A new study has found that those who experience migraines are more likely to develop tinnitus than those who do not[i]. The researchers report that these findings support the newly-proposed concept of ‘cochlear migraine’. A commentary article, reporting on the study, helps to place these findings in context[ii].
The existence of a distinct disorder, known as ‘cochlear migraine’, could be suggestive of an alternative cause of hearing loss to, for example, noise exposure.
Researchers propose a diagnosis of ‘cochlear migraine’ when cochlear dysfunction (hearing loss, tinnitus, sudden deafness) and migraine both occur at the same time.
This disorder is distinct from vestibular migraine or Meniere’s disease, because there is no dizziness or vertigo involved. It is therefore important to consider the relationship between migraine and dizziness. Episodic dizziness is highly prevalent and it is symptom of both vestibular migraine and Meniere’s disease.
In this feature article, we provide an outline of migraine, vestibular migraine and Meniere’s disease, as ‘cochlear migraine’ diagnosis is based on both vestibular migraine and Meniere’s being ruled out. We go on to introduce the concept of ‘cochlear migraine’ and discuss the findings of the new study.
What Are Migraines?
Migraine is a condition of altered sensory perception[iii], not a synonym for headache. Although most common types of migraine involve a headache, many do not.
A common, or classical migraine, often presents itself as a moderate to severe headache felt on one side of the head. The headache can often be accompanied by symptoms such as nausea, vomiting, and increased sensitivity to light and sound. Migraines usually begin in early adulthood and are common. According to the NHS, approximately 1 in 5 women (20%) and 1 in 15 men (7%) are affected[iv].
Types of migraine, include:
- Migraine with aura: there are specific warning signs just before the migraine begins, e.g. seeing flashing lights;
- Migraine without aura: the migraine occurs without specific warning signs. This is the most common type;
- Migraine aura without headache, or silent migraine: an aura, or other migraine symptoms, are experienced, but without any headache.
As such, headache is a symptom of migraine, but not all patients with migraines have headaches.
The exact cause of migraine is unknown, though it is thought to be due to temporary changes in the chemicals, nerves and blood vessels in the brain. In the past, it was thought that migraine was mainly due to changes in blood vessels in the brain, but emerging evidence suggests that migraine is caused by nerve cell changes. It is not clear what causes these changes, but it is possible that some people have a genetic predisposition to migraines.
In some cases, migraine attacks may be triggered by certain foods or drinks, stress, tiredness, menstruation, and a range of other factors. The NHS website lists shift work as a physical trigger for migraine[v].
Vestibular migraine and Meniere’s disease are two disorders which may result in individuals experiencing vertigo.
The link between migraine and vertigo has been recognized since the 19th century. In the past 30 years, the diagnosis of vestibular migraine, a disorder in which the patient experiences both migraine and vertigo, has arisen.
Vestibular migraine is typically associated with nausea, vomiting, sweating, flushing, diarrhoea and visual changes, such as blurring, flashing lights and difficulty when focusing. Patients may also have difficulty concentrating, face heightened sensitivity to light and sound, and suffer with fatigue[vi].
A vestibular migraine patient experiences recurrent vestibular symptoms, such as balance disorders, a spinning sensation (vertigo), and migraines, generally at the same time. As a result, other causes of the vestibular symptoms are usually excluded.
The criteria for vestibular migraine is at least 5 episodes of moderate to severe ‘vestibular symptoms’, lasting from 5 minutes to 72 hours, a current or previous history of migraines (with or without aura), and one or more migraine features (migraine-like headache, heat/light sensitivity, aura) experienced during most of the vestibular episodes[vii].
‘Vestibular symptoms’ that qualify for the diagnosis of vestibular migraine include spontaneous vertigo (perception of either a person or surroundings spinning, with no external cause), vertigo that occurs after moving the head, vertigo triggered by moving visual stimulus, and dizziness and nausea caused by motion of the head.
Meniere’s disease is a condition of the inner ear that causes sudden attacks of:
- Vertigo – feeling of spinning
- Feeling of pressure or fullness in the ear – aural fullness
- Hearing loss
Meniere’s patients may also experience nausea or vomiting. Symptoms typically happen all at the same time, and an episode can last for several minutes or hours. It can take more than 1 day for symptoms to completely disappear. Usually 1 one ear is affected, but over time the condition may develop in both ears. An attack of hearing loss without vertigo is uncommon. Attacks can occur in clusters or several times within the same week, but may also be separated by weeks, months or years[viii]. The NHS website lists migraine among the factors thought to increase the risk of Meniere’s disease[ix]. As the disease progresses, hearing levels may fluctuate, but not return to normal, and may eventually remain below a 60 dB hearing level[x].
Meniere’s is often used synonymously with endolymphatic hydrops. Endolymphatic hydrops is a disorder of the vestibular system, which is the body system responsible for balance and spatial orientation. Endolymphatic hydrops is thought to result from abnormal fluctuations in endolymph fluid, which fills the hearing and balance structures of the inner ear. All Meniere’s patients have endolymphatic hydrops, but it is possible to be diagnosed with endolymphatic hydrops without having Meniere’s[xi].
It was previously believed that migraine activity would be unlikely to produce cochlear symptoms, such as hearing loss and tinnitus. The presence of sensorineural hearing loss has been suggested to be the main difference between those with Meniere’s and those with vestibular migraine; it was assumed that those with Meniere’s would have hearing loss and those with vestibular migraines would not. However, there is a growing body of evidence, to which this new study adds, of association and causal relationship between migraine and development of cochlear symptoms.
A novel diagnosis of ‘cochlear migraine’ is proposed by the authors of a new study[xii]. The researchers arrived at this diagnosis by considering patients who experienced long-term, one-sided fluctuating hearing loss, aural fullness and tinnitus, but who never developed vertigo or only experienced mild dizziness. Patients of this description did not meet the criteria for vestibular migraine, but reported migraine-related symptoms and family history of migraine. Some patients may have been diagnosed with Meniere’s. The researchers coined the term ‘cochlear migraine’ to describe these patients.
The main criteria for ‘cochlear migraine’ includes recurrent one-sided sensorineural hearing loss and a feeling of aural fullness in the affected ear, without vertigo, that fails to meet the criteria for vestibular migraine and Meniere’s disease (both of which include the presence of vertigo). Other minor clinical features include aura before hearing loss, accompanying tinnitus, family history of migraine, migraine headaches, chronic headaches or neck stiffness on the side of the hearing loss, sensitivity to light or sound, motion sickness and sensitivity to atmospheric pressure changes. If vertigo develops, patients may be diagnosed, instead, with vestibular migraine or Meniere’s.
‘Cochlear migraine’ differs from cochlear Meniere’s disease in two ways, according to the researchers. Firstly, cochlear Meniere’s disease is characterized by long-term, progressive worsening of hearing loss without any recovery, and is not associated with any migraine-related clinical symptoms or history. Secondly, the mechanisms of the disorders are different. The proposed mechanism for cochlear Meniere’s disease is endolymphatic hydrops, affecting the cochlea, whereas ‘cochlear migraine’ is suggested to be the effect of migraine-related vascular spasm, or neurogenic inflammation.
It is suggested that ‘cochlear migraine’ may initially manifest (or be diagnosed as) sudden deafness, due to sudden onset of hearing loss. The researchers suggest that if a sudden deafness patient later develops atypical changes in hearing, such as fluctuation or deterioration, a diagnosis of ‘cochlear migraine’ should be considered. They also opine that ‘cochlear migraine’ may develop into Meniere’s if and when vertigo develops.
The researchers emphasise that a diagnosis of ‘cochlear migraine’ is a proposed theoretical concept, based only on clinical experience (rather than on evidence for a physiological mechanism).
Background and Study Aims
The aim of the study was to investigate the risk of cochlear disorders (tinnitus, sensorineural hearing impairment and/or sudden deafness) in patients with a history of migraines. Although it was not explicitly stated, another aim of the study was to find evidence for or against the ‘cochlear migraine’ theory. In the introduction to the study, the authors emphasise that while headaches are a symptom of migraine, not all migraines cause headaches.
Design of the Study
Claims data from the Taiwan Longitudinal Health Insurance Database was used to identify patients who were diagnosed with migraine between 1 January 1996 and 31 December 2012. Initially, 996,333 patients, who received a diagnosis of migraine, were identified. These were narrowed down to those who received a diagnosis twice within 3 months, without pre-existing diseases, leaving a total of 1,056 patients as the sample to be studied. A total of 4,224 control patients were also identified from the database and matched to the cases. Incidence rates of tinnitus, sensorineural hearing loss and sudden deafness were compared between the 2 groups.
Results of the Study
The researchers found that, depending on the type of analysis used, migraine patients were between 2.5 and 3 times as likely as non-migraine patients to experience cochlear disorders. These findings were statistically significant, meaning that, irrespective of error risk, the migraine group were always at higher risk of developing cochlear disorders than the non-migraine group. Among the migraine patients, the incidence rate of cochlear disorders was 81.4 per million people per year, and among the non-migraine patients, the incidence rate was 29.4 per million people per year.
The cumulative incidence of cochlear disorders in the migraine cohort was 12.2%, which is significantly higher than the cumulative incidence rate of 5.5% in the non-migraine group.
When the different types of cochlear disorders were analysed separately, the strongest effect was found for tinnitus. Migraine patients were 3.3 times more likely than non-migraine patients to experience tinnitus, 1.03 times more like to experience sensorineural hearing loss and 1.22 times more likely to experience sudden deafness. The findings of increased risk of sensorineural hearing loss and sudden deafness were not statistically significant, meaning that these increased risks could have occurred by chance. As such, the risk of hearing loss or deafness may potentially be the same in both the migraine and non-migraine groups.
Interpretation of the Study and ‘Cochlear Migraine’
The risk of cochlear disorders, particularly tinnitus, was found to be significantly higher among patients with a history of migraines. This may support the presence and/or concept of ‘cochlear migraine’. Future studies, which have been designed to provide more evidence of an association, is needed before the diagnosis of ‘cochlear migraine’ can be accepted. For example, evidence of a relationship between migraine, balance and hearing could be assisted by studies in patients with balance and hearing problems, who are treated with medications known to be effective for migraine symptoms.
Differentiation between vestibular migraine, Meniere’s disease and ‘cochlear migraine’ may be challenging, as there can be significant overlap between these conditions. The researchers suggest that some ‘cochlear migraine’ patients may develop Meniere’s disease once severe vertigo develops. Some studies have found that patients with vestibular migraine also had audiological symptoms, particularly tinnitus. However, they did not appear to have Meniere’s disease, because a test for endolymphatic hydrops, also known as an extratympanic electrocochleogram, produced normal results. What is more, another study found endolymphatic hydrops in a patient with migraine symptoms, absent of vertigo.
The researchers acknowledge the possibility that the study findings may reflect a central process (not cochlear) causing tinnitus. This possibility would need to be investigated using audiometry and other cochlear function testing.
To be included in the migraine group, the patient had to have experienced 2 migraines in a 3-month period. The findings of this study therefore reflect an association among severe migraine sufferers, which may not be observed in all migraine sufferers. This is a limitation of the study results.
Nonetheless, if future evidence is supportive of the existence of ‘cochlear migraine’, it could be the case that patient hearing loss is attributed to this disorder. Patients would not necessarily have experienced headaches, as not all migraines present with headaches. Some patients without history of headaches could therefore be surprised to receive such a diagnosis.
[i] Hwang, J.-H., Tsai, S.-J., Liu, T.-C., Chen, Y.-C. & Lai, J.-T. Association of Tinnitus and Other Cochlear Disorders With a History of Migraines. JAMA Otolaryngol Head Neck Surg (2018). doi:10.1001/jamaoto.2018.0939 https://jamanetwork.com/journals/jamaotolaryngology/article-abstract/2687206 (Accessed 18 July 2018).
[ii] Lin, H. W. & Djalilian, H. R. The Role of Migraine in Hearing and Balance Symptoms. JAMA Otolaryngol Head Neck Surg (2018). doi:10.1001/jamaoto.2018.0947 https://jamanetwork.com/journals/jamaotolaryngology/article-abstract/2687205 (Accessed 18 July 2018).
[iii] Vestibular Migraine. Meniere’s Society. https://www.menieres.org.uk/information-and-support/symptoms-and-conditions/migraine-associated-vertigo (Accessed 17 July 2018).
[vi] Vestibular Migraine. Meniere’s Society. https://www.menieres.org.uk/information-and-support/symptoms-and-conditions/migraine-associated-vertigo (Accessed 17 July 2018).
[vii] Lempert, T. et al. Vestibular migraine: Diagnostic criteria. Journal of Vestibular Research 22, 167–172 (2012). https://content.iospress.com/download/journal-of-vestibular-research/ves00453?id=journal-of-vestibular-research%2Fves00453 (Accessed 17 July 2018).
[ix] NHS Choices. Meniere’s Disease: Causes. https://www.nhs.uk/conditions/menieres-disease/#causes (Accessed 17 July 2018).
[x] Meniere’s Society. Meniere’s disease. https://www.menieres.org.uk/information-and-support/symptoms-and-conditions/menieres-disease (Accessed 17 July 2018).
[xi] Endolymphatic hydrops, Meniere’s Society. https://www.menieres.org.uk/information-and-support/symptoms-and-conditions/endolymphatic-hydrops (Accessed 17 July 2018).
[xii] Lai, J.-T. & Liu, T.-C. Proposal for a New Diagnosis for Cochlear Migraine. JAMA Otolaryngol Head Neck Surg 144, 185–186 (2018). https://jamanetwork.com/journals/jamaotolaryngology/article-abstract/2668288 (Accessed 17 July 2018).