Shingles and brain abcess Flashcards
Aetiology and PPx of Shingles?
(VZV) usually within the dorsal root ganglia, primary infection with VZV caused chickenpox, following which the virus remains in the sensory ganglia. Development of shingles can suggest a decline in cell-mediated immunity due to increasing age or malignancy.
Epidemiology of shingles:
90% of children are exposed to varicella zoster (chickenpox) before 16, however this an affect all ages and incidence and severity increases with age. Shingles is seen as a disease of the elderly, but anyone over 70 is eligible for shingles vaccine. Shingles CANNOT be caught from contact with a person with chickenpox.
Risk factors of Shingles?
1) Increasing age
2) Immunocompromised
3) HIV, Hodgkins, bone marrow transplant
Pathophys of shingles?
1) Viral infection affecting peripheral nerves. 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. This results in perineurial and intramural inflammation.
2) In immunocompromised patients, the most frequent site of reactivation is the thoracic nerves followed by the ophthalmic branch of the trigeminal nerves. Can also affect C, L, S nerve roots.
3) Person with sweeping shingles rash can cause chicken pox in a non-immune person after close contact.
Clinical presentation of Shingles?
1) Pre-eruptive phase - pain and parasthesia with no skin lesions within dermatomal distribution (lasts for days).
2) Myalgia, malaise, fever, headache may be present.
3) Eruption - may be over a week this this phase - rash appears consisting of papules and vesicles WITHIN dermatomal distribution and does not extend beyond.
4) Drying and crust formation occurs over the next week with full resolution within 2/3 weeks, patients are infectious until lesions are dried.
Differential diagnosis of shingles?
1) Before rash appears pain may come for chest or abdomen - cholecystitis, or renal stones.
2) Cluster headaches and migraines
3) Atopic eczema, contact dermatitis, impetigo, herpes simplex
Diagnosis of shingles?
1) Clinical - eruption of rash is diagnostic
Treatment of shingles?
1) Oral antiviral therapy must begin within 72 hours of rash (to minimise risk of Post-herpetic neuralgia): Oral Aciclovir (x5D) OR Oral Valaciclovir (x2D) OR Oral Famciclovir (x2D)
2) Topical antibiotic treatment for secondary bacterial infection
3) Analgesia - iBuprofen
What complications can occur with shingles?
1) Ophthalmic branch of trigeminal nerve if damaged will affect sight.
2) Post-herpetic neuralgia (PHN): Burning, intractable pain lasting for more than 4 months after developing shingles, occurs in 10% of patients (often elderly), and this pain responds poorly to analgesics.
How do you treat post herpetic neuralgia?
1) TCA - amitriptyline
2) Gabapentin
3) Carbamazepine
What is a brain abscess?
A pus-filled swelling in the brain
Aetiology of a brain abscess?
1) Infection - extensions of sepsis from the middle ear/sinuses
2) Trauma or surgery to the scalp
3) Penetrating head injuries
4) Embolic events - from endocarditis
Clinical presentation of a brain abscess?
1) Depends on site of abscess - those in critical areas such as motor cortex will present earlier with focal neurological signs.
2) Signs of raised ICP - headache, drowsiness, vomitting, ALOC, papilloedema.
3) Systemic signs of infection
Treatment of brain abscesses?
1) Surgical - craniotomy with abscess cavity debridement (may reform since head is closed during surgery)
2) Antibiotics: IV Vancomycin, IV Ceftriaxone + IV Metronidazole
3) Steroids to decrease ICP - dexamethasone
