| IHS | Diagnosis | ICD-10 |
|---|---|---|
| 5 | HEADACHE ATTRIBUTED TO HEAD AND/OR NECK TRAUMA | G44.88 |
General comment
Primary or secondary headache or both?
When a new headache occurs for the first time in close temporal relation to a known trauma, it is coded as a secondary headache attributed to the trauma. This is also true if the headache has the characteristics of migraine, tension-type headache or cluster headache. When a pre-existing primary headache is made worse in close temporal relation to a trauma, there are two possibilities, and judgment is required. The patient can either be given only the diagnosis of the pre-existing primary headache or be given both this diagnosis and the diagnosis of headache attributed to the trauma. Factors that support adding the latter diagnosis are: a very close temporal relation to the trauma, a marked worsening of the pre-existing headache, very good evidence that the particular kind of trauma can aggravate the primary headache and, finally, improvement of the headache after recovery from the trauma.
Definite, probable or chronic?
In many cases of secondary headache, the diagnosis is definite only when headache resolves or greatly improves within a specified time after effective treatment or spontaneous remission of the causative disorder. In such cases this temporal relation is an essential part of the evidence of causation. This is not so in the case of trauma: causation is established by onset in close temporal relation to trauma, whilst it is well recognised that headache after trauma often persists. When this occurs, for example after head trauma, 5.2 Chronic post-traumatic headache is diagnosed. Until sufficient time for recovery has elapsed, the diagnosis of 5.1 Acute post-traumatic headache is definite if the criteria are fulfilled. The same applies after whiplash injury. There is no option for a diagnosis of Headache probably attributed to head and/or neck trauma.
Introduction
Headache is a symptom that may occur after injury to the head, neck or brain. Frequently, headache that results from head trauma is accompanied by other symptoms such as dizziness, difficulty in concentration, nervousness, personality changes and insomnia. This constellation of symptoms is known as the post-traumatic syndrome; amongst them, headache is usually the most prominent.
A variety of pain patterns may develop after head injury, and may closely resemble primary headache disorders, most frequently tension-type headache, in more than 80% of patients. In some cases, typical migraine with or without aura may be triggered, and a cluster-like syndrome has been described in a few patients.
It is easy to establish the relationship between a headache and head or neck trauma when the headache develops immediately or in the first days after trauma has occurred. On the other hand it is very difficult when a headache develops weeks or even months after trauma, especially when the majority of these headaches have the pattern of tension-type headache and the prevalence of this type of headache in the population is very high. Such late-onset post-traumatic headaches have been described in anecdotal reports but not in case-control studies.
There are recognised risk factors for a poor outcome after head injury or whiplash injury. Women have a higher risk for post-traumatic headache, and increasing age is associated with less-rapid and less-complete recovery. Mechanical factors such as the position of the head at impact - rotated or inclined - increase the risk of headache after the trauma. The relationship between severity of the injury and severity of the post-traumatic syndrome has not been conclusively established. Although there are some controversial data, most studies suggest that post-traumatic headache is less frequent when the head injury is more severe. However, the causal relationship between head and/or neck trauma and headache is difficult to establish in some cases with very mild trauma.
The role of litigation in the persistence of headache is still discussed, and some studies show a reduction of headache in countries where the accident victims do not receive compensation. 5.2 Chronic post-traumatic headache and 5.4 Chronic post-whiplash injury headache are often part of the post-traumatic syndrome in which the complex inter-relationship between organic and psychosocial factors is difficult to assess.
