Parkinson's Disease Overview

Parkinson's Disease

• Parkinson's disease is a neurodegenerative disorder primarily affecting the basal ganglia.
• It most often affects individuals over 60 years old.
• Extrapyramidal system is a key component; includes centers and tracts that control activity in the spinal cord,excluding the pyramidal tract.
• It also encompasses diverse systems that extend throughout the central nervous system, with multiple final descending tracts.
• Essential components of the extrapyramidal system include: areas 6 and 8 & 4, basal ganglia, thalamus, subthalamus, red nucleus, substantia nigra, brain stem reticular nuclei, and other nuclei, and descending tracts.
• Basal ganglia, a group of grey matter nuclei in the cerebral hemispheres (caudate nucleus, putamen, globus pallidus), plays a crucial role in regulating the extrapyramidal system.
• The putamen and head of the caudate nucleus form the corpus striatum, while the putamen and internal portion of the globus pallidus form the lentiform nucleus.
• Basal ganglia and their connections are essential to the extrapyramidal system.
• Extrapyramidal tracts are final pathways influencing activities; they originate in the brainstem and terminate in the spinal cord via interneurons.
• Key tracts include rubrospinal, tectospinal, vestibulospinal (lateral and medial), and reticulospinal (pontine and medullary).

Function of the Extrapyramidal System

• Regulates postural muscle tone.
• Facilitates voluntary movement initiation.
• Controls emotional and involuntary movements.
• Regulates and scales background posture during movements and learned motor skills.
• Influences cortical activity via connections with basal ganglia.
• Influences activity of the central nervous system (CNS) through descending pathways.

Basal Ganglia and Cortical Activation

• Dopamine is a neurotransmitter crucial for smooth, purposeful movement, transmitting signals between the substantia nigra and corpus striatum.
• Basal ganglia influence cortical motor activity through two circuits:
  • Direct pathway: striatum inhibits globus pallidus, activated by D1 dopamine receptors, to increase thalamic activation.
  • Indirect pathway: striatum facilitates globus pallidus, inhibited by D2 dopamine receptors, to decrease thalamic activation.

Extrapyramidal Tracts

• Acts primarily on interneurons (mainly gamma motor neurons).
• Facilitates extensor muscles, and has some inhibitory effect on flexors.
• Maintains posture and proximal control.

Disorders of the Extrapyramidal System

• Parkinson's disease is the most common extrapyramidal disorder in adults.
• It involves degeneration of the substantia nigra and subsequent dopaminergic stimulation of the nigrostriatal tract.
• This imbalance between dopamine and acetylcholine transmitters may constitute the hallmark of Parkinson's disease.

Causes of Parkinson's Disease

• Primary Parkinson's: idiopathic degeneration of substantia nigra (SN).
• Secondary Parkinsonism (Parkinsonian disease): affects the basal ganglia due to vascular ischemia, encephalitis, trauma, toxins (e.g., manganese), drugs, or neoplasms.

Manifestations of Parkinson's Disease

• Characterized by four cardinal features: tremors, bradykinesia, rigidity, and postural instability.
• Tremors: static or resting tremors, more prominent at rest, but can interfere with movement.
• Bradykinesia: slowness of both voluntary and involuntary movements, including facial expressions.
• Rigidity: increased muscle tone, leading to resistance in passive movements.
• Postural instability: impaired balance and postural control may lead to falls.
• Additional symptoms can include speech problems, swallowing difficulties, cognitive impairments, such as depression, and the "on-off" phenomenon.

Cognitive Manifestations

• Depression: a direct consequence of the disease's pathology (decreased dopamine) and a reactive response to motor problems.
• Bradyphrenia: slowness of thought. Narcolepsy: daytime sleepiness
• Memory problems: reduced memory functions can lead to dementia
• On and off phenomenon: fluctuations in motor function related to drug use.

Assessment Scales

• The Modified Hoehn and Yahr scale, and the Montreal Cognitive Assessment (MoCA) are used to assess the stage and cognitive function in patients with Parkinson's disease.

Assessment of Parkinson's Patients

• Accurate standardized scales, such as the Functional Independence Measure (FIM), are crucial for assessing and tracking progress.
• Assessments should consider medication effects, time of day, any age-related issues, and other aspects, such as vision and hearing.

Speech and Cranial Nerve Assessment

• Characteristic features: monotonous speech, diminished emotional range, and reduced speech volume.
• Difficulties with eye movements, and other cranial nerve functions may be present.
• Loss of glabellar reflex and potential swallowing difficulties may also occur.

Sensory Assessment

• In Parkinson's, there's typically no direct sensory impairment.
• Difficulty in organizing sensory input for postural control is possible.

Motor Function Assessment

• Rigidity, slowness, loss of motor control, static tremors, and posture are often characteristic.
• Specific assessments like the timed up and go test, as well as diadochokinetic tests are relevant tools for evaluation.

Respiratory Assessment

• Rigidity decreases the lung's expansion and may lead to decreased respiratory function, contributing to fatigue, reduced lung capacity, and deconditioning.

ADL (Activities of Daily Living) Assessment

• Patient's independence in daily tasks is important, so assessment needs to be accurate and standardized, using the Functional Independence Measure (FIM).
• Factors including medication timing and age-related factors should be considered and accounted for.

Explore the essential aspects of Parkinson's disease, a neurodegenerative disorder that primarily affects individuals over 60. This quiz dives into the role of the basal ganglia and extrapyramidal system in regulating motor activity. Test your understanding of its components and the impact on nervous system functions.