Edoardo Caronna, MD and Patricia Pozo-Rosich, MD, PhD, Neurology Department, Hospital Universitari Vall d’Hebron, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain; and Headache and Neurological Pain Research Group, Vall d’Hebron Research Institute, Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain. Dr. Pozo-Rosich also serves on the boards of the International Headache Society and Council of the European Headache Federation and is an editor for various peer-reviewed journals, including Cephalalgia and Headache.
Headache is a symptom of the coronavirus disease 2019 (Covid-19), caused by the novel, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the pandemic began, researchers have tried to describe, understand, and help clinicians manage headache in the setting of Covid-19.
The reason is simple: Headache is common, often debilitating, and difficult to treat.1
Moreover, headache could manifest both in the acute phase of the infection and, once the infection has resolved, in the post-acute phase.1 Therefore, it is critical for clinicians to know more about headache, as headache can be a common reason that patients seek help, both in the specialized and non-specialized medical care setting.
Definitions and manifestations
While the first step in such a communication would be to define headache attributed to Covid-19, no specific definition exists, as this is a new disease. Therefore, headache attributed to Covid-19 should be defined under the diagnostic criteria, as contained in the International Classification of Headache Disorders-3, as headache attributed to a systemic viral infection.2 As this is a secondary headache appearing with an infection, the treating physician needs to rule out possible underlying meningitis and/or encephalitis in the diagnosis. Moreover, other secondary headaches (eg, cerebral venous thrombosis) may appear, so clinicians need to carefully evaluate patients with headache during Covid-19 to detect signs or symptoms that point to other etiologies.
It is also advisable to know the clinical manifestations of headache attributed to Covid-19. Studies published so far have observed two main phenotypes of headache in the acute phase of the infection: one resembles migraine, the other, a tension-type headache.1,3 Although patients with history of migraine who contract Covid-19 report headache that is more similar to primary headache disorder,4 two relevant aspects should be considered. Namely, migraine-like features can be observed in patients without personal migraine history; and Covid-19 patients with such history may perceive that headache they experience in the infection’s acute phase differs from their usual experience, especially regarding increased severity or duration.5,6 Of note, headache can be a prodromal symptom of the SARS-CoV-2 infection.1
Evolution of a headache
Because headache appearing after the acute phase of the infection can persist, often manifesting migraine-like features, it is inordinately helpful for clinicians to know its evolution.1 This persistent headache, sometimes referred to as post-covid headache, is not aptly named because the post-covid headache is not just one type of headache, but instead can manifest as different headache types.
A recently published case series in Headache discussed three Covid patients who all experienced persistent headache during the infection’s post-acute phase.7 These patients experienced a migraine-like phenotype as have others with mild Covid-19, but their personal history of migraine, as well as their experience with Covid-19 related headache, were substantially different. Some patients had personal migraine history while others did not; some patients experienced no headache in the acute phase but did so in the post-acute phase; and the concomitant symptoms of the post-acute phase, such as insomnia, memory loss, dizziness, fatigue, and brain fog, were differentially expressed by patients.7
This case series introduces the concept that patients with no prior history of migraine or any other primary headache disorder can develop a de novo headache because of their SARS-CoV-2 infection. Moreover, it could manifest as a new daily persistent headache. And patients with personal history of migraine may experience sudden chronification in their headache’s characteristics, rather than develop a new type of headache.7
In another study, soon to be published in Cephalalgia, researchers observed that the median duration of headache in the acute phase is 2 weeks. This multicenter Spanish study, in which data on headache duration were available for 874 patients, found that 16% of these particular patients had persistent headache after 9 months. According to this study, headache that does not resolve within the first 3 months is less likely to do so later on.
Treatment
For clinicians, the significance of these findings is straightforward: Patients with headache experienced in the infection’s acute phase that does not seem to resolve post-infection requires continued medical attention. Patients should be monitored, carefully managed, and treated to avoid the onset of a persisting headache. This applies to patients with or without personal migraine history.
But which treatments should be prescribed? As there are no specific therapies for headache attributed to Covid-19, either in the acute or post-acute phase of the infection, clinicians must turn to existing therapies.
As with patients with migraine, patients with persistent headache post-Covid infection need a headache prevention strategy.
The strategy should be based on the following principles:
- treat headache
- treat comorbidities including mood disorders, insomnia, and so on
- avoid complications such as medication overuse, which may be very common in these patients.
Acute medications
Despite the lack of specific literature on this matter, migraine-like phenotypes may respond to triptans and probably, where available, lasmiditan and gepants. These medications probably represent a therapeutic option for Covid patients with headache, but before prescribing them clinicians should carefully evaluate their use.
Before deciding on the prescription, clinicians should consider not only the medications’ most common contraindications, but also those that are related to Covid-19: the phase of the infection (acute/post-acute); the infection’s severity; and the presence of other Covid-related health problems. The concerns over the use of nonsteroidal anti-inflammatory medications (NSAIDs) and corticosteroids, raised when the pandemic first struck, have greatly dissipated.8,9 Some patients with prolonged headache may benefit from a brief cycle of corticosteroids, similar to the treatment given to those patients with status migrainosus. Nerve blocks could also be considered.
Preventive medications
Drugs can be prescribed according to the headache phenotype too, but there are no published studies that specifically evaluate headache prevention treatments in patients with persistent headache post-infection. The case series mentioned earlier in this article recorded that patients whose headaches were treated with amitriptyline and onabotulinumtoxinA had reported variable treatment responses to this regimen, according to the patients’ characteristics.7
However, one important question regarding the safety of Covid patients with migraine – specifically patients on preventive treatments during the infection’s acute phase – has been somewhat resolved.
Medications such as renin-angiotensin system (RAS) blockers, suspected of possible involvement in the SARs-CoV-2 pathogenicity, seem to be safe.8,10 And, in another multicenter Spanish study, researchers found that the use of anti-CGRP monoclonal antibodies did not seem to be associated with worse Covid-19 outcomes despite the possible implication of CGRP in modulating inflammatory responses during a viral infection.11
The study of anti-CGRP monoclonal antibodies could be important in the future for another reason: To see whether these medications could be effective as a preventive treatment in patients with persistent headache after Covid-19, regardless of whether these patients have personal migraine history.
An interesting and important message to close this article. Although headache experienced in the infection’s acute phase could be extremely disabling for patients, the evidence points to the presence of headache as a marker of a better Covid-19 prognosis, in terms of a shorter infection period and a lower risk of mortality among hospitalized patients.1,3,12
This brief communication contains current information to help clinicians treat and inform their patients with Covid-sourced headache. Yet, we must keep in mind that the majority of the data reported here and published in the literature refer to studies conducted during the first wave of the pandemic. The emergence of new SARS-CoV-2 variants and vaccines have enormously changed the disease’s clinical presentation and course, so future studies are warranted to re-assess the validity of these findings under new conditions.