20: Peripheral Neurology - Bennett

Question 1

three forms of neuropathies

Answer 1

segmental demyelination
axonal degeneration
wallerian degeneration

Question 2

seletive loss of individual myelin internodes with preservation of axon

Answer 2

segmental demyelinationn

remaining schwann cells can proliferate and remyelinate, but reconstituted sheaths are thinner with shorter internodal length

Question 3

proximally the axon will degenerate back to node of ranvier with possible chromatolysis of cell body

distally the axon and its myelin sheath disintergrate and are digested by the schwann cell

Answer 3

wallerian degeneration

occurs after transection of axon

Question 4

dysfunction of neuron renders it unable to maintain its axon

Answer 4

axonal dgeneration

begins at peripheral terminal of the axon and proceeds toward cell body with chromatolysis of cell body

if dysfunction can be halted, regeneration and recovery of n. function can occur

Question 5

persistent impairment of motor function over wks, or months signifies segmental demyelination, axonal interruption, or destruction of motor neurons

Answer 5

motor paralysis

feature of most polyneuropathies is the distribution (muscles of feet and legs affected first and most severely)

Question 6

state in which the affected muscles ripple and quiver and occasionally cramp

Answer 6

neuromyotonia

use of muscles increases this activity and there is a reduction in efficiency. which the pt experiences as stiffness and heaviness

Question 7

where does sensory loss tend to affect?

Answer 7

distal segments of limbs, preferably in the legs

pattern 1: loss of touch, vibratory, 2pt discrimination, joint position sense LARGE fibers

pattern 2: loss of paina nd temp with lesser impairment of pressure, vibratory and position sense SMALL fibers

Question 8

tingling, or burning pain induced by tactile stimuli

Answer 8

dysesthesia

ex: touch foot lightly and the pt says it is painful

stimuli will also radiate and persist after the stimulus is withdrawn

Question 9

propioceptive deafferentation with retention of a reasonable degree of motor function

Answer 9

basis of ataxia of gait and limb movement

Question 10

two most frequent manifestations of autonomic disorders

Answer 10

anhydrosis

orthostatic hypertension

occur in small fiber polyneuropahties

other manifestations: un-reactive pupils, lack of tears and saliva, impotence, weak bladder and bowel sphincters

Question 11

a neuropathic syndrome is determined by:

Answer 11

mode of evolution

clinical presentation

Question 12

describe acute axonal polyreuropathy

Answer 12

• evolves over several days
• porphyric neuropaty and massive intoxication
• renal and liver failure
• 14-21 d polyneuropahty, progresses for 2-3 wks then a plateau is reached
• recovery requires months
• associated with alcoholism
• pure sensory, no m. involvement

Question 13

describe subacute axonal polyneuropathy

Answer 13

• evolves in wks
• usually toxic or metabolic
• tend to be chronic in evolution
• management involves removing the offending agent or treating the systemic disorder
• sensory v. motor deficit dependent upon toxic agent
• seen in Parkinson’s pt supplemented with cobalamin / B6

Question 14

describe chronic axonal polyneuropathy

Answer 14

• progression from 6 mo to 60 yr
• absence of positive symptoms mostly a motor deficit, and absence of systemic disorder
• genetically determined neuropathy
• relapsing-remitting motor and sensory deficit
• charact - similar to CIDP
• autosomal dominant

Question 15

acute demyelinating polyneuropathy =

Answer 15

synonymous with guillain-barre syndrome

• virus usually precedes the neuropathy, in the majority of cases
• charact
• acute rise of total prtn in CSF in 1st wk

Question 16

charact =

Answer 16

areflexic motor parlayss iwth mild sensory disturbance, prognosis is good

Question 17

describe subacute demyelinating polyneuropathy

Answer 17

• acquired neuropathies
• tend to be relapsing and remitting neuropathy
• • diptheria toxin
• clinical features similar to GBS but differs in tempo, course and absence of discernable eventa

Question 18

describe chronic demyelinating polyneuropathy

Answer 18

• wide variety of disorders
• present as mixed axonal-demyelinating finding
• motor and snesory manifestation
• difficult to determine the primary event (axonal degenration ro demyelination)

Question 19

charcot marie toot =

Answer 19

characterized by demyelinating and remylination motor and sensory defiicts

stork leg appearance

thenar and hypothenar wasting

pes cavus, hammertoes

Question 20

roussy-levy =

Answer 20

variant of freidrixh’s ataxia and CMT
static tremor with mild distal weakness and sensory loss

pes cavus, claw foot

Question 21

describe GBS

Answer 21

• acute ascending motor paralysis
• triggered by virus
• weakness is most common symptom, but leg pain, tingling and numbness are initial complaints
• reflexes absent
• respiratory failure willensue
• isntability of heart rate and blood pressure
• CSF prtn is increased without pleocytosis

Question 22

tx GBS

Answer 22

plasmapharesis

immunoglobulin

Question 23

tx neuropathies with inflammation

Answer 23

glucocorticoid
immunosuppressants
plasmapharesis

Question 24

neuropathies with disproteinemia are consistent with…

Answer 24

axonal degeneration
‘
assoc b/q polyneuropahty and multiple myeloma and macrogobulinemia

sensorimotor

does not reverse with suppression of myeloma

Question 25

describe alcohol neuropathy

Answer 25

• senosorimotor caused by axonal degeneration (pain and paresthesia)

optiic atrophy and myopathy can also be seen

Question 26

drug induced neuropathy

Answer 26

subacute course

reversible

Question 27

_____ of diabetics show evidence of peripheral neuropathy

Answer 27

2/3

occurs after long standing hyperglycemia

Question 28

most commonly recognized form of diabetic neuropathy

Answer 28

distal symmetric,

primarily sensory polyneuropathy

“stoking-glove”

Question 29

loss of lg sensory and motor fibers –>

Answer 29

diminished light touch and proprioception, the latter resuting in ataxic gait and unsteadiness, as well as loss of muscle function of the feet, and then the ahnds

Question 30

loss of small fibers –>

Answer 30

diminished pain and temperature perception

Question 31

spontaneous uncomfortable sensations

Answer 31

neuropathic paresthesias

if occur with contact = dysesthesia

Question 32

atrophic skin
loss of nails
sweating abnormalities

Answer 32

autonomic neuropathy

Question 33

structural changes from advanced neuropathy are from

Answer 33

ligamentous laxity and m. weakness

• prominence of metatarsal heads
• crowding of toes
• subluxation of tarsal and metatarsal heads

Question 34

tx mild pain at night only

Answer 34

amitriptyline
nortriptyline
imipramine

TCAs

Question 35

acnti-convulsants

Answer 35

gabapentin (neurontin)

lyrica (pregabalin)

Question 36

good for superficial pain

Answer 36

capsaicin

depletes substance P from the terminals and central connections of cfibers

Question 37

local anesthetic

Answer 37

mexiletine

Question 38

muscle relaxants

Answer 38

baclofen and metaxalone

analgesic treatment when associated with muscle cramping

Question 39

agents that increase circulation to nerve by altering viscosity and blood flow

Answer 39

trental (pentoxyifylline)
alters viscosity and blood flow

pletal (cilostazol)
alters viscosity by inhibiting platelet aggregation

Question 40

serotonin-norepinephrine re-uptake inhibitor

Answer 40

cymbalta (duloxetine)

Question 41

how does acupuncture help?

Answer 41

stimulation of these centers, release neurotransmitters

endorphins which promote analgesia circulate in blood and CSF

enkephalins which block the incoming pain signal

Question 42

describe subacute demyelinating polyneuropathy

Answer 42

• acquired neuropathy
• tend to be relapsing and remitting
• similar to GBS but differs in tempo, coures, and absence of discernable events
• may be induced by diptheria toxin