Understanding the Connection Between Migraines, Posttraumatic Headaches

To what extent are posttraumatic headache (PTH) and migraine related? In a presentation at the Migraine Trust International Symposium, Todd J. Schwedt, MD, professor of neurology at the Mayo Clinic in Arizona, reviewed the similarities of various overlapping symptoms and their severity.

PTH and migraine have several areas where they share similarities: clinical symptoms, pathophysiology, and overlap in research brain imaging findings. In addition, migraine is a strong risk factor for developing persistent PTH, said Schwedt, who is also chair of Neurology Research at the Mayo Clinic’s Arizona campus.

According to The International Classification of Headache Disorders, 3rd Edition (ICHD 3), a de novo headache occurring with another disorder that is known to be causing it is always diagnosed as secondary headache—even when the new headache has the same primary characteristics of a primary headache, he said.

On the other hand, when a primary headache becomes worse after an injury, there are 3 possibilities, he said, again citing the ICHD 3. It could be a coincidence; it could be an aggravation of the primary headache; or it could be a new headache.

When describing these headaches, Schwedt cautioned his audience to be specific in their use of terminology. While these headaches are typically described in line with the other headache they may most closely resemble, such as “PTH with a migraine-like phenotype” he said, terms such as “posttraumatic migraine” or “posttraumatic tension-type headache” should not be used. Such imprecise language might seem to imply that the pathophysiology is the same, he said.

To review the symptoms shared by the 2 conditions, he briefly discussed 2 studies.

One, published earlier this year, was a phenotyping analysis of 100 individuals with persistent PTH. The most common headache phenotype was chronic migraine-like headache (n = 61) followed by combined episodic migraine-like and tension-type-like headache (n = 29). Nine participants reported “pure” chronic tension-type-like headache. 

Another study explored the phenotyping of a random sample of US military members. The recently deployed soldiers included those with (n = 557) and without (n = 1030) a history of a recent mild traumatic brain injury (mTBI; concussion). mTBI+ soldiers were subdivided as PTH+ (n = 230) and PTH– (n = 327).

The study restricted results to soldiers with headaches, consisting of 94% of the mTBI+ group and 76% of the mTBI– group. All headache/migraine features (except for headache duration) were more common or more severe in the PTH+ group compared with the nonconcussed group (mTBI–) and compared with the concussed group with nontraumatic headaches (PTH–).

In the mTBI– and PTH– groups, headaches were similar. Symptoms most common to PTH+ included allodynia, visual aura, sensory aura, daily headache, and continuous headache. More of the patients in the the PTH+ group sought medical care for headache (62%) vs the PTH– group (20%) or the mTBI– group (13%) (P < .008).

"As anticipated, those with migraine as well as those with posttraumatic headache had more severe symptoms of allodynia and hyperacusis and photophobia compared to the healthy controls, and the severity of the symptoms was more or less similar between the migraine group and the posttraumatic headache group,” said Schwedt, discussing the severity of symptoms in the context of their similarity to migraine.

The only exception to this was in the hyperacusis group, where the symptoms were even more severe in those with PTH.

The are many other associated symptoms between the 2 conditions, including dizziness, cognitive dysfunction, anxiety, depression, sleep problems, fatigue extracranial pain, and autonomic dysfunction, he said.

One study compared symptoms of autonomic dysfunction in PTH and migraine compared with healthy controls; it appeared that patients with PTH had even more symptoms than patients with migraine.

Some have argued that TBI is just “unmasking an individual person’s predisposition to migraine,” but Schwedt said that PTH happens in people without a personal or family history of migraine. While migraine is a risk factor for PTH, it can’t explain all cases, as many with PTH do not have migraine in their background.

In addition, PTH often resolves on its own, whereas migraine does not. When PTH does not go away, it often does not respond to migraine medication, he said, although erenumab might be helpful for some patients. Patients with PTH also have lower pain thresholds than individuals with migraine.

Research currently under review is attempting to see if imaging data can help resolve diagnostic questions about PTH. A classification model was used that included both clinical features and imaging data. The model was applied to 34 patients with migraine and 47 patients with persistent PTH. Adding imaging data to the model boosted the accuracy of differentiating between the 2 conditions from 70.7% to 76.8%, he said.

Given the links between the 2 conditions, Schwedt said some headaches after TBI might be migraine exacerbations or new-onset migraine followed by injury. But including the differences between them, he said PTH is typically a distinct headache type after TBI.