Lower Motor Neuron vs Upper Motor Neuron Injuries

Question 1

def upper motor neuron

Answer 1

originate in the cerebral cortex (motor cortex) and travel down the brain stem or spinal cord

Question 1

def lower motor neuron

Answer 1

any motor neuron outside of the spinal cord that innervates muscles

transmit signal from upper motor neuron tot eh effector muscle

Question 2

peripheral nerves are lower motor neurons? (T/F)

Answer 2

T

Question 3

cranial nerves are lower motor neurons (T/F)

Answer 3

T

Question 4

how might a lower motor neuron injury present?

Answer 4

• flaccid paralysis ➔ no voluntary or involuntary control of muscles
• no DTR
• fasciculations (re: tongue w/ CN 12 damage)
• muscle cramps

Question 5

how might an upper motor neuron injury present?

Answer 5

• spastic paralysis ➔ no voluntary control of muscles
• spasticity ➔ extension in upper extremities and flexion in lower extremities
• hyperreflexia
• still have DTR
• increased tone (think parkinson’s cogwheel or leadpipe)
• pronator drift
• Hoffman or Babinski sign

Question 6

what is a fasciulation?

Answer 6

muscle twitch

Question 7

what is a mononeuropathy?

Answer 7

damage to a single peripheral nerve

Question 8

what is a polyneuropathy?

Answer 8

diffuse peripheral nerve disorder – multiple peripheral nerves involved

not confined to the distribution of a single nerve of limb

relatively symmetrical

Question 9

common causes of peripheral nerve dysfunction?

Answer 9

DANG THERAPIST

D - diabetes
A - alcohol (>10Y)
N - nutrient deficiency (B12, folate, thiamine) or nerve compression
G - GBS

T - trauma, toxin
H - hereditary (charcot-marie-tooth)
E - environmental (drugs/toxins) or endocrine
R - radiculopathy or rheumatic
A - amyloidosis
P - Pb (lead)
I - Infections (HIV)
S - systemic disease or sarcoidosis
T - tumours

Question 10

MC cause of mononeuropathy?

Answer 10

trauma - laceration, compression

Question 11

MC cause of polyneuropathy?

Answer 11

metabolic – Diabetes, nutritional deficiencies, thyroid

Question 12

common chief complaint for neuropathies?

Answer 12

numbness
muscle weakness
paresthesias
pain
stocking glove distribution
atrophy

central nervous system problems would have more autonomic disturbances, gait, sleep, visual, bowel and urinary changes

Question 13

difference between a neuropathy and radiculopathy?

Answer 13

radiculopathy - compression of the nerve root at the spine

neuropathy - damage of the peripheral nerve

Question 14

common dx of mononeuropathies?

Answer 14

carpal tunnel - compression of the median nerve

Peroneal nerve palsy

Saturday night palsy - radial nerve compression

cubital tunnel syndrome - compression of ulnar nerve

Question 15

in general how do you tx neuropathies?

Answer 15

1. tx the underlying cause
2. supportive care to minimize disability and pain
   - assistive devices
   - splinting or bracing at night time
   - occupational and physical therapy
   - pharmacologic: NSAIDs/Tylenol, gabapentin (antiseizure med) for neuropathic pain

consider surgery to. leave tension or fix laceration

Question 16

causes of fixed mononeuropathy?

Answer 16

compression vs hard surface – casting, cramping position, tumour

trapped nerves in narrow anatomical space

Question 17

causes of transient mononeuropathy?

Answer 17

repetitive actions causing trauma to the nerve

stretch injury

Question 18

causes of non-compression related neuropathy

Answer 18

infections - herpes, HIV
colds
radiation
ischemia
trauma

Question 19

RF for mononeuropathy

Answer 19

pregnancy
Rheumatoid arthritis
weight gain

Question 20

thenar muscle wasting is a sign of ________

Answer 20

carpal tunnel syndrome

Question 21

what specific investigation helps with neuropathies?

Answer 21

EMG ➔ tell you if its a myelopathy (spinal cord injury) or a neuropathy

nerve conduction study ➔ axonal vs demyelination

Question 22

how to tx GBS? or acute causes of polyneuropathy?

Answer 22

plasma exchange or IVIg