Neuropathy, Myopathy, and Motor Neuron Disease

Question 1

mononeuropathy

Answer 1

involvement of a single major named nerve usually by trauma or compression (median n at wrist, ulnar n at elbow, common peroneal n at fibular head)

Question 2

polyneuropathy (peripheral neuropathy)

Answer 2

d/o of multiple major and small nerves or branches

Question 3

what happens in the most common polyneuropathies

Answer 3

s/s are symmetrical and sensory loss or impairment occurs early and often remains prominent

Question 4

where does numbness and tingling usually befin

Answer 4

distally in the toes and feet, later affecting the fingers and hands

Question 5

what happens if autonomic nerves are involved

Answer 5

• orthostatic hypotension
• incontinence
• impotence
• sweating abnormalities

Question 6

what are the basic pathological processes in neuropathy?

Answer 6

demyelination and axonal degeneration

Question 7

demyelination

Answer 7

• characterizes a mononeuropathy from focal compression such as carpal tunnel syndrome where median n is compressed at the wrist
• also primary process of G-Barre (acute polyneuropathy)

Question 8

role of axonal degeneration

Answer 8

-if neuropathy progresses over time or is initially several axonal degen may also occur with less chance for recovery

Question 9

Wallerian degeneration

Answer 9

when there is a more severe crush or penetrating focal nerve injury, axonal loss occurs via wally
-axons and myelin degenerate distal to the point of nerve injury

Question 10

polyneuropathies from toximetabolic causes

Answer 10

mostly have axonal degeneration as the primary pathology

Question 11

multiple mononeuropathy

Answer 11

can be d/t systemic illness which is inflamm/ai (SLE), infiltrative (sarcoidosis), or infectious (leprosy)

Question 12

causes of polyneuropathy

Answer 12

• meds (chemo)
• neurotoxins
• alcoholism
• malnutrition and vitamin deficiencies

Question 13

role of EMG in diagnosis

Answer 13

-tests the electrical activity and function of nerves and muscles

Question 14

sural (sensory nerve) biopsy

Answer 14

• used when the clinical pic or EMG suggests a chronic polyneuropathy d/t an inflamm, immune-mediated, or vasculitic cause
• leaves permanent numbness along lateral foot

Question 15

oral medications for neuropathic pain

Answer 15

• anticonvulsants (Gabapentin, Pregabalin, Carbamazepine)

- antidepressants (Duloxetine, Amitriptyline)

Question 16

Guillain-Barre

Answer 16

• one of the most rapidly progressive polyneuropathies
• usually s/p recent viral illness
• immune system targets peripheral nerve myelin
• ascending areflexic paralysis (lower limbs affected first)

Question 17

how can you hasten recovery for G-B

Answer 17

plasmapheresis or IVIG infusion

Question 18

what is one of the most common chronic polyneuropathies (occurs over months to yrs)

Answer 18

DM-which may also cause:

• isolated or multiple mononeuropathies
• autonomic neuropathies (diabetic gastroparesis or orthostatic hypoTN)
• cranial neuropathies (diabetic third nerve palsy)

Question 19

what are some other causes of polyneuropathies?

Answer 19

• metabolic or endocrine disorders
• rheumatologic disease
• cancer or myeloma
• infection
• nutritional deficiencies
• toxins

Question 20

characteristics of most myopathies

Answer 20

-proximal weakness or fatigue, nml sensation, and late loss of reflexes after significant atrophy has occurred

Question 21

CK creatine kinase

Answer 21

muscle enzyme often nonspecifically elevated in disease of muscle

Question 22

polymyositis

Answer 22

inflammation of multiple muscle, may be d/t infections or drug reactions
-refers to ai dz affecting muscle

Question 23

dermatomyositis

Answer 23

-both skin (rash involving periorbital areas and knuckles) and muscle are involved

Question 24

Duchenne’s (X-linked) muscular dystrophy

Answer 24

deficiency of muscle dystrophin (important structural protein)

• Gower’s manuever
• calf muscles: pseudohypertrophy (fat and connective tissue)

Question 25

myotonic dystrophy type 1 (AD)

Answer 25

- d/t excessive trinucleotide DNA repeats on c. 19; producing an abnml protein kinase in muscle fibers - weakness affects the distal limbs, neck, face, and jaws

Question 26

myotonia

Answer 26

- peculiar impaired relaxation of muscle after volitional contraction - difficulty letting go of handshake or doorknob - also: cataracts, frontal baldness, infertility, cardiac arrhythmias

Question 27

UMN (CS+CB)

Answer 27

-UMN comprise the corticospinal tract (control anterior horn cells) and corticobulbar tract (CN motor nuclei-LMN)

Question 28

BULB

Answer 28

-refers to lower brain stem, location of the CN motor nuclei that innervate muscles of the jaws, face, palate, pharynx, larynx, and tongue

Question 29

spinal muscular atrophy

Answer 29

- group of disorder involving just anterior horn cells - clinical findings: LMN signs - Werdnig-Hoffman=example of infantile onset

Question 30

primary lateral sclerosis

Answer 30

- familial degeneration of corticospinal tract in lateral columns of the spinal cord not due to structural (spinal stenosis from degenerative arthritis) or metabolic (vit b12 deficiency) lesions - weakness + UMN signs

Question 31

pseudobulbar palsy

Answer 31

-encompasses several d/o where only the corticobulbar tract is involved, causing facial wealness, impaired chewing dysarthria, dysphagia and hoarseness

Question 32

what is the most common motor neuron dz

Answer 32

ALS

Question 33

motor neuron dz diagnosis

Answer 33

should be made over a long period of time

Question 34

ALS epi

Answer 34

-40-70 yo , M>W

Question 35

ALS early s/s

Answer 35

- may start with focal weakness and atrophy in a limb such as a shoulder or leg (foot drop) - spreads and becomes bilateral

Question 36

ALS later

Answer 36

- both UMN and LMN degenerate + widespread fasciculations - extraocular muscles and sphincters of bladder and bowel are spared - rarely familial--SOD enzyme defective; more commonly sporadic

Question 37

ALS pathological findings

Answer 37

- degeneration of corticospinal and corticobulbar tracts - gliosis and loss of anterior horn cells and puramidal neurons - neurogenic atrophy of muscle

Question 38

ALS mimics

Answer 38

- cervical radiculomyelopathy (LMN in UE, UMN in LE) - stroke - rare ai neuromuscular disorders

Question 39

ALS drugs

Answer 39

-Riluzole-opposes excitotoxic effect of glutamate at the NMDA receptors of motor neurons

Question 40

**most common site of ulnar nerve entrapment**

Answer 40

elbow where the ulnar nerve lies at the medial epicondylar groove

Question 41

ulnar nerve syndrome

Answer 41

-dec sensation over 4th and 5th fingers and weak grip d/t involvement of interosseous muscles of the hand