Peripheral Nerve Diseases Flashcards
What are the four type of peripheral nerve diseases?
- Inflammatory neuropathies
- Infectious polyneuropathies
- Hereditary neuropathies
- Acquired metabolic/toxic neuropathies
What is one type of inflammatory Neuropathy?
Guillain-Barre Syndrome
What is the pathogenesis/timeline of Guillain-Barre syndrome?
“Acute inflammatory demyelinating polyradiculoneuropathy”
- 2/3 of cases preceded by acute flu-like illness (Campylobacter, CMV, EBV, Mycoplasma, influenza virus)
- T cells and macrophages cause segmental demyelination; antibodies also present [patients get better when antibodies are taken out - plasmaphoresis]
- Remyelination follows
Neuropathy
Problem with nerves
Guillain-Barre Syndrome
- Immune mediated disease
- Body starts attacking virus and then begins attacking myelin
- Life-threatening disease of the PNS
- Flu-like illness, then acute ascending paralysis (starts at feet)
- Immune-mediated demyelination
- Usually resolves with time
Where does Guillain-Barre target and what does it look like on a slide?
- Inflammation around venules, nerves [look dark red/pink on H&E stain]
- Lymphocytes, macrophages, plasma cells
- Widely distributed through PNS
- Most intense in spinal and cranial nerve motor roots and adjacent nerves
What does Guillain-Barre look like in the clinic?
- Symmetric, ascending paralysis
- Rapid-onset weakness, loss of deep tendon reflexes
- Some loss of sensation
- Elevated CSF protein (no lymphocytes though)
- 2-5% mortality (respiratory paralysis, autonomic instability, cardiac arrest, complications of treatment)
- Respiratory therapy may be needed
What type of demyelination happens in Guillain-Barre?
Segmental demyelination - some segments affected, some not
What are the two forms of Infectious polyneuropathies that we studied?
Leprosy & Varicella-Zoster
Describe Leprosy/Hansen Disease:
- Slowly progressive infection of skin and nerves
- Caused by myobacterium leprae
- Transmitted through resp. droplets
- Endemic in poor, tropical countries
- Causes disabling deformities
What are the characteristics of Mycobacterium leprae?
- Acid-fast, obligate intracellular bacterium
- Grows poorly in culture
- Cell wall doesn’t stain with gram stain!
- Hard to kill in normal ways - body forms granulomas to attack and eat the bugs (LIKE TB)
- Bacteria does not like to be too hot
- Only grows at skin temperature
What are the two types of Leprosy?
- Tuberculoid (less severe)
- Lepromatous (more severe)
Describe Tuberculoid Leprosy:
- Less severe, localized
- Dry, scaly skin lesions
- Nerve degeneration (anaesthesia, ulcers, contractures)
- Nice T-cell response to the bug, with nice granuloma formation
What does Tuberculoid leprosy look like?
- Large, red circular lesions on back or other parts
- Granuloma with lighter colored outer rim seen in H&E slides
- Few bugs shown on H&E
- Macrophages form the granuloma
- Nerves may look inflamed with many lymphocytes on the H&E slides
Describe Lepromatous Leprosy:
- More severe, widespread
- Skin, nerves, eye, mouth, testes, hands, feet
- Patient’s immune system doesn’t respond
- Leonine facies <– lion face nodules
- Autoamputation may occur at extremities
What does Lepromatous Leprosy look like on H&E?
- Many macrophages are present making foam: FOAMY HISTIOCYTES
- TONS OF PINK BUGS
Describe Varicella-Zoster:
- Common viral infection of the PNS
- After chickenpox, virus remains dormant in sensory ganglia of cord, brainstem
- Reactivation: painful, vesicular, dermatomal rash (shingles - herpes zoster)
- Histology: neuronal destruction
What does herpes zoster look like on H&E? (can be in any herpes disease)
Multinucleated Giant cell - large, irregular, pink cell
What are hereditary neuropathies and what is an example of one?
- Hereditary, progressive, disabling syndromes
- May involve motor, sensory, and/or autonomic nerves
- May be related to amyloid deposition or metabolic disorders
- Most common: motor and sensory
- Hereditary Motor and Sensory Neuropathy Type I = Charcot-Marie-Tooth disease
What is Hereditary Motor and Sensory Neuropathy Type I?
- Charcot-Marie-Tooth disease, demyelinating type
- Repetitive demyelination and remyelination
- Muscle loss, loss of sensation but pain intact
- Childhood or early adulthood onset
- High arches, hammer toes, muscle atrophy
- Sometimes loss of muscle in lower leg - “bottle leg”
- Normal life span
What do nerves look like on a slide form a CMT patient?
- Onion bulb formation/layers seen around the nerve
- Since nerves have been demyelinated and demyelinated so many times, they look onion-like
What are the two types of acquired metabolic/toxic neuropathies we talked about?
- Peripheral Neuropathy in Diabetes
- Neuropathies associated with malignancy
Tell me about peripheral neuropathy in diabetes:
- COMMON!
- Most common manifestation: symmetric sensory and motor neuropathy involving distal nerves
- Dec. pain sensation in distal extremities
- Some patients also have autonomic neuropathy and/or asymmetric neuropathy
- Diabetes - patients don’t heal well due to circulation
- Usually Glove & Stocking distribution
- Can develop deep ulcers!
Autoamputation:
From multiple repeated infectious lesions that heal up in a way that causes odd shaped lesions
