Comment on Paranasal sinus opacification in headache sufferers: A population-based imaging study (the HUNT study-MRI)

We have read the articles by Hansen et al. (1), published in the May issue of Cephalalgia, with great interest. The authors performed a cross-sectional study of 844 randomly selected participants using MRI and in conclusion found that migraine, tension-type headache, and unclassified headache were not associated with an increased degree of paranasal sinus opacification at MRI. Also, we have read Lal and Scher’s comment (2) on the above-mentioned article. Lal and Scher commented that the major strengths of this study were its population-based design, the large sample size, and the use of a validated headache classification. We are very grateful for the provision of excellent information about the causal relationship between rhinosinusitis and headache, which our research mainly focuses on. However, we want to make some comments about Hansen’s study.

First, Hansen’s group used the total sum of paranasal sinus opacification on MRI to compare the group of headache-free participants with each of the headache groups. They described opacification in five paired paranasal sinuses measured at their maximum thickness in millimeters and recorded if ≥ 1 mm, as opacification < 1 mm was considered normal or insignificant. We totally agree that MRI is highly sensitive for detecting mucosal thickening of the paranasal sinuses. However, we should keep in mind that an understanding of the physiologic nasal cycle is essential for interpreting the data about mucosal thickening. In normal adults, changes in the nasal mucosal volume occur cyclically, alternating from side to side, and the time course of each cycle varies from 50 minutes to six hours. Mucosal volume changes are observed in the mucosa of the turbinates, the nasal septum, lateral wall and cavity floor and nasolacrimal ducts (3). Among the paranasal sinuses, only the mucosa of ethmoidal sinuses is affected by the physiologic nasal cycle (3). Rak et al. (4) reported in their study using MRI that 1–2 mm areas of mucosal thickening in the ethmoid sinuses occur in 63% of asymptomatic patients and this minimal mucosal thickening in the ethmoid sinuses is thought to be a normal variant, possibly a function of the physiologic nasal cycle. Also, they concluded that mucosal thickening of up to 3 mm is common and lacks clinical significance in asymptomatic patients, since statistically significant differences between symptomatic and asymptomatic groups were seen only in those patients with normal sinuses and in those with 4 mm or more of mucosal thickening (4).

Second, as Lal and Scher mentioned (2), the most important change of the diagnostic criteria for 11.5 in ICHD-III beta is that chronic rhinosinusitis (CRS) has been recognized as a cause of headache if confirmed by careful objective criteria and temporal correlation since recent studies have supported causal relationships. However, otolaryngologists usually use clinical diagnostic criteria established by the 1997 Task Force on Rhinosinusitis (RSTF) of the American Academy of Otolaryngology–Head and Neck Surgery and updated in the 2016 International Consensus Statement on Rhinosinusitis (ICOR). Since prior studies using RSTF criteria have shown poor correlation between symptoms and endoscopic or radiographic evidence of CRS, updated 2016 ICOR diagnostic criteria emphasized the need for objective evidence of sinonasal inflammation to confirm the diagnosis of CRS (5). However, they may overestimate the prevalence of CRS since both criteria still include pain as a symptom contributing to its diagnosis (5). Recently, Hirsch et al. (5) reported that removing facial pain, ear pain, dental pain, and headache in clinical diagnostic criteria increased specificity without a concordant loss in sensitivity.

Last, we want to point out one minor correction. In the part of study sample, the age range of enrolled participants was different. In the second paragraph, the age range was between 50 and 65, but in the last sentence, the age range was described as “between 50 and 66”.