Dr. Louie: Neuropathy and EMG

Question 1

What are the clinical features of neuropathy?

Answer 1

stocking/glove numbness
exclusively or initially in legs
loss of sensation: feet feel like walking on logs
tingling: pain and needles
pain: burning, shooting, allodynia
unsteadiness/imbalance particularly when vision taken away
weakness (greater distally)

Question 2

What are some characteristics of the weakness associated w neuropathy?

Answer 2

greater distally than proximally
unable to grip, open jar, execute fine movements
foot drop / tripping over feet
dropping objects from hands

Question 3

What are some bulbar/cranial nerve symptoms associated w neuropathy?

Answer 3

diplopia
ptosis
dysarthria

Question 4

What are some sensory features associated w neuropathy?

Answer 4

loss of pinprick sensation in distal extremities
loss of temperature
hypersensitivity/allodynia
proprioception testing (Romberg test)

Question 5

What are some motor features associated w neuropathy?

Answer 5

mostly distal atrophy with or without fasciculations
weakness evident in distal groups
tremor
diminished to absent deep tendon reflexes
pes cavus deformity of foot
steppage gait with foot drop

Question 6

What are some bulbar features that are notable during a physical exam?

Answer 6

diplopia
ptosis
facial asymmetry
tongue weakness/atrophy
pupillary abnormalities

Question 7

What is one caveat when performing EMGs?

Answer 7

slowing latencies or conduction velocities can be due to cold limb skin temperature

Question 8

What could decreased sensory or motor amplitudes suggest?

Answer 8

axonal damage

Question 9

What may delayed distal latencies or slowed conduction velocities suggest?

Answer 9

demyelination

Question 10

What may abnormal temporal dispersion or conduction block be suggestive of?

Answer 10

demyelination disease or focal nerve impingement

Question 11

What may delayed or absent F-responses or H-reflexes be suggestive of?

Answer 11

demyelination disease
radiculopathy
focal nerve compression

Question 12

In a needle electrode exam, what can increased insertional activity suggest?

Answer 12

muscle irritability, which can be seen in neuropathy or myopathy

Question 13

motor units are high-amplitude, polyphasic with decreased recruitment

Answer 13

denervation

Question 14

motor units are low-amplitude, polyphasic with increased recruitment

Answer 14

myopathic muscle

Question 15

What is EMG good for?

Answer 15

diagnosis of classification of peripheral neuropathy
diagnosis of major compressive mononeuropathies
diagnosis of myopathy
diagnosis of severe radiculopathy

Question 16

Decreased or absent sensory and motor amplitudes on NCS
Increased insertional activity with fibs and p-waves and possibly CRDs as abnormal spontaneous activity
High-amplitude, polyphasic motor unit potentials with decreased recruitment on motor unit analysis

Answer 16

axonal neuropathy

Question 17

NCS showing markedly delayed distal latencies and slowed conduction velocities
Abnormal temporal dispersion or conduction block
Markedly delayed F-wave latencies or absent F-waves
Needle EMG: Increased insertional activity with p-waves, fibs as abnormal spontaneous activity
High-amplitude, polyphasic motor unit potentials with decreased recruitment

Answer 17

deymyelinating neuropathy

Question 18

Decreased sensory amplitudes or absent sensory responses
Decreased or absent motor responses
EMG showing fibs, p-waves, fasciculations exclusively in muscles supplied by suspect nerve. Motor unit potentials of those muscles are large, polyphasic with decreased recruitment

Answer 18

compressive neuropathy

Question 19

Normal sensory nerve conductions
Normal or decreased motor amplitudes
Delayed or absent F-responses
EMG: fibs, p-waves, CRDs in appropriate myotome. In those muscles, motor unit potentials are large and polyphasic with decreased recruitment. Paraspinous muscles are most sensitive for these changes.
EMG/NCS can be normal in patients with a significant radiculopathy. Need to correlate with imaging.

Answer 19

Radiculopathy

Question 20

Diabetic Neuropathy
Other metabolic neuropathies
Vasculitic neuropathy
Hereditary neuropathy

Answer 20

types of axonal neuropathy

Question 21

Guillain-Barre syndrome
MGUS-related neuropathies
Selected toxic neuropathies—Toluene
Hereditary demyelinating neuropathies—Charcot-Marie-Tooth Disease

Answer 21

demyelinating neuropathy

Question 22

What should you do if a neuropathy is not treatable?

Answer 22

supportive care