Diseases of the Peripheral Nerves

Question 1

3 distinct histopathologic changes in a peripheral nerve

Answer 1

segmental demyelination
wallerian degeneration
axonal degeneration

Question 2

Focal degeneration of the myelin sheath with sparing of the axon

Answer 2

segmental demyelination

disappearance of the sheath over segments of variable length

Question 3

“dying forward”

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

Answer 3

Wallerian Degeneration

Question 4

“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

Answer 4

Axonal Degeneration

Question 5

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

Answer 5

wallerian and axonal degeneration

Question 6

exception to the length-dependent pattern typical of axonal degeneration

Answer 6

porphyria - presents more of proximal weakness

Question 7

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

Answer 7

90 to 120 days

75 to 80%

Question 8

in GBS,

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

Answer 8

CMV
EBV
Campylobacter 
Mycoplasma pneumoniae
Lyme diseases

Question 9

define albuminocytologic dissociation

Answer 9

increase in protein without cells

Question 10

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

Answer 10

deposition of complement on the inner layer of myelin

Question 11

antibodies found in GBS patients with ophthalmoplegia

Answer 11

anti-GQ1b

Question 12

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

Answer 12

anti-GM1

high titers being associated with cases that follow Campylobacter infections

Question 13

antibodies associated with pharyngeal-brachial-cervical variant of GBS

Answer 13

GD1a or GT1b

Question 14

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

Answer 14

Critical illness Polyneuropathy

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

Question 15

EMG/NCS and CSF finding in Critical Illness Polyneuropathy

Answer 15

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

vs demeylinative form of GBS

Question 16

True or False

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

Answer 16

FALSE

Question 17

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

Answer 17

Acute Sensory Neuronopathy

Acute Sensory Ganglionopathy

Question 18

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.

Answer 18

Diphtheric Polyneuropathy

Question 19

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

Answer 19

porphyric polyneuropathy

autosomal dominant
not associated with cutaneoussensitivity to light

Question 20

metabolic defect in Porphyric Polyneuropathy

Answer 20

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

Question 21

diagnosis in porphyric polyneuropathy

Answer 21

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

Question 22

Treatment in porphyric polyneuropathy

Answer 22

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

Question 23

drugs implicated during recurrent attacks in porphyric polyneuropathy

Answer 23

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

Question 24

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

Answer 24

lung

Question 25

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

Answer 25

True

Question 26

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)

Answer 26

Arsenical Polyneuropathy

Question 27

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

Answer 27

Lead Neuropathy | Plumbism

Question 28

pathologic changes in lead neuropathy

Answer 28

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

Question 29

Associated medical findings in lead neuropathy/toxicity

Answer 29

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

Question 30

Treatment in Lead toxicity/neuropathy

Answer 30

penicillamine generally safe and administered orally | preferable to dimercaprol and EDTA

Question 31

antineoplastic drugs that can cause sensory polyneuropathy (5)

Answer 31

cisplatin carboplatin bortezomib pacliatxel, docetaxel

Question 32

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

Answer 32

vincristine

Question 33

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

Answer 33

isoniazid

Question 34

treatment for isoniazid neuropathy

Answer 34

150 to 450 mg/day of pyridoxine

Question 35

cardiac drug that may cause motor-sensory neuropathy

Answer 35

amiodarone

Question 36

Clinical Syndromes of Diabetic Neuropathy

Answer 36

(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

Question 37

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

Answer 37

Diabetic Ophthalmoplegia

Question 38

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

Answer 38

Femoral Sciatic Peroneal recovery is the rule :)

Question 39

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

Answer 39

Campylobacter jejuni

Question 40

in GBS other common antecedent events or associated illness

Answer 40

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

Question 41

GBS | earliest immunologic event

Answer 41

complement deposition on myelin surface

Question 42

earliest symptoms in GBs

Answer 42

paresthesias and numbness in toes and fingers

Question 43

major clinical manifestation in GBS

Answer 43

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.

Question 44

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.

Answer 44

true

Question 45

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.

Answer 45

15%

Question 46

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.

Answer 46

axonal form

Question 47

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

Answer 47

False prolonged and incomplete.

Question 48

GBS variant Fisher syndrome

Answer 48

ataxia areflexia ophthalmoplegia

Question 49

most important laboratory aids in GBS

Answer 49

electrodiagnostic exam and CSF examination

Question 50

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

Answer 50

4 to 6 weeks

Question 51

frequent early diagnostic findings in GBS

Answer 51

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

Question 52

MRI of spinal cord in GBS

Answer 52

gadolinium enhancement of cauda equina

Question 53

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

Answer 53

20 | 1.5 L

Question 54

oneiric hallucinations

Answer 54

bizarre waking dreams or hallucinations after weeks of immobilization

Question 55

when to institute treatment in GBS

Answer 55

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

Question 56

results of large randomized trials regarding plasma exchange in GBS

Answer 56

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

Question 57

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

Answer 57

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

Question 58

regimen for plasma exchange in GBS

Answer 58

advised regimen of plasma exchange removes a total of | 200 to 250 mL/kg of plasma in 4 to 6 treatments on alternate days

Question 59

IVIg regimen in GBS

Answer 59

0.4 g/kg per day for 5 days

Question 60

infrequent complications of IVIg

Answer 60

renal failure proteinuria aseptic meningitis

Question 61

mortality rate of GBS

Answer 61

3-5%

Question 62

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

Answer 62

6 to 18 months

Question 63

recurrence rate of acute polyneuropathy

Answer 63

5 to10 %