| IHS | Diagnosis | ICD-10 |
|---|---|---|
| 10 | HEADACHE ATTRIBUTED TO DISORDER OF HOMOEOSTASIS | G44.882 |
| Coded elsewhere | 7.1.2 Headache attributed to intracranial hypertension secondary to metabolic, toxic or hormonal causes . | |
General comment
Primary or secondary headache or both?
When a new headache occurs for the first time in close temporal relation to a disorder of homoeostasis, it is coded as a secondary headache attributed to that disorder. 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 disorder of homoeostasis, 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 disorder of homoeostasis. Factors that support adding the latter diagnosis are: a very close temporal relation to the disorder of homoeostasis, a marked worsening of the pre-existing headache, very good evidence that the disorder of homoeostasis can aggravate the primary headache and, finally, improvement or resolution of the headache after relief from the disorder of homoeostasis.
Definite, probable or chronic?
A diagnosis of Headache attributed to disorder of homoeostasis usually becomes definite only when the headache resolves or greatly improves after effective treatment or spontaneous remission of the disorder. If this disorder cannot be treated effectively or does not remit spontaneously, or when there has been insufficient time for this to happen, a diagnosis of Headache probably attributed to disorder of homoeostasis is usually applied.
The alternative, when the disorder of homoeostasis is effectively treated or remits spontaneously but headache does not resolve or markedly improve after 3 months, is a diagnosis of A10.8 Chronic post-homoeostasis disorder headache. This is described only in the appendix as such headaches have been poorly documented, and research is needed to establish better criteria for causation.
Introduction
Headache disorders described here were previously referred to as Headache associated with metabolic or systemic disease. However, Headache attributed to disorder of homoeostasis was felt to capture more accurately the true nature of these headache disorders. Headaches caused by significant disturbances in arterial pressure and by myocardial ischaemia are now included in this section. In addition, disorders of homoeostatic mechanisms affecting a variety of organ systems, including altered arterial blood gases, volume disturbances as in dialysis and disorders of endocrine function, are covered here. Headache attributed to fasting is also included.
