Investigation of neuropathic pain component by the stage of a disease of the herpes zoster associated pain patients received pain clinic treatments

Introduction: In a retrospective study on patients with zoster-associated pain, we reported the patients were associated with various neuropathic pain components and high VAS values regardless of their disease stages. In the present study, we prospectively followed another group of patients to evaluate those components in each of the stages. Subjects : The subject group was comprised of 76 patients who first visited our clinic between June 2013 and January 2015 with their onsets of zoster-associated pain within 30 days of the first visits. Methods: Two neuropathic pain screening questionnaires including the Neuropathic Pain Screening Questionnaire (Japan-Q) and the Pain DETECT Questionnaire (PDQ) were used to track the patients for six months. The questionnaires and Visual Analogue Scale (VAS) evaluations were conducted at each of the acute stage (up to 30 days from the onset), the subacute stage (one to three months) and the chronic stage (the fourth month and after). Results : Sixty-four patients remained in the subject group throughout the course of the study. The median values of the scores at the acute: subacute: chronic stages were 12 : 4 : 3 for Japan-Q, 15 : 9 : 7 for PDQ and 71.5 : 27.5 : 9.5 for VAS (mm). The numbers of patients with neuropathic pain components more strongly manifested at those stages were 53 (68%) : 14 (18%) : 10 (13%) for Japan-Q scores of 9 or higher and 61 (78%) : 35 (45%) : 21 (27%) for PDQ of 11 or higher. The correlation coefficients between the Japan-Q scores and VAS at the stages were 0.38 : 0.38 : 0.46 while the same between the PDQ scores and VAS were 0.42 : 0.29 : 0.44 indicating moderate correlations at the chronic stage of the pain with both of the questionnaires. Discussion: While dermatitis and neuritis are common complications of herpes zoster, the fact that the patients experiencing intense pain in the acute phase exhibit neuropathic pain components may suggest the severity of neuritis is more manifested than the other complication. Although the patients diagnosed in our clinic in their acute stages exhibited high scores for the neuropathic pain components and VAS, both declined over time suggesting early intervention by pain specialists may be useful in achieving good therapeutic outcomes, even though spontaneous remission may not be completely ruled out.