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Develop a systematic approach to recognizing headache, referring emergencies

Issue: November 2012

ByLen V. Hua, OD, PhD

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Headache, or cephalgia, is among the most common comorbid symptoms that patients name as part of their chief complaints for an eye examination. Sometimes headache is the primary reason for an eye visit. Additionally, young patients are often referred by primary care providers or internists for an eye check when headache is a symptom.

Headache is so common that virtually everyone has experienced at least one headache episode in a lifetime. Every health care provider has encountered at least one patient with headache in their career. Fortunately, most headaches encountered in medical settings are benign in nature; the pain often disappears spontaneously or with treatment over a short period of time. Mortality or permanent morbidity secondary to headache is rare.

Nevertheless, headache is one of those medical symptoms that many health care providers do not like to hear about or manage because headache has a plethora of etiologies. Despite the fact that most headaches are benign, there still lies a small risk that the headache is a true emergency, and misdiagnosing or missing a true emergency can lead to a loss of a limb or life.

Len V. Hua

According to the most recent edition of the International Classification of Headache Disorders (ICHD-2), more than 200 disease entities that share headache as a common symptom were categorized, each with specific, detailed diagnostic criteria. Therefore, most physicians can focus only on a limited and relevant subset of diseases that is practical and manageable by their specialties; the rest require further consultation with subspecialists or tertiary care.

It is difficult to know the incidence and prevalence of headache, because headache is not a disease, but a commonly shared symptom of many disorders. Moreover, patients seek care for headache at various medical settings including primary care, vision care, dental care and even in the emergency department. According to the National Hospital Ambulatory Medical Care Survey in 2002, headache was the fifth most common primary complaint of patients presenting to the emergency department in the U.S., representing more than 3 million patients each year.

There are a dozen possible differential diagnoses for headache.

In the eye care setting, most providers would see at least one patient with headache as a primary or comorbid symptom per week, and some clinicians may see more than one headache a day. In an attempt to boost the confidence and comfort of eye care providers at managing headache encounters, this article focuses on several worrisome headaches and discusses possible pitfalls to avoid and minimize the potential risk of misdiagnosis or neglect.

The role of an eye care provider in the evaluation and management of headache is unique from other health care providers in that the first set of questions to address are: “Is the headache vision-related or originated in the eye?” and “Otherwise, is it a headache emergency or urgency?” Thus, the two major goals of the encounter are to relieve headache by optical correction and vision therapy if the headache is vision-related and to refer patients to a neuro-ophthalmologist, neurologist or neurosurgeon for further evaluation and intervention of potential disabling or life-threatening etiology. The most important part of the examination, however, still comes in the beginning of the encounter, with a thorough case history. The table on page 15 summarizes some of key components of a case history to provide a better understanding of the symptom and possible differential diagnoses.

Vision-related, ocular-originated headache

Vision-related headaches tend to affect two patient populations: school-age children, in association with school work, and pre-presbyopic adults, in association with prolonged office work. These headaches are often located around the frontal or temporal aspects of the head with eye strain or asthenopia as a co-existing symptom. The headache is likely induced by small ocular misalignments or binocular anomalies, which can be examined and diagnosed with visual tests of binocular function.

Convergence insufficiency is the best-studied form of binocular anomalies, but accommodative dysfunction is also well documented. If a binocular anomaly is confirmed as the cause of the headache, spectacle correction, prism and/or vision therapy could be prescribed as an effective relief or resolution of the eyestrain and headache symptoms over a short period of time for both school-age children and pre-presbyopes with computer vision syndrome.

One possible pitfall to underdiagnosis or misdiagnosis of vision-related headache is that many primary eye care physicians, particularly those with high-volume practices, or ophthalmological subspecialists do not have enough time or lack the skill to do a proficient binocular analysis for these groups of patients. The solution to this discrepancy is to refer patients suspected of binocular anomalies to colleagues who specialize in pediatric eye care and vision therapy. Alternatively, one can reschedule these patients and allocate sufficient time to perform binocular analysis for accurate diagnosis of a binocular anomaly. Mitchell and Scheiman wrote one of the best reference manuals on the topic, which can be used as a refresher on binocular anomaly and its management.

It is important to note that sinus headache should be part of the differential diagnosis for frontal headache. As such, questioning the patient about recent history of cold or flu and applying gentle pressure along the sinuses (upper bridge of the nose) could aid in the diagnosis.

In addition to the more common ocular misalignment, binocular anomaly and sinus headaches, an ocular-originated headache, especially in an acute setting, is a markedly elevated intraocular pressure secondary to a sudden obstruction of aqueous humor drainage in angle closure. The headache in this situation is actually referred from the eye to the ipsilateral hemicranium and can last for a few hours. In addition to ipsilateral headache and brow ache, patients often present with the “hot eye” signs of ciliary injection, corneal edema and mid-dilated pupil. Vomiting, photophobia and decreased visual acuity are frequent comorbid symptoms as well.

Generally, eye care practitioners are more apt and better equipped to diagnose acute closure of the angle than other health care providers because eye care physicians routinely use slit lamp biomicroscopy, Goldmann applanation tonometry and gonioscopy to diagnose angle closure. Without proper instruments and tests such as gonioscopy and tonometry, acute angle closure may be misdiagnosed as migraine with aura. Therefore, if acute angle closure is suspected by physicians without the capability to do the necessary ocular tests, the patient must be referred for an emergent ophthalmic consultation and management.

Headache emergencies

Once the question of vision-related headache is addressed, the next task for eye care providers is to be able to recognize potential headache emergencies that need to be referred immediately to the emergency department or neurosurgeon for life-saving neurosurgical intervention.

The table below summarizes important clinical features and interventions for some entities that are covered in this article. For more extensive coverage on diagnosis and management of headache emergencies, refer to ICHD-2 and a recent review by Friedman and Lipton.

First, worst, sudden onset

Most headaches that present to an eye clinic are likely benign in nature. However, if the headache is of a sudden onset and the patient describes it as “the worst headache of my life,” the sudden and intense nature of the symptom may be a harbinger of a serious condition that warrants a referral for diagnostic imaging and prompt surgical intervention. Even though many of these turn out to be either self-limited or one of the benign recurrent headaches, such as migraine, tension or cluster headache, it is better to err on the safe side than face a slim chance of misdiagnosing a headache emergency with dire consequence.

Headaches of cerebrovascular origins tend to fall into the sudden and intense category. Aneurysmal subarachnoid hemorrhage, cervical artery dissection and pituitary apoplexy are discussed below.

Subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) ranks high on the list of differential diagnoses for patients with a history of recent head trauma and ensuing headache. In addition to trauma, many SAH cases can result from ruptured saccular aneurysms. First, worst and sudden onset is one important red flag to suspect SAH, which frequently starts with a unilateral intense “thunderclap” headache. Other associated symptoms that can aid in the diagnosis include nausea, vomiting, confusion, nuchal rigidity and, less frequently, fever and cardiac dysrhythmia. In mild and early cases, less associated features are evident. Furthermore, a recent prospective case series (n=101) identified about half of the SAH patients with abnormal funduscopic signs. Disc swelling was seen in 85 (42.1%) and retinal hemorrhage in 51 (25.2%) of the eyes. Therefore, a funduscopic exam should be conducted.

SAH is a neurosurgical emergency, because if it is not intervened in a timely fashion, up to half of the patients die before reaching the emergency room, while the other half are left with long-term disability. The diagnosis is confirmed by computed tomography (CT) scan without contrast or magnetic resonance imaging (MRI), T2 or flair. If neuroimaging cannot identify hemorrhage in non-traumatic cases, lumbar puncture to test cerebral spinal fluid for evidence of blood or blood byproduct could be performed.

The challenge and dangerous pitfall with SAH cases are those that start with a small, mildly symptomatic leak followed by a more severe, disabling and life-threatening bleed over days or weeks. In these cases, the initial headache may be dismissed as benign after the pain disappears spontaneously or with analgesics. The patients may have false assurance and will not seek further medical attention even when the symptom recurs with higher intensity. Emergency physicians are well trained to recognize SAH and avoid this pitfall, but eye care practitioners can also play role in educating patients about the associated features of SAH and reminding patients to call or return to the emergency room when more intense symptoms recur after discharge.

One additional condition worth mentioning is compression of the third cranial nerve (CN-3) from an expanding aneurysm of the posterior communicating artery or the basilar artery, which often manifests with a sudden onset of unilateral ptosis, pupil-involving CN-3 palsy and severe headache. Therefore, one clinical pearl to remember is that any painful pupil-involving CN-3 palsy is a true emergency that requires prompt referral for diagnostic imaging, until proven otherwise.

Cervical artery dissection

Cervical artery dissection (CAD) can arise from a carotid or vertebral artery dissection, each of which can occur spontaneously or be precipitated by even a minor insult around the neck such as vigorous coughing or massage. A tear in the inner arterial layer and its subsequent separation from the outer arterial wall can form a flap in the lumen of the vessel. The hinge can serve as a site for gradual accumulation of lipid deposits, which initially impedes then blocks the blood supply to the head and brain. As a result, CAD is the most common cause of potentially life-threatening stroke in young adults between ages of 35 and 50.

CAD may mimic SAH because of its sudden-onset headache, but it differs from SAH with the associated feature of unilateral severe and persistent pain along the neck and face ipsilateral to the dissected artery for days. Furthermore, signs of Horner’s syndrome (miosis and ptosis) and retinal ischemia (transient monocular visual loss) support clues of internal carotid artery dissection.

Diagnosis is based on extensive imaging of the neck and head using a combination of MRI, magnetic resonance angiography (MRA), CT and, in doubtful cases, conventional angiography. Once the diagnosis is confirmed, the patient is treated with heparin followed by warfarin for 3 to 6 months.

One important clinical pearl to keep in mind is that CAD is the cause if a patient presents with a new-onset headache associated with ipsilateral Horner’s syndrome, tinnitus or neck pain, until proven otherwise. Another possible aid in diagnosis is to do a physical examination of the neck and head for tenderness, which eye care providers seldom do as part of an eye examination.

Pituitary apoplexy

The pituitary gland is located at the sella turcica, a recess in the base of the skull. It regulates and releases most of the hormones necessary for normal physiology. Its blood supply is made up of a network of fine hypophyseal vessels.

Pituitary apoplexy (an old terminology for a stroke) occurs when there is a hemorrhage or an infarct to the pituitary gland that results in an acute hormonal deficiency with incipient manifestation of adrenal crisis (low cortisol), followed by hypoglycemia, hypotension, coma and death. The most common cause of pituitary apoplexy is pituitary adenoma, which is reported to carry a higher risk of infarct or hemorrhage than other brain tumors. As the adenoma enlarges, the gland out-grows its blood supply leading to the area of infarct, or the blood vessels become more fragile leading to a bleed.

Sudden severe “thunderclap” headache is a common initial symptom accompanied by a reduction in visual acuity and field or diplopia caused by compression of the cranial nerves adjacent to the gland. Visual field testing should be performed in suspected cases because more than half of these patients show a classic bitemporal superior quandrantic defect due to compression on the optic chiasm.

Nausea and vomiting, fever or diminished level of consciousness may also be an associated symptom. The diagnosis is made with MRI because it is more sensitive than CT scan for detecting intrasellar pathology.

Intravenous corticosteroid and surgical decompression are required in many cases, and long-term hormone supplementation is needed to correct pituitary hormone deficiencies. The clinical pearl for this condition is that any patient with acute onset of diplopia secondary to cranial nerve (CN) 3, 4, 5 and 6 palsies, decreased vision and extreme headache must be referred for diagnostic imaging to rule out pituitary apoplexy.

Headache with risk of irreversible vision loss

The next task on the list is to recognize those headaches that can lead to permanent vision loss if the diagnosis is missed or timely management is delayed. Giant cell arteritis (GCA), idiopathic intracranial hypertension and tumor of the brain fall into this category.

Giant cell arteritis

GCA, formerly known as temporal arteritis or Horton’s disease, is a form of vasculitis affecting the large and medium arteries. “Giant cell” is a term used to describe the histological appearance of enlarged macrophages that are in the process of digesting foreign bodies or micro-organisms. It is also a histological marker of inflammation. “Temporal arteritis” is still used by many clinicians because the temporal artery is the most frequently affected site; however, other large vessels including the aorta may also be involved.

GCA affects twice as many women as men and more Caucasians than African Americans older than 55 years. Up to one-fourth of GCA coexists with polymyalgia rheumatica, an inflammatory disease manifesting as pain and stiffness in the neck, shoulder and hips. Other diseases associated with GCA include systemic lupus erythematosus and rheumatoid arthritis.

Typical symptoms for GCA are bitemporal headache with tenderness to the touch on the scalp. The patient may have pain in the jaw when chewing (jaw claudication), but visual disturbance is the main reason that brings affected individuals to the eye clinic. The biggest concern is irreversible visual impairment or complete blindness secondary to anterior ischemic optic neuropathy. Furthermore, the risk of it affecting the fellow eye within the following week is relatively high, so palpation of temporal arteries for nodules and tenderness is an essential aid to the diagnosis in addition to a thorough history.

If the patient is suspected of having GCA, oral prednisone (1 mg/kg/d) must be administered immediately, even before diagnosis is confirmed by additional tests. Erythrocyte sedimentation rate (>60 mm/h) and C-reactive protein are inflammatory markers that must be part of the laboratory work-up for GCA, but temporal artery biopsy is still the gold standard for a definitive diagnosis. Duplex scanning of the temporal arteries can be performed to visualize a thickened arterial wall (a halo sign on axial sections). A general clinical pearl here is that GCA should be a part of the differential diagnoses in patients older than 55 years with a new onset of headache and visual disturbance.

Idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH), previously known as pseudotumor cerebri, is a relatively rare neurologic condition seen primarily in young obese women of childbearing age. The cause of IIH is not known, hence the term “idiopathic” is used, but congestion of venous flow has been proposed as a possible mechanism because clinical reports have shown that some IIH patients have narrow cerebral sinuses and veins. Further support for possible venous congestion comes from a strong link between obesity and IIH. Obesity may obstruct venous exit out of the brain, hence weight loss is relatively effective for headache relief or resolution in many IIH patients. Other causes of IIH could arise from adverse side effects of systemic medications.

The medications that have been implicated in increasing intracranial pressure include isotretinoin, tetracyclines and contraceptives. Chronic and progressive headache is a key symptom accompanied by nausea, vomiting, tinnitus and visual disturbance including diplopia (CN VI palsy). However, in the mild or early stage, patients may be asymptomatic and are diagnosed incidentally after a comprehensive eye examination revealing papilledema and enlarged blind spots on visual field.

IIH is a diagnosis of exclusion, which means that brain scans must be performed to rule out “true” tumor. Then lumbar puncture is required to confirm intracranial hypertension (>200 mm H2O in the non-obese, >250 mm H2O in the obese). Moreover, lumbar puncture also can be therapeutic to relieve the pressure and symptoms.

Oral acetazolamide (500 mg twice daily) can be given to the patient in-office to reduce the intracranial pressure before urgent referral to a neurologist or neuro-ophthalmologist. Alternatively, corticosteroids also have been used, but slow tapering is needed to prevent rebound headache. Optic nerve sheath fenestration or cerebrospinal fluid diversion is performed to reverse or prevent further vision loss.

One potential pitfall with IIH is that it may be misdiagnosed as chronic migraine with aura if careful optic nerve head analysis is not done, thus optic nerve examination must be performed on every patient with headache, especially for young obese women.

Space-occupying lesion

The first and worst thought some patients have about newly onset headache is the possibility of a brain tumor, which often is not the case, thus a clear reassurance in many cases is as important as a specific diagnosis. A thorough case history is essential to come up with possible differential diagnoses and ways to educate the patient. If there is even a slight suspicion of a brain tumor based on case history and clinical experience, the patient must be informed, reassured and referred for a comprehensive brain imaging.

Some of the red flags associated with space-occupying lesions are: new-onset or different headache accompanied by focal neurologic perturb, such as seizures, difficulty speaking and weakness in the limbs; headaches that awaken patients from sleep or are worst in the morning; headaches that get worse over time; and headaches that worsen with the Valsalva’s maneuver.

Intracranial neoplasms can develop from the primary site in the brain, meninges or skull or as a result of metastasis from other cancers such as lung, breast, gastrointestinal or kidney. Corticosteroids can temporarily alleviate the symptoms by resolving brain edema, but definitive treatment is required depending on tumor size, type, location and overall prognosis.

Headaches secondary to chemical exposure

Two common chemically induced headaches are often neglected as part of differential diagnoses: carbon monoxide poisoning and medication over-use.

Carbon monoxide poisoning

Carbon monoxide (CO) is a toxic gas that can kill an individual leaving little trace of evidence because it is colorless, odorless and tasteless. CO is made as a byproduct when organic matter is not fully burned and converted to carbon dioxide (CO2) due to the lack of oxygen. Therefore, CO is potentially produced whenever and wherever combustion of organic matters takes place. Human exposure to CO happens most commonly in domestic and industrial settings. Older cars, gasoline-powered tools, heaters and cooking appliances are likely to release more CO as a byproduct. Exposure of greater than 100 parts per million is harmful to health.

CO is poisonous because it out-competes oxygen for binding to hemoglobin and significantly reduces the oxygen-carrying capacity of the blood, leading to widespread tissue hypoxia. CO poisoning is the most common cause of poisoning in the U.S. and the world, nevertheless, it still remains highly unrecognized and misdiagnosed.

Headaches, lightheadedness, confusion and flu-like effects are early symptoms of acute CO poisoning, whereas chronic exposure to low levels of CO can lead to depression, confusion and memory loss.

Treatment for acute CO poisoning is to remove the person from the exposure and administer 100% oxygen; however, prevention is the key to minimizing the incidence of CO poisoning and saving lives. CO detectors should be recommended for each level of the home or building. A few sign posts to aid in diagnosing CO-induced headache are an associated flulike symptom in the winter months when heaters are in use and other co-residents are also affected. Moreover, headaches get better when the patient leaves the area of exposure.

Medication-overuse headache

Medication-overuse headache (MOH), also known as rebound headache, has been recognized and classified only very recently by ICHD in 2004. As the name implies, MOH is caused by chronic overuse of certain types of medications. Patients with migraines or tension headaches are more prone to MOH because the medications used to treat these conditions can transform acute episodes into chronic daily headaches. Triptans, ergotamines, nonsteroidal anti-inflammatory drugs, opioids and psychotropics have all been implicated in MOH.

The exact mechanism by which MOH develops is unknown, but genetic predisposition may play a major role. MOH is relatively common and has been estimated to affect 1% to 2% of the population, qualifying as the third most prevalent type of headache. Up to 25% of chronic daily headaches may be attributed to overuse of medications.

The diagnostic criteria include daily headaches for more than 15 days in 1 month, the patient is taking more than one analgesic drug for longer than 3 months, and the headache is markedly worsened during medication overuse. If MOH is the correct diagnosis, discontinuation of the drugs will resolve the headache or result in it reverting to its previous pattern within 2 months; otherwise, the diagnosis must be discarded.

MOH is a usual suspect in a patient with a pre-existing primary headache who experiences a different pattern of headache or a worse headache with the use of medications. Fortunately, MOH is not one of the headache emergencies, but it is big concern and nuisance to the patient. Patient education and comanagement with the primary care physician are the best approaches.

An approach to headache

Most headaches encountered by eye care providers are due to the patient’s primary care providers suspecting that the symptom is eye or vision-related. Our job is to learn about the symptom and decide whether it is a manageable vision-related condition or a condition that needs to be referred to neurological specialists for further work-up and intervention. Fortunately, most headaches that present to an eye clinic are benign and vision-related, and optical correction or vision therapy can relieve or resolve the symptom in most cases.

Furthermore, primary headaches such as migraine, tension and cluster headaches most likely have been managed by a primary care provider, a neurologist or a headache specialist. What remains at the center of our focus is to recognize headache urgencies and emergencies. Therefore, a clinical approach to headache is to start with a thorough case history covering the clinical features outlined in the first table. As the responses are received, the clinician must be able to pick up red flags for headache urgencies and emergencies and perform the appropriate tests to strengthen the preliminary suspicion of causes.

The tables and the figure contain summaries of important clinical features of some headache emergencies and urgencies that can assist in the design of such an intake form.

Albeit rare in the eye care setting, clinicians should watch out for patients with drug seeking behavior. The patient may intentionally fake or exaggerate headache with the hope of getting a prescription for an agent of choice, usually a narcotic. It is an additional challenge that the practitioner needs to know how to handle such a patient in a considerate and nonjudgmental way for satisfactory solution, because this patient can be apprehensive and hostile as a result of the insinuation.

In summary, headache is one of the most common symptoms that present in an eye care setting, but it is also one of the most complex symptoms that eye care practitioners need to manage for a few reasons. More than 200 entities of headaches are known and classified, it is difficult to reach an accurate diagnosis within the allotted time for an encounter and headache emergency or urgency is always par for the course. Therefore, it is important to develop a systematic approach to recognize and refer headache emergencies and urgencies. One final rule of thumb is that any headache that is sudden in onset, maximal at onset and different in nature from an existing condition demands a referral for brain imaging.

Disclosure: Hua has no relevant financial interests to disclose.