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Flashcards in Muscle & Nerve Path Deck (33):
1

Peripheral causes of numbness

1. polyneuropathy
2. peripheral entrapment neuropathy
3. Radiculopathies
4. Brachial plexus lesions

2

Can nerves store energy?

Not very much - so much has good circulation to meet the high metabolic demand

3

fibrillations

spontaneous contraction of de-innervated muscle fibers

4

fasiculations

spontaneous discharge of a motor unit due to irritation or damage

5

Amyotrophic lateral sclerosis (ALS)

degeneration of anterior horn cells and upper motor neurons - many genetic factors (SOD is most common mutation)

6

lower motor neuron symptoms

atrophy, fasciculations, decr. reflexes

7

upper motor neuron symptoms

spasticity, incr. reflexes, upgoing toes

8

Primary lateral sclerosis

like ALS but only affects lower motor neurons and has better prognosis (10+ yrs)

9

ALS disease progression

starts unilaterally and spreads to both sides in months, survival is 3-5 yrs, death due to respiratory weakness and infection

10

Tx for ALS

nothing good. Riluzole can delay progression slightly

11

3 patterns of peripheral neuropathy

1. mononeuropathy
2. radiculopathy
3. polyneuropathy

12

Characteristics of mononeuropathy

often due to trauma causing nerve entrapment, presents with paresthesias when the region is tapped (Tinel sign)

13

Causes of radiculopathy

1. intervertebral disc herniation (young)
2. degenerative changes (older)

14

Characteristics of radiculopathy

symptoms follow a well defined pathway, symptoms often caused by stretching or pinching when coughing, sneezing..etc. Usually not a lot of sensory loss bc of degree of overlap with other nerves.

15

polyneuropathy

diffuse peripheral nerve damage

16

What is the most common cause of polyneuropathy?

Diabetes (after that many things can cause it - nutritional deficiencies (B12), infections, toxins, metabolic issues, inflammation...etc).

17

What is Guillain-Barre?

autoimmune syndrome following infectious disease that presents with acute, rapid severe weakeness (polyneuropathy)

18

Mononeuritis multiplex

condition caused by decr. blood flow to nerves or an autoimmune destruction of axon or myelin that can happen most commonly with diabetes in the lumbar plexus. causes decr. patellar reflex

19

Myasthenia Gravis

autoimmune disease against nicotinic receptors at the NMJ. leads to ptosis, diplopia, weakness with sustained or repetitive use of the muscle

20

Lambert-Eaton Syndrome

myasthenic syndrome that may be associated with carcinoma - defective Ca channel leads to hip girdle weakness that progresses. weakness improves with exercise (facilitation)

21

What virus can produce impairment of the NMJ?

C. Botulinum with Botulinum toxin (binds synaptobrevin and blocks Ach release)

22

Classic presentation of myopathies

symmetrical, proximal muscle weakness and incr. muscle enzymes (CK levels). must biopsy to be sure.

23

What are 3 categories of myopathies that cause muscle cell destruction?

1. Muscular dystrophies
2. Metabolic Myopathies
3. Inflammatory Myopathy

24

What are muscular dystrophies?

noninflammatory degenerative conditions of muscle (ex. Duchenne, Becker, facioscapulohumoral, limb-girdle, oculopharyngeal, & myotonic dystrophies)

25

Duchenne and Becker Dystrophies

X-linked recessive disorder due to mutated dystrophin
Duchenne - presents in boys in childhood (kids never run) - death in 20's due to cardiomyopathy
Becker's - milder version of Duchenne

26

What are metabolic myopathies?

Myopathies due to thyroid disease, meds, toxins, mitochondrial myopathies - present with exercise intolerance or cramping

27

What is polymyositis?

inflammatory myopathy characterized by insidious, symmetrical onset of proximal weakness in 30-60 yr olds

28

What is dermatomyositis?

polymyositis presentation + red/purple rash (esp over eyelids and joints) - high association with lymphoma and other cancers

29

What is inclusion body myositis?

It is a slowly progressing inflammatory myopathy that often present distally in hands.

30

What are two categories of diseases that cause functional deficits in muscles (channelopathies)?

1. myotonic disorders (2 types - distal and proximal)
2. periodic paralysis

31

What is the difference between congenital myotonia and paramyotonia congenita?

congenital myotonia - sx improve with exercise
paramyotonia congenital - sx worsen with exercise

32

Limb Girdle Dystrophy

Muscual dystrophy that can be caused by many different mutations that progresses slowly and can stop altogether - present in adolescence or early adulthood

33

What is chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)?

It is a condition with relapsing or progressive polyneuropathy that causes asymmetric weakness and sensory loss and is associated with very high CSF protein levels. Reflexes are lost early in this as well as acute IDP bc heavily myelinated fibers are affected first.