Temporomandibular Disorders And Migraine Headache: Comorbid Conditions?

摘要

Migraine headache and temporomandibular disorders represent two conditions that affect a significant portion of the population. The relationship between tension-type headache, formerly called musculo-skeletal headache, and myalgia of the masticatory muscles has been known and demonstrated in many patients. However, few studies show a significant association between vascular headache or migraine and temporomandibular disorders. Increasing evidence suggests a potential link in the etiology and course of these seemingly distinct pain disorders. This paper reviews these two conditions and discusses the possible connection between migraine headache and temporomandibular disorders. Headache Head pain is one of the ten most common presenting symptoms in general medical practices. Recurring headaches occur in 76% of women and 57% of men. (1, 2) The incidence of headache is 39% at age six and increases to 70% by 15 years of age. (1) It is estimated that headache is responsible for up to one million days of school and one hundred and fifty million days of work missed per year. Headache afflicts a large portion of the population and with its varying severity can result in discomfort, disruption of daily activity, and occasionally debilitating pain. Although about 30% of headache sufferers are periodically functionally impaired, many do not seek medical care.In the neurology literature, the incidence of tension-type headache, the most prevalent form of headache, is reported to affect over two-thirds of the general population. Migraine headaches affect 18% of women and 6% of men, although its onset is within the first three decades of life. Cluster headache is far less common in the general population, with a prevalence rate of 0.1 to 0.3%. Family physicians and specialists in neurology seek to rule out an organic cause of primary and secondary headache. Unfortunately, the difficulties in distinguishing headaches based on clinical presentation rarely lead to the uncovering of an organic etiologic factor, and rarely lead to the diagnosis of comorbid conditions such as TMD. This results in frequent empiric management of headache without the evaluation of TMD as a potentially treatable comorbid condition. (2)The incidence of migraine headache peaks between the ages of 30 and 40, decreases with rising income, and is highest among Caucasians. It is estimated that $1.4 to $17.2 billion is spent on migraine headache treatment and numerous work days are missed annually making it a significant public health problem. More concerning, is recent evidence linking migraine headache to other more significant neurologic and psychiatric disorders, including epilepsy, stroke, and depression. (3)Genetic factors play an important role in the development of migraine headaches, with 70-90% of patients having a positive family history for migraine. Traditional concepts regarding the pathogenesis of headache crudely separated this disorder into the muscle contraction theory of tension-type headache and the vascular theory of migraine. Current concepts point to both a neurogenic theory and the role of serotonin in migraine. This neurogenic theory of migraine proposes that the pain originates in the structures of the brain, affecting ascending and descending pathways. In addition, a primary neuronal event is followed by secondary vascular changes whereby, neuronal activation, vascular dilation, and muscle spasm all promote and propagate head pain. The very core of these disturbances appear to be channel dysfunction leading to neuronal hyperexcitability. The complex processes in the pathogenesis of migraine are summarized in Figure 1. Although many forms and variants of migraine headache exist, many of them demonstrate specific phases including a prodrome, aura, headache, and postdrome or recovery.