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Question 1

What is the pathology of MYASTHENIA GRAVIS?

Answer 1

Auto-Ab against Ach-R -> Skeletal muscle weakness that WORSENS with use (at end of day) + Sensation/Reflexes PRESERVED

Question 2

What is the age range of MG pts?

Answer 2

WOMEN - 20-30

MEN - 50-70

Question 3

What are the most common initial Sx of MG?

Answer 3

PTOSIS + DIPLOPIA + BLURRED VISION

Question 4

What constitutes a MYASTHENIC CRISIS? What is the Tx

Answer 4

DIAPHRAGMATIC + INTERCOSTAL FATIGUE -> RESPIRATORY FAILURE

Tx = Requires mechanical ventilation

Question 5

What is the most SPECIFIC diagnostic test for MG?

Answer 5

Ach-R Ab

However 20% of pts with clinical MG ares still Ab negative

Question 6

What pharmacological drug is used to diagnose MG?

Answer 6

EDROPHONIUM (tensilon test) - AchE Inhibitor -> Causes MARKED improvement of Sx
But HIGH FALSE POSITIVE RATE

Question 7

What other tests can be done to support diagnosis of MG? (other than Ach-R antibody and tensilon test)

Answer 7

1) EMG - Decremental response to repetitive stimulation of motor nerves
2) CT Thorax - THYMOMA (present in only 10-15% of MG pts, histologically abnormal in 75% pts

Question 8

What are 3 classes of medications that can EXACERBATE MG symptoms?

Answer 8

1) ANTIBIOTICS - AMIOGLYCOSIDES + TETRACYCLINES
2) BETA BLOCKER
3) ANTI-ARRHYTHMIC - 1A (DISOPYRAMIDE, PROCAINAMIDE), 1B (LIDOCAINE)

Question 9

What is the mainstay Tx for MG in reducing symptoms?

Answer 9

PYRIDOSTIGMINE - ACHE INHIBITOR

Question 10

What surgical treatment is available to MG pts? What is an absolute indication for this treatmnet?

Answer 10

THYMECTOMY - symptomatic benefit + complete remission EVEN if pt does not have thymoma

Absolute indication = THYMOMA (even if it’s benign)

Question 11

If pt responds poorly to AchE inhibitors, what’s the 2nd line pharmacological drug? If this 2nd line doesn’t work, what are the two 3rd line agents?

Answer 11

2nd line = CORTICOSTEROIDS

3rd line = AZATHIOPRINE, CYCLOSPORINE

Question 12

If ALL medical therapy does not work on MG pts OR if pt is at respiratory failure MG crisis, then what is the last resort?

Answer 12

IVIG -> PLASMAPHARESIS (removes auto-Ab to post-synaptic Ach-R)

Question 13

Which vital sign should serially be monitored in MG pts?

Answer 13

FVC - FVC of 15 = indication for intubation (LOW THRESHOLD for pts in myasthenic crisis)

Question 14

What are the three main clinical symptom differences between MG and LAMBERT EATON?

Answer 14

MG: Worsens with muscle use + eye involvement (almost always initial)

LE: Better with muscle repetitive use + SPARES eyes + ABSENT DEEP TENDON REFLEXES

Question 15

1yo boy who has thigh/hip/pelvic girdle weakness and has calf pseudohypertrophy. + Gower maneuver (uses hands to get up) + Waddling gait. Eventually dies by the age of 30 due to respiratory failure and dilated cardiomyopathy. What is the inheritance pattern? What is the genetic basis?

Answer 15

DUCHENNE MUSCULAR DYSTROPHY = frameshift/non-sense = DELETION

X-linked Recessive - More commonly seen in boys

Question 16

What is the first line Tx for DUCHENNE MUSCULAR DYSTROPHY?

Answer 16

PREDNISONE - Increase in strength, muscle fn, pulm fn

Question 17

What is the milder form of X-linked muscle dystrophy that has a later onset in adolescence or early adulthood? What is the inheritance pattern and genetic basis?

Answer 17

BECKER

X-linked recessive: Non-frameshift mutation -> Partially functional dystrophin

Question 18

Hereditary cause of muscle weakness: Maternal inheritance + Ragged red muscle fibers = ?

Answer 18

MITOCHONDRIAL DISORDER

Question 19

Muscle cramping after exercise due to glycogen phosphorylase deficiency. What is the inheritance pattern?

Answer 19

MC ARRDLE - AUTOSOMAL RECESSIVE

Question 20

What are similar clinical sx of POLIOMYELITIS and GBS?

Answer 20

POLIO - Infection of anterior horn cells + motor neurons of spinal cord/brainstem (LMN)

GBS - Demyelination of motor nerves (LMN)

SAME: Absent DTR, Nl sensation, flaccid atrophic muscles, legs most commonly involved first. Respiratory and cardiac involvement possible.
DIFFERENT: GBS generally symmetric (bilateral). Polio = asymmetric. GBS = ascending pattern of weakness

Question 21

Ddx of ABSENT DTR:

Answer 21

GBS, POLIOMYELITIS, LAMBERT-EATON SYNDROME, CAUDA EQUINA SYNDROME, tick borne paralysis

Question 22

What is the main distinguishing feature between CAUDA EQUINA and CONUS MEDULLARIS?

Answer 22

CAUDA EQUINA (Nerve root problem) = LMN signs (HYPO/AREFLEXIA)

CONUS MEDULLARIS (Spine cord) = UMN + LMN (HYPER-REFLEXIA)

Question 23

What are some other distinguishing features between CAUDA EQUINA SYNDROME and CONUS MEDULLARIS SYNDROME?

Answer 23

CES: Saddle anesthesia, LATE ONSET bladder dysfunction, ASYMMETRIC motor weakness, HYPOreflexia

CMS: Perianal anesthesia, EARLY ONSET bladder dysfn, SYMMETRIC motor weakness, HYPERreflexia

Question 24

LOSS OF MOTOR/SENSORY + LOSS OF RECTAL TONE + URINARY RETENTION = Emergent __?

Answer 24

SPINAL CORD COMPRESSION