midterm 2 questions neuromusc 2

What is the primary pathological feature of Parkinson's disease?

Degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to dopamine deficiency in the nigrostriatal pathway.

What are Lewy bodies, and what protein are they composed of?

Abnormal protein aggregates (misfolded alpha-synuclein) found inside neurons, pathognomonic for PD.

List the 4 cardinal motor symptoms of PD

Resting tremor ("pill-rolling"), bradykinesia, rigidity ("lead-pipe" or "cogwheel"), postural instability

Name two early non-motor symptoms of PD.

Loss of smell (anosmia) and constipation (due to decreased intestinal motility)

What does Braak staging describe in PD?

The progression of alpha-synuclein deposition, starting in the olfactory bulb and lower brainstem (Stage 1-2) before reaching the substantia nigra (Stage 3-4).

What is the first-line pharmacological treatment for PD?

Dopamine agonists (e.g., pramipexole) or L-DOPA (levodopa) to replace dopamine.

What percentage of substantia nigra cell loss is required before motor symptoms appear?

~80%

Which pathway is hyperactive in PD due to dopamine loss?

Indirect pathway (inhibits movement).

What is the characteristic gait in PD called?

Festinating gait (shuffling, short steps, reduced arm swing)

True or False: Lewy bodies are only found in PD

False (also seen in Dementia with Lewy Bodies)

How does the direct pathway facilitate movement?

Striatum → GPi inhibition → disinhibits thalamus → increases motor cortex activity ("gas pedal")

How does the indirect pathway inhibit movement?

Striatum → GPe inhibition → disinhibits STN → excites GPi → inhibits thalamus ("brakes")

How does dopamine affect the direct/indirect pathways?

Excites direct (D1 receptors), inhibits indirect (D2 receptors) → net promotion of movement.

What happens if the sub thalamic nucleus (STN) is lesioned?

Hemiballismus (flailing movements) due to loss of inhibitory control

Which basal ganglia nucleus is the major output to the thalamus?

Globus pallidus interna (GPi)

What neurotransmitter is depleted in PD?

Dopamine

What is the effect of increased GPi activity on movement?

Inhibits movement (increased "braking")

What are the 3 functional divisions of the cerebellum?

Vestibulocerebellum (balance), Spinocerebellum (limb coordination), Cerebrocerebellum (motor planning)

What cerebellar sign is tested by finger-to-nose?

Dysmetria (overshooting/undershooting targets)

Which peduncle carries most efferent fibers?

Superior cerebellar peduncle (output to thalamus/red nucleus)

Why does cerebellar lesion cause ipsilateral symptoms?

Output decussates twice (cerebellum → contralateral cortex → contralateral limbs)

What artery supplies the flocculonodular lobe?

AICA (anterior inferior cerebellar artery)

What are the two major types of tremors and how do they differ?

Resting tremor (occurs at rest, seen in PD) vs. intention tremor (worsens with movement, seen in cerebellar disease)

What are postural tremors and what conditions are they associated with?

Tremors during sustained posture; seen in anxiety, hyperthyroidism, essential tremor, excessive caffeine.

What are tics and in which population are they most commonly seen?

Repetitive, stereotyped muscle contractions, often in the face and shoulders; more common in children.

What is Tourette’s Syndrome characterized by?

Vocal and motor tics, often starting in childhood; more common in males (3:1)

What tremor is characteristic of Wilson’s Disease?

Wing-beating tremor

What is the cause of Wilson’s Disease?

Genetic defect in copper metabolism leading to copper buildup in liver, basal ganglia, and eyes.

What are hemiballistic movements?

Rapid, flailing movements of the proximal extremities.

What is chorea and give an example of a disease that causes it?

Brief, rapid, jerky involuntary movements; e.g., Huntington's Disease

How does athetosis differ from chorea?

Athetosis is slower, writhing movements often seen in cerebral palsy

What is dystonia?

Sustained, twisting involuntary contractions that may affect large areas of the body.

What is spasmodic dysphonia?

A speech disorder caused by spasms in the vocal cords, leading to strained or broken voice.

What is tardive dyskinesia and what causes it?

Involuntary lip and tongue movements due to long-term use of antipsychotics

Which tremor worsens with movement and is typical of cerebellar disease?

Intention tremor

What are some triggers of postural tremors?

Hyperthyroidism, anxiety/stress, essential (familial) tremor, excessive caffeine intake

What distinguishes tics from other movement disorders?

Tics are habitual, stereotyped, and can be voluntarily suppressed temporarily

What types of tics are seen in Tourette’s Syndrome?

Motor tics and vocal tics (e.g., grunting, throat clearing, coprolalia)

What causes the wing-beating tremor in Wilson’s Disease?

Copper accumulation due to a genetic defect in a copper-binding protein

What involuntary movement is described as flailing proximal extremity motions?

HemiballismWhich condition presents with jerky distal limb movements and is genetic?

Which condition presents with jerky distal limb movements and is genetic?

Huntington’s Disease (a type of chorea)

What are slower, writhing movements often seen in cerebral palsy called?

Athetosis

What are the signs of dystonia?

Sustained twisting postures involving larger body regions like the trunk

What is the usual cause of tardive dyskinesia?

Long-term use of psychotropic (antipsychotic) medications

What is the main role of the basal ganglia in motor control?

It tonically inhibits motor cortex activity—acts like "brakes" on movement

What are the major symptoms of basal ganglia lesions?

Dyskinesias – either hyperkinesia (involuntary movements) or hypokinesia (bradykinesia/akinesia)

Are basal ganglia connections ipsilateral or contralateral to the motor cortex?

Ipsilateral

What is the effect of a unilateral basal ganglia lesion?

Contralateral dyskinesia

What are the five components of the basal ganglia?

Caudate, Putamen, Globus pallidus, Subthalamic nucleus, Substantia nigra.

What makes up the striatum?

Caudate + Putamen

What forms the lenticular nucleus?

Putamen + Globus pallidus

What is the major input nucleus of the BG?

Striatum

What is the major output nucleus of the BG?

Globus pallidus internus (GPi)

What does the direct pathway do to movement?

Disinhibits the thalamus ➝ increases motor cortex activity ➝ facilitates movement ("gas")

What does the indirect pathway do?

Inhibits the thalamus ➝ decreases motor cortex activity ➝ inhibits movement ("brakes")

How does dopamine from the substantia nigra influence movement?

Excites the direct pathway (+) and inhibits the indirect pathway (-), both promoting movement.

What are the three structures that make up the corpus striatum?

Caudate, Putamen, and Globus pallidus

Which BG structure excites the direct pathway and inhibits the indirect pathway?

Substantia nigra pars compacta (via dopamine release)

What is the net effect of dopamine on motor activity via basal ganglia pathways?

Dopamine facilitates movement by exciting the direct pathway and inhibiting the indirect pathway

What is the effect of the direct pathway on the thalamus and movement?

It disinhibits the thalamus, which increases motor cortex activity and facilitates movement ("gas")

What is the effect of the indirect pathway on the thalamus and movement?

It inhibits the thalamus, decreasing motor cortex activity and inhibiting movement ("brakes")

What percentage of brain volume and neurons does the cerebellum contain?

~10% of volume, >50% of neurons

Is the cerebellum an upper motor neuron (UMN)?

No, it influences UMNs but is not one itself.

What are the 7 main functions of the cerebellum?

Balance, head/eye coordination, posture, limb movement coordination, motor planning, motor learning, cognitive/affective regulation.

What are signs of cerebellar dysfunction?

Ataxia (incoordination), dysmetria, dysdiadochokinesis, intention tremor, balance issues

What are the three cerebellar lobes and their functional names?

Anterior = Paleocerebellum

Posterior = Neocerebellum

Flocculonodular = Archicerebellum

What are the 3 functional divisions of the cerebellum?

Vestibulocerebellum (flocculonodular lobe)

Spinocerebellum (vermis & intermediate zones)

Cerebrocerebellum (lateral hemispheres)

What is the main output pathway of the cerebellum?

From deep cerebellar nuclei via superior cerebellar peduncle to contralateral thalamus/motor cortex.

What are the 4 deep cerebellar nuclei (medial to lateral)?

Fastigial, Globose, Emboliform, Dentate

Which fibers synapse directly on Purkinje cells?

Climbing fibers (from inferior olivary nucleus)

Which cerebellar fibers synapse first on granule cells?

Mossy fibers

What cells provide cerebellar cortical output?

Purkinje cells (inhibitory to deep nuclei)

What side of the body is affected by cerebellar lesions?

Ipsilateral side (due to double decussation)

What are two hallmark signs of cerebellar limb dysfunction?

Dysmetria (inaccurate targeting) and dysdiadochokinesis (poor rapid alternating movements)Which lobe of the cerebellum is the oldest phylogenetically?

Which lobe of the cerebellum is the oldest phylogenetically?

Flocculonodular lobe (Archicerebellum)

What is the function of the vestibulocerebellum?

Balance and coordination of head and eye movements

What do Purkinje cells do?

They are the output neurons of the cerebellar cortex and inhibit the deep cerebellar nuclei

Which cerebellar input fibers project directly to Purkinje cells?

Climbing fibers (from the inferior olivary nucleus)

What tract carries motor planning information from cortex to cerebellum?

Cortico-ponto-cerebellar tract (via middle cerebellar peduncle)

Which cerebellar peduncle carries output to the thalamus?

Superior cerebellar peduncle

What are the three longitudinal zones of the cerebellar cortex?

Medial (vermal), intermediate (paravermal), and lateral (hemispheric) zones

Which zone controls trunk posture via the medial motor system?

Medial zone (vermal region) of the spinocerebellum

What type of tremor is associated with cerebellar dysfunction?

Intention tremor

What is "myopathy"?

A disease of the muscle tissue causing weakness or dysfunction

What pattern of weakness is typical in myopathies?

Bilateral, proximal limb weakness (shoulder and pelvic girdles)

What are common causes of myopathy?

Genetics, inflammation, drugs/toxins, and cancer (paraneoplastic)

What is Gower’s sign and what does it indicate?

Using hands to "walk up" thighs to stand up; indicates proximal muscle weakness.

What is Trendelenburg sign?

Pelvic drop when lifting one leg, indicating weakness of contralateral gluteus medius.

What lab finding is elevated in Duchenne muscular dystrophy?

reatine phosphokinase (CPK)

What protein is deficient in Duchenne’s muscular dystrophy?

Dystrophin

What is pseudohypertrophy?

Enlargement of muscles (usually calves) due to fat and connective tissue replacement—not true hypertrophy

What diagnostic tests are used for myopathy?

Blood tests (CPK), EMG/NCV studies, and muscle biopsy

What distinguishes myopathy from a neuropathy clinically?

Myopathy shows proximal weakness without sensory deficits; neuropathy often affects distal muscles and involves sensory loss

What type of muscle weakness pattern is typical in myopathies?

Bilateral proximal limb weakness, especially in the shoulder and pelvic girdleWhat is Gower’s sign and what does it tell you?

What is Gower’s sign and what does it tell you?

It's when a patient uses their hands to "walk up" their legs to stand; it indicates proximal muscle weakness, commonly seen in Duchenne’s

What muscle is weak when a positive Trendelenburg sign is seen?

Gluteus medius on the contralateral side of the dropped pelvis

What protein is deficient in Duchenne’s muscular dystrophy?

Dystrophin

What causes pseudohypertrophy of the calves?

Fat and connective tissue replacement of muscle fibers, not true muscle growth

What lab test is commonly elevated in Duchenne’s?

Creatine phosphokinase (CPK)

Which muscle group is usually affected first in most myopathies?

Proximal limb muscles