Discussion
Headache is a common finding in preschoolers. In this study, we analyzed the clinical features of these patients and found that the headaches were relatively benign. In the case of headache in preschool children, it is often difficult to listen to accurate history. However, since about 40% of headache can be diagnosed according to ICHD 3-beta, clinician's efforts should be made for this. There are few studies about headache in preschoolers compared to school-aged children [
4,
7,
8]. Also, those studies mainly analyzed only primary headache or migraine, one of the most common diagnoses. This study did not limit participants to those with a specific diagnosis; rather, it included all patients with primary or secondary headache. We also focused on more specific age groups, so detailed aspects of headache in preschools could be investigated according to various factors.
Checking the results of this research in detail, the number of patients tended to gradually increase with age. Hernandez-Latorre and Roig [
9] showed that more patients in the older groups experienced their first headache, while the number of patients with headache visiting the hospital increased with age until 7 years of age. There were only a few patients in the relatively younger groups, especially the group <3 years of age, even with no female patients. Parents may miss the expressions of headache that their young kid tries to show or misunderstand the specific symptoms shown by kids as just routine complains due to the linguistic limits of children that age.
With regard to the proportion of male to female patients with headache, Mavromichalis et al. [
10] showed that the sex ratio of patients with headache who are younger than 7–9 years was half and half, similar to Laurell et al. [
11] In the current study, the prevalence of headache in male patients consistently increased with age except in the age group <3, which included only 2 male and no female patients. In other words, the rate of male patients with headache was low in the younger groups, whereas that of female patients decreased gradually as age increased. Interestingly, there were a few suggestions in Korea such as the study of Hong et al. [
3] with low ratio of female headache patients of younger ages. That article has some similarities with the current research: the patient data were collected in single Korean hospital for relatively short period and shared the Korean social stereotype that males should be braver than females. Those variables might have caused the differences in the male and female ratio in Korean reports compared to articles from other countries.
Mean disease duration was 5.8±7.9 months in this study. In addition to duration, other factors such as pain severity or frequency would affect the degree of suffering in daily life, which may lead headache patients to visit hospitals and obtain clinical treatment. Considering attack frequency first, in the current study, 65.8% of patients reported a headache more than 1 time per week, whereas 12.3% experienced pain less than once per a week. Battistella et al. [
4] showed that 61% of preschoolers had more than 1 attack per week: 1–3 attacks per week in 47%, and more than 4 attacks per week in 14%. This result is similar to that of the present study in terms of the percentage with a frequency greater than half of all of the subjects.
The attack duration is generally shorter in younger children [
3]. Battistella et al. [
4] showed that the attack lasted for less than 1 hour in 52% of preschooler subjects, 1–2 hours in 20%, 2–5 hours in 18%, and >5 hours in 10%. Raieli et al. [
7] suggested that 76.6% of the headache patients <6 years of age reported an attack duration of <1 hour, whereas 18.9% and 43.2% complained of pain for 1 hour and <2 hours, respectively. These studies support the results of this study on attack duration since almost half of the preschool patients reported having the attack for <2 hours and fewer subjects reported a duration of >2 hours.
Considering pain location in the current study, lateral areas were most commonly affected, followed by parietal and occipital areas. Virtanen et al. [
8] suggested that 6-year-old patients reported bilateral (80%), forehead (77%), above the eyes (71%), unilateral (24%), whole head (16%), occipital (8%), and temples (5%) as the pain locations. Despite differences in options, the results were similar within the current study in the way that unilateral and bilateral pain was commonly reported compared to relatively less common pain in the occipital areas. The majority of patients in the current study reported having no accompanying symptoms. Nausea or vomiting was mentioned by patients with any related symptoms, followed by photophobia or phonophobia and dizziness. Battistella et al. [
4] showed that 54% of preschool patients reported phonophobia, followed by 52% with photophobia, 20% with nausea, and 18% with vomiting. Similarly, Eidlitz-Markus et al. [
12] suggested that photophobia (56%) and phonophobia (54.3%) were the most common associated symptoms in patients younger than 7. They also reported that vomiting (44%) and nausea (12.4%) took the second rank, whereas only 1.9% of the patients experienced dizziness. The current study had some gaps compared to prior studies in terms of having a relatively smaller percentage of patients with these 2 associated symptoms, but the most patients had nausea or vomiting.
Topics such as pain location and related symptoms are quite subjective due to patients’ level of ability to express their pain, but >40% of patients could not explain their pain. Especially for related symptoms, preschoolers were unable to express themselves fluently, which makes their symptoms underestimated or differently estimated. They also might not be able to clearly understand some of the difficult symptoms of the questionnaires. Also, the answering rate of “unexplained” decreased considerably in attack frequency (21.9%) or attack duration (30.9%). This might have happened because those topics could be answered by parents who closely observed their young children. However, even these meticulous parents could not completely recognize attack frequency and duration since some significant moments were missing or forgotten. Finally, only 2 patients (1.4%) could not explain the disease duration. This may imply that the disease duration is a relatively easier topic to answer broadly for both children and parents compared to other topics.
The average VAS score for pain severity was 5.1±2.2, in which a score of 0 means no pain and a score of 10 stands for the most severe pain. Patients express pain severity using a specific number based on their thoughts or feelings. Despite VAS subjectivity, the answering rate (62.3%) was relatively high among the topics for which only the patients themselves can provide an exact answer. Various facial expressions are accompanied by scores in the survey, which might help preschoolers understand the scale [
13]. Mirshra et al. [
14] investigated headache severity using the VAS for children >6 years of age, and the Faces scale by the International Association for the Study of Pain was used for 3- to 6-year-old children. They suggested that 7.1% of patients reported a pain degree as a score of <3, 31.0% reported a score of 3–5, 47.6% had a score of 6–8, and 14.3% had a score of 9–10. Although the exact data were not given, the average VAS score was derived as approximately 6.0±3.1 using the median value of each score [
14]. Small gaps in the score compared to the present study could be considered quite marginal if considering a wider range of subject age and smaller number of subjects.
A family history of headache was reported by 28.1% of patients in this study. Some articles suggested that a family headache history, especially maternal, is significantly correlated with headache in childhood [
15]. Cuvellier et al. [
16] showed that 73.5% of pediatric patients had a family history of headache, and the maternal history was the highest at 61.7%. Cavestro et al. [
17] suggested that >90% of children aged 3–5 years with headache had a positive family history of headache similar to the findings of the study by Kroner-Herwig et al. [
18] Also, environmental or social factors shared with family members could affect the occurrence or aggravation of childhood headache. Children with headaches seem to have fewer caring people [
19] and parents with a lower education level than children without headache [
20].
None of the blood test findings was abnormal except in 1 patient with a clinically high level of TSH (12.62 μIU/mL) diagnosed with subclinical hypothyroidism. Hagen et al. [
21] reported that headache was less probable in women with a TSH level≥10 mU/L than in those with a normal TSH (0.2±4 mU/L). In contrast, Harbeck et al. [
22] suggested that a TSH deficiency was associated with fewer headaches than an adequate TSH level. Although controversial suggestions persist and only 1 patient in this study had an abnormal TSH level, there might be a correlation between headache and TSH level. Therefore, it would be meaningful if future studies could investigate the connections between them and include sufficient subjects with a high TSH level.
Brain MRI and EEG were used to identify the causes of headache, especially for secondary headaches such as congenital malformation. Park et al. [
23] reported that 3 of 53 children had unusual results including subdural hematoma, cavernous hemangioma, or subarachnoid cyst. They also suggested that 17% of the patients had abnormal EEG outcomes including abnormal background activity (7.5%), focal spike/sharp (7.5%), or paroxysmal slow wave (1.9%). In this study, sinusitis was considered as the cause of secondary headache, and with congenital abnormality, thought to be the cause of headache in about 12% of all patients. Although only a few patients had positive findings in both studies, a future study including a number of patients with positive results on brain MRI and EEG would be helpful to aid our understanding of the characteristics of preschoolers with headache.
The most common headache-related diagnosis of children is migraine, followed by tension-type headache, similar to the diagnosis patterns seen in adults [
3]. Mavromichalis et al. [
10] suggested that 6.2% of 4- to 6-year-old patients had migraine, and the prevalence of migraine increased gradually with age as in other studies [
3,
10]. The results of this study similarly showed a tendency for the percentage of migraine or probable migraine to be the highest, followed by tension-type headache. In the current study, 71.2% of patients did not have specific diagnoses. Inclusion of data from a limited place and time might have caused this result; in addition, the ICHD 3-beta version has less diagnostic power for children.
Acetaminophen, ibuprofen, and naproxen sodium were used in a total of 26 patients in this study and are usually applied for children patients with acute headache [
24]. Topiramate and amitriptyline were chosen as preventive medicines for 3 patients. According to Ahn and Shin [
24], these treatments are recommended if headache occurs more than once per a week or severe headache causing the child to be absent from school occurs more than once per month. Piazza et al. [
25] reported that half of patients were treated with acute medication such as ketoprofen or paracetamol and 13.6% took a prophylactic pharmacological treatment. They suggested that medication overuse in headache therapy is a problem and that rational treatments are necessary to improve most patients. Regarding prognosis, more than half of patients improved, 3 underwent transfers to the department of neurosurgery, and 1 was transferred to the department of neurology. Tracing them, 2 patients showed repeated improvement and degeneration that resulted in subsequent hospital visits, while the other 2 were lost to follow-up. Kienbacher et al. [
26] suggested that some factors such as female sex or longer follow-up period would positively affect the prognosis despite controversy and that early intervention might improve the prognosis of migraine and tensiontype headache in children and adolescents.
The present study has 2 limitations. First, prospective data accumulation would be required to decrease losses and ensure study accuracy. Also, we had difficulty finding the exact data needed in the retrospective medical chart reviews. The other limitation is that the current study was based on the data of patients at a single medical center during a relatively short period of time. Extending the record review period and performing consistent follow-up for each patient would enable the collection of broader data. It would also be of great help to collect additional patients by cooperating with other hospitals and then draw more universal conclusions.
The present study aimed to aid in the understanding and diagnosis of headache in childhood by investigating the various characteristics of preschoolers with headache. In summary, headache in preschool children has a relatively benign course, and diagnosis is possible according to ICHD 3-beta if history taking is detailed. In some cases, the cause of secondary headache can be identified through various investigations. In the future, more studies focusing on headache in this young age group are needed that will consider the features of children with headaches by age.