Headache is among the most common of human maladies. So much so that it is generally (and often incorrectly) assumed to be understood, especially by doctors. The classification of headache, with formal definitions of different diagnostic entities, by the International Headache Society into (1) primary—occurring in the absence of external causes, and (2) secondary—some of which may have sinister cause, has greatly simplified the description, understanding, and management of this often challenging symptom. It also allows those headaches with serious or life-threatening consequences to be...
Headache is among the most common of human maladies. So much so that it is generally (and often incorrectly) assumed to be understood, especially by doctors. The classification of headache, with formal definitions of different diagnostic entities, by the International Headache Society into (1) primary—occurring in the absence of external causes, and (2) secondary—some of which may have sinister cause, has greatly simplified the description, understanding, and management of this often challenging symptom. It also allows those headaches with serious or life-threatening consequences to be distinguished from other forms.
Pathophysiology of primary headaches
The key structures involved in producing pain appear to be the following: (1) large intracranial vessels and the dura mater, (2) trigeminal nerve, (3) higher centres in the thalamus and cortex, (4) modulatory centres in the diencephalon and brainstem.
Two of the commonest and best studied primary headaches, migraine and cluster headache, should be regarded as having a neurovascular origin. Migraine might be part of the spectrum of diseases known as channelopathies or ionopathies: the three genes currently identified as being genes responsible for familial hemiplegic migraine alter ion fluxs. Moreover, studies of the more common forms of migraine across large patient cohorts, genome wide associated studies (GWAS), have implicated excitatory, in particular glutamatergic, transmission to be key to the pathophysiology.
Epidemiology and clinical features—this episodic disorder affects 12 to 15% of the population in any one year, and about 45% of females over their lifetime; it can be highly disabling. It presents with headache, often throbbing and generally accompanied by other features such as sensitivity to light, sound, or movement, and often with nausea or (less often) vomiting, but none of the features is compulsory. For example, the migraine aura—visual disturbances with flashing lights or zigzag lines moving across the fields or other neurological symptoms—is reported in only about 25% of patients. It is noteworthy that the word migraine is used to describe the diagnosis—a patient has migraine; as well as an individual attack—a patient is having a migraine. Although a subtle distinction this concept underpins the fact that not all attacks, in all patients, every day, need to conform to standard diagnostic criteria.
Treatment—principles of management include (1) explanation—migraine is an inherited tendency to have headache and cannot therefore be ‘cured’; (2) the condition can be modified and controlled by lifestyle adjustment and the use of medicines; (3) it is not life-threatening; (4) management takes time and cooperation. Most migraine sufferers will benefit from a healthy diet, regular exercise, regular sleep patterns, avoiding excess caffeine and alcohol, and (as far as practical) modifying or minimizing changes in stress. Preventive drug treatments include pizotifen, β-blockers, some tricyclics, some anticonvulsants, flunarizine, and methysergide. Acute treatments include (often in combination with an antiemetic) nonspecific drugs such as aspirin, paracetamol (acetaminophen) and NSAIDs, and specific agents such as triptans, serotonin 5-HT1B/1D receptor agonists, and ergot derivatives. In the next years newer agents, ditans (serotonin 5-HT1F receptor agonists), and gepants (calcitonin gene-related peptide (CGRP) receptor antagonists) will offer novel and added benefits to patients with migraine and the physicians who treat them.
Tension-type headache is common, unexplained, and completely featureless, with no nausea, no vomiting, no photophobia, no phonophobia, no osmophobia, no throbbing, and no aggravation with movement. It is referred to by patients as annoying rather than disabling. When episodic, it is generally amenable to simple analgesics; when chronic, amitriptyline is the only proven treatment.
Trigeminal–autonomic cephalalgias (TACs)
Cluster headache—characterized by bouts of excruciating retro-orbital boring pain associated with ipsilateral symptoms of cranial parasympathetic activation (a red or watering eye, the nose running or blocking) or cranial sympathetic dysfunction (eyelid droop). Prevention is with agents including verapamil, lithium, topiramate oral corticosteroids, and methysergide. Treatments for acute attacks include oxygen inhalation, sumatriptan by subcutaneous injection or nasal spray, and zolmitriptan by nasal spray.
Other conditions—these include (1) paroxysmal hemicrania, (2) short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing or cranial autonomic activation (SUNCT/SUNA), and (3) hemicrania continua.
Other primary headaches
Specific conditions include (1) cough headache, (2) exertional headache, (3) sex headache, (4) thunderclap headache, (5) cold stimulus headache, (6) external traction headache, (7) stabbing headache, (8) nummular headache, and (9) hypnic headache. Many of these can present with chronic daily headache and are often misdiagnosed as tension-type headache, but they can readily be identified from the history, often leading to effective and specific treatments, an important element of which is reduction/elimination of analgesic overuse.
New daily persistent headache—this typically presents with abrupt onset of headache that then persists. Possible causes include: (1) primary—migrainous type, featureless (tension-type); (2) secondary—subarachnoid haemorrhage, low cerebrospinal fluid volume headache, raised cerebrospinal fluid pressure headache, post-traumatic headache, chronic meningitis, giant cell arteritis. Effective and specific treatments are available for many of these conditions if a precise diagnosis can be made.
Clinical approach—the length of the history is crucial: if this is short, the patient requires prompt attention; if this is long, then time and patience are needed rather than alacrity. Associated fever, sudden onset of pain, or the presence of neurological signs need a positive diagnosis of a benign disorder or require brain imaging with CT or MRI.
Causes and management—medically sinister headaches requiring urgent attention include subarachnoid haemorrhage, meningitis, giant cell arteritis, and raised intracranial pressure. Other important causes of secondary headache include low volume (pressure) cerebrospinal fluid, post-traumatic headache, and cerviocogenic headache. Many of these disorders require persistent diagnostic skills and investigation; but when combined with knowledge of general principles, including the anatomy and physiology of the key cranial structures, the management of headache is generally productive and beneficial for the sufferer.
Chapter. 14708 words. Illustrated.
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