Dr. Louie: Neuropathy and EMG Flashcards
What are the clinical features of neuropathy?
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)
What are some characteristics of the weakness associated w neuropathy?
greater distally than proximally
unable to grip, open jar, execute fine movements
foot drop / tripping over feet
dropping objects from hands
What are some bulbar/cranial nerve symptoms associated w neuropathy?
diplopia
ptosis
dysarthria
What are some sensory features associated w neuropathy?
loss of pinprick sensation in distal extremities
loss of temperature
hypersensitivity/allodynia
proprioception testing (Romberg test)
What are some motor features associated w neuropathy?
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
What are some bulbar features that are notable during a physical exam?
diplopia ptosis facial asymmetry tongue weakness/atrophy pupillary abnormalities
What is one caveat when performing EMGs?
slowing latencies or conduction velocities can be due to cold limb skin temperature
What could decreased sensory or motor amplitudes suggest?
axonal damage
What may delayed distal latencies or slowed conduction velocities suggest?
demyelination
What may abnormal temporal dispersion or conduction block be suggestive of?
demyelination disease or focal nerve impingement
What may delayed or absent F-responses or H-reflexes be suggestive of?
demyelination disease
radiculopathy
focal nerve compression
In a needle electrode exam, what can increased insertional activity suggest?
muscle irritability, which can be seen in neuropathy or myopathy
motor units are high-amplitude, polyphasic with decreased recruitment
denervation
motor units are low-amplitude, polyphasic with increased recruitment
myopathic muscle
What is EMG good for?
diagnosis of classification of peripheral neuropathy
diagnosis of major compressive mononeuropathies
diagnosis of myopathy
diagnosis of severe radiculopathy
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
axonal neuropathy
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
deymyelinating neuropathy
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
compressive neuropathy
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.
Radiculopathy
Diabetic Neuropathy
Other metabolic neuropathies
Vasculitic neuropathy
Hereditary neuropathy
types of axonal neuropathy
Guillain-Barre syndrome
MGUS-related neuropathies
Selected toxic neuropathies—Toluene
Hereditary demyelinating neuropathies—Charcot-Marie-Tooth Disease
demyelinating neuropathy
What should you do if a neuropathy is not treatable?
supportive care
