disorders of the motor unit

Question 1

central/ upper motor neuron lesion

tone, reflexes, atrophy, fasciculations, sensory patterns

Answer 1

increased tone, hypertonia
increased reflexes hyperreflexia
no atrophy
fasciculations (small twitches) absent
sensory patterns: central pattern

seizures and cognitive abnormalities

Question 2

peripheral/ lower motor neurons lesion

tone, reflexes, atrophy, fasciculations, sensory patterns

Answer 2

tone: decreased, hypotonia
reflexes: decreased, hyporeflexia
atrophy: significant

fasciculations: present
sensory patterns: peripheral pattern

Question 3

motor unit components

Answer 3

Alpha lower motor neuron (Cell body located in ventral horn, axon forming peripheral nerve)

neuromuscular junction
muscle

Question 4

guillain-barre

Answer 4

an acquired neuropathy casued by an immune mediated demyelination of peripheral nerve axons

rapid onset of symptoms usually following an infection , symptoms peak at 2-3 weeks

Ascending weakness beginning in the distal limbs and progressing proximally

areflexia

Rx: immunosuppression with intravenous immunoglobulins not steroids, prolonged recovery

Question 5

charcot marie tooth

Answer 5

a congenital sensory and motor neuropathy (affecting lower motor neurons)
progressive sensory loss occurs distally
progressive weakness occurs distally
Charcot foot- high arch and claw toes

Rx: no cure, maintain movement, strength and flexibility with therapy

Question 6

spinal muscular atrophy

Answer 6

a congenital, progressive loss of lower motor neurons, SMN1 gene
2nd most common autosomal recessive disease
progressive motor weakness and eventual muscle atrophy
Fasciculations
Rx: Nusinersen

Question 7

myasthenia gravis

Answer 7

an autoimmune disease of the neuromuscular junction
fatigable weakness
ptosis
proximal muscles more susceptible that distal
Rx: immunosuppression, pyridostigmine (AchE inhib)

Question 8

Muscular dystrophy

Answer 8

X-linked family of diseases that lead to progressive weakness and muscle degeneration
Growers sign- proximal muscle weakness leads patients to walk up their own body when rising from a squat or prone position

Rx: no cure, steroids

Question 9

Amyotrophic Lateral sclerosis (ALS)

Answer 9

an acquired upper and lower motor neuron disease
slowly progressive motor weakness
progressively increased muscle tone

Rx: none