Migraines are thought of as normal neurological functions interspersed with episodes of headaches. At least 20% of migraineurs meeting the International Headache Society criteria have changed the pattern from episodes of migraine into patterns of chronic headache. Chronic headache often does not return to normal neurological function. This evolving process from episodic headache to chronic headache is called transformation. In the population segment of chronic daily headache, migraine appears to be a progressive neurological disease. The decline of normal neurological function between episodes of migraine greatly exacerbates the migraine syndrome.
Transformation is a process that occurs usually over years. Usually the migraineur starts off having acute episodic migraines. As someone continues to have migraines over time, the pain can occur more often and start merging together with a mixed headache pattern of lower severity migraines intermingled with more severe episodes. The mixed headache pattern can further transform into chronic daily headache. These transformed headaches can be caused by rebound phenomenon or can happen by reasons that are not fully understood at the present time.
A threshold can refer to a horizontal piece of building material beneath a doorway or window, but the meaning is different in medical jargon. Threshold refers to the point at which stimulus or stimuli are of sufficient intensity to produce an effect. The threshold for migraines can be lowered (migraines may happen more easily) by having repeated migraines. Facilitation or kindling describe this phenomenon. Migraines make the sensitive body more sensitive. In other words, migraines breed migraines. The lower threshold for migraines is made easier as though kindling were put on a fire. Uncontrolled migraines not only cause more migraines but eventually cause transformed migraines. A severe stimulus, injury, illness, or stress can provoke the nervous system to generate uncontrolled migraines. The migraine pain changes over time. This change is called transformation. You can imagine one of your kid’s transformers changing from a robot to a plane or car, but can you imagine your migraines changing from a more classic presentation to chronic neck pain, sinus pain, or constant headache. Well believe it or not, over time migraines do transform. Usually a decade or more is necessary for transformation of episodic to chronic migraine. One of the sincere goals of my new book, Doctor, Why Do I Feel This Way?, is to prevent transformation in migraineurs who have not reached this stage.
An example of severe stimulus is smoking. The trigeminal nerve (sensation of the face) and the cervical (neck) nerves are adjacent to each other in the brain stem (the base of the brain). What affects one affects the other. Migraineurs who smoke usually will develop neck problems. It is absolutely essential for the migraineur who smokes to abstain! Smoke is a smell. The sensitivity to the smell is the problem! Also secondhand smoke, perfumes, and severe allergies are major problems. Neck pain can be debilitating and frustrating. The migraineur with neckaches can develop extreme sensitivity to stress and after years will frequently develop fibromyalgia.