Cephalgia · What Is It, Types, Causes, and More

Cephalgia, more commonly known as a headache, refers to pain affecting the head, face, or neck, and can be classified as either primary or secondary. Primary headaches can be painful, but they typically do not result from underlying disease or structural problems and are usually harmless. The exact mechanism underlying primary cephalgia is unknown, but it is thought to involve abnormal activation of pain pathways and dysregulated neurovascular and inflammatory processes.  

Secondary headaches typically have a sudden onset and are extremely painful. These often result from an underlying illness or trauma triggering pain-sensitive areas in the head, neck, or face. Secondary headaches are less common than primary headaches, but they are typically more serious and are accompanied by additional symptoms related to the underlying condition. 

In an acute setting, it is important to distinguish between primary and secondary headaches with thorough history and neurologic exam so as not to miss important diagnoses that may require imaging and potentially intervention (e.g., subarachnoid hemorrhage).

Cephalgia can have various causes, depending on whether it is classified as primary or secondary.  

Primary cephalgia has a wide range of risk factors, including family history, advanced age, and disorders of the head, neck, or face. Increased stress, poor diet, dehydration, consumption of certain kinds of alcohol, sleep disturbances, hormonal changes, and certain medications can also be triggering factors. Environmental factors that may induce or worsen a headache include changes in weather and exposure to bright, pulsating lights. The risk of certain types of primary cephalgia can vary depending on an individual’s age and sex.

Meanwhile, secondary cephalgia can be caused by brain tumors, infections, brain hemorrhages, injury or trauma to the neck or brain. Secondary cephalgia can also be a side effect of certain medications, or result from sleep apnea, carbon monoxide poisoning, oxygen deprivation (i.e., hypoxia), and recreational drug or alcohol usage.  

Primary cephalgia is generally acute, occurring suddenly and lasting for a relatively short period of time. Among the several types of acute cephalgia, tension headaches and migraine headaches are the most common. Tension headaches are characterized by mild to moderate pain around the entire head, as if squeezed by a tight elastic band. Tension headaches may be treated with rest, hydration, and over-the-counter pain-relieving medications, such as acetaminophen or ibuprofen.  

Migraine headaches result from an increased sensitivity to movement, light, or other triggers. In addition to pain, other symptoms of migraines include fatigue, nausea, dizziness, visual disturbances, and irritability. Resting in a dark, quiet space, massages, application of hot or cold compresses, and pain-relieving medications may help alleviate migraines. Over-the-counter medications, like nonsteroidal anti-inflammatory drugs, and prescription medications, such as triptans, help reduce migraine pain. Newer options, including calcitonin gene-related peptide (CGRP) receptor antagonists (gepants) and CGRP-targeting monoclonal antibodies, are now considered a first-line option for migraine prevention, and ditans, such as lasmiditan, offer an alternative acute treatment for individuals who cannot take triptans. However, frequent use of migraine medications can lead to an increase in migraine frequency. 

Other types of acute headaches include cough-related headaches, headaches due to physical activity, trigeminal autonomic cephalgia (TAC), trigeminal neuralgia, hypnic headaches, and cold stimulus headaches.  

TAC is a type of primary headache characterized by unilateral intense pain in the trigeminal nerve area (eye, temple, cheek, jaw), along with autonomic symptoms (watering eye, red eye, drooping eyelid, and leaking nose) on the same side. The duration and frequency of TAC episodes vary depending on the type. Types of TAC include cluster headaches, paroxysmal hemicrania, hemicrania continua, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA). Cluster headaches, characterized by unilateral severe pain to the eye or temple, are the most commonly occurring TAC.