EMG/NM Flashcards
Define innervation ratio
amount of fibers belonging to an axon is the innervation ratio
EDX studies evaluate only ______ fibers
Ia
What happens with the following parameters of nerves with temperature decreasing from 32 to 30? Latency, amplitude, duration, conduction velocity, phases
Prolonged, increased, increased, decreased, increased
Propagation of nerve signal along axon is known as
saltatory conduction (going from one node to another)
How much ACh molecules per quanta? How wide is synaptic cleft?
5000-10000 molecules;
200-300 Angstroms
Sarcomere runs from;
what binds to troponin-tropomyosin complex?
Z-line to Z-line;
Calcium
Axonal regrowth occurs approximately
1 mm/day, or 1 in/month
Ohm’s Law
Current = Voltage/resistance
Which needle requires a separate reference electrode to perform EMG?
Monopolar
What could potentially happen with reversal of stimulator’s cathode and anode?
Anodal block; hyperpolarization of nerve and inhibition of AP production
CV of newborn is _____ % of an adult; at 1 year, ____ % of an adult; what age is CV that of an adult?
50%;
80%;
3-5 yrs of age
CV drops _______ m/sec per 1 degree dropped
2.4
H-reflex: what type of reflex? Initiated with what type of stimulation? Stimulates what type of fibers, causing _______ sensory and motor responses
Monosynaptic effectively;
submaximal;
1a afferent;
orthodromic
A wave occurs at ______ latency
constant
What is synkinesis?
Aberrant regen of axons after facial nerve injuries leading to re-innervation of inappropriate muscles (lip twitching with closing eye; crocodile tears when chewing)
What does SSEP monitor for?
- Peripheral nerve injuries
- CNS lesions like MS
- Intra-operative monitoring of spinal surgery
Median nerve SSEP markers: N9, N11, N13, P14, N18, N20?
N9: Erb's point N11: Roots N13: Cervicomedullary junction P14: Lower brainstem N18 Rostral brainstem N20 Primary cortical somatosensory receiving area
MEPPs represent
release of individual quanta across NMJ
When do you see satellite potentials?
Early reinnervation and trail main MUAP; time-locked potentials
Optimal # of muscles to screen for cervical or lumbar radic?
6 muscles if paraspinals are included
Muscles with dual innervation
Pec major, brachialis, FDP, lumbricals, FPB, pectineus, adductor magnus, biceps femoris
With nerve root avulsion, see ______ CMAP’s with _______ SNAP’s
absent, normal
What does AIN supply?
FPL, 1/2 of FDP, and PQ
In CTS maximal slowing is across the _________, whereas in peripheral neuropathy, the _______ ________ is more abnormal
wrist;
distal segment
What does initial positive deflection of median nerve CMAP at antecubital fossa but not at wrist mean? Where would the higher CMAP amplitude be?
Martin-Gruber anastomosis;
elbow
What’s a Riche-Cannieu anastomosis?
Connection of recurrent branch of median nerve in hand to deep motor branch of ulnar nerve (ulnar hand)
Radial nerve muscles innervated below the spiral groove?
BR, ECRL
Where is a Monteggia fx?
Proximal 1/3 of the ulna with dislocation of the radial head
What is the only peripheral nerve injury localized to the trunk level?
Suprascapular neuropathy
What muscle technically innervated by peroneal nerve is spared with common peroneal neuropathy?
Short head of biceps femoris
EMG recording of the external anal sphincter has ______ activity at rest. What is seen during defecation with regards to activity?
continuous;
Preserved or increased activity during prolonged substantial rectal distension during defecation
What is often the first sign in AIDP/GBS? What means poorer prognosis for those with GBS?
Ascending numbness;
CMAP amplitude < 20%, nerve CV < 40%, F-wave absent
Most common type of neuropathy for HIV patients?
Distal symmetric polyneuropathy (sensory and autonomic fibers)
For rep nerve stim (RNS), decrease of greater than _______ % amplitude from first to fifth waveform is significant
10
Define jitter
Prolonged time between interpotential discharges of muscle fibers belonging to same motor unit
Central core disease associated with
malignant hyperthermia
Where do you most commonly see abnormal activity on EMG in poly/dermatomyositis?
Paraspinals
What is the ambulation status of each type of SMA?
SMA1: Never sits independently
SMA2: Independent sitting, assistive device for standing and walking
SMA3: Independent standing/walking
Findings on SFEMG for ALS?
Increased jitter and fiber density
