Anterior Horn, PERIPHERAL NERVES, NMJ Disorders

Question 1

ALS*, SMA, polio, West Nile are what class of nerve disorder?

Answer 1

Anterior horn cell disorders

Question 2

Cervical & lumbar spine; brachial & lumbosacral plexus are what class of nerve disorder?

Answer 2

Radiculopathies and plexopathies

Question 3

Mononeuropathies* – carpal tunnel, ulnar & peroneal palsy.

Polyneuropathies – genetic (CMT), diabetes, systemic illness, vitamin deficiency, toxic.

Are what type of disorders?

Answer 3

Neuropathies

Question 4

Myasthenia*, LEMS, botulism, organophosphate poisoning are what class of disorder?

Answer 4

Neuromuscular junction disorders

Question 5

What are the Myopathies?

Answer 5

Dystrophies*, myositis, metabolic, toxic & endocrine myopathies

Question 6

UMN vs LMN?

__1__– spastic tone; incr. reflexes; emotional
__2__– decr. tone & reflexes; atrophy

Answer 6

1. UMN
2. LMN

BOTH: Weakness
Rapidity, location, progression
Atrophy, hypertrophy, deformities
Other
Sensory loss; cramps; pain

Question 7

What is the name of a autoimmune disorder, ab to NMJ acetylcholine receptor?

Answer 7

Myasthenia Gravis

Question 8

What is the Tx for Myasthenia Gravis?

Answer 8

1. Cholinesterase inhibitor → temporary increase in strength and improve decrement following repetitive nerve stimulation
   Edrophonium (IV)
   Pyridostimine (oral)
2. Immunosuppression:
   Prednisone
   Immunosuppressive agents (azathioprine, mycophenolate mofitil)
3. Plasma exchange, IVIG infusion
4. Thymectomy

Question 9

How do you Dx Myasthenia Gravis?

Answer 9

Diagnosis via presence of ACHR antibodies in serum

Question 10

What are the clinical features of Myasthenia Gravis?

Answer 10

Diagnosis via presence of ACHR antibodies in serum

Question 11

What is the disease that is one of the hereditary motor and sensory neuropathies, a group of varied inherited disorders of the peripheral nervous system characterised by progressive loss of muscle tissue and touch sensation across various parts of the body.

Answer 11

Charcot–Marie–Tooth disease

Question 12

What is Amyotrophic Lateral Sclerosis (ALS)?

Answer 12

Pathologic changes:
Progressive weakness and wasting due to degeneration of brainstem and spinal cord lower motor neurons
Coexisting spasticity and hyperreflexia due to degeneration of upper motor neurons
Hyperreflexia + pathological reflexes (Hoffman, crossed adductor, Babinski)

Question 13

What are the clinical features of Amyotrophic Lateral Sclerosis (ALS)?

Answer 13

WEAKNESS

Typically sporadic
Foot drop
Speech may be slurred or spastic
Cognitive defects may be seen
Normal sensory exam
Diaphragm weakness
Impaired swallowing → aspiration pneumonia

Question 14

ALS frequency _____ (increase or decrease) with age?

Answer 14

increases.

ALS affects male more, reasons unknown.

Question 15

How do you Tx ALS?

Answer 15

Disease-specific: pathogenesis based
riluzole: of proven benefit
many past and pending trials of agents
complementary/alternative medicine (CAM)
widely used
symptom-specific
improve QOL and longevity

Question 16

How does Becker Muscular Dystrophy different from DMD?

Answer 16

Differs from Duchenne, only in that it has a later onset, has more benign course, and survival is longer.

Mental impairment seen less often.

Question 17

What is the genetic defect in DMD?

Answer 17

Genetic defect: XR, deletion, duplication, and point mutations on X chromosome.

Only boys.

Question 18

What are the clinical features of DMD?

Answer 18

• Clumsy waddling gait from first walking.
• Accentuation of lumbar lordosis → protuberant abdomen.
• Calf enlargement.
• Right heel cords, toe walking.
• Gower’s maneuver - trouble rising from floor.
• Subnormal intelligence.
• Eye movements, swallowing and sensation unaffected.
• Increasing proximal weakness with age
• Eventually wheelchair bound, and succumb to respiratory or heart failure by late teens or 20s.

Question 19

What is the only drug that helps with ALS? Does it treat ALS?

Answer 19

riluzole: of proven benefit
many past and pending trials of agents
complementary/alternative medicine (CAM)
widely used symptom-specific.
improve QOL and longevity.

Does not cure!

Question 20

What is the best drug you can use for muscle cramps? (no longer available in the US)

Answer 20

quinine

Question 21

dysphagia: ?

Answer 21

Difficulty swallowing

Question 22

dysarthria: ?

Answer 22

difficult or unclear articulation of speech that is otherwise linguistically normal.

Question 23

What are the (2) subtypes of Charcot–Marie–Tooth disease?

Answer 23

CMT1A

CMT2

Question 24

Charcot-Marie-Tooth Disease that presents as slow nerve conduction velocities + demyelinating neuropathy: Hereditary motor and sensory neuropathy.

Is of which subtype?

Answer 24

CMT1A

Question 25

Charcot-Marie-Tooth Disease that presents as normal nerve conduction velocities + axonal degeneration. Hereditary motor and sensory neuropathy. Is of which subtype?

Answer 25

CMT2

Question 26

What is the genetic defect of Charcot-Marie-Tooth Disease? (2)

Answer 26

1. AD (CMT1 and CMT2) CMT1A = Duplication in DNA containing peripheral myelin protein gene (PMP22) 2. AR (CMT4)

Question 27

What are the clinical features of Charcot-Marie-Tooth Disease?

Answer 27

1) Onset of walking normal, but distal (hands and feet) weakness and sensory loss develop slowly over first two decades of life, not usually confined to wheelchair. 2) Impaired/delayed walking as infants, confined to wheelchair later in life. 3) Adult onset, does not appear until age 40

Question 28

PMP22 gene is ~ with what disorder?

Answer 28

CMT disease

Question 29

Describe the CMT1A/HNPP mutation?

Answer 29

A 1.4 Mb duplication on chr 17 (PMP22 gene) causes CMT1A. - Distal weakness, sensory loss and deformities - 10% are de novo mutations. - Repeats on either side of gene (CMT1A REPS) are hot spot for recombination - Deletion of the same locus causes HNPP; Focal weakness and sensory loss.

Question 30

What are the classifications of diabetic neuropathies?

Answer 30

- Sensory or sensorimotor distal polyneuropathy Stocking/glove numbness and burning pain Foot drop and weak hand muscles - Autonomic neuropathy Hypotension, diarrhea, impotence, urinary retention ``` - Mononeuropathy Cranial nerve (3, 6,7) or peripheral (median, ulnar, peroneal ``` - Lumbosacral plexopathy Pelvic girdle pain; asymmetric hip flexor weakness

Question 31

what is the most common subtype of diabetic neuropathies?

Answer 31

Sensory or sensorimotor distal polyneuropathy. - Stocking/glove numbness and burning pain. - Foot drop and weak hand muscles

Question 32

In Carpal Tunnel, what park of the hand is atrophy?

Answer 32

The Thenar (hypothenar)

Question 33

What is the Tx of diabetic neuropathy?

Answer 33

Good metabolic control of diabetes. Foot hygiene to avoid ulceration & infection Night light; well fitting shoes. Pain management anticonvulsants, antidepressants, analgesics. Autonomic symptoms Diarrhea- codeine, diphenoxylate Hypotension –fluorocortisone, midodrine Urinary retention –regular voiding; suprapubic pressure. Make sure to TAKE CARE OF FOOT!

Question 34

What is the initial complaint of diabetic neuropathy?

Answer 34

Initial complaints: numbness, burning in feet → spreads up legs, into hands. - Weakness of foot dorsiflexor muscles → slapping foot drop gait. - Grip strength and fine hand dexterity diminished

Question 35

What are the positive exam findings of diabetic neuropathy??

Answer 35

- Pin sensation loss in “stocking-glove” distribution. - Loss of position, vibration, and light touch. - Loss of pain and temperature sensation. - Decreased reflexes.

Question 36

What is the autonomic dysfunction ~ with diabetic neuropathy?

Answer 36

Postural hypotension, diarrhea, impotence, urinary retention, increased sweating

Question 37

Explain the effects of cholinesterase inhibitors on nondepolarizing vs. depolarizing neuromuscular blocking agents.

Answer 37

AChEIs can help overcome a block of AChRs by curare (nondepolarizing blocking agent), but AChEIs potentiate effects of succinylcholine (depolarizing neuromuscular blocking agent).

Question 38

What is a tensilon? And what does a positive tensilon test = ?

Answer 38

Tensilon inhibits the breakdown of acetylcholine so that it accumulates and has a prolonged effect. Effects include miosis; increased intestinal and skeletal muscle tone; bronchial constriction; bradycardia; increased salivation, lacrimation, and sweating. Myasthenia gravis.

Question 39

In Myasthenia gravis, what happens to the thymus?

Answer 39

abnormal hyperplasia of the thymus. (vs. normal involution with age)

Question 40

involution: ?

Answer 40

the shrinkage of an organ in old age or when inactive, e.g., of the uterus after childbirth.

Question 41

What is Succinylcholine and its MOA?

Answer 41

Succinylcholine: N-M receptor agonist (2-ACh molecules joined) Initial stimulation → muscle fasciculations Depolarization does not allow repolarization and subsequent AP → flaccid paralysis Flaccid paralysis is POTENTIATED by AChEIs

Question 42

Explain what happens with brief versus prolonged stimulation of nicotinic cholinergic receptors.

Answer 42

- Prolonged receptor activation prevents the muscle cell membrane from repolarizing, thus preventing subsequent AP → flaccid paralysis. - Brief stimulation allows depolarization, repolarization, and then finally a subsequent AP to take place.

Question 43

Plexopathy: ?

Answer 43

Plexopathy is a disorder affecting a network of nerves, blood vessels, or lymph vessels.[1] The region of nerves it affects are at the brachial or lumbosacral plexus. Symptoms include pain, loss of motor control, and sensory deficits

Question 44

Mononeuropathy: ?

Answer 44

Mononeuropathy is a type of neuropathy that only affects a single nerve.[5] Diagnostically, it is important to distinguish it from polyneuropathy because when a single nerve is affected, it is more likely to be due to localized trauma or infection.