8/30 Neuropathy - Glendinning Flashcards Preview

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Flashcards in 8/30 Neuropathy - Glendinning Deck (25):
1

peripheral neuropathy

lesions affecting peripheral nervous system

  • cranial nerves
  • spinal nerves
  • peripheral nerves
  • nerve plexuses

2

symptoms of neuropathy vary depending on...

 

potential symptoms

  • whether myelin or axons are affected
  • which axons are affected
  • where the axons are affected

 

symptoms can include:

  • weakness, muscle atrophy
  • loss of reflexes
  • loss of sensation (numbness)
  • abnormal sensation (tingling, burning) - paresthesia
  • pain
  • autonomic changes (sweating, HR, vascular)

3

neurotpathic pain

different from nociceptive  pain (tissue might be damaged, but nerves/nervous system intact)

  • arises from lesions in peripheral and central nervous system
  • can include burning, shooting, stinging pain mixed with areas of numbness
  • can include changes in pin threshold, quality of pain, and spontaneous pain

DEPRESSION is a common feature of chronic pain

ex. herpes zoster, trigeminal neuralgia

  • antidepressants and anti-epileptics are primary drugs used to treat neuropathic pain

4

radiculopathy

vs

mononeuropathy

vs

plexopathy

vs

polyneuropathy

all FOCAL LESIONS

 

radiculopathy: sx follow a nerve root pattern (dermatome or myotome)

  • often caused by compression of nerve roots from protruding discs

mononeuropathy: sx follow a peripheral nerve

  • often caused by injuries

plexopathy: sx follow a nerve plexus

polyneuropathy: generalized process affects peripheral nerves → distal and symmetrical sensorimotor (poss autonomic) distribution 

  • "glove and stocking" pattern
  • common causes: diabetes, alcohol, hypothyroidism, vitB12 def; also pts in intensive care

5

"Wallerian degeneration"

peripheral neuropathy results from damage/injury to cell bodies, axons, or myelin sheaths → leads to "Wallerian degeneration" aka "dying forward"

 

1. distal axonal degeneration

2. "chromatolysis" of cell body

  • nucleolus expands and moves to cell wall, Nissel substance disintegrates

3. recruitment of macrophages

 

proximal stump can recover at rate of 1-2mm/day

6

"dying back" of axons

conditions that affect the health of the neuron (ex. metabolic diseases) → "dying back"

  • can be accompanied by loss of myelin

longer axons most susceptible and are affected first → distal extremities are affected first

7

"segmental demyelination"

occurs when myelin sheaths are damaged by trauma or disease

  • myelin may be affected secondarily to axonal death

sx of demyelination detected by Nerve Conduction tests, revealing:

  • conduction block
  • slowed conduction velocity

myelin and conduction can return in days to weeks

 

trauma affecting myelin : metaphorical "nerve concussion" - rapid effect, slow recovery

8

non-traumatic peripheral neuropathies

 

nutritional/metabolid

  • diabetes mellitus
  • vitamin def
  • uremia

9

non-traumatic peripheral neuropathies

 

toxic drugs

other toxins

  • drugs
    • vinblastine, vincristine (affect microtubule formation)
    • paclitaxel, cochicine, INH
  • toxins
    • alcohol, lead, aluminum, arsenic, mercury, acrylamide

 

10

non-traumatic peripheral neuropathies

 

vasculopathic

 

inflammatory

 

infection

  • vasculitis, amyloidosis

 

  • autoimmune: systemic lupus erythematosus, rheumatoid arthritis, sarcoidosis, Sjogren syndrome, Guillain Barre syndrome
  • chronic infl demyelinating polyneuropathy

 

  • herpes zoster
  • leprosy
  • HIV
  • Lyme disease

11

non-traumatic peripheral neuropathies

 

inherited

  • Charcot-Marie-Tooth neuropathy

12

diabetic neuropathy

  • most common compliation of diabetes
    • 30% of diabetic patients
    • 75-80% have subclinical neuropathy
    • 16% have chronic neuropathic pain
  • greatest source of M&M
    • 50-75% of all amputations

13

length-dependent diabetic polyneuropathy

  • accounts for 80+% of patients with diabetic neuropathy

 

sx start in feet → more to more proximal legs and and distal upper limbs

  • "glove and stocking" pattern of sensory loss
  • paresthesias, dysesthesias, numbness/tingling/burning
  • motor weakness of distal limbs
  • can lead to trophic changes : calluses and plantar ulcers

14

pathophys of diabetic neuropathy

axonal degen, dying back, and demyelination occur

  • includes effects related to ischemia, oxidative stress, infl processes

 

sensory neurons more affected than motor, but both may be affected

  • sensory often involves just small unmyelinated and myelinated fibers : small fiber polyneuropathy

15

vitamin B12 deficiency

  • most common metabolic neuropathy
    • 3-16% prevalence in US; 21% in geriatric pop
  • may affect peripheral nerves, optic nerves, spinal cord, brain
  • most common feature: loss of vibration sense
  • sx affect distal limbs, but begin more commonly in upper limb

16

subacute combined degeneration

primary or secondary effect of B12 definiciency in which lateral and dorsal columns of spinal cord affected

  • can lead to sx of ataxia and spasticity occuring together with sx of peripheral neuropathy

17

causes of B12 deficiency

B12 ingested through animal protein → deficiency often seen in vegans/vegetarians or people with gluten sensitivity/malabsorption

 

may also see pernicious anemia also bc B12 needed to produce red blood

 

18

pathophys of B12 deficiency neuropathy

without B12, myelin production is abnormal → decreased nerve conduction velocity

 

need to differentiate from MS, but once you do, treat with B12 therapy

19

Guillan Barré

 

aka

acute inflammatory demyelinating polyneuropathy (AIDP)

 

most common cause of acute paralysis seen in clinical practice

  • incidence 1/100k
  • all countries, all ages, all seasons

most rapidly progressing and potentially fatal form of neuropathy

20

major features of Guillain Barré

primarily motor symptoms

  • ascending symmetric paralysis → acute cases? can affect breathing and require resp support

may begin with parasthesias in toes/fingers, aching in thighs/back

 

2 sx used to make diagnosis

  • decreased nerve conduction velocity (with conduction blocks)
  • increased protein in CSF with normal cell count (albuminocytologic dissociation)

21

cause of GBS

60% of time, GB begins 1-3 weeks after infection or vaccination

ex. Campylobacter jejuni or Herpesvirus infection (NOT a definitive link!)

 

infection causes an autoimmune/infl attack on peripheral myelin

22

GBS inflammatory process

widespread infl process affecting myelin sheaths

  • lymphocytes attach to vessel wall → migrate through wall and enlarge
  • lymphocytes attack myelin (segmental demyelination); axons may also be affected
  • severe cases → nerve cell body may die

see presence of polymorphonuclear leukocytes

 

23

dx of GB

usually follows inf or vaccination

2 more important diagnostic tests are:

  • CSF analysis → increased protein
  • nerve conduction test → decreased cond velocity

24

Charcot-Marie-Tooth Disease

"hereditary motor and sensory neuropathy"

  • group of several hereditary diseases that directly affect either myelin (CMT1) or axons (CMT2)


 

25

CMT1

most common: CMT1 (myelin) → combined motor/sensory neuropathy

  • primarily affects distal muscle, esp affecting peroneal nerve
  • bc of demyelination, small fiber types carrying pain and temp are not affected
  • frequently occurs with pes cabus and hammertoes (true for all CMT)

 

prevalence: 1/2500

typical onset: late childhood

ID: slow progressive nature, decr cond velocity in all nerves

  • can see fewer numbers of myelinated axons in peripheral nerves

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