The authors also describe headaches associated with impaired cerebrospinal fluid (CSF) dynamics such as intracranial hypertension and inflammatory conditions such as giant cell arteritis.

Clinical Pain Advisor interviewed Nauman Tariq, MD, assistant professor of neurology at Johns Hopkins University School of Medicine and director of the Johns Hopkins Headache Center.

Clinical Pain Advisor: What are the most clinically relevant types of nonmigraine primary headache and facial pain?

Dr Tariq: Cluster headache is unique because it presents with cranial autonomic symptoms such as conjunctivitis, nasal congestion, rhinorrhea, and ptosis. This is a very severe headache that is usually focused around the periorbital region and is more common in men and smokers. The critical feature of cluster headache is that it is timed — its duration must be between 15 minutes and 3 hours or it is not classified as a cluster headache. Magnetic resonance imaging studies show activation in the same areas of the brain in cluster headache and migraine — the hypothalamus and midbrain. The hypothalamus has a major role in cluster headache — hence the cranial autonomic symptoms. This type of headache may be missed in a family medical setting and warrants referral to a headache center.

Trigeminal neuralgias present with sharp, stabbing face pain lasting a few seconds, followed by a refractory period without pain, and this cycle may repeat multiple times. As a unique feature, these are often associated with cutaneous triggers like brushing one’s teeth, shaving, and even cold wind on the face. Many of these patients have a neurovascular compression of the trigeminal nerve — which can demyelinate the nerve and cause pulsating pain — and frequently responds well to microvascular decompression. First-line medications include carbamazepine and oxcarbazepine.

Postconcussion headache has been an increasing focus of discussion in the literature and in the news over the past 2 years. Postconcussion headache can develop even in patients without a history of migraine, with lasting symptoms that resemble migraine symptoms. In a study of veterans with mild to moderate traumatic brain injury, 35% had persistent headache even 5 years after concussion.6

Hemicrania continua is a unique type of headache that is side locked, with the same autonomic symptoms as cluster headache. However, it is continuous, and not timed like cluster headache. These headaches are so rare that they can be misdiagnosed, sometimes for years. In the ICHD, the diagnostic criteria require that this headache must respond to indomethacin — if it does not, then you must consider another type of headache like cervicogenic headache. Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID) with a chemical structure that is different from the other NSAIDs but similar to melatonin and with high CSF penetration. In practice, if an unusual headache does not fulfill the migraine criteria, we will often prescribe indomethacin for 2 to 3 weeks to see whether it responds.

Persistent idiopathic facial pain often occurs after a dental procedure, but it is very rare considering the number of dental procedures performed. I do think this phenomenon is underreported in the literature. In the last 5 years I have seen maybe 20 to 25 patients who have been unresponsive to all treatments. Patients may experience 30% to 40% relief from various treatments. In meetings, my colleagues and I persistently view this condition as a challenge. Once it becomes chronic, it is very hard to treat. It is a type of facial pain that does not respect the trigeminal branch boundaries. Compared with trigeminal neuralgias, which will affect one division or another, persistent idiopathic facial pain is sometimes diffuse all over the face. It would be helpful if clinicians would collect those cases for a larger cohort study. This may ultimately prompt larger studies to investigate biomarkers and try to identify predictors of persistent facial pain that is unresponsive to treatment.

Clinical Pain Advisor: What are some key takeaways for clinicians regarding this topic?

Dr Tariq: Accurate diagnosis is very important because we do not have biomarkers to distinguish among the different types of headache, as in the way troponin is used in cardiac care, for example. There is some preliminary progress in the research, but those studies are very small. Thus, we have to rely on those set criteria, and many times, adequate experience and training are required to pick up the less common types of headache.

When the physician in an outpatient clinic is dealing with an unusual type of headache, I recommend that they visit the ICHD website, which features straightforward diagnostic criteria for the range of headache types. If a patient does not respond after a couple of treatment trials, then refer the person to a neurologist or headache specialist.

Often, patients can improve significantly with treatment, but if they have to wait 4 to 5 years to receive an accurate diagnosis, that is a lot of time living with unnecessary symptoms and disability, and their prognosis may worsen.

Clinical Pain Advisor: What are remaining needs in this area in terms of research, physician education, or otherwise?

Dr Tariq: Although the National Institutes of Health (NIH) has allocated some funds and grants for research on headache and facial pain, these funds are insufficient, considering the scope of the problem. For example, expenditures related to migraine total billions of dollars in the United States alone. This gap is recognized by industry, which provides research funding (about 90% of research in this area is industry funded). Ideally, however, we would like to have NIH-funded studies to reduce the risk for bias.

Additionally, we need funding for more fellowships focusing on headache specialization, and we need a greater focus on headache in neurology residencies. It is currently not a mandatory elective, but I think we should require at least 4 weeks in a headache center.

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1. National Institute of Neurological Disorders and Stroke. Headache: Hope Through Research. Updated July 6, 2018. Accessed April 25, 2019.

2. Ahmed F. Headache disorders: differentiating and managing the common subtypes. Br J Pain. 2012;6(3):124-132.

3. Vgontzas A, Rizzoli PB. Nonmigraine headache and facial pain. Med Clin North Am. 2019;103(2):235-250.

4. Alvis-Miranda HR, Milena Castellar-Leones S, Alcala-Cerra G, Moscote-Salazar LR. Cerebral sinus venous thrombosis. J Neurosci Rural Pract. 2013;4(4):427-438.

5. Sattar A, Manousakis G, Jensen MB. Systematic review of reversible cerebral vasoconstriction syndrome. Expert Rev Cardiovasc Ther. 2010;8(10):1417-1421.

6. Hoffman JM, Lucas S, Dikmen S, et al. Natural history of headache after traumatic brain injury. J Neurotrauma. 2011;28(9):1719-1725.