Treatment of Postherpetic Neuralgia

Clinical Briefs
By Louis Kuritzky, MD

Best management of postherpetic neuralgia (PHN) remains problematic, since a variety of reports suggest modest favorable effects of a diversity of interventions, with little confirmation of relative efficacy through head-to-head comparative trials. This systematic literature review included 27 randomized controlled trials felt to be methodologically sound to assess outcomes of pain and quality of life as impacted by topical (eg, lidocaine patch, capsaicin cream), oral (eg, amitriptyline, gabapentin, opioid analgesia), and other (eg, acupuncture, TENS) therapies.

Literature analysis indicated that tricyclic antidepressants (TCA) provide the best evidence for efficacy, though conclusions are limited by the short duration of trials (none > 8 weeks). Topical capsaicin, gabapentin, and opioid analgesia were also found effective. For refractory patients, methylprednisolone and bupivacaine sympathetic blocks merit consideration. Tools for which insufficient evidence to establish efficacy was found include lidocaine patch, benzydamine cream, tramadol, vincristine, and iontophoresis. Treatments deemed unlikely to be of benefit included benzodiazepines, dextromethorphan, acyclovir, and acupuncture.

Among the demonstrated effective agents, side effect profile, cost, and ease of administration ultimately determine which agent will be preferred for an individual patient.

Alper BS, et al. J Fam Pract. 2002;51: 121-128.

Plasma Homocysteine as a Risk Factor for Dementia and Alzheimer’s Disease

Elevated homocysteine (HCYS) levels have been correlated with vascular toxicity, in particular, coronary heart disease. Conflicting reports on the relationship between HCYS and cognitive function have left the issue unresolved. Data from the Framingham Study, which details the relationship between dementia (DEM), Alzheimer’s disease (ALZ) and HCYS, is presented in this study by Seshadri and colleagues.

The population studied (n = 1092) had undergone measurement of HCYS in 1986-1990, and almost all of them (86%) had had measurements obtained in the 1979-1982 time period also. Only subjects who were free of dementia at inception of the trial were included.

Over 8 years’ observation, 111 subjects developed dementia (83 = ALZ); for every 5 mcmol/L increase in HCYS, the risk of ALZ increased 40%. This progressive increase in risk was not altered by adjustment for gender or age. Interestingly, since it is well known that supplementation with folate, B12, and pyridoxine may have a favorable effect upon HCYS, adjustment for plasma levels of these vitamins did not alter the relationship between HCYS and subsequent development of DEM/ALZ. It remains to be shown by interventional trials whether reductions in HCYS can translate into reduced risk for dementia. 

Seshadri S, et al. N Engl J Med. 2002; 346:476-483.

Rapid Suppression of Alcohol Withdrawal Syndrome by Baclofen

For persons with chronic alcohol abuse habits, alcohol withdrawal is both psychologically and physically difficult, and not without risk. The distressing symptoms of withdrawal often begin 6-24 hours after initiation of abstinence, and animal studies have suggested that baclofen suppresses alcohol withdrawal syndrome symptoms. Since baclofen has also been shown to favorably effect alcohol craving and intake in persons suffering alcohol dependency, a trial to assess its use in severe alcohol withdrawal syndrome was undertaken.

Addolorato and colleagues studied 5 patients who scored higher than 20 on the Clinical Institute Withdrawal Assessment for Alcohol scale, indicative of severe alcohol withdrawal syndrome. Subjects received 10 mg baclofen orally initially, and then 10 mg orally every 8 hours for 30 days, with measurement of the Withdrawal Assessment for Alcohol scale daily for 1 week, and then weekly for the remaining 3 weeks of the treatment course.

All 5 of the patients reported rapid (within 2 hours) alcohol withdrawal symptom resolution after administration of 10 mg baclofen. Similarly, all patients were able to remain abstinent and asymptomatic using baclofen 10 mg q.8.h. The remarkably favorable outcome of this small study suggests need for a larger scale trial of this method.

Addolorato G, et al. Am J Med. 2002; 112:226-229.

Dr. Kuritzky, Clinical Assistant Professor, University of Florida, Gainesville, is Associate Editor of Internal Medicine Alert.