[Herpes Zoster and post-herpetic neuralgia: everything to revise?]

The treatment and prevention of the algic symptomatology of Post-Herpetic Neuralgia (PHN) are problems still to be solved. In our opinion the reason of this failure is to be found in an insufficient knowledge of the pathophysiological phenomena which cause the PHN. In fact, many fundamental aspects, such as its "temporal" and symptomatological definition and its pathogenesis are still unsolved. This revision tries to focus the problems and discrepancies hindering an improvement in PHN treatment and prevention. The literature reports three different symptomatological levels after herpes zoster acute phase: patients affected by pain and/or allodynia, patients with "abnormal sensations" (anesthesia, paresthesia, dysesthesia, prickling, itching, burning, etc.,) and patients in "complete recovery". Only two studies have analyzed the final incidence of these symptomatologies. Therefore, it is absolutely unclear whether the patients in "abnormal sensations", that is with a symptomatology which is definitely less weakening than pain, have to be considered in PHN (patients with pain) or in "complete recovery". On the contrary, from a clinical and physiopathological point of view this symptomatological difference may have a great importance: the symptomatological non-distinction could be the cause of the disagreement concerning PHN incidence data; this distinction could differentiate and compare in a reliable way the effects of the various therapies reported in the literature. The lack of a symptomatological classification does not facilitate a verification of the physiopathological hypothesis of PHN onset and maintenance. The differentiation among pain, "abnormal sensations" and "complete recovery" could correlate these three symptomatological conditions to the anatomopathological and viral data which according to literature characterize the evolution of Herpes Zoster acute phase in PHN. This would largely help to improve the therapeutic strategy.