3 - Extrapyramidal Systems Flashcards by John Castillo

Major contributors to the motor system:

Pyramidal Motor System (direct and indirect)

Planning and initiating voluntary motor movement and muscle tone

How well did you know this?

Not at all

Perfectly

Major contributors to the motor system:

Cerebellum

Balance, equilibrium and real time motor adjustment

NO direct projection to the cortical spinal system

Clinical: Voluntary movement disorders (ipsilateral)

How well did you know this?

Not at all

Perfectly

Major contributors to the motor system:

Extrapyramidal Motor System

Motor programming–plan, initiate, maintain

Habitual behaviors–procedural learning

NO direct projections to the cortical spinal system

Involuntary movement disorders (contralateral)

How well did you know this?

Not at all

Perfectly

Where do Basal Ganglia and Cerebellum nuclei project?

To Thalamus

NOT direct to spinal cord

How well did you know this?

Not at all

Perfectly

What connects basal ganglia to thalamus?

What type of signals does it send?

Globus Pallidus

Inhibitory ONLY; levels of this just change

How well did you know this?

Not at all

Perfectly

What connects cerebellum to thalamus?

Deep cerebellar nuclei

How well did you know this?

Not at all

Perfectly

Substantia Nigra:

Pars Compacta vs Pars Reticularis

Pars Compacta - neurons contain melanin

Parts Reticularis - neurons DONT contain melanin

How well did you know this?

Not at all

Perfectly

Clinical:

Hypokinetic vs Hyperkinetic Disorders

Hypokinetic: Parkinson’s

Hyperkinetic: Huntingtons chorea, Ballismus dystonia

Movement disorder is always contralateral to the injury or lesion

How well did you know this?

Not at all

Perfectly

Clinical: Parkinson’s Disease

Pathways?

Degeneration of the DA neurons in the SNc

Hypokinetic Disorder

Reduced excitation of the Direct (Go) excitatory pathway = hard to initiate movement

Reduced inhibitory drive of Indirect (No Go) inhibitory pathway = hard to release thalamus from inhibition to start movement

*Both pathways affected

How well did you know this?

Not at all

Perfectly

Parkinson’s Disease

Motor Symptoms

Resting tremor

Cogwheel rigidity

Bradykinesia (slowness in movement)

- decreased size of handwriting, loss of voluntary movement

Unsteady gait, retropulsion
Speech and swalling disturbances

How well did you know this?

Not at all

Perfectly

Parkinson’s Disease

Non-motor Symptoms

Sensory Abnormalities - Olfactory (often 1st), Parathesia (dermal sensation)

Autonomic Dysfunction

Depression/Anxiety/Sleep Disorders

Masked facies and ‘reptillian stare’

Dementia

Akathisia (restlessness)

How well did you know this?

Not at all

Perfectly

Clinical: Tremor

General Definition and Differentiating Myoclonus?

Rhythmic or semi-rhythmic oscillating movements that can be fast or slow

Can differentiate from myoclonus in that tremor has both agonsit and antagonist muscles are activated; resulting in BIDIRECTIONAL movements

How well did you know this?

Not at all

Perfectly

Clinical: Essential Tremor

Familial, benign, or senile tremor–most common

Effects upper extremities, head, tongue, lips, and vocal cords

How well did you know this?

Not at all

Perfectly

Clinical: Resting Tremor

Occurs when limbs are relaxed and decrease in intensity or disappear when the limb is moved

Usually involves upper extremities, includes pill roll tremor

How well did you know this?

Not at all

Perfectly

Clinical: Intention Tremor (Ataxic Tremor)

Produced with purposeful movement toward a target, such as lifting a finger to touch nose

Usually worsens as you get closer to target

How well did you know this?

Not at all

Perfectly

Clinical: Postural Tremor

Occurs when the limbs are actively held in position against gravity and disappears at rest

How well did you know this?

Not at all

Perfectly

UMN Lesion vs Basal Ganglio Lesion?

Rigity is key

UMN = clasp knife

Basal Ganglia = ratchet like interuptions; Cogwheel Rigidity

How well did you know this?

Not at all

Perfectly

Clinical: Parkinson’s Pathology

Synucleinopathy?

Iron?

90% cases unknown origin

Degeneration of DA neurons in the SNc indicated by loss of melanin-containing neurons

Type of proteinopathy caused by protein misfolding and involves presence of Lewy Bodies that positively stain for alpha-synuclein

- - -

Abnormal accumulation of iron in the melanin-containing degenerating neurons

How well did you know this?

Not at all

Perfectly

Clinical: Parkinson’s Treatment Strategies

Drugs / Side Effects

Drugs:

Levodopa + carbidopa

MAO inhibitors (slow breakdown of DA)

COMT inhibitors (slow breakdown of L-dopa)

Side Effects:

Dyskinesia/hypokinesia: on-off phenomena due to high dose followed by decreeasing drug levels
L-dopa induced dyskinesia after long-term use of L-Dopa

How well did you know this?

Not at all

Perfectly

Clinical: Parkinson’s Disease Treatment Strategies

Surgery

Thalamotomy - radiofrequency ablation

Deep Brain Stimulation (DBS) - electrodes implated contralateral; pulse generator provides high-frequency electrical stimulation

Symptoms: Dysarthria and balance

How well did you know this?

Not at all

Perfectly

Clinical: Wilson’s Disease

Copper metabolism disease that causes progressive degeneration of the LIVER and BASAL GANGLIA

Present earlier in life (20s)

Symptoms:

Rings in cornea

Wing beating tremor

rigidity, bradykinesia, impaired speech, psychiatric symptoms, abnormal liver panel

Clinical: Huntington’s Disease

Autosomal dominant linked to expansion of CAG triplet repeat sequency

Progressive Striatal Neurodegenerative Disease

Targets: Striatum (caudate/putamen), particularly enkephalin-containing neurons in indirect pathways

***Net effect is INCREASED thalamic EXCITATION due to REDUCED INHIBITION through the Indirect pathway***

LOSS OF CONTROL OF INDIRECT PATHWAY

Clinical: Huntington’s Disease Symptoms

Hyperkinetic Disorder that includes all 4 basal ganglia functions (movement, eye control, emotion, cognition)

Symptoms show 30-40

Symptoms:

Choreiform Movement

Athetosis

Psychiatric disturbances (depression, anciety, OCD, manic-like behavior)

Dystonic posturing

Tics

Dementia

Clinical: Chorea Movements

Fluid or jerky involuntary movements of varying qyality

Can be mistaken for fidgeting

Severe: Frantic, constantly occurring movements that interrupt voluntary movements

Hemi-chorea is observed with contralateral infarct, hemorrghage, tumor, abscess, or focal lesion

Clinical: Athetosis

Slower form of **chorea,** characterized by continuous, involuntary writing movements that prevent maintains of stable posture

Clinical: Dystonia

Abnormal or distorted posturing of the limbs, trunk, or face due to **sustained contraction of muscles (Charlie Horse)** Painful; can result in hypertophy Can be generalized (whole body), unilateral, or focused

Clinical: Tics Example?

Urge to perform a sudden brief action Motor tics: face, neck, eye blinks, and less often in extremities Vocal tics: brief grunts, coughing barking Example: **Tourette's Syndrom**

Clinical: Ballismus

Wild flinging movement of the extremities **Subthalamic Nucleus Lesion,** results in net **INCREASE** in thalamic **EXCITATION** due to **REDUCED INHIBITION** via the **INDIRECT PATHWAYS** = **HYPERKINETIC** effect

Clinical: Hemiballismus

Unilateral (contralateral to lesion) flinging movements to to unilateral lesion to **one subthalamic nucleus** Usually Stoke, hemorrhage, tumor, infection, or inflammation

Clinical: Causes of Disease of Direct/In Direct Pathway Stroke/Infarct

Anterior and Middle Cerebral Arteries supply Striatum Anterior Choroidal Arteries supple the striatum Posterior Cerebral Artery supplies the SN

Clinical: Causes of Disease of Direct/In Direct Pathway Medication

**D2 Antagonists (no-go, inhibitory)** such as anti-psychotics can result in irrecversible development of **tardive dyskinesia** (involuntary movement of the tongue lips, face, trunk, and extremities)

Clinical: Causes of Disease of Direct/In Direct Pathway Other Causes

Tumor Carbon Monoxide Poisoning Pesticides

What is the rough transmission of neural signals through the body movement loop? Cortical Input -\> Striatum -\> Pallidum -\> Thalamus -\>

**Cortical Input**: Motor, Premotor, Somatosensory **Striatum**: Putamen **Pallidum**: Lateral Globus Pallidus, Internal Segment **Thalamus**: Ventral Lateral, and Ventral Anterior Nuclei Cycles **back to cortical targets**

What separates the Striatum/Neostriatum? What compromises the Neostriatum?

Separated by the **internal capsule** - - - Neostriatum = Caudate + Putamen

What comprises Lentiform Nucleus?

Lentiform Nucleus = Putamen+Globus Pallidus

What comprises the Corpus Striatum?

Corpus Striatum = Caudate+Putamen+Globus Pallidus \***Principle component of the extrapyramidal system\***

What are GPe and GPi?

Globus Pallidus External, Globus Pallidus Internal Globus Pallidus allows Basal Ganglia to send **inhibitory signals** to the Thalamus

Neurotransmitters: Major Input + Type? Major Output + Type?

**Input:** Glutamate (excitatory) Dopamine (modulatory) **Output**: GABA (inhibitory)

What is the main neurotransmitter of the following: Cortico-Striatal Pathway Nigro-Striatal Pathway Thalamo-Striatal Pathway

Cortico-Striatal = Glutamate (excitatory) Nigro-Striatal = Dopamine (modulatory) Thalamo-Striatal = Glutamate (excitatory)

What can be said for the activity of GPi (Globus Pallidus Internal) neurons?

They are **inhibitory** and **tonically active (No-Go Indirect path)**

Direct Pathway - GO Travel Path? Net Effect? Neurotransmitter + Receptor End Result

Travel: Striatum direct to Globus Pallidus Int. (GPi) or Pars Reticularis (SNr) Net: Facilitates Movement; **excitations** through thalamic connections to motor/pre-motor cortex NT / RX: **Dopamine + D1-receptors (excitatory)** **\*\*DECREASE Direct = Decrease GO = INCREASE Inhibition (Thalamus) = LESS movement\*\***

Indirect Pathway - NO GO Travel Path? Net Effect? Neurotransmitter + Receptor End Result

Travel: Striatum direct to **Globus Pallidus Ext. (GPe)** and **Subthalamic nucleus** to **Globus Pallidus Int. (GPi)** or **Pars Compacta (SNc)** Net: **Inhibits movement** through thalamic connections to motor/pre-motor cortex NT / RX: Dopamine + **D2**-receptors (**inhibitory**) **\*\*DECREASE Indirect = Decrease NO-GO = DECREASE Inhibition (Thalamus) = MORE movement\*\***

What three nuclei make up the corpus striatum?

Caudate Putamen Glubus Pallidus

What are 3 incoming projections to the neostriatum and what neurotransmitter do they use?

1. Cortico-Striatal: **Glutamate (+)** 2. Nigro-Striatal: **Dopamine** 3. Thalamo-Striatal: **Glutamate (+)**

What are two major outputs from the neostriatum and what neurotransmitters do they use?

1. Glubus Pallidus - Thalamus 2. Neostriatum - SNr **Both NT's are GABAergic Inhibitory**

Are D1 or D2 receptors excitatory and what is this kind of neuron?

D1 = Excitatory Neurotransmitter = Dopamine D2 = Inhibitory Neurotransmitter = Dopamine - - - **Medium Spiny Neurons**

What is the Parkinson's Triad of Symptom, and what nuclei are affected?

1. Resting tremor 2. Cogwheel Rigidity 3. Bradykinesia (slowness in movement) - - - **Dopaminergic Neurons from SNc**

What symptoms differentiate PD, Wilson's and Huntington's

Parkinson's: **Olfactory dysfunction, Reptillian stare, speech/swalling** Wilsons: **Wing Beating, Corneal Rings** Huntington: **Choreiform movement, Tics**