- positive sharp waves - fibrillations

- nodal sprouts - terminal sprouts - Early (nascent polyphasic potentials and RFR) - Late (RFR and giant complex polyphasics)

Unit III Flashcards by Philip Dale

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

KRS 327.10

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

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

False; only certified PTs are reimbursed for EMG testing

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What is the primary goal of rehabilitation?

optimization of motor control

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What is a motor unit?

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

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

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

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

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What is the effect of NMES on denervated muscles?

delays reinnervation if applied too soon

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How does EMG testing assist clinical decision-making?

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

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What are the three important physiology principles?

separation of charge
“all-or-none” depolarization
volume conduction

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Resting membrane potential is maintained by:

semi-permeable membrane = passive flow of ions

2. sodium-potassium pump (active transport)

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What are the three functions of myelin?

speeds up conduction
conserves energy
conserves space

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

neuropraxia
axonotmesis
neurotmesis

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Neuropraxia

transient loss of myelin

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Axonotmesis

degeneration/injury to the axon; Wallerian degeneration occurs

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Neurotmesis

injury to the epineurium nerve sheath

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Signs of denervation

positive sharp waves

- fibrillations

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What changes occur in the cell body following denervation?

central chromatolysis

- nissl substance gets darker

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Signs of nerve regeneration are indicated by:

polyphasic voluntary motor units

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Re-innervation

nodal sprouts
terminal sprouts
Early (nascent polyphasic potentials and RFR)
Late (RFR and giant complex polyphasics)

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Sources of error associated with EMG instrumentation

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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

Segmental demyelination

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nerve conduction study
abnormal almost immediately after onset
mild to moderate compression, auto-immune disorders, etc.

Axonal degeneration

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needle EMG
21 days post-onset (7-14 days for paraspinals)
severe compression, ischemia, inflammation

EMG testing principles

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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)

Influencing factors

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upper vs. lower extremity
age = decreased 10% per decade after 60 YOA
temperature
anatomical anomalies

NCS abnormalities

- slowed latency = myelin issue - reduced amplitude = axonal issue - attenuated duration = sawtooth appearance - slowed conduction velocity - absent response

Repetitive stimulation will demonstrate a ___ abnormality

neuromuscular junction

Normal NCS

≤ 4.0 milliseconds

Treatment for mild CTS

- prolonged DML = 4.0-5.4 | - observation, conservative Rx

Treatment for moderate CTS

- prolonged DML = 5.4-7.2 | - conservative modalities first; surgery later if needed

Treatment for severe CTS

- prolonged DML = >7.2 - surgery strongly recommended - increased fibrillations, polyphasic VMUs, or electrical silence

Treatment for severe CTS

- prolonged DML = >7.2 - surgery strongly recommended - increased fibrillations, polyphasic VMUs, or electrical silence

Steps of EMG testing

- insertion (300 milliseconds) - Rest - Minimal contraction - Maximal contraction

Abnormal EMG findings at rest

- 1+ = induced by electrode movement - 1-2+ = spontantoue appearance - 3+ = many spontaneuous potentials - 4+ = screen filled with abnormal potentials

Reduced insertional activity

- resistance to needle movement in tissue - associated with chronic denervation - fibrotic degeneration, fat infiltration - "woody" feel

Increased insertional activity

- after cessation of needle movement | - associated with myotonic disorders, myogenic disorders, and denervation

Smaller than normal amplitudes may be the result of:

axonal degeneration or myopathy

What is the most sensitive imaging study for spinal stenosis?

CT myelography

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%

Non-invasive quantitative EMG

- patient follow-up - children - measure response to Rx

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)

Recruitment EMG Biofeedback

- peripheral nerve injury - muscle weakness (post-immobilization, joint surgery, deconditioning) - muscle transfers - postural control

Relaxation EMG Biofeedback

- stress-related ANS arousal - pain (migraine, tension headaches) - spasticity - rigidity (i.e. adult onset torticollis)

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

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?

Appropriate patient selection for EMG biofeedback

Myopathy will demonstrate what on EMG?

smaller than normal amplitudes, highly polyphasic, short duration MUPs

Normal MUP Duration

3 to 12 msec

According to Haig et al, what is the most significant predictors of LSS?

paraspinal mapping and absent tibialis H-reflex

Unit III Flashcards

(48 cards)