Neuromuscular systems for quiz

Down Syndrome

• core cause: trisomy 21 (extra 21st chromosome)

• physiological link: lower cerebellum weight, which likely causes coordination difficulties

• motor comparison: impacts are similar to aging (though for different reasons)

• slower speed: longer reaction and movement times

• reduced precision: irregular movement trajectories and high variability

• muscle strategy: preferences for co-activation patterns during movement, reactions, and posture

• grip: utilizes a high safety margin during grip tasks

• significant improvement: training/rehab can lead to stunning progress

• benefits: increases speed, coordination, and force production while reducing inefficient muscle co-contraction

muscular dystrophies

• genetic disorder that causes progressive weakness and degeneration of skeletal muscles

• effects males more than females

duchenne muscular dystrophy

• mutation of a gene responsible for dystrophin, a protein involved in a maintaining integrity of muscle fibers

• clinical symptoms present at 2 to 6 years; all muscles are ultimately affected

• late to walk; waddling, unsteady gait

• respirator dependence by the age of 20

becker dystrophy

• similar to duchenne dystrophy; mutation of a gene responsible for dystrophin

• clinical symptoms appear in adolescence

• slower disease progression; longer life expectancy

myotonic dystrophy

• most common adult form of muscular dystrophy

• myotonia: prolonged episode of muscle activity after its voluntary contraction

• commonly in finger and facial muscles

• high stepping, flopping footed gait (drop foot)

• long face; drooping eyelids

Mononeuropathies (one peripheral nerve is affected, slowed conduction in a single nerve)

• reduced amplitude of motor and sensory potentials

• signs of denervation

  • Tunnel syndrome: entrapment of the median nerve at the wrist most common mononeuropathy

  • ulnar nerve can be entrapped near the elbow

  • Brachial plexus lesion: mostly seen in muscles innervated by the median and ulnar nerve (stinger injury in football)

  • peroneal: peroneal pressure palsy

  • tibial: tarsal tunnel syndrome

  • sciatic nerve

diabetes mellitus (not a neuromuscular disease but can have neuromuscular consequences)

• peripheral sensory neuropathy: damage to nerves that handle sensation

• peripheral motor neuropathy: damage to nerve that control muscle movement

• autonomic dysfunction: loss of involuntary nerve function (like heart rate or digestion)

• peripheral tissue atrophy: wasting away of tissue leading to :

  • loss of balance and coordination

  • higher risk of falls, fractures, and bruises

Guillian-Barre Syndrome

• auto-immune disorder that causes neuropathy by affecting multiple neurons in the peripheral nervous systems

• reduces muscle fiber recruitment and may cause conduction block (interrupted signals)

• can lead to permanent axonal loss if not treated quickly

• sensory symptoms: tingling and pain

• motor symptoms: muscle weakness

• determined via lumbar puncture (spinal tap) and nerve conduction

• The condition is treatable

• even after treatment, some permanent numbness and muscle weakness may remain

amyotrophic lateral sclerosis (ALS, lou gehrig’s disease)

• upper motor neuron syndrome (affects the motor neurons in the primary motor area)

• the earliest symptoms may include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg slurred and nasal speech, or difficulty chewing or swallowing

• patient have increasing problems with moving, swallowing (dysphagia) and speaking or forming words

• patient have tight or stiff muscle (spasticity) and exaggerated reflexes(hyperreflexia)

• degeneration and symptoms get progressively worse over time and lead to respirator dependence

spinal cord injury (most common cause is motor vehicle accidents)

o   Paresis: partial loss of voluntary control of muscle activity

o   Plegia: total loss of voluntary motor control

o   Para: two extremities are involved: forelimbs (arms) or hindlimbs (legs)

o   Hemi: half of the body (left or right) is involved (typically from a stroke or brain injury)

o   Quadri: all four extremities are involved

o   Spastic: with positive signs of spasticity (hyperreflexia)

o   Flaccid: without positive signs of spasticity (areflexia)

o   Cervical Injuries

§  Commonly quadriplegia

§  Above the C-4 level may require a ventilator

§  C-5 injuries often result in shoulder and biceps control, but no control at the wrist or hand

§  C-6 injuries generally yield wrist control, but no hand function

§  C-7 and T-1 injuries: can straighten arms but may have dexterity problems with the hand and fingers

thoracic lumbar injuries

• commonly paraplegia

• hands not affected

• at T-1 to T-8 poor trunk control as the result of lack of abdominal muscle control

• lower T injuries (T-9 to T-12) allow good trunk control and good abdominal muscle control, sitting balance is very good

• lumbar and sacral injuries yield decreasing control of the hip flexors and legs

Multiple sclerosis

• Demyelination of axons within the CNS

• Auto-immune disorder, the immune system attacks the myelin sheath, leaving the axon exposed, causing it to harden (sclerosis)

• Possible signs and symptoms (can cause both motor and sensory issues)

• Blurred vision, impaired visual acuity

• Impairment of balance

• Intentional tremor

• Discoordination of limbs

• Dysarthria

• Facial weakness and numbness

• Tingling in hands and arms

• Discoordination (if spindle afferents are affected)

• Instability of stance (if lower limbs are affected)

• Feeling of heaviness in arms and legs

• Dragging of legs

• Weakness, even acute paraplegia

• Spasticity

• Fatigue

  • Viewed as a very different feeling from generic fatigue

  • Disproportionate to the amount of effort

  • Possibly debilitating

  • Loss of force has a clear central component

  • Apparent neural component to the fatigue

Parkinson’s Disease

• hypokinetic disorder specifically effects dopamine production in the substantia nigra of the basal ganglia

• sign and symptoms

• Bradykinesia

• tremor

• postural deficits

deficit in APA’s

increased PPR

• rigidity (resistance of motion)

• difficulty initiating movements like walking

• Higher variability in both single and multi-joint movement, difficulty with movement that requires accuracy

• shuffling gat (short, choppy steps)

Huntingdon’s Disease

• hyperkinetic disorder of the basal ganglia specifically affects the caudate nucleus and putamen (striatum)

  • neurodegenerative disorder

  • heredity (the gene has been located)

  • starts in midlife

  • characterized by chorea and dementia

  • motor disorder

  • depression

  • irritability

  • loss of social skills

  • Death typically occurs within after 15-20 years after onset of symptoms

  • chorea

    • generalized, irregular, restless, often pseudo-purposive movements (fidgeting hand movements, dancelike gait, clumsiness, slurry speech)

    • all part of the body are involved

    • at early stages, chorea can be suppressed voluntarily and looks like restlessness or movements under emotional stress

    • at later stages, it can be masked by rigidity and bradykinesia

Cerebellar Disorder

§  Delay in movement initiation (clumsiness, but movement execution is not prevented)

§  Incomplete and inaccurate movement forms (errors of force, velocity, and timing)

§  Muscle strength is diminished somewhat (gait changes include wide base stance, truncal tremor, irregularly placed steps, excessive leg lift)

§  Lack of coordination (ataxia)

§  Intention tremor

§  Astasia-abasia

§  Dysarthria

wilson’s disease

o   Excessive copper deposits in the brain (specifically the cerebral cortex and basal ganglia, also in the liver and other internal organs)

o   Can be diagnosed by looking for copper rings around the iris of the eye (Kayser-Fleischer ring)

o   Signs and symptoms include:

§  Tremor

§  Slurred speech

§  Masklike face

§  Shuffling gait

§  Stooped posture

§  Changes in mental/psychological functioning

Cerebral Palsy

o   Non-progressive disorder in young children that persists throughout the lifespan, causes problems with motor function such as ataxia, spasticity, dystonia, and dysarthria.

o   Can also cause epilepsy, reduced mental capacity, and visual disturbances.

o   Possible causes:

§  Complications of labor and delivery

§  Preterm birth, very low birth weight

§  Hypoxia

§  Genetic factors

§  Infections during pregnancy

§  Commonly seen CNS congenital malformations