Post herpetic neuralgia

Question 1

what causes post herpetic neuralgia?

Answer 1

herpes zoster (reactivation of latent varicella zoster virus infection

Question 2

Symptoms of herpes zoster or shingles?

Answer 2

unilateral dermatomal rash, may have systemic symptoms of fever, malaise, headache prior to rash development.

Question 3

Two time intervals that define herpes zoster rash is based on time interval:

Answer 3

acute neuritis (pain that is up to 30 days from rash onset or subacute neuritis (pain that resolves within 4 months of rash onset)

Question 4

treatment of symptoms of herpes zoster (name the tx)

Answer 4

NSAIDS, Tylenol, opioid combinations

Question 5

What is post herpetic neuralgia

Answer 5

persistent pain 4 months after rash onset and about 10-15% of pts who have herpes zoster develop this.

Question 6

Treatment of post herpetic neuralgia (PHN)

Answer 6

tricyclic antidepressants (nortriptyline, desipramine)

start low and tirate to lowest effective dose

can use pregabalin or gabapentin, or topical lidocaine patches or opiods

Question 7

Side effects of TCAs?

Answer 7

arrhythmias

most anticholinergic - dry mouth, constipation, dizziness, sedation

Question 8

Do we ever use carbamazepine?

Answer 8

no. IT’s more for trigeminal neuralgia (related to compression of cranial nerve 5, not used to tx PHN.

Question 9

Do we every use capsaicin cream in post herpetic neuralgia?

Answer 9

not a first line because it causes intolerable stinging or burning or erthyema in 1/3 of pts. Can be used for moderate cases

Question 10

Does antiviral therapy help with post herpetic neuralgia PHN?

Answer 10

YEs only if given within 72 hrs (decreases length and severity of symptoms) in pts >50 yrs and uncomplicated herpes zoster

Question 11

What antiviral therapies are used to tx herpes zoster?

Answer 11

acyclovir, famciclovir, valacyclovir for 7 days.