewy Body Dementia

• Lewy bodies are abnormal protein clumps of alpha-synuclein that accumulate in neurons, primarily in the substantia nigra in Parkinson's disease, contributing to motor symptoms.
• Lewy Body Dementia (LBD) is a condition where Lewy bodies are present in areas involved in memory and cognition, leading to dementia and cognitive decline in addition to Parkinsonian motor symptoms.

Glabella Tap

• Glabella tap is a clinical sign where gentle taps on the forehead trigger a blink reflex.
• In Parkinson's disease, glabella tap may cause repetitive blinking (Myerson sign), often seen due to rigidity and bradykinesia.

Biopsychosocial Symptoms of Dementia

• Dementia often has biological symptoms like cognitive decline, memory loss, language difficulties, and motor dysfunction.
• Psychological symptoms include anxiety, depression, mood swings, and personality changes.
• Social symptoms consist of social withdrawal, difficulty with daily activities, and loss of independence.

Early Signs of Parkinson's Disease

• Hyposmia (loss of smell) and REM sleep behavior disorder are often early signs of Parkinson's disease before motor symptoms appear.

Bradykinesia

• Bradykinesia is the slowness of movement, impairing the ability to initiate and complete movements, making daily activities difficult.

TRAP of Parkinson's Disease

• TRAP is an acronym of the four main motor symptoms of Parkinson's disease: Tremor, Rigidity, Akinesia, Postural instability.

Parkinsonian Gait

• A typical Parkinsonian gait involves shuffling steps, reduced arm swing, forward flexion of the trunk, and difficulty turning.

Dysphagia in Parkinson's Disease

• Dysphagia (difficulty swallowing) is a significant concern in Parkinson's as it can lead to aspiration pneumonia and hospitalization.

Autonomic Dysfunction in Parkinson's

• Autonomic dysfunctions in Parkinson's disease include urinary retention, constipation, and orthostatic hypotension.

Non-Motor Symptoms of Parkinson's

• Non-motor symptoms can include cognitive decline and dementia, mood disturbances, sleep disorders, fatigue, and pain.

Neuropsychiatric Symptoms

• Neuropsychiatric symptoms include depression, anxiety, and psychosis, which are common in later stages such as hallucinations and delusions of Parkinson's disease.

Levodopa

• Levodopa (combined with carbidopa) is the most commonly used medication to treat Parkinson's disease.

Levodopa Mechanism of Action

• Levodopa is a precursor to dopamine that crosses the blood-brain barrier and is converted into dopamine in the brain.
• Levodopa helps compensate for the loss of dopamine-producing neurons in Parkinson's disease.

Levodopa Metabolism

• Levodopa is converted into dopamine in the brain and is also metabolized outside the brain into dopamine and other metabolites by enzymes like dopamine decarboxylase.

Levodopa and Carbidopa

• Carbidopa is added to levodopa to prevent its premature conversion into dopamine in the periphery, reducing side effects like nausea and ensuring more levodopa reaches the brain.

Cala Device

• The Cala device is a wearable neurostimulation device used to treat essential tremor.
• It delivers electrical stimulation to the wrist through the skin, which can help reduce tremors by modulating nerve activity.