Headache disorders

Symptoms

• Headache

 

Epidemiology

• Globally, it has been estimated that prevalence among adults of current headache disorder (symptomatic at least once within the last year) is about 50%. 
• Half to three quarters of adults aged 18–65 years in the world have had headache in the last year and, among those individuals, 30% or more have reported migraine. 
• Headache on 15 or more days every month affects 1.7–4% of the world’s adult population. 
• Despite regional variations, headache disorders are a worldwide problem, affecting people of all ages, races, income levels and geographical areas. 
• In the Global Burden of Disease Study, updated in 2013, migraine on its own was found to be the sixth highest cause worldwide of years lost due to disability (YLD). Headache disorders collectively were third highest. 
• In an outpatient clinic setting, most headaches are benign. Fewer than 1% of outpatients with non-acute headache have a serious underlying cause. In the Emergency Department, there will be a much higher prevalence of serious underlying pathology presenting with headache.

 

Physiology

• There are no pain receptors in the central nervous system. Any painful stimulation of the CNS structures will not be detected.
• The brain is surrounded by the meninges, periosteum and scalp. It contains venous sinuses and blood vessels. All of these structures contain pain receptors.
• Incoming sensory information can be modulated in the CNS. CNS abnormalities can alter the duration, severity, localisation and character of pain sensation.
• The perception of pain can originate in the CNS, despite a lack of sensory input.

 

Pathophysiology

Many types of headaches are poorly understood, with little pathological evidence to support the clinical findings.
The causes of headaches can be divided into:

• Dysfunction of the central nervous system.
• Dysfunction of peripheral nervous system.
• Stimulation of functional pain receptors and sensory nerves in the structures near the brain.

There are some widely believed ‘headache myths':

• My bad eyesight explains my headache: Frequency of 'headache associated with refractive errors' is associated with 6.7% of patients with refractive error, compared to 0% of control subjects. With adequate refractive correction, 38% of these patients had complete remission of pain and 72.5% reported a significant improvement.
• High blood pressure explains my headache: Malignant hypertension can cause headache, but this is rare.
• Sinus problems explain my headaches: Sinusitis can cause headache, but it is rarely the explanation for recurrent or chronic headache.

 

Classification

The IHS (International Headache Society) have created a classification system called the ICHD-3.

• Primary headache disorders

• Secondary headache disorders

• Painful lesions of the cranial nerves and other facial pain

• Other headache disorders

  • Headache presentations with insufficient evidence to make an accurate diagnosis at that time.
  • Diagnosis of headache disorder which has not yet been described in the classification system. 

 

Diagnosis

• Medical history must involve a systemic pain assessment. (For example: SOCRATES). 
• Imaging does not help to confirm or differentiate primary headache disorders, but it exclude some secondary disorders.

Applying the surgical sieve to the complaint of "headache"

 

Sources

1. World Health Organisation, 2018, http://www.who.int 
2. The International Classification of Headache Disorders, 3rd edition, International Headache Society, 2018 
3. Guyton and Hall Textbook of Medical Physiology, 11e, July 2005 
4. Kumar & Clark’s Clinical Medicine 9e, July 2016 
5. Kumar & Clark’s Cases in Clinical Medicine, 3e, 2013