STOWE, VERMONT—The third edition of the International Classification of Headache Disorders will soon be available on the website of the International Headache Society, Morris Levin, MD, reported at the 23rd Annual Headache Symposium of the Headache Cooperative of New England. The document will be presented in a “beta version,” and headache specialists are encouraged to review it and submit comments, said Dr. Levin, a neurologist at the Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire. The classification will be incorporated into the 11th edition of the World Health Organization’s International Classification of Diseases, “which is unusual for a subset or specialty,” said Dr. Levin.
Frequency of Headaches in Chronic Migraine Has Decreased
The third edition of the classification contains various modifications to the section on primary headache. For example, the new definition of chronic migraine is eight migraine headaches or headaches that respond to migraine treatment per month and seven or more additional headaches per month. The previous definition of chronic migraine was 15 or more migraines per month.
Because of growing evidence that benign positional vertigo is a migraine variant, the condition was included in the migraine chapter of the new classification. In the same chapter, typical aura with migraine headache was renamed “migraine with typical aura.”
Basilar type migraine has been renamed “migraine with brainstem aura.” To receive this diagnosis, a patient must have at least two brainstem symptoms, which include dysarthria, vertigo, tinnitus, hypoacusis, diplopia, ataxia, and consciousness alteration. Neurologists may argue, however, that these symptoms indicate cortical dysfunction, rather than brainstem dysfunction, said Dr. Levin.
The chapter about trigeminal autonomic cephalalgias has undergone several changes in the new classification. Short, unilateral, neuralgiform (SUN) headaches were combined into one entity with two subcategories. SUN headaches accompanied by conjunctival injectional tearing are called SUNCT, and SUN headaches with other autonomic features are called SUNA. In addition, the duration of SUN headaches is now from one to 600 seconds instead of 0.5 to 600 seconds. SUN headaches can be episodic or chronic. Also, hemicrania continua is now in the chapter about trigeminal autonomic cephalalgias instead of the chapter about other primary headaches.
Cold stimulus headache and external compression headache were added to the chapter about other primary headaches. The same chapter contains primary headache associated with sexual activity, a new entity that combines orgasmic headache and preorgasmic headache. The definition of new daily persistent headache also was broadened to include migrainous headaches, which constitutes “an important change,” said Dr. Levin.
No Specific Features Required for Medication Overuse Headache
It can be difficult to know whether a headache is primary or secondary, noted Dr. Levin. A secondary headache should occur close in time to the cause of the disorder and often improves if the cause is removed. But a headache’s failure to resolve when its ostensible cause is removed “is not evidence against secondary headache,” he added. Unlike the previous edition of the classification, the new edition does not require the headache to resolve when the ostensible cause is removed.
“If the headache has features of a particular primary headache, but has arisen after a presumed secondary cause, classify it as a secondary headache,” said Dr. Levin. “That’s the best way to do it. On the other hand, [you should] treat it like the primary headache that it resembles.”
The description of medication overuse headache has changed in the new classification. Particular headache features are no longer required for this diagnosis, because “secondary headaches can take on many different morphologies,” said Dr. Levin. The new classification also does not require medication overuse headache to resolve after discontinuation of the overused medication.
Because medication overuse headache can be hard to distinguish from chronic migraine, the new classification suggests that clinicians who suspect medication overuse code a patient for probable medication overuse headache and probable chronic migraine. “When there are more data to support one or the other, you can change the diagnosis,” explained Dr. Levin.
Appendix Includes Various New Headaches
The new classification also includes various additions to the appendix, which is “probably the most interesting part of the whole document,” according to Dr. Levin. One addition, vestibular migraine, may be appropriate for patients who have episodic vertigo with or without headache. At least 50% of vestibular migraine episodes must be associated with at least one migraine feature, according to the classification. The diagnosis is important, because the condition “may respond to migraine treatment,” said Dr. Levin.
Although the new classification requires postconcussive headaches to appear within seven days of injury, the appendix now contains an entry called post-traumatic headache with delayed onset. The definition for cervicogenic headache has become broader, allowing for several more possible conditions to produce this type of secondary headache. Also, the appendix includes several more proposed subtypes of cervicogenic headache.