Our study included 130 patients with migraine-type headache according to 3rd edition (ICHD-III-beta). We found that 81.5% of them were misdiagnosed and managed as sinusitis. The similarity of sinusitis symptoms and migraine complicates the diagnostic evaluation process. Although both historical and new data show that nasal symptoms frequently accompany a migraine, these symptoms are not required by the ICHD-III-beta diagnostic criteria for a migraine.
Our data are in agreement with the study of Schreiber and colleagues  which included approximately 3000 patients with a history of self-described or physician-diagnosed “sinus” headache and they determined that 80% of patients met ICHD criteria for migraine. Our data are also in agreement with the other previous studies [3, 9, 14, 15] which reported that “sinus headache” is one of the most commonly reported terms used in combination with a migraine diagnosis and most patients presenting with a “sinus headache” may not actually have a rhino sinusitis associated headache.
Migraine can be mistaken for rhinosinusitis because of similarity in location of the headache and the commonly accompanying nasal autonomic symptoms. The presence or absence of purulent nasal discharge and/or other features diagnostic of acute rhinosinusitis help to differentiate these conditions . In order to properly establish a diagnosis of migraine, it is essential to know the ICHD criteria and apply these criteria in clinical practice.
We demonstrated that chronic migraine was significantly higher in patients misdiagnosed with sinusitis. MOH was reported only in those patients. A delay in the diagnosis of migraine led to chronification of the headache and transformation, in some cases, into MOH.
We found that the diagnosis of migraine was delayed in more than 80% of our cohort up to 38 years. Eross and colleagues  similarly found that their patients waited 25.3 years (longest of 62 years) prior to the correct diagnosis. Previous studies showed this as well [4, 5]. The diagnostic delay in our cohort could be explained by the presence of sinus pain, sinus congestion and nasal discharge during headache attacks. These symptoms have been reported with previous studies which concluded that presence of autonomic symptoms during migraine attacks often leads to confusion and incorrect diagnosis of sinusitis [16, 17]. The ICHD criteria do not highlight the presence of cranial autonomic symptoms in the disorder, or perhaps more usefully comment upon them. This may help general practitioner and otorhinolaryngology specialist to be aware of the phenotyping overlap.
The majority of our patients had at least one investigation looking at the sinuses which were all normal. This result is similar to previous results which demonstrated that patients with “sinus headache” did not have findings suggestive of sinusitis on endoscopy or CT scan  and over 50% of them were diagnosed with migraine later . These unnecessary investigations increase time delay to obtain the correct diagnosis and management .
We demonstrated that 56% of the misdiagnosed patients had consulted a primary care physician and 44% of them an otorhinolaryngology specialist before the diagnosis of migraine was made. We are in agreement with Foroughipour and colleagues  who studied 58 patients with the diagnosis of sinusitis made by a primary care physician. After comprehensive otorhinolaryngologic and neurologic evaluation, the final diagnoses was migraine in 68% of the patients. Furthermore, our study demonstrated that the misdiagnosed patient received either medical in 87.7%, or surgical treatment in 12.3% of them without relieve of their symptoms in 84.9% and 76.9% respectively. However, migraine headache improved in 68.9% after proper diagnosis and treatment. These results are similar to that of Foroughipour and colleagues  who reported that recurrent antibiotic therapy was received by 66% patients and therapeutic nasal septoplasty was performed in 16% of the patients with a final diagnosis of migraine.
An appropriate recognition of migraine in patients who complain about sinus headaches may help to minimize the suffering and unnecessary interventions, start migraine directed therapy  and improve quality of life .