L&D NM Disorders Study Set: Key Terms & Definitions

types of neuro-electrophysiologic testing

EMG and nerve conduction studies (NCS)

nerve conduction studies processes

nerves are electrically stimulated through the skin using electrodes, AP produced by stimulus are recorded

compound muscle (motor) action potential aka

CMAP

CMAP

the response of the innervated muscle if a motor nerve is stimulated

sensory nerve action potential aka

SNAP

SNAP

the responses recorded along the nerve if a sensory nerve is stimulated

what does EMG measure

measures muscle response/electrical activity in response to a nerve's stimulation of the muscle

what electrical activity does an EMG measures

activity at rest, with slight contraction and with forceful contraction

what can EMG detect

primary muscle pathology

changes in muscle caused by nerve disease

dx of CP

clinical

evaluation of a child with CP often requires

serial examinations (4 month exam usually most predictive)

dx CP is usually made at what age

12-24 months

labs in CP may be useful for what

determining etiology of CP

examples of labs to order in CP

congenital infections > TORCH titers

genetic testing (r/o other conditions)

MRI in CP

structural brain changes d/t underlying etiology, or normal

when to use EEG in CP

if seizure activity suspected

upon dx of CP, goals if history and PE are to:

1. ID clinical features and classification

2. r/o progressive/neurodegenerative condition

3. establish tx goals and priorities

ice pack test is used in

MG

ice pack test is based on what principle

neuromuscular transmission improves at lower muscle temperatures

how can ptosis be overcome temporarily in pts with MG

direct cooling of eyelid muscles

how is ice pack test performed

1. place ice on closed lid for 2 mins

2. remove ice and assess extent of ptosis

positive ice pack test result

improvement of ptosis

positive ice pack test in MG is what?

suggestive, but not diagnostic of MG

labs for MG

anti-acetylcholine receptor antibodies (80-90% sensitivity for MG dx)

if acetylcholine receptor antibodies are negative but high suspicion for MG, what test do you order next?

muscle specific tyrosine kinase (MuSK) antibodies

pts with antibodies to MuSK are more likely to have what sx compared to those with antibodies to acetylcholine receptors?

facial, respiratory, and proximal muscle weakness

NCS in MG

decrementing amplitudes of CAMP during repetitive nerve stimulation (RNS) testing

EMG in MG

disturbance of neuromuscular transmission

CT chest in MG

to r/o thymoma (indicated in most patients)

CDC criteria that suggests suspicion of botulism

1. at least 1 specific sx of cranial neuropathy

2. at least 1 specific sign of cranial neuropathy

3. lack of fever

what to do if botulism is suspected (diagnostically)

contact health department > toxin detection, C. Botulinum growth

supportive EMG and NCS findings in botulism

with repetitive stimulation of motor nerves at fast rates, the muscle response increases in size progressively

MS essentials to dx

episodic neuro sx

<55 y/o at onset

single lesion can't explain clinical findings (multiple foci)

key to dx MS

MRI brain and spinal cord

MRI results MS

white matter changes

what is needed to make the dx of MS

evidence 2+ different regions of central nervous white matter have been affected at different times

DI for MS

MRI

LP

visual/auditory/somatosensory evoked potentials

LP for MS

oligoclonal bands (only CSF, not blood)

mild lymphocytosis

elevated IgG

T1-weighted MRI of MS will show

hypointense "black holes" (areas of axonal damage)

T2-weighted MRI of MS will show

info about total number of lesions