Page 301 Acute Pain Management
P. 301
9.6.2 Herpes zoster-associated pain
Herpes zoster (HZ) (shingles) is caused by reactivation of the varicella‐zoster virus (VZV),
which lies dormant in dorsal root and cranial nerve ganglia following primary infection with
chickenpox (varicella), usually in childhood (Schmader & Dworkin, 2008). There is a marked
increase in the risk of shingles with increasing age and with diseases and drugs that impair
immunity: the lifetime risk is estimated at 20% to 30%, and up to 50% in those who reach
85 years of age (Schmader & Dworkin, 2008).
HZ‐associated pain occurs in up to 80% of those affected and may occur before onset of the
characteristic rash (during the prodrome), with onset of the rash, or following its resolution
(postherpetic neuralgia). The pain varies in intensity and is described as ‘burning’, ‘throbbing’
or ‘shooting’; itching, dysaesthesias, and allodynia may also be present (Dworkin et al, 2008).
In the majority of cases, HZ is an acute self‐limiting disease, although not infrequently, it may
progress to postherpetic neuralgia (PHN) (pain that persists for more than 3 months after the
onset of HZ). The incidence of PHN increases with age (over 50 years), occurring in up to 75%
of patients aged 70 years or over who had shingles (Johnson & Whitton, 2004). Early, aggressive
treatment of HZ infection and pain may reduce the incidence of PHN, although data on
preventive strategies are limited.
Prevention of herpes zoster
A live attenuated VZV vaccine (Zostavax®) is available for the prevention of HZ (and PHN) in
individuals over 60 years of age. A large, multicentre, randomised placebo‐controlled trial
(The Shingles Prevention Study) demonstrated its efficacy, with a reduction in the incidence
of HZ by 51.3%, PHN by 66.5 % and HZ‐associated ‘burden of illness’ by 61.1% (Oxman et al,
2005). The estimated number‐needed‐to‐vaccinate to prevent a case of HZ was 11 (CI: 10‐13)
and for PHN 43 (CI: 33‐53) (Brisson, 2008 Level III‐3). The Advisory Committee for Immunization
Practices of the US Centres for Disease Control and Prevention recommends vaccination with
live, attenuated VZV for all persons aged 60 years or over, even if they have had a previous
episode of HZ (Harpaz et al, 2008) as has the Pharmaceutical Benefits Advisory Committee of the
Australian Government Department of Health and Ageing (PBAC, 2008).
Treatment of herpes zoster-associated pain
Antiviral agents
Acyclovir, valaciclovir or famciclovir, given within 72 hours of onset of the rash accelerated the CHAPTER 9
resolution of HZ pain (Beutner et al, 1995 Level II; Wood et al, 1996 Level I; Jackson et al, 1997 Level I;
Tyring et al, 2000 Level II). Famciclovir, in various doses and frequencies, was as effective as
acyclovir for HZ‐related outcomes, including pain (Shafran et al, 2004 Level II; Shen et al, 2004
Level II). Famciclovir or valaciclovir have replaced acyclovir as the drugs of choice in the
treatment of HZ, because of more favourable pharmacokinetics and simpler dosing profiles
(Cunningham et al, 2008).
Opioids, tramadol and paracetamol
HZ‐associated pain may be severe and early and effective treatment is essential. Multimodal
analgesia, with regular paracetamol in addition to an opioid such as oxycodone (Dworkin et al,
2007; Cunningham et al, 2008; Dwyer & Cunningham, 2002) or tramadol as required, has been
recommended.
Oxycodone CR but not gabapentin was effective in significantly reducing the average worst
pain during the first 14 days of HZ compared with placebo, although the group of patients
taking oxycodone had a much higher rate of withdrawal from the trial, primarily because of
constipation (Dworkin et al, 2009 Level II).
Acute pain management: scientific evidence 253
