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Herpes Zoster (Pathophysiology (Resulting in perineurial and intramural…
Herpes Zoster
Pathophysiology
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In immunocompromised patients, the most frequent site of reactivation is the thoracic nerves followed by the ophthalmic division of the trigeminal nerve
When latent virus is reactivated in the dorsal root ganglia it travels down the affected nerve via the sensory root in DERMATOMAL DISTRIBUTION over a period of 3-4 days
Can also affect the cervical, lumbar and sacral nerve roots
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Clinical Presentation
Malaise, myalgia, headache and fever can be present
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Rash - consists of papule and vesicles RESTRICTED to SAME DERMATOME - neuritic pain, crust formation & drying occurs over the next week with resolution in 2-3 weeks, patients are infectious until lesions are dried, RASH DOESN'T EXTEND OUTSIDE DERMATOME
Key Facts
Primary infection with VZV causes chickenpox, following which the virus remains latent in sensory ganglia
Development of shingles may indicate a decline in cell-mediated immunity such as that due to age or malignancy
Caused by reactivation of varicella zoster virus, usually within the dorsal root ganglia
Risk Factors
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HIV, Hodgkin's lymphoma and bone marrow transplants
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Differential Diagnosis
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Atopic eczema, contact dermatitis, herpes simplex or impetigo
Before rash appears the pain may come from chest or there may be abdominal pain - may think cholecystitis or renal stones
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Complications
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Post herpetic neuralgia - pain lasting for more than 4 months after developing shingles. Treat with tricyclic antidepressant, anti-epileptic, anti-convulsant
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