The authors of this current study tidily sum up the problem with post-traumatic headache (PTH): "Headache is the most common neurologic symptom following minor closed head injury. There is often a lack of objective evidence supporting an organic basis of cerebral pathology in these cases." The authors of this study set out to search for that organic basis.
The study compared 35 PTH sufferers with 92 patients with migraine and 49 non-headache control subjects. The cerebral blood flow of all participants was measured, using the "xenon Xe 133 inhalation technique." This imaging method involves the detection of a radioactive gas (Xe 133) inhaled by the subject, which shows the flow of blood through the brain.
The researchers found significant differences in blood flow of the PTH patients as compared to the migraine and nonheadache control subjects, and the authors explain how this abnormal blood flow is related to brain injury:
"Traumatic brain injury does not mechanically tear axons but rather causes focal intra-axonal change that leads to progressive axonal swelling and ultimately leads to disconnection. These pathobiological changes impact on the normal functioning of a cell, as well as neurotransmitters, neuromodulators, and electrical brain activity. This can result in interference with the regulatory capacity of the central, peripheral, autonomic, and vasomotor systems, impacting on CBF [cerebral blood flow]."
The use of cerebral blood flow imaging is useful, in that it can detect changes in the functioning of the brain that are not visible with other imaging techniques. In fact, the authors conclude by stating that this new method may forever change the status of PTH patients.
"If these findings are replicated in a prospective, controlled, randomized study, rCBF may be used as an objective test of organic pathology in mCHI [mild closed head injury]. Documenting organic disease in minor head injury headache has far reaching implications for the medical, legal, and insurance communities."
Gilkey SJ, Ramadan NM, Aurora TK, Welch KMA. Cerebral blood flow in chronic posttraumatic headache. Headache 1997;37:583-587.