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Electrophysiology > Unit III > Flashcards

Unit III Flashcards

(48 cards)

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1
Q

What section supports EMG/NCS in the KY state practice act?

A

KRS 327.10

“…evaluations performed to determine…nerve and muscle function including subcutaneous bioelectrical potentials…”

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2
Q

T/F: Medicare recognizes and reimburses EMG services performed by ABPTS certified and non-certified clinicians

A

False; only certified PTs are reimbursed for EMG testing

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3
Q

What is the primary goal of rehabilitation?

A

optimization of motor control

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4
Q

What is a motor unit?

A

anterior horn cell > nerve root > plexus > nerve (proper) > NMJ > muscle fibers innervated by nerve

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5
Q

What is the relationship between lateral ankle sprains and the tibialis posterior?

A

86% of patients with grade III demonstrated denervation of the gastrocnemius/soleus complex; patients have difficulty eccentrically lowering their foot to the ground

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6
Q

What is the relationship between proximal shoulder dislocations and proximal humeral neck fractures and EMG changes?

A

54% of patients demonstrated EMG changes following proximal humeral neck fractures

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7
Q

What is the effect of NMES on denervated muscles?

A

delays reinnervation if applied too soon

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8
Q

How does EMG testing assist clinical decision-making?

A
  • diagnosis
  • prognosis
  • motor unit recruitment
  • aggressiveness
  • timeframes
  • refer/triage
  • when the patient is safe to return to sport, work, etc.
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9
Q

What are the three important physiology principles?

A
  • separation of charge
  • “all-or-none” depolarization
  • volume conduction
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10
Q

Resting membrane potential is maintained by:

A
  1. semi-permeable membrane = passive flow of ions

2. sodium-potassium pump (active transport)

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11
Q

What are the three functions of myelin?

A
  1. speeds up conduction
  2. conserves energy
  3. conserves space
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12
Q

What are the three categories of nerve injury described by Seddon in 1945?

A
  1. neuropraxia
  2. axonotmesis
  3. neurotmesis
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13
Q

Neuropraxia

A

transient loss of myelin

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14
Q

Axonotmesis

A

degeneration/injury to the axon; Wallerian degeneration occurs

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15
Q

Neurotmesis

A

injury to the epineurium nerve sheath

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16
Q

Signs of denervation

A
  • positive sharp waves

- fibrillations

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17
Q

What changes occur in the cell body following denervation?

A
  • central chromatolysis

- nissl substance gets darker

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18
Q

Signs of nerve regeneration are indicated by:

A

polyphasic voluntary motor units

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19
Q

Re-innervation

A
  • nodal sprouts
  • terminal sprouts
  • Early (nascent polyphasic potentials and RFR)
  • Late (RFR and giant complex polyphasics)
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20
Q

Sources of error associated with EMG instrumentation

Study These Flashcards
A
  • dirty electrodes
  • broken lead wires
  • poor ground
  • too much electrode gel
  • fluorescent lights
  • cell phone signal
  • incorrect connection of electrodes at pre-amp box
  • power line load
  • the motor of high-low tables
21
Q

Segmental demyelination

Study These Flashcards
A
  • nerve conduction study
  • abnormal almost immediately after onset
  • mild to moderate compression, auto-immune disorders, etc.
22
Q

Axonal degeneration

Study These Flashcards
A
  • needle EMG
  • 21 days post-onset (7-14 days for paraspinals)
  • severe compression, ischemia, inflammation
23
Q

EMG testing principles

Study These Flashcards
A
  • examine motor and sensory when possible
  • test several segments of nerve suspected
  • may need to test upper and lower limb nerves
  • test when likely to obtain the optimal diagnostic yield (≥21 days)
24
Q

Influencing factors

Study These Flashcards
A
  • upper vs. lower extremity
  • age = decreased 10% per decade after 60 YOA
  • temperature
  • anatomical anomalies
25
NCS abnormalities
- slowed latency = myelin issue - reduced amplitude = axonal issue - attenuated duration = sawtooth appearance - slowed conduction velocity - absent response
26
Repetitive stimulation will demonstrate a ___ abnormality
neuromuscular junction
27
Normal NCS
≤ 4.0 milliseconds
28
Treatment for mild CTS
- prolonged DML = 4.0-5.4 | - observation, conservative Rx
29
Treatment for moderate CTS
- prolonged DML = 5.4-7.2 | - conservative modalities first; surgery later if needed
30
Treatment for severe CTS
- prolonged DML = >7.2 - surgery strongly recommended - increased fibrillations, polyphasic VMUs, or electrical silence
31
Treatment for severe CTS
- prolonged DML = >7.2 - surgery strongly recommended - increased fibrillations, polyphasic VMUs, or electrical silence
32
Steps of EMG testing
- insertion (300 milliseconds) - Rest - Minimal contraction - Maximal contraction
33
Abnormal EMG findings at rest
- 1+ = induced by electrode movement - 1-2+ = spontantoue appearance - 3+ = many spontaneuous potentials - 4+ = screen filled with abnormal potentials
34
Reduced insertional activity
- resistance to needle movement in tissue - associated with chronic denervation - fibrotic degeneration, fat infiltration - "woody" feel
35
Increased insertional activity
- after cessation of needle movement | - associated with myotonic disorders, myogenic disorders, and denervation
36
Smaller than normal amplitudes may be the result of:
axonal degeneration or myopathy
37
What is the most sensitive imaging study for spinal stenosis?
CT myelography
38
Typical nEMG findings in lumbar spinal stenosis
- early = little if any abnormality - over time = conduction block, axonal loss, demyelination or re-myelination - first change may be absent H-reflexes - Bilateral findings in up to 50-87%
39
Non-invasive quantitative EMG
- patient follow-up - children - measure response to Rx
40
Rationale for EMG biofeedback
- adjunct to a total rehab program - control of motor unit activity with EMG ( recruitment, relaxation) - contraindications (gel, tape skin irritations, and metabolic confusion)
41
Recruitment EMG Biofeedback
- peripheral nerve injury - muscle weakness (post-immobilization, joint surgery, deconditioning) - muscle transfers - postural control
42
Relaxation EMG Biofeedback
- stress-related ANS arousal - pain (migraine, tension headaches) - spasticity - rigidity (i.e. adult onset torticollis)
43
EMG Biofeedback Goals
- increase amplitude - increase the total number of MUs firing - increase frequency of MU firing - restore joint movement - return motor unit recruitment to normal to protect and move joint properly
44
Appropriate patient selection for EMG biofeedback
- Does patient have motor impairment? - Does motor impairment seem likely to benefit from biofeedback information? - Does patient demonstrate the ability for voluntary control? - Is patient sufficiently motivated and cognitively aware to use feedback info?
45
Appropriate patient selection for EMG biofeedback
- Does patient have motor impairment? - Does motor impairment seem likely to benefit from biofeedback information? - Does patient demonstrate the ability for voluntary control? - Is patient sufficiently motivated and cognitively aware to use feedback info?
46
Myopathy will demonstrate what on EMG?
smaller than normal amplitudes, highly polyphasic, short duration MUPs
47
Normal MUP Duration
3 to 12 msec
48
According to Haig et al, what is the most significant predictors of LSS?
paraspinal mapping and absent tibialis H-reflex

Electrophysiology (2 decks)

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