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ADAMS > Diseases of the Peripheral Nerves > Flashcards

Diseases of the Peripheral Nerves Flashcards

1
Q

3 distinct histopathologic changes in a peripheral nerve

A

segmental demyelination
wallerian degeneration
axonal degeneration

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2
Q

Focal degeneration of the myelin sheath with sparing of the axon

A

segmental demyelination

disappearance of the sheath over segments of variable length

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3
Q

“dying forward”

process in which the nerve degenerates from the point of axonal damage outward

A

Wallerian Degeneration

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4
Q

“dying back”
the axon is affected progressively from the distal-most site to the proximal
with dissolution of myelin that occurs roughly parallel with axonal change

A

Axonal Degeneration

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5
Q

which of the three cause muscle atrophy?
segmental demyelination
wallerian degeneration
axonal degeneration

A

wallerian and axonal degeneration

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6
Q

exception to the length-dependent pattern typical of axonal degeneration

A

porphyria - presents more of proximal weakness

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7
Q

Maximum degree of denervation atrophy after an acute injury to the axons occurs in _____ days and reduces _____% of muscle volume

A

90 to 120 days

75 to 80%

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8
Q

in GBS,

Other common antecedent events or associated illness include viral exanthems in children, bacterial infection

A 
CMV
EBV
Campylobacter 
Mycoplasma pneumoniae
Lyme diseases
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9
Q

define albuminocytologic dissociation

A

increase in protein without cells

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10
Q

Earliest change seen by Hafer-Macko and colleagues in the pathogenesis of GBS

A

deposition of complement on the inner layer of myelin

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11
Q

antibodies found in GBS patients with ophthalmoplegia

A

anti-GQ1b

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12
Q

antibodies found in GBS pts with predominantly motor presentation and to axonal damage

A

anti-GM1

high titers being associated with cases that follow Campylobacter infections

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13
Q

antibodies associated with pharyngeal-brachial-cervical variant of GBS

A

GD1a or GT1b

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14
Q

this neuropathy causes difficulty in weaning a patient from the ventilator even as the underlying critical illness comes under control

A

Critical illness Polyneuropathy

predominantly of motor type
sensory symptoms are mild
cranial nerves are spared
few or no dysautonomic symptoms

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15
Q

EMG/NCS and CSF finding in Critical Illness Polyneuropathy

A

in CIP: EMG NCS - primary axonal process with early denervation, normal CSF

vs demeylinative form of GBS

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16
Q

True or False

Differentiating Critical illness polyneuropathy from critical illness myopathy and from the axonal form of GBS is easy.

A

FALSE

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17
Q

Rapidly evolving sensory ataxia, areflexia, numbness and pain beginning in the face and spreading to involve the entire body
symptoms begain within 4 to 12 days following institution of penicillin therapy for a febrile illness
no weakness or muscle atrophy
NCV: absent or slowed sensory conduction, no abnormalities of motor nerve conduction and signs of denervation

A

Acute Sensory Neuronopathy

Acute Sensory Ganglionopathy

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18
Q

A polyneuropathy appearing 5-8 weeks later
acute or subacute limb weakness with paresthesias and distal loss of vibratory and position sense
weakness involves all extremities at the same time or may descend from arms to legs
may impair respiration
High protein in CSF 50-200mg/dL
Deaths that occur after the pharyngeal infection has subsided - cardiomyopathy; severe polyneuropathy then respiratory paralysis

segemental demyelination without inflammatory reaction of spina roots, ganglia, adjacent soinal nerves
anterior hornsm axons and muscle fibers remain normal.

A

Diphtheric Polyneuropathy

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19
Q

rapidly advancing, relapsing naturem acute onset more or less symmetrical and mainly motor polyneuropathy often with abdominal pain, psychosis (delirium or confusion) and convulsions

symptoms begin in feet and legs
weakness predominates in the proximal muscles of the limbs and limb girdle muscles, loss of knee jerks with preservation of ankle reflexes

A

porphyric polyneuropathy

autosomal dominant
not associated with cutaneoussensitivity to light

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20
Q

metabolic defect in Porphyric Polyneuropathy

A

metabolic defect is in the liver
marked by increased production and urinary excretion of porphobilinogen and of the porphyrin precursor
delta aminolevulinic acid

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21
Q

diagnosis in porphyric polyneuropathy

A

demonstration of large amounts or porphobilinogen and delta-aminolevulinic acid in urine

urine turns dark when standing as a consequence of the formation of porphobilin, oxidative product

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22
Q

Treatment in porphyric polyneuropathy

A

IV glucose and intravenous hematin 4mg/kg daily for 3 to 14 days

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23
Q

drugs implicated during recurrent attacks in porphyric polyneuropathy

A

sulfonamides, griseofulvin, estrogens, barbiturates, phenytoin,, succinimide anticonvulsant

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24
Q

Carcinoma of the _____ accounts for approximately 50% of the cases of paraneoplastic sensorimotor polyneuropathy

A

lung

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25
Q

True or False

Arsenical neuropathy is categorized as of the dying-back (axonal degeneration) type

A

True

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26
Q

Neuropathic symptoms develop slowly over a period of weeks or months
gastrointestinal symptoms may precede the polyneuropathy, associated with anemia, jaundice, brownish cutaneous pigmentation, hyperkeratosis of palms and soles, white transverse banding of the Nails (Mees lines)

A

Arsenical Polyneuropathy

27
Q

it occurs following chronic exposure to paint or fumes (smelting industries or burning batteries)
from ingestion of liquor distilled in pipes

characteristic presnetation: motor mononeuropathy in the distribution of the radial nerves (wrist and finger drop)
may have sensory loss in radial territory of hand
foot-drop, less common

A

Lead Neuropathy

Plumbism

28
Q

pathologic changes in lead neuropathy

A

axonal degeneration with secondayr myelin change and swelling and chromatolysis of anterior horn cells

lead accumulates in the nerve cells or to endothelial capillary cells causing edema

29
Q

Associated medical findings in lead neuropathy/toxicity

A 
anemia
basophilic stippling or red blood cell precursors in bone marrow
lead line along the gingival margins
colicky abdomina pain
constipation
30
Q

Treatment in Lead toxicity/neuropathy

A

penicillamine generally safe and administered orally

preferable to dimercaprol and EDTA

31
Q

antineoplastic drugs that can cause sensory polyneuropathy (5)

A

cisplatin
carboplatin
bortezomib
pacliatxel, docetaxel

32
Q

antineoplastic agent most widely used in the tretament of lymphoma and leukemia
may cause some degree of weakness preceding sesory loss
extensors of fingers
dorsiflexors of toe and feet causing foot drop

A

vincristine

33
Q

antimicrobial drug that causes symptoms of neuropathy
interferes with pyridoxine metabolism, by inhibiting the phosphorylation of pyridoxine and decreasing the tissue levels of its active form pyridoxal phosphate

A

isoniazid

34
Q

treatment for isoniazid neuropathy

A

150 to 450 mg/day of pyridoxine

35
Q

cardiac drug that may cause motor-sensory neuropathy

A

amiodarone

36
Q

Clinical Syndromes of Diabetic Neuropathy

A

(1) the most common as noted is a distal, symmetrical, primarily sensory polyneuropathy affecting feet and legs in a chronic, slowly progressive manner; the others are
(2) acute ophthalmoplegia that affects the third, and less often the sixth, cranial nerve on one side;
(3) acute mononeuropathy of limbs or trunk including a painful thoracolumbar radiculopathy;
(4) an acute or subacute painful, asymmetrical, predominantly motor, multiple neuropathy affecting the upper lumbar roots and the proximal leg muscles (“diabetic amyotrophy”);
(5) a more symmetrical, proximal motor weakness and wasting, usually without pain and with variable sensory loss, pursuing a subacute or chronic course; and
(6) an autonomic neuropathy involving bowel, bladder, sweating and circulatory reflexes

37
Q

in diabetic patients, isolated painful third nerve palsy with sparing of pupillary function

A

Diabetic Ophthalmoplegia

38
Q

peripheral nerves most commonly affected in diabetic Mononeuropathy (3, FSP)

A

Femoral
Sciatic
Peroneal

recovery is the rule :)

39
Q

in GBS

most frequent identifiable antecedent infection, but it accounts for only a relatively limited proportion of cases

A

Campylobacter jejuni

40
Q

in GBS other common antecedent events or associated illness

A

cytomegalovirus [CMV],
Epstein-Barr virus [EBV],
HIV), and less often, bacterial infections other than Campylobacter (Mycoplasma pneumoniae, Lyme disease)

41
Q

GBS

earliest immunologic event

A

complement deposition on myelin surface

42
Q

earliest symptoms in GBs

A

paresthesias and numbness in toes and fingers

43
Q

major clinical manifestation in GBS

A

weakness that evolves more or less symmetrically over a period of several days or a week or two

proximal and distal muscles are involved usually the lower extremities before the upper
Weakness progresses in approximately 5 percent of patients to total motor paralysis with respiratory failure within a few days. In severe cases, the ocular motor nerves are paralyzed and even the pupils may be unreactive.

44
Q

True or False
In GBS.

More than half of the patients complain of pain and an aching discomfort in the muscles, mainly those of the hips, thighs, and back. These symptoms precede weakness and may be mistaken for lumbar disc disease, back strain, and orthopedic diseases.

A

true

45
Q

in GBS

Urinary retention occurs in approximately ___ percent of patients soon after the onset of weakness, but catheterization is seldom required for more than a few days.

A

15%

46
Q

Unlike the common form of demyelinating GBS, muscle atrophy became apparent relatively early in the _______ form (within weeks). The defining feature was the presence of numerous electrically inexcitable motor nerves and signs of extensive denervation.

A

axonal form

47
Q

True or False

Most experience with the generalized axonal form of GBS indicates that recovery is good.

A

False

prolonged and incomplete.

48
Q

GBS variant

Fisher syndrome

A

ataxia
areflexia
ophthalmoplegia

49
Q

most important laboratory aids in GBS

A

electrodiagnostic exam and CSF examination

50
Q

CSF in GBS

The protein content is usually normal during the first few days of illness, but then it rises, reaching a peak in ______ weeks and persisting at a variably elevated level for many weeks

A

4 to 6 weeks

51
Q

frequent early diagnostic findings in GBS

A

reduction in the amplitude of muscle action potentials, slowed conduction velocity, and conduction block in motor nerves, singly or in combination
Prolonged distal latencies and reduced distal amplitudes (reflecting distal conduction block) and prolonged or absent F responses (indicating involvement of proximal parts of motor nerves and roots) all reflecting focal areas of demyelination

The H reflex is almost always much delayed

52
Q

MRI of spinal cord in GBS

A

gadolinium enhancement of cauda equina

53
Q

A rough estimate of breathing capacity may be obtained by having the patient count quickly on one deep breath. The ability to reach ______ generally corresponds to a vital capacity of greater than _____ L

A

20

1.5 L

54
Q

oneiric hallucinations

A

bizarre waking dreams or hallucinations after weeks of immobilization

55
Q

when to institute treatment in GBS

A

If the patient becomes unable to walk, shows a reduction in vital capacity, or signs of oropharyngeal weakness, plasma exchange or IVIg is instituted promptly

56
Q

results of large randomized trials regarding plasma exchange in GBS

A

In patients who are treated within 2 weeks of onset, there is an approximate halving of the period of hospitalization, of the duration of mechanical ventilation, and of the time required to achieve independent ambulation.

However, in the largest trial, if the first plasma exchange was delayed for 2 weeks or longer after the onset of the disease, the procedure was of little value. Nonetheless, if a patient continues to progress in the third or fourth week of illness, it is probably still appropriate to institute the exchanges

57
Q

most important predictors to responsiveness of GBS to plasma exchange
same with overall prognosis

A

patient’s age (responders are younger) and the preservation of motor compound muscle action potential amplitudes prior to instituting treatment

58
Q

regimen for plasma exchange in GBS

A

advised regimen of plasma exchange removes a total of

200 to 250 mL/kg of plasma in 4 to 6 treatments on alternate days

59
Q

IVIg regimen in GBS

A

0.4 g/kg per day for 5 days

60
Q

infrequent complications of IVIg

A

renal failure
proteinuria
aseptic meningitis

61
Q

mortality rate of GBS

A

3-5%

62
Q

in GBS

The speed of recovery varies, but its pace is steady. Often, it occurs within a few weeks or months; however, if axons have been damaged, their regeneration may require ___ to ____months or longer

A

6 to 18 months

63
Q

recurrence rate of acute polyneuropathy

A

5 to10 %

ADAMS (29 decks)

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