Do men feel less pain due to their hormones? Recent research show that testosterone reduces the feeling of pain in males ý at least in sparrows. A research team from Belgium and USA treated male sparrows with testosterone and then measured their reaction times to a slight pain stimulus by immersing the birds’ legs in a glass of warm water. At temperatures below 51°C it took a long time before the birds removed their legs from the water.

Higher temperatures are unpleasant for the birds and they therefore react quicker with hotter water. The scientists established that at 52°C sparrows treated with testosterone left their legs in the water three times longer than untreated birds. However, if the sparrows were given a drug to block the effect of testosterone then they removed their legs even at 48°C, a temperature at which they normally showed little discomfort.

Does my patient have an increased risk of suffering from chronic neuralgia even after shingles has healed? American scientists have identified a set of indicators to assist in answering such questions. The incidence of shingles caused by the varicella zoster virus (VZ virus) related to the herpes simplex virus is about 400 in 100 000 inhabitants.

The majority of patients suffer from moderate to severe acute zoster pain in the form of neuritis lasting about one month. However, it is not uncommon for the symptoms to become chronic after the dermal lesions have healed. Post-herpetic neuralgia (PHN) occurs in approximately 20 – 25% of all shingles patients considerably limiting the quality of life of those affected and their relatives. Previously it was only known that age plays a role in the development of PHN.

Professor Dworkin and his team from the University of Rochester School of Medicine in New York examined the additional risk factors that contribute to the development of PHN. To do so the authors examined data from 965 immunocompetent herpes zoster patients from two different clinical studies. Pain persisting for 120 days after the onset of shingles was defined as PHN.

The combined analysis showed that age, gender (women develop PHN more frequently) and the severity of the acute pain were significantly associated with PHN. Both symptoms which were already noticeable before the rash had developed and its severity and dissemination affected the risk of PHN.