An initial and fundamentally important step in the management of headache is to differentiate those headaches that are the result of other, often serious, conditions ('secondary' headaches) from headaches that are not caused by an underlying disease process ('primary' headaches).
Although symptomatic treatment of pain is also necessary in secondary headaches, it is crucial to treat the underlying cause. In the case of a brain tumour, this may mean surgical excision or a shunt to reduce raised intracranial pressure; antibiotics for bacterial meningitis; and surgical drainage of an intracranial haemorrhage.
Primary headaches are the far larger group, and include tension, migraine, and cluster headaches. They can be treated in two ways – either with preventive treatment, or with rescue treatment once the pain starts. Prevention is of course far preferable, and can be achieved in most patients.
The Migraine Generator
In order to understand the treatment rationale for primary headaches, it is necessary to understand the pain-producing mechanism. Current theory recognises the presence of a centre in the brain from which the headaches are triggered. It is generally known as the “migraine generator”.
In headache sufferers, the migraine generator is thought to be more sensitive than in non-headache sufferers. Because of this it discharges more easily, resulting in headache or migraine. Incoming sensory messages from the structures making up the head and neck, terminate in the migraine generator. When there are sufficient incoming messages, the migraine generator fires, and causes a headache. There are broadly two ways to prevent the headaches. One is to reduce the sensitivity of the migraine centre with medication, and the other is to reduce the number of incoming impulses reaching the migraine generator.