In recent years, research implicating biochemical abnormalities in various pathological conditions has spiralled. Headache is an area in which numerous research studies have been conducted examining biochemical alterations. We have noticed several similarities in biochemical changes reported to occur in migraine and in experimental traumatic brain injury. The most common symptom in mild head injury or mild traumatic brain injury is headache which, in many instances, resembles migraine but has a poorly understood pathophysiology. Biochemical mechanisms believed to be similar in both conditions include: increased extracellular potassium and intracellular sodium, calcium, and chloride; excessive release of excitatory amino acids; alterations in serotonin; abnormalities in catecholamines and endogenous opioids; decline in magnesium levels and increase in intracellular calcium; impaired glucose utilization; abnormalities in nitric oxide formation and function; and alterations in neuropeptides. In this paper, these proposed biochemical alterations will be reviewed and compared. Very similar alterations suggest posttraumatic headache associated with mild head injury and migraine may share a common headache pathway.

A variety of symptoms (postconcussion symptoms) have been consistently reported following mild head or neck injury. One symptom which may have been under reported is cognitive impairment. We conducted a retrospective study of 100 patients presenting for evaluation and treatment of posttraumatic headache at our headache clinic. Sixty-five percent reported difficulties with either memory, concentration, and/or thinking. The most common cognitive symptoms reported were concentration+memory problems, concentration + memory + thinking difficulties, concentration disturbances, and difficulty remembering, respectively. Subjects in both groups (with cognitive symptoms and without cognitive symptoms) were similar in age, but females seemed more predisposed than males to cognitive impairment following mild head injury. It is suggested that clinicians thoroughly evaluate patients for cognitive symptoms, particularly when patients have a permanent condition and are subsequently involved in litigation.

In the headache literature, there exists a great deal of discrepancy regarding when posttraumatic headache (PTH) may be classified as chronic. Although chronic pain is usually described as pain persisting for longer than six months, many view chronic posttraumatic headache as persisting for more than two months, including the International Headache Society criteria. Observations made by Brenner and Friedman in 1944 have been repeatedly cited for this determination. Surprisingly, a review of this original source revealed that the term "chronic" was never used when discussing posttraumatic headache over two months duration. The authors, in fact, suggested two months as an "arbitrary" dividing line. Recent studies suggest that many patients with PTH continue to improve or change over the first six months but start to plateau after that time. We feel six months serves as a better time indicator for defining chronicity in cases of posttraumatic headache. This would be more consistent with the current literature concerning chronic pain and the international Headache Society criteria for chronic tension headache.

Although biofeedback in the treatment of migraine and tension-type headache has been widely researched, there is little research examining biofeedback therapy in posttraumatic headache (PTH). In this retrospective study, 40 subjects with PTH who had received biofeedback-assisted relaxation at our headache clinic were questioned at least 3 months following the completion of therapy. Subjects were queried about improvements in headache, increases in ability to relax and cope with pain, and overall benefits, lasting effectiveness, and continued use of biofeedback in daily life. Results indicate 53% reported at least moderate improvement in headaches; 80% reported at least moderate improvement in ability to relax and cope with pain; 93% found biofeedback helpful to some degree; 85% felt headache relief achieved through biofeedback had continued at least somewhat; and 95% stated they were continuing to use biofeedback skills in daily life. A correlation analysis revealed a negative relationship between response to biofeedback and increased chronicity of the disorder. In other words, the more chronic the disorder, the poorer the response to treatment. A stepwise regression analysis found that chronicity of the disorder and number of treatment sessions significantly affected response to treatment. Data suggest that biofeedback-assisted relaxation should at least be considered when planning treatment strategies for posttraumatic headache.

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