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BRAIN BATTACK > CH46: Neuromuscular Junction, Myotonias and Persistent Muscle Fiber Activity > Flashcards

CH46: Neuromuscular Junction, Myotonias and Persistent Muscle Fiber Activity Flashcards

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1
Q

Peak of age of first symptoms of Myasthenia Gravis (p. 1470)

A

20-30 for women, 50-60 for men

Of patients with thymoma, 50-60 years and males predominate

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2
Q

Describe the eye weakness of Myasthenia (p. 1470)

A

ocular palsies and ptosis are usually accompanied by weakness of eye closure
sustained upward gaze will induce or exaggerate ptosis and may uncover myasthenic ocular motor weakness

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3
Q

Twitching of the upper eyelid that appears a moment after the patient moves the eyes from a downward to primary position (p. 1470)

A

Cogan sign

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4
Q

Of the trunk muscles this muscle is most affected by Myasthenia (p. 1470)

A

Erector spinae

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5
Q

MGFA grading (p. 1471)

A 
Class
I eye symptoms only
II mild
III moderate
IV severe
V intubated except during surgery

A- predominantly limb, axial muscles or both
B- predominantly oropharyngeal, respiratory muscles

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6
Q

Mortality rate of MG (p. 1472)

A

before 30% but now less than 5%

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7
Q

How many percent of MG had generalization more than 2 years after isolated ocular manifestations (p. 1472)

A

15%

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8
Q

Some of the muscles in MG remain permanently weak such as (p. 1472)

A

anterior tibialis
triceps
portions of face

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9
Q

Pathologic finding of the thymus of MG patients (p. 1472)

A

lymphoid follicles with active germinal centers

In terms of tumors: 1. histiocytic cells 2. lymphocytic cells

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10
Q

Ultrastructural alterations in patients with MG (p. 1473)

A

reduction and simplification in the surface area of the post synaptic membrane [sparse, shallow, abnormally wide, or absent secondary synaptic clefts]

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11
Q

Neuromuscular transmission is impaired in several ways (p. 1474)

A
  1. antibodies block the binding of Ach to the AChR
  2. serum IgG from MG patients induce a degradation rate of AchR
  3. Antibodies cause a complement- mediated destruction of postsynaptic folds
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12
Q

Decrementing response in MG (p. 1474)

A

rapid reduction in the amplitude of compound muscle action potentials during a series of repetitive stimulations of a peripheral nerve at a rate of 3 per second

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13
Q

Findings in singe fiber EMG in MG (p. 1475)

A

inconstancy of the normally invariant interval between the firing of muscle fibers connected to the same motor unit

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14
Q

MOA of neostigmine (p. 1475)

A

prolong and exaggerate the effects of ACh in the synapse and thereby produce an increment in muscle power in the patient with myasthenia

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15
Q

Clinical effect of edrophonium and neostigmine (p. 1475)

A

5 min with edrophonium

60 min with neostigmine

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16
Q

Antibody findings in MG (p. 1475)

A

found 80-90% of patients with generalized myasthenia

60% of those with ocular myasthenia

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17
Q

enzyme that plays a role in supporting the normal structure of the post synaptic membrane and in the arrangement of AChR but its main function may be in developmental synaptic differentiation (p. 1475)

A

muscle specific kinase

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18
Q

MG vs botulism (p. 1476)

A

In botulism, pupils are usually large and unreactive, and the eye signs are followed in rapid succession by involvement of bulbar, trunk and limb muscles

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19
Q

Adverse effect of Mycophenolate (p. 1478)

A

Diarrhea

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20
Q

Remission rate of thymectomy (p. 1478)

A

35% provided that the procedure is done in the first year or 2 after onset of the disease
Maximal effect after 3 years

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21
Q

An impending cholinergic effect is betrayed by this finding (p. 1480)

A

constriction of pupils

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22
Q

Clinical presentation difference of Lambert- Eaton syndrome

A

muscles of the trunk, shoulder girdle, pelvic girdle and lower extremities are those that become weak and fatigable

symmetrical muscle weakness with fatigability of proximal muscles, dry mouth, sphincter disturbances, aching muscles and diminished reflexes

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23
Q

Cancer associated with Lambert- Eaton Myasthenic Syndrome (p. 1481)

A

60% small cell lung cancer but also with breast cancer, prostate, stomach, rectum and lymphomas

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24
Q

Pathology of LEMS (p. 1482)

A

defect in the release of ACh quanta from the presynaptic nerve terminals

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25
Q

Treatment for LEMS (p. 1482)

A

3,4- diaminopyridine

At times, prednisone and Azathioprine

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26
Q

Localization of congenital myasthenic syndrome (p. 1483)

A

3/4 of the case, presynaptic

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27
Q

Clinical presentation of congenital myasthenic syndrome (p. 1483)

A

Increase in ptosis, and in bulbar and respiratory weakness when crying

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28
Q

congenital myasthenia caused by a recessive mutation in this gene that causes simplified structure of the synapse but no alteration in acetylcholine receptor (p. 1484)

A

DOK 7

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29
Q

Anthrogryposis, pterygia and respiratory distress (p. 1484)

A

Escobar syndrome

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30
Q

Myotonia, muscle hypertrophy, nonprogressive course, dominant inheritance (p. 1485)

A

Thomsen Disease

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31
Q

Channel affected by Thomsen Disease (p. 1485)

A

Voltage-gated Chloride channel gene (CLCN1)

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32
Q

Thomsen vs cramp (p. 1485)

A

The myotonic spasm is painless but after prolonged activity

33
Q

Congenital myotonia presentation in children (p. 1487)

A

infant’s eyes are noted to open slowly after it has been crying or sneezing and its legs are consciously stiff as the child tries to take its. first steps

34
Q

patient unable to release a handshake, must slowly open the fingers one at a time (p. 1487)

A

grip myotonia

35
Q

myoedema vs myotonia (p. 1487)

A

unlike the lump or ridge produced in hypothyroid or cachectic muscle, the myotonic contraction involves an entire fasciculus or an entire muscle

36
Q

idiomuscular irritability vs myotonia (p. 1487)

A

unlike idiomuscular irritability, it persists for several seconds

37
Q

biopsy finding in Thomsen disease (p. 1487)

A

enlargement of muscle fibers, this change occurs only in hypertrophied muscles

38
Q

Mild form of Thomsen diseae (p. 1487)

A

Myotonia levior

39
Q

Treatment for Thomsen disease (p. 1487)

A

Procainamide and mexiletine

Phenytoin in soem cases

40
Q

Autosomal recessive congenital myotonia
Chloride ion channel of the muscle fiber membrane
will manifest at 10-14 years old
Transient weakness follows an initial muscle contraction
In contrast to Thomsen, CK may be elevated (p. 1488)

A

Becker Disease

41
Q

sodium channel diseases (p. 1488)

A

Hyperkalemic periodic paralysis

paramyotonia congenita

42
Q

Unit defective in sodium channel gene of sodium channel disease (p. 1488)

A

Alpha

43
Q

Weakness appearing after a period of rest that follows exercise (p. 1488)

A

Hyperkalemic Periodic Paralysis

44
Q

Weakness developing during exercise and worsening as the exercise continues (p. 1489)

A

Paramyotoniua congenita (Eulenburg disease)

45
Q

EMG findings in paramyotonia congenita (p. 1489)

A

myotonic discharges in all muscles even at normal temperatures

46
Q

Treatment for Sodium channel diseases (p. 1489)

A 
Acetazolamide
Dichlorphenamide
Hydrochlorothiazide
Mexilitine
Albuterol, salbutamol
Procainamide
47
Q

In sodium channel diseases, the normal action potential in all neural and muscular tissue, membrane depolarization is terminated by 2 events (p. 1490)

A
  1. depolarization induced inactivation of the sodium channel

2. subsequent action of the outward potassium current

48
Q

Calcium channel diseases (p. 1491)

A

Hypokalemic periodic paralysis

49
Q

Distribution of paralysis in hypokalemic periodic paralysis (p. 1491)

A

limbs than trunk muscles;

proximal than distal

50
Q

EMG findings of hypokalemic periodic paralysis (p. 1491)

A

associated with a decrease in the amplitude, eventual loss of muscle action potentials and failure of excitation by supramaximal stimulation of peripheral nerve or by strong voluntary effort

51
Q

Pathologic finding of hypokalemic periodic paralysis (p. 1492)

A

vacuolization of the sarcoplasm

52
Q

Treatment for hypokalemic periodic paralysis (p. 1492)

A

Low sodium diet
Avoidance of large meals
Acetazolamide
Dichlorphenamide

53
Q

Clinical manifestation of malignant hyperthermia (p. 1493)

A

jaw muscles unexpectedly become tense rather than relaxed and soon rigidity extends to all of the muscles

54
Q

Only valid diagnostic testing in malignant hyperthermia (p. 1493)

A

in vitro exposure of a muscle biopsy specimen to halothane and to caffeine and detection of muscle contracture with both agents

55
Q

Treatment for malignant hyperthermia (p. 1493)

A

dantrolene

56
Q

Potassium channel diseases (p. 1493)

A

Andersen- Tawil Disease

Morvan Syndrome

57
Q

Triad of Andersen-Tawil Disease (p. 1493)

A 
periodic potassium sensitive weakness
ventricular dysrhymti with long QT syndrome
dysmorphic features (micrognathia, short stature, scaphocephaly, hypertelorism, broad nose, low-set ears, short index fingers)
58
Q

gene affected by Andersen- Tawil Diseases (p. 1493)

A

dominant- negative mutation in KCNJ2

59
Q

abnormality in the voltage-gated potassium channel
result of paraneoplastic reaction tho thymoma
continuous muscle fiber activity or neuromyotonnia (p. 1493)

A

Morvan syndrome (Choree Fibrillaire)

60
Q

Contracted muscle (unlike in cramp, continuous muscular activity syndrome, myotonia and other involuntary spasms) no longer use energy for which reason they are almost silent electrically in EMG (p. 1495)

A

physiologic contracture

61
Q

muscle contract and relax slowly
myoedema
basis is slowness in the reaccumulation of calcium ions in the ER and in the disengagement of actin and myosin filaments (p. 1495)

A

Pseudomyotonia

62
Q

EMG of tetanus (p. 1495)

A

expected interference pattern of muscle action potentials

63
Q

Clinical manifestation of black widow spider bite (p. 1495)

A

cramps and spasms and then a painful rigidity of abdominal, trunk and leg muscles followed by weakness

64
Q

localization of black widow spider venom (p. 1495)

A

presynaptic; rapidly releases quanta of ACh

65
Q

Treatment of Black Widow Spider Bite (p. 1495)

A

Calcium gluconate
Diazepine
IV magnesium sulfate

66
Q

State of abnormal rippling muscle activity maybe generalized or limited to one part of the body such as muscles of the shoulder or of the lower extremity (p. 1496)

A

myokymia

67
Q

EMG findings of myokimia (p. 1496)

A

repetitive firing of 1 motor unit firing at 5 to 60 Hz and recurring regularly at 0.2 to 10 s intervals

68
Q

Continuous muscle fiber activity
hyperexcitability of terminal parts of motor nerve fibers
from partial loss of motor innervation and compensatory collateral sprouting of surviving axons
armadillo syndrome (p. 1497)

A

Isaacs syndrome

69
Q

Treatment for Isaacs syndrome (p. 1497)

A

Phenytoin

Carbamazeine

70
Q

Persistent and intense muscle spasms
Proximal lower limbs and lumbar paraspinal muscles
robotic appearance to walking and an exaggerated lumbar lordosis
rock-like mobility (p. 1497)

A

Stiffman syndrome

71
Q

EMG of stiffman syndrome (p. 1497)

A

activated but normally configured motor units

no evidence of distal motor nerve disturbance

72
Q

central origin of Stiffman syndrome is proved by (p. 1497)

A

absence during sleep, during general anesthesia and with proximal nerve block

73
Q

About 2/3 of Stiffman syndrome, have this antibody (p. 1498)

A

anti-GAD

74
Q

Treatment for Stiffman syndrome (p. 1498)

A

Diazepam

75
Q

Rippling muscle disease
- unusual sensitivity to stretch manifested by rippling waves of muscle contraction

Which protein is problematic? (p. 1498)

A

caveolin

76
Q

Continuous muscle fiber activity, stiffness and blepharospasm with obvious dysmorphic features (dwardism, pinched face with low- set ears, blepharophimosis, high-arched palate, receding chin, diffuse metaphyseal and epiphyseal bone dysplasia with flattened vertebrae) p. 1499

A

Schwartz- Jampel syndrome

77
Q

problem in Schartz- Jampel syndrome (p. 1499)

A

Perlacan

78
Q

Electron microscopy findings in Schartz- Jampel syndrome (p. 1499)

A

dilated T system
Z-band streaming
dilatation of mitochondria

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