PNS Pathology Flashcards
What organism causes leprosy?
Mycobacterium leprae
MC cranial neuropathy in Lyme. What is this commonly misDx’d as?
Facial neuropathy. Bell’s palsy
MC viral pathogen affecting PNS
Varicella zoster virus
Nerve cut or crushed. Part of the axon is separate from neuron cell body. Bead-like degeneration distal to injury.
Wallerian degeneration
Wallerian degeneration begins _____ hours after a lesion.
24-36
Axonal degeneration is followed by degradation of _____ and infiltration by _____
myelin sheath
MO
____ and ____ clear cellular debris from axonal degeneration
MO and schwann cells
What three CNs account for majority of CN mononeuropathies MC in clinical practice?
CN III, CN V, CN VII
MC cranial nerve neuropathy
Bell’s palsy
Pts with Bell’s Palsy may have Hx of ____
URI preceeding 1-3 weeks
Organism that is possible cause of Bell’s palsy
HSV I
Artery most often responsible for compression of trigeminal nerve root?
Superior cerebellar
Damage to CN III results in this type of gaze
down and out
Mononeuropathies are most often related to _____
compression of the nerve
MC sites of ulnar nerve entrapment
elbow, then wrist
Ulnar nerve injuries affect what digits?
4 and 5
Carpal tunnel injury affects what digits?
1-3 and half of 4
What area of the body is affected by Meralgia paresthetica?
anterolateral thigh
What nerve is affected in Meralgia paresthetica? What is the injury to the nerve?
lateral cutaneous nerve of thigh
compression by inguinal ligament
Of the types of neuropathies related to diabetes, what type is MC?
Distal symmetrical and sensorimotor neuropathy
What is thought to be the most important underlying cause of diabetic neuropathy?
Ischemia and hypoxia caused by microvascular disease from endothelial inflammation and atherosclerosis
What is another proposed mechanism for diabetic neuropathy?
Accumulation of sorbitol and depletion of inositol results in reduced NaKATPase
Some pts with diabetic polyneuropathy also have ___
diabetic autonomic neuropathy
polyneuropathy develops in ___% of pts with chronic renal failure
60%
Chief pathological finding in uremic neuropathy
axonal degeneration
MC cause of acute generalized paralysis in the US
Guillain-Barre syndrome
Condition involving stripping of myelin from axons by macrophages which slows or blocks nerve conduction
Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP)
CIPD or GBS?
A) Insidous onset
B) Major autonomic or respiratory involvement
C)Relapsing and remitting
A) CIPD
B) GBS
C) CIPD
T or F: The neurologic deficits that may be seen as a consequence of paraneoplastic syndromes are a result of metastasis to an involved nerve or nerves
F, are not
Most toxic neuropathies begin distally or proximally? Slow or rapid progression?
distally
slow
Metal exposure neuropathy A) Predominantly motor B) CNS effects predominate C) Abd pain, vomiting, diarrhea, skin and nail D) Predilection for upper limbs
A. Lead
B. Mercury
C. Arsenic
D. Lead
Blockage of voluntary motor and autonomic cholinergic neuromuscular junctions by neurotoxin prevents motor fiber stimulation in what illness? Caused by what organism?
Botulism
Clostridium botulinum
Examples of common infectious diseases associated with secondary neuropathies include?
Leprosy
HIV/AIDS
Lyme
Varicella zoster
Mycobacterial disease that is one of the most common causes of polyneuropathy worldwide
Leprosy
Main symptom of neuropathy in HIV/AIDS pts
continuous burning discomfort mostly in feet, sensory loss
Areas of body MC affected by shingles
Thoracic and trigeminal (especially ophthalmic branch) dermatomes
Characteristic histo of herpes zoster
multinucleated giant cell with most nuclear material at periphery of nuclei
What type of histological preparation is used to see herpes zoster?
Tzank smear
Hutchinson’s sign
skin lesion on tip of nose. may precede ophthalmic herpes zoster
Ramsay-Hunt syndrome
Herpes zoster oticus with facial paralysis
Condition of pain persisting more than 4 to 8 weeks after healing of herpes zoster skin lesions
Postherpetic neuralgia
Schwannoma
Schwann cells proliferate out of control resulting in a benign bundle of cells that can compress the nerve
Benign primary intracranial tumor of myelin forming cells of CN VIII)
Vestibular schwannoma or acoustic neuroma
Common benign spindle cell tumor of peripheral nerves
Neurofibroma
T or F: Neurofibroma is associated with solitary tumors
F
In neurofibromatosis type 1, what CN is often involved?
CN VIII
but any can be affected
Skin lesion characteristic of cutaneous neurofibromas
café au lait spots
Neurofibromatosis Type I or 2? A) mutation of neurofibromin, a tumor suppressor gene B) Usually unilateral C) mutation of protein merlin D) Bilateral hearing loss
A) Type 1
B) Type 1
C) Type 2
D) Type 2
Characterized by elongated cells in parallel bundles. May resemble of neurofibroma. Benign with no atypia, rare mitotic figures
Perineuroma
Tumor usually arises from major nerves in neck, forearm, lower leg, or buttocks. 50% associated with underlying neurofibromatosis
Malignant peripheral nerve sheath tumor (MPNST) aka malignant schwannoma
Histo of MPNST
increased cellularity and disordered arrangement of Schwann cells. palisading, serpentine. large gaping vascular spaces
