Abstract
Dear Sir We would like to draw your attention to—in our view—problematic aspects of the current diagnostic criteria of the International Classification of Headache Disorders (ICDH-II) for post-traumatic headache (1).
According to the International Headache Society classification, the onset of headache within 7 days after trauma is critical for diagnosing post-traumatic headache, provided that there has not been any headache prior to the trauma or if a previously diagnosed idiopathic headache syndrome is worsened by the trauma. If the situation is normalized within 3 months, the headache is called acute post-traumatic headache. Beyond that time limit, it is called chronic post-traumatic headache.
We have to face two major problems with this definition in our daily practice. These seem even to be accentuated in cases of mild traumatic brain injury (MTBI).
First, in the absence of a biomarker for headache, there is the problem of objectivity. This is especially difficult to handle from the insurance point of view, as the occurrence of headache after trauma has been shown to follow not only head or neck trauma, but also trauma to other parts of the body excluding the head (2). Mickevičiene et al. (3) found that headache after 3 months and 1 year did not differ significantly between head-injured patients and non-head-injured controls.
The second problem is to try to determine causality. The aetiology of headache following trauma is not yet well investigated. The development of acute headache after head and neck trauma is nevertheless well accepted, and in case of concussion is part of the so-called post-concussional syndrome. According to Lennaerts and Couch (4), acute post-traumatic headache develops in 80% of cases. Several pathomechanisms are hypothesized, e.g. cerebrospinal fluid leakage after whiplash injury (5). Interestingly, an inverse relation between the development of headache and the severity of the head trauma is well known (6–8). This is an important and strong argument against the frequently diagnosed chronic ‘post-traumatic’—meaning due to the actual trauma—headache after MTBI. The term ‘post-traumatic’ itself is ambiguous. Although per se it does not imply a direct causal relationship, it is often assumed to be so with its consequences in diagnostic, therapeutic and medicolegal aspects.
What does the diagnosis ‘headache attributed to mild head injury’ and ‘headache attributed to whiplash injury’ actually mean for the patients? Their headache is seen and attributed solely to the trauma, both by themselves as well as by their physician, who is most often a family practitioner. The time lag until a specialist/neurologist is consulted and involved in the diagnosis is often considerable. This is a problem, as in our experience it means that the patient often uses acute pain medication on a daily basis, which leads to the development of medication overuse headache in a significant number of patients. This is an iatrogenic situation, as the treating physicians prescribe the drugs themselves or do not prevent the patient from taking daily over-the-counter preparations. In an unknown number of patients, this mechanism even remains unrecognized.
In our view, the temporal criteria for diagnosing post-traumatic headache are not sufficient, which might explain that chronic post-traumatic headache seems to be overdiagnosed. The consequence is that important differential diagnoses are not considered. From a therapeutic point of view, the diagnosis of chronic post-traumatic headache tends to be a limiting and counterproductive factor, and even more so if the important differential diagnosis of medication overuse headache is missed. The false attribution of chronic headache to solely a trauma is enforced by the diagnosis of ‘post-traumatic headache’, which can be the beginning of an ongoing vicious circle.
What should be done? In our opinion the classification criteria for the diagnosis ‘chronic post-traumatic headache’ need to be supplemented. We propose to include a clear statement into ICDH-II concerning the importance of the differential diagnosis ‘Medication Overuse Headache’. This seems highly relevant, as there are data suggesting that response to prophylactic therapy is only given if the patient does not overuse acute headache medication (9). Further, there is a need for further studies in this context, preferably from other research groups, to add to the results of previous studies (10).