Electrophysiological Testing

Duration

15-60 min depending on goal

Electromyography (EMG)

Experimental technique concerned with development, recording, and analysis of myoelectric signals (electrical activity of the mm)

- The study of motor unit activity

Good at identifying: ___?

Location, severity, PNS issue, anterior horn issues

- Not good at identifying the cause

CNS Issues that can be Identified

1. Normal EMG testing

2. Abnormal MRI

Electrophysiological Testing

Recording, analysis, and interpretations of bioelectrical activity of mm and nn

Electrophysiological Testing Purpose

- To determine functional integrity of n or m

- Determine location, magnitude, distribution, and duration of compromise/injury

Electrophysiological Testing is Comprised of: (2)

1. Nerve conduction studies (NCS)

2. Needle electromyography (EMG) assessment

4 Uses of EMG

1. Medical research

2. Rehab

3. Sports science

4. Ergonomics

Benefits of EMG (5)

1. To "look" directly into the m

2. Measurement of m performance

3. Decision making before/after surgery

4. Training regimens

5. Helps pts "find" their mm

Biofeedback

Use of electrical instrumentation to measure, process, and feed back the myoelectrical signals from skeletal m in order to allow the pt to gain better volitional control over the m

- Goal may be to decrease or increase activity

Biofeedback does not create ___?

A contraction or measure force output

Neuropraxia

Conduction block without axonal injury

- Typically myelin injury or condition

Axonotmesis

Disruption of axonal continuity and myelin involvement

Neurotmesis

Disruption of axon, myelin, and connective tissue sheath

Demyelination

Decreased n conduction velocity

Degeneration

Decreased amplitude of response

Nerve Conduction Studies Affected by ___ (4)?

1. Upper vs lower body

2. Length of axon (limb length)

3. Limb temp

4. Age

Compound Muscle Action Potential (CMAP)

Represents the summation of all underlying individual m fiber action potentials

- Biphasic with an initial neg

Sensory Nerve Action Potential (SNAP)

Compound potential that represents the summation of all the individual sensory fiber action potentials

- Usually biphasic or triphasic

Nerve Conduction Velocity

Distance/time

(forearm = 58m/s elbow = 42m/s)

Interpreting Motor Responses: Latency (ms)

Slowed or delayed with demyelination (reflects decreased NCV)

Interpreting Motor Responses: Duration

Prolonged with demyelination pathology

Interpreting Motor Responses: Amplitude of Response (mV)

Represents number of functioning motor units inn by n being tested (degeneration)