pediatric electrodiagnostic evaluation

Question 1

timing of myelination

Answer 1

begins between 10th and 15th week of gestation

Completed 5 years

8-10 years of age, asked on same diameter as adults

Question 2

nerve conduction velocity premie versus term infant

Answer 2

21 meters per second for premature

28 m/s term

Normal adult is considered 60 m/s

Normal nerve conduction velocity by 3-5 years

Question 3

sensory nerve conduction velocity adult versus child

Answer 3

approximately 50% of adult values by 4 years of age

Question 4

his H-reflex easier to obtain preterm internal minutes versus open

Answer 4

can be obtained from most nerves premature in term infants

After age 1 generally only the tibial and median nerves

Question 5

describe f waves childhood to adult

Answer 5

mean ulnar nerve is 14.6 ms from infancy to 2-1/2 years, gradually increasing until 20 years of age

the lag time between infancy in 2-1/2 years is due to factors of increasing nerve conduction speed of the arm growing

Question 6

effective repetitive stimulation on compound muscle action potential

Answer 6

infant show greater decrement indicating that they have less neuromuscular junction reserved

Question 7

3 factors that determine conduction velocity

Answer 7

1. myelination
2. diameter of fiber
3. internodal difference

Question 8

In general, what is the motor conduction velocity of infants versus adults?

Answer 8

One Half

Question 9

CMAP (Compound muscle action potential) amplitudes adults compared to infants?

When do they normalize

Answer 9

In general, less than 1/2 infant v adult

normalizes by age 10

Question 10

How does sensory nerve maturation compare with motor?

Answer 10

About the same

Sometimes double peak due to different maturation rates of different kinds of axons

Question 11

F-waves in newborns and young infants

Answer 11

20 msec or less upper

30 msec or less lower

Can be measured from all limbs

Question 12

Speak to the H-Reflex peds v adult

Answer 12

Evident in upper and lower in most infants and then the upper is lost during childhood

Question 13

Characterize Motor Unit Action Potentials in infants

Answer 13

Low microvolts (2,000 max, usually less than 1,000 age 0-3)

Very short duration

Recruitment is chaotic

Question 14

Name 5 general categories in the differential diagnosis for the diagnosis of infantile hypotonia

Answer 14

1. Cerebral Hypotonia
2. Spinal cord
3. Polyneuropathies
4. Neuromuscular junction
5. Myopathies

Question 15

Causes of acute onset hypotonia in infant

Answer 15

1. AIDP (acute inflammatory demyelinating polyneuropathy)
2. Infantile polymyositis
3. Infantile form of myasthenia
4. Toxin
5. Acute onset myelopathy

Question 16

Electrodiagnostic findings in CMT

Answer 16

CMT1 (early onset, 50% less MCV, less temporal dispersion than AIDP)

CMT2 (axonal form, CMAP and SNAP amplitudes reduced, NCV mildly reduced, Needle EMG shows denervation/renervation)

Question 17

Characteristics of AIDP (Acute Inflammatory Demyelinating Polyneuropathy - Guillian Barre Syndrome)

Answer 17

Acute rapid ascending paralysis starting with lowers typically.

Classic findings:

1. Absent or prolonged F-wayves
2. Slowing of proximal and distal conduction velocity
3. Reduced CMAP amplitude with block and temporal dispersion

Question 18

Are fibs and psw seen at full-term

Question 19

What is the best diagnosis to look for and prove with Electrodiagnostics

Answer 19

Spinal Muscle Atrophy, SMA

Question 20

Electrodiagnostics in SMA

Answer 20

Motor: DECREASED AMPLITUDE

Sensory: Normal

Spontaneous: Fibs, spontaneous rhythmic motor unit firing

Motor units: Decreased number

Question 21

Electrodiagnostics in HMSN III (Hereditary Motor Sensory Atrophy). Dejerine-Sotas

Answer 21

Motor: Very prolonged

Sensory: Prolonged or absent

Spontaneous activity: None

Question 22

Inflammatory Polyneuropathy

Answer 22

Motor: Decreased amplitude, velocity and block

Question 23

Botulism

Answer 23

Motor: Decreased amplitude, normal velocity, incremental with repetitive nerve stim of greater than 20 Hz

Question 24

Common Polyneuropathy

Answer 24

CMT

Question 25

Findings in CMT

Answer 25

Distal latencies severely prolonged with high temporal dispersion

EMG, defibs and PSW

Question 26

Findings in Myotonic Dystrophy

Answer 26

Dive bombers, profuse and positive sharp waves

Question 27

Critical illness polyneuropathy (CIP)

Answer 27

is a type of intensive care unit acquired weakness (ICU-AW). It is described as a distal axonal sensory-motor polyneuropathy affecting limb and respiratory muscles, and rarely the facial muscles. Limbs are usually affected symmetrically, distal more than proximal

Question 28

Electrodiagnostic findings in Critial Illness Polyneuropathy

Answer 28

reduced amplitude (CMAP) and sensory nerve action potential (SNAP),

normal to minimally reduced nerve conduction velocity.

No decremental response will be seen on repetitive nerve stimulation.

Electromyography may show fibrillation potentials and positive sharp waves.

Motor unit potential, if recordable, may initially be normal, but would later be polyphasic and large in amplitude

Question 29

Kid motor conduction velocities

20s

30s

40s 50s

Answer 29

20s = birth to 3 mo.

30s = 3 - 6 mo.

40s = 6 mo. to 2 yrs

50s = 2 and above

Question 30

F-waves apparent in small kids

Question 31

Dive bomber

Answer 31

Myotonic muscular dystophy

Question 32

FDA dose Botox kids

Question 33

Hip internal rotation

Answer 33

Question 34

Hip external

Answer 34

see pic

Question 35

Thigh foot

Answer 35

Question 36

Foot progression angle

Answer 36

See pic