Gulf War Illness Nasal Irrigation Study

Inclusion Criteria: * English fluency and basic reading and writing literacy. * Deployment to the Persian Gulf (e.g., Iraq, Kuwait, Saudi Arabia) for the purpose of Operation Desert Shield or Operation Desert Storm during the first Gulf War (1990-1991). * Meeting criteria for a diagnosis of GWI as based on the "Kansas" GWI case definition; only the Kansas case definition (from among the several currently used case definitions) can differentiate between Gulf War-deployed and non-deployed Gulf era veterans. * Meeting criteria for a diagnosis of chronic rhinosinusitis (CRS) using self-reported symptoms and based on clinical guidelines; eligible subjects will report: • sinonasal symptoms for at least 12 weeks; • a constellation of sinonasal symptoms including either two or more major factors, or 1 major and 2 minor factors (see Table 1 below), or chronic nasal purulence for 12 or more weeks; and • a moderate to severe HRQoL impact (≥ 3 points on a 0-10 Likert severity scale) as assessed by a single item question:11 "What has been the average level of your sinus symptoms daily over the past month on a 0-10 scale?" This item is consistent with eligibility criteria used in prior NI studies. * Chronic fatigue of moderate-to-severe severity defined as scoring at least 3 points on a single question (0-10 Likert scale): "What has been the average level of your daily fatigue over the past month on a 0-10 scale?" Exclusion Criteria: * Self-reported pregnancy. * Current use of liquid NI…