Chin Med J (Taipei) 1998;61:S28.

Update in the Management of Postherpetic Neuralgia

Ping-Wing Lui, M.D., PhD.

Division of Neuroanesthesia, Department of Anesthesiology, Veterans General Hospital-Taipei, Taipei, Taiwan, R.O.C.

Abstract

The epidemiology and pathogenesis of herpes zoster have well been characterized in numerous clinical studies. After the remission of the acute phase, some patients are predisposed to develop postherpetic neuralgia in the affected area, which may persist life-long and fail to respond to most currently available treatments.

Treatment of Established Postherpetic Neuralgia (PHN):

* Topical application of aspirin/diethyl ether (ADE),lidocaine, EMLA or capsaicin cream --- a double-blind, controlled trial of topical ADE or lidocaine attenuated pain with a short-term benefit. Burning pain was elicited during the application of capsaicin, which was intolerable to some patients.
* Tricyclic antidepressant drugs (amitriptyline, desipramine) --- serotonin-selective TCAs were of little value and with many adverse effects.
* Anticonvulsant drugs (carbamazepine) --- reduced lancinating neuropathic pain, but was ineffective for continuous pain.
* Neuropharmacologic interventions --- neuroablation was treatments of last resort for intractable pain. TENS provided partial relief of pain, but deserved a try because of its noninvasiveness.
* Iontophoresis of corticosteroid --- 60-80% PHN patients gave good response.
* Epidural spinal cord stimulation --- of some value.

Prevention of PHN:
* Corticosteroids --- the effect was controversial
* Sympathetic nerve blocks (early intervention) --- reduced acute pain but was uncertain whether they could provide prevention
* Antiviral drugs --- oral famciclovir (500 mg, tid, 7 days) was effective
* Combination therapy --- prednisolone (40 mg daily) + acyclovir

Future Approaches:
* Well controlled clinical studies are needed
* Early interventions with TCA or anticonvulsant
* NMDA antagonists (ketamine, dextromethorphan)
* Immunization, of high risk patients (with live Oka-strain vaccine)

[Chin Med J (Taipei) 1998;61:S28.]