PNS And Skeletal M

Question 1

Neuromuscular diseases are a group of disorders that typically present with what?

Answer 1

Weaknes, muscle pain and sensory deficits

Question 2

What information do thin unmyelinated fibers convey?

Answer 2

Autonomic functions, pain and temp; slowest conduction speeds due to lack of myelin and small diameter

Question 3

What information do large diameter axons with thick myelin sheaths convey?

Answer 3

Light touch and motor signals; fast conduction speed

Question 4

How do pts with peripheral neuropathy generally describe their pain?

Answer 4

As tingling, stabbing, burning or “pins and needles”

Question 5

What is Bell’s palsy?

Answer 5

A mononeuropathy affecting CN VII —> facial muscle paralysis; occurs between 15-60 yo and generally resolves spontaenously

Question 6

What are the sx of Bell’s palsy?

Answer 6

One sided facial droop within 48-72 hours of initial sx; assoc with URI and DM; facial tingling, mid severe HA/neck pain, memory problems, balance issues, ipsilateral limb paresthesias, ipsilateral limb weakness and sense of clumsiness

Question 7

What are other examples of infectious polyneurpathies?

Answer 7

Lyme dz and HIV

Question 8

What is lyme dz polyneuropathy?

Answer 8

Second and 3rd stages of dz; polyradiculoneuropathy; unilateral or bilateral facial N palsies

Question 9

What is HIV polyneuropathy?

Answer 9

Early stage HIV infection; mononeuritis multiplex, demyelinating DO that resembles Guillain-Barre, chronic inflammatory demyelinating polyradiculoneuropathy; later stages assoc with distal sensory neuropathy

Question 10

Disorders that impair function of the NMJ tend to present with what?

Answer 10

Painless weakness and fatigue

Question 11

What is the development of skeletal M?

Answer 11

During embryogenesis skeletal M develops thru fusion of mononucleated precursor cells (myoblasts) into multinucleated myotubes; these matre into myofibers of varying length that contain 1000s of nuclei; in adults these myofibers are arranged in fascicles each associated with a small pool of stem cells (satellite cells) which can contribute to muscle regeneration following injury

Question 12

What is juvenile dematomyositis?

Answer 12

Avg age of onset 7 yo; MC inflammatory myopathy in children; calcinosis and lipodystrophy; less likely to be associated with myositis specific Abs, cardiac involvement, ILD or an undelrying malignnacy

Question 13

What is the first line tx for inflammatory myopathies?

Answer 13

Corticosteoids

Question 14

If a pt has a steroid resisant inflammatory myopathy, what is used to tx their condition?

Answer 14

Immunosuppressive drugs or steroid sparing agents (azathioprine and MTX)

Question 15

What is 3rd line tx for inflammatory myopathies?

Answer 15

IVIg, cyclophosphamide, cyclosporine and rituximab

Question 16

Inclusion body myositis usually responds poorly to what?

Answer 16

Steroids or immunosuppressive tx

Question 17

Which gene is associated with malignant hyperthermia?

Answer 17

RYR1 gene (ryanodine receptor); 19q13.2

Question 18

When do congenital myopathies present?

Answer 18

In infancy with M defects that tend to be static or to improve over time; assoc with developmental abnormalities of the CNS as well as progressive M damage

Question 19

What are muscular dystrophies?

Answer 19

Progressive muscle damage with sx presenting after infancy (between childhood and adulthood)

Question 20

What are some congenital conditions with defects in ECM surrounding myofibers?

Answer 20

Ullrich congential muscular dsytrophy (UCMD) which leads to hypotonia, proximal contractures and distal hyperextensibility; Merosin deficiency

Question 21

What are some congential conditions with abnormalities in receptors for ECM?

Answer 21

Congenital muscular dystrophy as well as developmental defects of the CNS and eyes that cause seizures, intellectual disability and blindness

Question 22

Which proteins are involved in limb girdle muscular dystrophy?

Answer 22

Sarcoglyan complex of proteins

Question 23

What are the two general patterns of muscle dysfunction seen in diseases of lipid or glycogen metabolism?

Answer 23

Sx with exervise or fasting (severe muscle cramping and pain or extensive muscle necrosis aka rhabdomyolysis) + slowly progressive muscle damage wihtout episodic manifestations

Question 24

What is spinal muscular atrophy?

Answer 24

Neuropathic disorder, loss of neurons —> muscle weakness and atrophy

Question 25

What is floppy infant?

Answer 25

Infants with neurologic or neuromuscular dz may present with generalized hypotonia

Question 26

The DDx for infantile hypotonia includes what?

Answer 26

Primary disease of SKM including congential myasthenic syndromes, myotonia, myopathies, muscular dystrophies; abnormalities of the brain (encephalopathy) or neuronopathies (SMA)

Question 27

What are the characteristics of NF1?

Answer 27

Cafe au lait spots and Lisch nodules; optic pathway glioma; 17q11 coding for neurofibromin protien

Question 28

What are the characteristics of NF2?

Answer 28

Bilateral acoustic schwannomas, NF2 plaque; 22q12 coding for merlin protein

Question 29

What are the characteristics of VHL?

Answer 29

Hemangioblastoma of the cerebellum/spine, retinal angioma; 3q25

Question 30

What are the characteristics of tuberous sclerosis?

Answer 30

Subendymal giant cell astrocytoma, ash leaf spots, retinal astrocytoma (mulberry lesion); 9q34, TCS1, hamartin

Question 31

What are the characteristics for NBCC (gorlin syndrome)?

Answer 31

Medulloblastoma, BCC; 9q22.3 PTCH gene

Question 32

What are the characteristics of Lhermitte-Duclos/cowden syndrome?

Answer 32

Dysplastic gangliocytoma of the cerebellum, facial trichilemmoma (cowden syndrome); 10q23.3 PTEN gene

Question 33

What are the characteristics of Li-Fraumeni syndrome?

Answer 33

Malignant glioma; 17q p53