Introduction

Headache is one of the most common medical complaints of humankind, accounting for more than 18 million outpatient visits per year in the United States. The International Headache Society (IHS) classification system (ICHD‐3) [1] divides headache into primary and secondary disorders. In a primary headache disorder, headache is the disorder. In a secondary headache disorder, headache is attributable to another disorder.

Evaluation and diagnostic testing

Headache diagnosis is based on a history, physical and neurologic examination. Characteristics helpful in diagnosis include age at onset; headache frequency, duration, location and severity; factors associated with initiation, exacerbation or remission; accompanying symptoms; and preceding conditions.

Recurrent episodic severe headaches with onset in adolescence or early adulthood suggests a primary headache disorder. A sudden‐onset severe (thunderclap) headache suggests a subarachnoid hemorrhage (SAH) or reversible cerebral vasoconstriction syndrome (RCVS) if recurrent. In patients over 50 years of age, tenderness on palpation of the temporal arteries accompanied by scalp tenderness, jaw claudication or visual changes suggests giant cell arteritis (GCA). Neck stiffness may indicate meningeal irritation due to infection or SAH hemorrhage. Papilledema indicates increased intracranial pressure. Focal neurologic symptoms or mental status changes typically accompany structural lesions. History may suggest the cause of headache: for example, recent head trauma, hemophilia, alcoholism or anticoagulant therapy may suggest a subdural hematoma.

Testing serves to exclude organic causes of headache, rule out coexistent diseases that could complicate treatment and establish a baseline for and exclude contraindications to drug treatment.

Patients require urgent neuroimaging [computed tomography (CT) or magnetic resonance imaging (MRI)] when any of the following is present:

1. Sudden‐onset thunderclap headache;
   
2. Altered mental status
   
3. New seizure
   
4. Focal neurologic deficits;
   
5. Papilledema; or
   
6. Severe hypertension.

Except in an emergency situation or when an MRI cannot be done, MRI is preferred to CT. In addition, an anormal CT scan does not rule out SAH, meningitis or encephalitis; lumbar puncture is indicated when they are suspected. Patients with unusual persistent headaches may also require lumbar puncture.

Symptoms requiring prompt imaging include a change in prior headache pattern, new‐onset headache after age 55, systemic symptoms (e.g. weight loss), secondary risk factors (e.g. cancer, HIV, head trauma) or chronic unexplained headache. MRI, magnetic resonance angiography (MRA) and/or magnetic resonance venography (MRV) are preferred; these tests can show many causes of headache (e.g. carotid dissection, cerebral vein thrombosis, pituitary apoplexy, vascular malformations, cerebral vasculitis, Chiari type I malformation) that can be missed on CT.

Other tests are used if specific disorders are suspected (e.g. erythrocyte sedimentation rate for GCA).

Migraine

Migraine is a chronic neurologic disease characterized by episodic attacks of headache and associated symptoms [2]. In the United States about 17.6% of women and 6% of men had one migraine attack in the previous year [3].

Description of the migraine attack

The migraine attack can consist of premonitory, aura, headache and postdrome phases. Premonitory symptoms may include psychological, neurologic, constitutional or autonomic features (depression, cognitive dysfunction and food cravings) and can occur hours to days before headache onset.

The migraine aura consists of focal neurologic symptoms that precede, accompany or (rarely) follow an attack. Aura usually develops over 5–20 minutes, lasts less than 60 minutes, can be visual, sensory or motor and may involve language or brainstem disturbances [1]. Headache usually follows within 60 minutes of the end of the aura.

The typical headache is unilateral, of gradual onset, throbbing, moderate to marked in severity and aggravated by movement [1]. It lasts 4–72 hours in adults and 2–48 hours in children [1].

Anorexia is common. Nausea occurs in almost 90% of patients, while vomiting occurs in about one‐third. Sensory hypersensitivity results in patients seeking a dark quiet room [2,4]. Patients may experience blurry vision, nasal stuffiness, anorexia, hunger, tenesmus, diarrhea, abdominal cramps, polyuria, facial pallor, sensations of heat or cold and sweating. Depression, fatigue, anxiety, nervousness, irritability and impairment of concentration are common.

The ICHD‐3 divides migraine into migraine without aura (Table 32.1) and migraine with aura (Table 32.2) [1]. Migraine persisting for more than 3 days defines “status migrainosus.” Migraine occurring 15 or more days per month is called chronic migraine (CM) (Table 32.2).

Basilar‐type migraine aura features brainstem symptoms: ataxia, vertigo, tinnitus, diplopia, nausea and vomiting, nystagmus, dysarthria, bilateral paresthesia, or a change in level of consciousness and cognition [1]. Hemiplegic migraine can be sporadic or familial [2,4]. Familial hemiplegic migraine (FHM) is an autosomal dominant disorder associated with attacks of migraine, with and without aura, and hemiparesis.

Pathophysiology

The migraine aura is believed to be caused by cortical spreading depression (CSD). Headache probably results from activation of meningeal and blood vessel nociceptors combined with a change in central pain modulation. Headache and its associated neurovascular changes are subserved by the trigeminal system. Stimulation results in the release of substance P and calcitonin gene‐related peptide (CGRP) from sensory C‐fiber terminals and neurogenic inflammation. Neurogenic inflammation sensitizes nerve fibers (peripheral sensitization), which now respond to previously innocuous stimuli, such as blood vessel pulsations, causing, in part, the pain of migraine. Brainstem activation also occurs in migraine without aura, in part because of increased activity of the endogenous anti‐nociceptive system. The migraine aura can trigger headache: CSD activates trigeminovascular afferents. In the absence of aura, CSD may occur in silent areas of the cortex or the cerebellum.

Treatment

Migraine treatment begins with making a diagnosis, explaining it to the patient and developing a treatment plan that considers comorbid conditions [2,4]. Treatment may be acute or preventive and patients may require both approaches. Acute treatment attempts to relieve the pain and impairment once an attack has begun. Preventive therapy is given to reduce the frequency, duration or severity of attacks. Additional benefits include improved responsiveness to acute attack treatment, improved function and reduced disability. In addition, lifestyle changes are also important, including healthy diet, regular physical exercise and relaxation strategies.

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