Headache is term used to describe pains located in the head including unpleasant sensations in the region of cranial vault.
Causes of headache is divided into
1. Intracranial causes:
- Space occupying lesions-tumour,abscess.
- Meningeal irritation-meningitis,subarchanoid haemorrhage.
- Vascular-cerebral haemorrhage,subdural haematoma.
- Head injury.
- Pseudotumour cerebri(benign intracranial hypertension).
2. Referred pain:
- Eyes-glaucoma,iritis,hypermetropia,astigmatism,eye strain.
- Ears- otitis media,mastoiditis.
- Teeth-dental root abscess.
- Paranasal sinuses-frontal or maxillary sinusitis.
- Cervical spondylosis.
3. Miscellaneous-migraine,temporal arteritis,cluster headache,tension headache.
- Mechanism of headache- brain itself is insensitive to pain as it is devoid of pain sensitive receptors. pain receptors are found in blood vessels at the base of brain,meninges,extracranial blood vessels,muscles of scalp,neck,face;paranasal sinuses,eyes,teeth. Pin sensitivity is dependent upon the nerves(sensory nerves).
- Headache is caused by stimulation of pain receptors,which occurs by traction,displacement or dilatation of intracranial or extracranial vessels or venous sinuses by raised intracranial pressure,raised pressure in venous sinuses in emphysema.
- Mechanical irritation eg intracranial lesions,head injury,chemical irritation eg migraine due to 5-HT histamine,inflammation eg temporal arteritis. meningeal irritation and traction eg meningitis,subarchanoid haemorrhage.
- Compression,traction or intrinsic disease of cranial and spinal nerves eg tumour,inflammtion.
- Prolonged contraction of cranial and cervical muscles eg cervical spondylosis,anxiety states.
- Pain due to stretching of pain sensitive nerve endings within the muscle fascicles,compression and traction of scalp blood vessels.
- Referred pain occurs via second and third divisions of 5th cranial nerve.