A headache is the phenomenon of pain in the head, and there is usually some underlying illness responsible for it. It is also, however, the symptom whose cause is hardest of all to identify.
In Summary
- Headache divides into primary and secondary types, and it appears across an unusually wide range of disease systems.
- Neurological, ENT, ophthalmic, dental and oral, musculoskeletal, infectious, general internal, and psychological causes all belong on the list.
- To these I would add three that are especially common in Korea today: digestive disorder, high blood sugar, and depression and anxiety.
- Recurrent or severe headache accompanied by neurological abnormality, vomiting, reduced consciousness or visual disturbance always requires specialist assessment and thorough investigation.
- No clinician can check every one of these systems. They listen to what the patient reports and explain it in terms of the commonest pattern, or of their own specialty.
- So it matters greatly that patients look carefully for conditions other than the headache itself, and observe what makes it worse and what eases it.
- Every living thing is a complex system by its very existence — but headache may be the most complex-system-like of all physiological phenomena and diseases.
Causes of Headache, System by System
Neurological disease. Cerebrovascular events — cerebral haemorrhage, infarction (stroke), subarachnoid haemorrhage, ruptured aneurysm — can produce sudden, severe headache. Subarachnoid haemorrhage in particular may bring a thunderclap headache together with reduced consciousness, vomiting and neck stiffness. A brain tumour presents as a slowly progressive headache with vomiting, visual field disturbance and neurological signs. Encephalitis and meningitis bring headache alongside fever, vomiting, reduced consciousness and seizures. Head trauma, and neuralgias such as trigeminal neuralgia, also belong here.
ENT disease. Sinusitis produces headache along with pain in the forehead, around the eyes and across the face. Otitis media and other ear conditions can do the same.
Ophthalmic disease. Glaucoma and intraocular inflammation bring headache together with raised intraocular pressure, reduced vision and eye pain. Refractive error and poor vision cause headache when the eyes are used for long stretches.
Dental and oral disease. Dental infection and temporomandibular joint disorder can carry through into headache.
Musculoskeletal disease. Cervicogenic headache, arising from abnormality or tension in the cervical spine, radiates from the occiput and the nape into the head.
Infectious disease. Colds, influenza and other systemic infections commonly bring headache along with fever and body aches.
General internal disease. Headache occurs in hypoxia, hypoglycaemia, hypertension, and endocrine disorders such as thyroid dysfunction. Drug overuse and withdrawal, alcohol, and toxic substances such as lead are causes; and in a hypertensive crisis, when blood pressure climbs abruptly, headache intensifies.
Other. Tension headache from psychological factors — stress, anxiety, depression — is common. Hormonal change through menstruation, pregnancy and menopause provokes headache. More rarely, parasitic infection, autoimmune disease and haematological disease are responsible.
Three More to Add for Korea Today
Reading through the general list, what seems underweighted is precisely what afflicts Koreans now. I think these three have to be considered alongside it.
Digestive disorder and vomiting. In gastrointestinal conditions such as gastritis, enteritis and functional dyspepsia, headache accompanies indigestion, nausea, vomiting and abdominal distension. In acute gastritis and functional gastrointestinal disorder especially, headache appears together with post-meal epigastric discomfort, bloating and belching. Where indigestion and headache recur or become chronic together, functional gastrointestinal disorder should be considered.
High blood sugar (diabetes). Headache commonly accompanies a raised blood glucose state. Recent research has found that headache and migraine are genetically associated with glycaemic measures such as fasting insulin and HbA1c, and some studies suggest glycaemic control may be a new treatment strategy for headache and migraine. When a person with diabetes has recurrent or severe headache, glycaemic control must be checked — both hypoglycaemia and hyperglycaemia can be the cause.
Depression and psychiatric conditions. Depression, anxiety disorder and panic disorder are closely bound up with headache. Rates of comorbid depression and anxiety are very high among chronic headache patients with migraine or cluster headache, and the more severe the headache, the greater the risk of depression. A long-running headache can generate depression; conversely, depression worsens headache. More than a third of cluster headache patients are reported to experience severe anxiety and depression.
Why Headache Is a Complex System
To treat a headache you have to know its cause — yet the range of possible causes is wide, and it is common for several factors to be tangled together.
Even at a clinic, no doctor can check every condition listed above. They listen to what the patient reports and explain it by reference to the commonest pattern, or to the problems of their own specialty. This is not a failure of diligence; it is structural.
So if you are the one with the headache, examine carefully whether you have some condition other than the headache, and observe for yourself what makes it worse and what relieves it. That observation becomes the most valuable information in the consulting room.
In Summary
Every living thing is a complex system simply by existing — but among physiological phenomena and diseases, headache may be the most complex-system-like of them all. One caveat stands above the rest, though: if a headache is recurrent or severe, or comes with neurological abnormality, vomiting, reduced consciousness or visual disturbance, seek specialist assessment and proper investigation before you settle in to observe it yourself.
Related reading: Is a Headache Too Much Energy, or Too Little? · Headache Is Heat Above, Cold Below
This article reflects the teaching and research of Professor Seungho Baek, Professor of Korean Medicine at Dongguk University College of Korean Medicine, specializing in Pathology and Oncology.
