Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

3: Neurosurgery > Chapter 27 Neurodiagnostics > Flashcards

Chapter 27 Neurodiagnostics Flashcards

(48 cards)

Start Studying
1
Q

Neuromuscular diseases can be broken down into

  • Neuropathy
  • Junctionopathy
  • Myopathy
  • (and neuromyopathies)

List the specific sites of potential disease for each category.

A

Neuropathy: Neuron (cell body, axon), Schwann cell, myelin

Junctionopathy: Pre-synaptic (i.e. faulty transmitter synthesis or release), synaptic (acetylcholine problem) or post-synaptic (affectign Ach-R e.g. MG)

Myopathy: sarcolemma, transverse tubules, organelles, myofilaments inclusions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a motorneuron unit?

A
  • Motor neuron (cell body, and its peripheral axon) supported by Schwann cells
  • NMJ
  • Myofibres innervated by motorneuron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is variability of myofibre type within a motor unit?

A

Single histochemical myofibre type, not a mixture of myofibre types

(not usually contiguous –> mosaic pattern)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Name the principal signs of myopathic syndrome

A
  • Generalised weakness
  • Exercise intolerance
  • Stiff/stilted gait
  • Tremors
  • Muscle atrophy
  • Muscle hypertropy
  • “Percussion dimple” contracture
  • Muscle pain
  • Limited joint movement eg contracture
  • Regurg
  • Flexion of head and neck
  • Trismus (=lockjaw)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the principal signs of motor neuropathic syndrome

A
  • Flaccid paresis/paralysis of innervated structures
  • Neuroenic muscle atrophy
  • Reduced reflexes and muscle tone
  • Muscle fasciculations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the principal signs of sensory neuropathic syndrome

A
  • Decreased response to noxious stimuli
  • Proprioceptive defifits
  • Abnormal sensation of face /trunks/lims/self mutilation
  • Reduced reflexed in absence of muscle atrophy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name general clinical signs of neuromuscular disorders

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Outline 7 step diagnostic workup plan for neuromuscular disease

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List 3 neuromuscular disorder ddx for large CK elevation (>10,000 IU/L)

A
  • Muscular dystrophies
  • Necrotising myopathies
  • Inflammatory myopathies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What specific test can be run in animals suspeted of having mitochondrial myopathy?

A

Post-exercise plasma pyruvate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Once haematuria has been ruled out, how is myoglobinuria distinguished from hemoglobinuria?

A

Ammonium sulfate precipitation test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is masticatory myositis diagnosed?

A

2M antibody test

2M myofibre = unique antigen present on muscles of mastication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are two specific tests for neuromuscluar diseases?

A
  • Electrodiagnostic testing
  • Muscle/nerve biopsy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define electromyography

A

Electromyography: Detection and characterization of electrical activity recorded from patient’s muscles

Allows accurate determination of distribution of muscles affected by neuromuscular disorder.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which 3 broad muscle locations shoudl be tested with EMG?

A

Proximal and distal appendicular muscles as well as axial muscles (usually limit testign to unilateral so that biopsies can be harvested from other side)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is normal EMG of muscle at rest (eg uGA)

A

Electrically silent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 4 types of EMG traces considered normal spontaneous activity

A
  • Insertional Activity
  • Miniature End Plate Potentials
  • End Plate Spike
  • Motor Unit Action Potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the 3 types of EMG traces considered abnormal spontaneous activity

A
  • Fibs and Sharps
  • Complex Repetitive Discharges
  • Myotonic Potentials
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

If selceting muscle for biopsy is it better to take mildly, moderately or severely affected muscle

A

moderate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does spontaneous activity mean in relation for EMG

Study These Flashcards
A

Potentials that are independent of mechanical stimulation.

21
Q

What can increased insertional activity on EMG mean?

And decreased?

Study These Flashcards
A

Increased: neuromuscular disease

Decreased: significant myofibre loss

22
Q

What causes miniature end plate potentials on EMG?

Study These Flashcards
A

Proximity to a NMJ

23
Q

What causes end plate spike on EMG?

Study These Flashcards
A

Normal spontaneous depolarisation of a single myofibre

24
Q

What causes motor unit action potential on EMG?

Study These Flashcards
A

normal muscle that isnt completely at rest e.g. light anaesthesia plane

25
What causes fibs and sharps on EMG?
Spontaneously firing, hypersensitive, single myofibres as result fo destabilization of sarcolemma membrane Secondary to denervating disease or primary myopathic change
26
What causes complex repetitive discharges on EMG?
Spontaneous discharge of single myofibre *plus* its surrounding myofibres. Usually seen with chronic denervation, maybe with myopathies
27
What causes (disease) myotonic potentials on EMG? How are they differentiated from complex repetitive discharges? Classic sound?
Seen with myotonia congenita, radiculopathies, polyneuropathies, Disctinguished from complex repetitive discharges by waxing and waning frequency "Dive bomber" potentials
28
What is the definition of nerve conduction study:
Recording and analysis of electric waveforms of biologic origin, elicited in response to electric or physiologic stimuli.
29
What is it that causes M wave on nerve conduction study
Orthodromic (normal direction) propagation of APs along a nerve, ACh release at NMJ and myofibre depolarization.
30
Comment on this motor nerve conduction velocity study
**Abnormal canine fibular motor nerve conduction study.** Note the polyphasia, temporal dispersion, and decrease in amplitude of the M-wave when compared with panel B. Motor nerve conduction velocities calculated in this 6-year-old dog were slowed: 39 m/s (hip to stifle) and 32 m/s (stifle to hock). These abnormalities are consistent with demyelination. **M waves at each site should have similar configuration.** Normal canine fibular motor nerve conduction study. Note that latency of the M-wave increases with greater distance between stimulating and recording electrodes. Motor nerve conduction velocities calculated in this 1-year-old dog were 69 m/s (hip to stifle) and 57 m/s (stifle to hock).
31
How are motor nerve conduction velocities calculated (formula)?
**MNCV (m/s) = Distance (mm) / (Proximal latency - Distal latency (ms))** Latencies are determined for each potential by marking the point at which the baseline deflects in an upward direction. Amplitudes may be measured between baseline and negative peak (although some investigators use negative-to-positive peak amplitude). Distances between the tips of the stimulating electrodes are measured to calculate nerve conduction velocities. It is this difference in distance over the difference in latency that determines the motor nerve conduction velocity, expressed in meters per second.
32
Which nerves can be used fr motor nerve conduction velocity testing? What GA consideration?
Fibular, tibial, radial, ulnar n. Keep patient warm as decreased temperature --\> slowed MNCV.
33
What M-wave changes are indicative of demyelinating process?
* Prolonged duration of deflection from - to baseline (i.e. increased wave width!) * Biphasic --\> polyphasic potential * (Diminished amplitude) * (Extreme slowing of MNCV)
34
What nerves can be used for sensory nerve conduction velocity
Fibular, radial, ulnar. Why not tibial (like with motor conuction studies)? Because involve stimulation at a site where nerve is mixed
35
On nerve conduction velocity study graph, how does sensory potential differ from motor (M-wave)
Sensory potential often polyphasic Somatosensory evoked potential study in a normal dog (B) and a dog with a sensorimotor polyneuropathy (C), following stimulation of the fibular nerve at the distal end of the fourth metatarsus (stimulus site). Somatosensory evoked potentials were recorded from the hock, stifle, hip, and L4-L5 (cord dorsum potential [CDP]). Latency measurements for sensory conduction velocity determinations are represented by T1, T2, T3, and T4. A, Diagram of electrode placement. B, Normal canine somatosensory evoked potential study. Although the somatosensory evoked potentials appear to be of similar amplitude at each recording site, the sensitivity increases from hock to L4-L5. Note that 1000 individual potentials (N = 1000 to right of figure) were averaged to produce these tracings
36
Comment on this sensory nerve conduction velocity study
Abnormal canine somatosensory evoked potential study. All sensory nerve action potentials are severely reduced in amplitude, and sensory nerve conduction velocities are slowed. Dispersion of the potentials is difficult to evaluate because potentials are barely distinguishable from background noise. Note that compared with panel B, 4000 individual potentials (N = 4000) were averaged in an attempt to minimize random background noise from the time-locked electrical signal. These abnormalities are consistent with a severe sensory neuropathy.
37
Name two tests to assess nerve root function
* F waves (tests ventral nerve root) * H reflex (tests dorsal and ventral nerve root) Called *late responses* as have longer latency than M wave
38
HOw can you tell the difference between a motor nerve conduction velocity graph vs sensory
Motor uses higher voltage (milivolts), n = 1 Sensory uses microvolts, uses average of several tests so look for n value!
39
Describe conduction pathway that generates f wave
Supramaximal stimulation --\> antidromic (reverse) motor nerve activation --\> additional volley in orthofromic direction therefore longer latency than m wave and latency longer the more distal the stimulation site (i.e. inverse to m wave latencies) Purely motor nerve testing A, Normal canine M-waves (left) and F-waves (right) recorded following fibular nerve stimulation at the hock (32 superimposed individual tracings). B, Normal canine M-waves (left) and F-waves (right) recorded following fibular nerve stimulation at the hip (32 superimposed individual tracings). Note the longer latency of the M-waves (left) and the reduced latency of the F-waves (right) compared with those in panel A.
40
Describe h reflex conduction pathway
Electrically elicited stretch reflex (i.e. like patella reflex) Afferent via sensory nerve efferent via motor nerve Normal canine H-waves recorded following fibular nerve stimulation at the hip using a low stimulus intensity (0.6 mA). Note that M-waves are not present (left). D, The same stimulation and recording sites as used in panel C, after a slight increase in stimulus intensity (to 1.0 mA). M-waves now are present (left).
41
What is advantage of late waves (i.e. f waves and h reflex) vs nerve conduction velocity studies?
Late waves assess function of most proximal segments of nerve.
42
What two electrophysiologic test assess NMJ?
* Repetitive Nerve Stimulation * Single Fibre Electromyography
43
What repetitive nerve stimulationo result is consitent with a junctionopathy?
Decremental response \>10% Repetitive nerve stimulation. at the hock. Note in the data table that M-wave amplitude (Peak amp mV), area under the M-wave (Area mVms), and percentage amplitude decrement (Amp decr %) remain constant with consecutive stimuli. B, Decremental response in a cat following 3-Hz fibular nerve stimulation at the hock. Note that amplitude and area under the M-wave decrease with consecutive stimuli, which is measured as a percentage amplitude decrement of 17% to 44%. The cat had muscular dystrophy. C, Facilitation in a dog following 30-Hz fibular nerve stimulation at the hock. Note that both area and amplitude of the M-wave are increased (i.e., the M-wave becomes taller and is more broad based). The increase in amplitude is represented by a negative Amp decr %. A cause could not be determined in this dog presenting with exercise-induced weakness that occurred in warm weather. D, *Pseudofacilitation* in a normal dog following 30-Hz fibular nerve stimulation at the hock. Note the increase in amplitude with no change in the area under the curve (i.e., the M-wave becomes taller and more narrow based). As in panel C, the increase in amplitude is represented by a negative Amp decr %.
44
Which test evaluates end-plate status?
Single fibre electromyography e.g. for aquired MG
45
Where is muscle biopsy typically obtained from?
Cranial tibial muscle
46
What tests should muscle biopsies be submitted for?
* Electron microscopy * Histo
47
Which nerve is commonly biopsied for generalised neuromuscular disease
common fibular nerve (or tibial or ulnar)
48
What complication shoul you warn re for nerve biopsy
Proprioceptive deficits with knuckling

3: Neurosurgery (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions