Peripheral Nerve Pathology - Alston Flashcards

1
Q

What are the characteristics of autonomic nerve fibers as well as pain and temperature sensation? What are their conduction speeds?

A

Thin, unmyelinated fibers, slow

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2
Q

What are the fiber characteristics of light touch and motor nerves? What is the conduction speed?

A

Large diameter, myelinated fibers, fast

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3
Q

Wallerian degeneration is the term to describe what type of neuropathic pattern?

A

Axonal neuropathy

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4
Q

What are the stages of neuronal regeneration after an axon is transected? (Characteristics of Wallerian degeneration)

A
  1. Day 1: Sheath disintigrates into spherical structures called myelin ovoids and macrophages are recruited to clean up.
  2. Outgrowth of new branches (Schwann cells guide the growth.)
  3. Pruning of sprouting axons
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5
Q

Traumatic neuromas (psuedotumor) can result when what part of the healing process fails as a result of Wallerian degeneration?

A

Failure of the outgrowing axons to find their target - whorled proliferation of axons and Schwann cells results in painful nodule

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6
Q

Reduction of signal strength would be a characteristic of what neuropathic change?

A

Axonal neuropathy (axonal loss)

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7
Q

Are axons sparing in demyelinating diseases?

A

Yes, typically myelin is the primary target.

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8
Q

How might Schwann cells and their myelin sheaths appear in a demyelinating disease?

A

Thinner and shorter

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9
Q

Slower nerve conduction would be a characteristic of what neuropathic change?

A

Demyelination

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10
Q

What part of the neuron is most commonly affected in neuronopathies? (Examples?)

A

Damage is at the level of the neuron cell body (viruses -herpes and certain toxins- platinum)

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11
Q

Mononeuropathies affect one or more nerves? What is the cause?

A

Single nerves are affected - often due to trauma, entrapment, infection

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12
Q

Polyneuropathies affect one or more nerves? Progression? Symmetric/asymmetric?

A

Usually multiple nerves symmetrically. Often start in feet and ascend w/ progression (stocking glove - hands start to be affected when deficit reaches knees)

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13
Q

Mononeuritis multiplex affects one or many nerves? Pattern? Often due to?

A

Damage is to several nerves, but in haphazard pattern - often due to vasculitis

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14
Q

Polyradiculoneuropathies are unique in that damage presents where? Symmetric/Asymmetric? Location?

A

Affect nerve roots as well as peripheral nerves - Symmetric in proximal and distal body

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15
Q

Pt has weakness in distal limbs that has advanced over the past few days since he, “got vaccinated.” Decreased sensation and +1 Reflexes in the lower extremities w/ slow nerve conduction velocity in the lower legs. CSF proteins are high. Papilledema present. What is the likely diagnosis? What kind of neuropathic process is occurring? Where? How is this process mediated? Outcome?

A

Guillain-Barré - Inflammatory (Peripheral) neuropathy resulting in prominant demyelination near the nerve root, but can be widespread peripherally. T- cell (immune) mediated. Can result in respiratory depression - most recover.

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16
Q

Pt has been treated with steroids after 2 years of progressive weakness starting at the feet bilaterally and ascending to his knees, now presenting in the hands. He has some sensory dysfxn. He has areflexia at the achilles and knees. The symptoms have relapsed and remitted over the whole course of illness, and is in remission after steroid Rx. Biopsy of myelin reveal IgG and IgM deposition and high macrophage content. Onion-bulb neurons are present as well. What is the diagnosis? What is the prevalence? How is this differentiated from Guillain-Barre?

A

Chronic Inflammatory Demyelinationg Poly(radiculo)neuropathy (CIDP) - most common acquired inflammatory peripheral neuropathy - time and course differentiate this disease from Guillain-Barre -

17
Q

Autoimmune diseases like RA, Sjögren syndrome, and SLE often take the form of what kind of neuropathy? How do they differ from vasculitic neuropathy?

A

Sensory or sensorimotor polyneuropathies - differ in that vasculitis is often secondary to other diseases

18
Q

Pt is being evaluated for numbness and tingling in the right hand and left foot. He has an Hx. of HTN and a family Hx. of heart disease with atherosclerosis. What is the likely diagnosis if the pt. is found to have a neuropathy? What pattern of neuropathy does this commonly follow? Inflammatory or non-inflammatory? Where is the neuronal damage? Biopsy of vasculature may reveal what?

A

Vasculitis neuropathy - mononeuritis multiplex - inflammatory - peripheral nerves w/ patchy axonal degeneration and loss - inflammatory infiltrates (macrophages, neutrophils, etc.) and vascular damage are used in identification

19
Q

Transient Pt with multiple gangrenous peripheral lesions and several missing fingers/toes presents to the emergency department. He has loss of sensation and pain in the feet and hands bilaterally as well as the face. Biopsy reveals Schwann cell destruction w/ proliferation of obligate intracellular pathogens. What is the likely invading pathogen? What is the neuropathic pattern?

A

Leprosy (Hansen Disease) aka mycobacterium leprae - specifically called “lepromatous leprosy” in this case - symmetric polyneuropathy - often affects pain fibers resulting in accidental traumatic injury, lesions, and gangrenous infection

20
Q

Tuberculoid leprosy differs from lepromatous leprosy in that it is characterized by what kind of reaction? What presents in the skin? What nerves are primarily affected?

A

Cell-mediated immune response to mycobacterium leprae - dermal nodules containing granulomatous inflammation in the skin - cutaneous nerves are infected resulting in fibrosis of peri/endoneurium

21
Q

Lyme disease can lead to what kind of neuropathy? Facial symptoms?

A

Polyradiculoneuropathy as well as unilateral/bilateral facial nerve palsies

22
Q

HIV can result in what type of neuropathy? What might its progression resemble initially?

A

Mononeuritis multiplex as well as demyelination resembling CIPD/guillian-Barre.

23
Q

What is the most common cause of peripheal neuropathy?

A

Diabetes

24
Q

Diabetes most commonly presents with what pattern of neuropathy? Ascending/Descending? Sensory or motor or both? Symmetric or not? What other neurological systems are affected? What is happening to the vasculature around the neurons? What occurs in the myelin?

A

Ascending distal symmetric sensorimotor polyneuropathy (numbness, loss of pain sensation, balance issues, paresthesia) - Autonomic dysfxn (sexual dysfxn, urinary issues, postural hypotension) (Asymmetric neuronal loss may be associated with vasculitis) - Endoneurial arterioles show thickening and periodic acid-Schiff positivity (aka PAS) - Myelin loss and stages of regeneration may be present

25
Q

Pt presents with muscle cramps, painful sensation when touched distally (distal dyesthesia), and areflexia w/ deep tendon reflexes. The pt experiences these symptoms symmetrically. What is the diagnosis? Demyelination or axonal?

A

Axonal loss due to uremic neuropathy

26
Q

Pt presents with carpal tunnel syndrome and sensory polyneuropathy distally. What hormone level may need to be evaluated?

A

Thyroid (hypothyroidism)

27
Q

B12 (cyanocobalamine) deficiency classically results in damage to what important neural structures?

A

Long tracts in the spinal cord as well as peripheral nerves

28
Q

Deficiency of thiamine (B1), Pyridoxine (B6), folate, vitamin E, copper and zinc are all associated w/ what pattern of neuropathy?

A

Peripheral neuropathy

29
Q

Pt presents with brachial and pelvic plexopathy and eventually develops drooping in the face before being evaluated by his physician. Scans reveal mononeuropathies from compression at the apex of the lung, the pelvis, and the base of the skill due to what?

A

Tumors

30
Q

Cisplatin and taxane can result in neuropathy. What are these treatments for?

A

Chemotherapeutic agents often result in neuropathy

31
Q

Man presents with a complex sensorimotor neuronopathy that began distally in an asymmetric and multifocal pattern. Blood tests reveal anti-Hu antibodies and elevated CD 8+ cells in the dorsal root ganglion. What is the likely cause of his symptoms?

A

Paraneoplastic disease process resulting in immunoglobulin attack of proteins similarly expressed on cancer cells and normal neurons.

32
Q

What types of cells might secrete monoclonal Ig or Ig fragments that damage nerves? What kinds of cancer may lead to this?

A

B-cells - lymphomas

33
Q

Genes encoding myelin, growth factors, proteins that regulate mitochondrial fxn, vesicle and axonal transport, heat shock proteins, and cell membrane structure and fxn may be associated with what group of neurological diseases?

A

(Hereditary) Inherited peripheral neuropathies

34
Q

Pt presents with distal muscle atrophy (peroneal muscle atrophy), sensory loss, and foot deformity (pes cavus). Biopsy reveals Schwann cell hyperplasia and onion bulb neurons. Some areas of nerve involvement are actually palpable. Genetic testing reveals CMT genes are involved. What is the likely diagnosis? What are the 3 CMT variations? What is the onset/pattern of inheritance? Associated genes for each?

A

Charcot-Marie-Tooth
(HMSN1) CMT1: Autosomal dom - most common - 20s age of onset - PMP22 (peripheral motor protein) on chromosome 17p11.2-p12
CMTX: X-linked - GJB1 gene (encoding connexin 32 - a gap jxn for Schwann cells)
(HMSN2) CMT2: (severest form) autosomal dom. - associated w/ axonal degeneration - early childhood onset - (MFN2 gene - required for normal mitochondrial fusion)

35
Q

What is the most common symptom of hereditary sensory neuropathy w/ or without autonomic neuropathy? What is the common result? Demyelination or axonal?

A

Loss of pain and temperature sensation - pain loss = frequent traumatic injury - typically axonal neuropathy

36
Q

Pt. presents with truncal and peroneal muscle atrophy and sensory loss with foot deformity. Tests and Hx reveal autosomal recessive pattern of inheritance in family. Enlarged nerves can be palpated in the skin. What si the diagnosis and the associated dysfxnal gene?

A
Dejerine-Sottas 
CMT 3 (HMSN3)