The prevalence of headache disorders, including migraine, tension-type headache, and MOH, is high . In population-based studies, migraine was found in 9.6 to 24.6%, and 1-year prevalence of TTH is in a wide range between 15 and 90%. In an Egyptian study conducted in Fayoum Governorate, the observed 1-year prevalence of migraine and episodic TTH was 17.3 and 24.5% respectively . In our series, we found that primary headache was present in 89%, while secondary headache in 10.2% and painful cranial neuropathy in 0.8%, and these results are in line with Guerrero and colleagues  who reported that primary headaches was present in 77.1% and secondary headaches in 10.9%. Among the total headache participants, we found that the percent of migraine and TTH was 50.6% and 33.6% respectively. The percent of other primary headache and TACs was 2.6% and 2.2% respectively. These results are consistent with those obtained from previous studies [20,21,22,23,24].
Pedraza and colleagues  reported that primary headache was present in 72% and secondary headache in 12%, and among the primary headache group, migraine was present in 53%, TTH in 10.5%, TACs in 2.5%, and other types of primary headache were present in 5.9%, and they explained the low rate of TTH in their series by the lower impact of TTH on the patients, and few patients seek medical consultation for their headaches .
In a Hungarian study conducted on 327 patients, primary headache migraine was found in 42%, TTH in 31%, cluster headache in 1%, and 26% had a combination headache . Many previous studies documented that migraine is the most frequently assigned diagnosis in specialist clinics or headache units [12, 25,26,27,28].
Although some previous studies reported that TTH is the most common type of primary headache all over the world , migraine was the most common presentation in our series, and this may be explained by the under-recognition of TTH by patients and health practitioners for its less disability than migraine.
In contrast, a Turkish study was conducted in 245 of headache patients and revealed that TTH was present in 70% and migraine only in 44.9%,  and this difference may be explained by a relatively small number of patients and different methodology as they used the ICHD-II criteria.
We reported that only 2.2% of total patients corresponds to TACs which is in line with the results obtained by Guerrero and colleagues  who reported that TACs were present in 2.6% of the patients and lower than that obtained by Dong and colleagues  who reported 5.3% of total patients were classified into TAC which may be explained by regional and racial reasons.
In our series, we found only 0.8% of the participants corresponds to painful cranial neuropathy namely trigeminal neuralgia, which is low frequency in comparison to Pedraza and colleagues  who reported that about 4% of the patients’ headaches corresponded to cranial neuralgias while Felício and colleagues  reported that 2.6% of the participants suffer from cranial neuralgias. This difference may be explained by the painful cranial neuralgias particularly trigeminal neuralgia (TN) which is a relatively rare condition with a lifetime prevalence of up to 0.3% , and most patients with TN consulted their dentist first.
As in previous studies [12, 19, 31], we found a low frequency (10.2%) of secondary headache. Among the patients with secondary headache, we found that the percent of MOH was 5.3% of total headache participants and 27.5% of the patients with secondary headache, a finding confirmed by previous studies [25, 32]. However, other studies reported higher frequency of secondary headaches ranging from 22.1 to 42% in which participants were selected from the emergency departments [33,34,35,36] because most of the emergency room (ER) doctors recognize headache as a disease with underlying somatic reasons, and some racial, regional, selection bias may contribute to these differences.
In this work, we found that headache attributed to cranial and/or cervical vascular disorder (group 6 of ICHD-III) which had been rarely observed (1.4%), and this may be due to the patients with cerebrovascular events, mostly coming to the emergency room (ER), and headache as a symptom may not attract the attention of the ER doctors.
We found women’s dominance in primary headache, particularly migraine because of the well-established hormone influence in migraine . The percent of female participants was 73.8% of the total number of the patients with male to female ratio of 1:2.3 which is in line with worldwide prevalence data from the 2015 Global Burden of Disease Study  showing that migraine is two to three times more prevalent in women than in men. Okumura and colleagues  reported that migraine about 3 times higher rate was observed in female than in male patients.
In the current study, we found that male to female ratio for TTH is 1:5 which indicates that women are more prone to TTH than in men, and this is in line with the previous studies that have reported that tension-type headache is more frequently seen in women with male to female ratio of 1:6 [39,40,41]. In contrast to El-Sherbiny and colleagues  who reported that male to female ratio for TTH was 2:3, Stovner and colleagues  observed that male to female ratio for TTH was 4:5 which is lower than our results as most of our series are females (73.8%) who consists about three fourths of the total number of the participants, and women are more likely to seek medical advice.
We found that episodic migraine was found in 40.6% of the total number of headache patients, chronic migraine in 10%, episodic TTH in 29.2% of the total number of headache participants, chronic TTH in 4.4%, and episodic cluster headache in 0.8% of the total number of headache participants, and this in agreement with previous study which reported that episodic migraine was present in 35.3%, chronic migraine in 3.9%, episodic TTH in 45.3%, chronic TTH in 5.6%, and cluster headache in 3.4% . Like previous studies [8, 43], we also found that primary headache disorders, especially, migraine is more common in urban areas.
This study is a cross-sectional study and not a population-based survey; moreover, patients with unclassified headache disorders (group 14) were excluded from this study; therefore, the data cannot be used to accurately estimate the prevalence of primary headaches, and epidemiological studies will be needed. Our data based on clinical background including Arabic version of headache questionnaire and brain imaging studies were not routinely done for all patients, and finally, we did not do any anxiety or depression scale for patients with TTH to investigate the underlying anxiety or depression. In spite of these limitations, the present study has shown the frequency and characteristics of different headache disorders according to ICHD-III.