Approximately one in five patients who presented with headache during the acute phase of COVID-19 developed chronic daily headache, according to a study published in Cephalalgia. The greater the headache’s intensity during the acute phase, the greater the likelihood that it would persist.
The research, carried out by members of the Headache Study Group of the Spanish Society of Neurology, evaluated the evolution of headache in more than 900 Spanish patients. Because they found that headache intensity during the acute phase was associated with a more prolonged duration of headache, the team stressed the importance of promptly evaluating patients who have had COVID-19 and who then experience persistent headache.
Long-term evolution unknown
Headache is a common symptom of COVID-19, but its long-term evolution remains unknown. The objective of this study was to evaluate the long-term duration of headache in patients who presented with this symptom during the acute phase of the disease.
Recruitment for this multicenter study took place in March and April 2020. The 905 patients who were enrolled came from six level 3 hospitals in Spain. All completed 9 months of neurologic follow-up.
Their median age was 51 years, 66.5% were women, and more than half (52.7%) had a history of primary headache. About half of the patients required hospitalization (50.5%); the rest were treated as outpatients. The most common headache phenotype was holocranial (67.8%) of severe intensity (50.6%).
Persistent headache common
In the 96.6% cases for which data were available, the median duration of headache was 14 days. The headache persisted at 1 month in 31.1% of patients, at 2 months in 21.5%, at 3 months in 19%, at 6 months in 16.8%, and at 9 months in 16.0%.
“The median duration of COVID-19 headache is around 2 weeks,” David García Azorín, MD, PhD, a member of the Spanish Society of Neurology and one of the coauthors of the study, said in an interview. “However, almost 20% of patients experience it for longer than that. When still present at 2 months, the headache is more likely to follow a chronic daily pattern.” Dr. García Azorín is a neurologist and clinical researcher at the headache unit of the Hospital Clínico Universitario in Valladolid, Spain.
“So, if the headache isn’t letting up, it’s important to make the most of that window of opportunity and provide treatment in that period of 6-12 weeks,” he continued. “To do this, the best option is to carry out preventive treatment so that the patient will have a better chance of recovering.”
Study participants whose headache persisted at 9 months were older and were mostly women. They were less likely to have had pneumonia or to have experienced stabbing pain, photophobia, or phonophobia. They reported that the headache got worse when they engaged in physical activity but less frequently manifested as a throbbing headache.
Secondary tension headaches
On the other hand, Jaime Rodríguez Vico, MD, head of the headache unit at the Jiménez Díaz Foundation Hospital in Madrid, said in an interview that, according to his case studies, the most striking characteristics of post–COVID-19 headaches “in general are secondary, with similarities to tension headaches that patients are able to differentiate from other clinical types of headache. In patients with migraine, very often we see that we’re dealing with a trigger. In other words, more migraines – and more intense ones at that – are brought about.”
He added: “Generally, post–COVID-19 headache usually lasts 1-2 weeks, but we have cases of it lasting several months and even over a year with persistent daily headache. These more persistent cases are probably connected to another type of pathology that makes them more susceptible to becoming chronic, something that occurs in another type of primary headache known as new daily persistent headache.”
Primary headache exacerbation
Dr. García Azorín pointed out that it’s not uncommon that among people who already have primary headache, their condition worsens after they become infected with SARS-CoV-2. However, many people differentiate the headache associated with the infection from their usual headache because after becoming infected, their headache is predominantly frontal, oppressive, and chronic.
“Having a prior history of headache is one of the factors that can increase the likelihood that a headache experienced while suffering from COVID-19 will become chronic,” he noted.
This study also found that, more often than not, patients with persistent headache at 9 months had migraine-like pain.
As for headaches in these patients beyond 9 months, “based on our research, the evolution is quite variable,” said Dr. Rodríguez Vico. “Our unit’s numbers are skewed due to the high number of migraine cases that we follow, and therefore our high volume of migraine patients who’ve gotten worse. The same thing happens with COVID-19 vaccines. Migraine is a polygenic disorder with multiple variants and a pathophysiology that we are just beginning to describe. This is why one patient is completely different from another. It’s a real challenge.”
Infections are a common cause of acute and chronic headache. The persistence of a headache after an infection may be caused by the infection becoming chronic, as happens in some types of chronic meningitis, such as tuberculous meningitis. It may also be caused by the persistence of a certain response and activation of the immune system or to the uncovering or worsening of a primary headache coincident with the infection, added Dr. García Azorín.
“Likewise, there are other people who have a biological predisposition to headache as a multifactorial disorder and polygenic disorder, such that a particular stimulus – from trauma or an infection to alcohol consumption – can cause them to develop a headache very similar to a migraine,” he said.
Providing prognosis and treatment
Certain factors can give an idea of how long the headache might last. The study’s univariate analysis showed that age, female sex, headache intensity, pressure-like quality, the presence of photophobia/phonophobia, and worsening with physical activity were associated with headache of longer duration. But in the multivariate analysis, only headache intensity during the acute phase remained statistically significant (hazard ratio, 0.655; 95% confidence interval, 0.582-0.737; P < .001).
When asked whether they planned to continue the study, Dr. García Azorín commented, “The main questions that have arisen from this study have been, above all: ‘Why does this headache happen?’ and ‘How can it be treated or avoided?’ To answer them, we’re looking into pain: which factors could predispose a person to it and which changes may be associated with its presence.”
In addition, different treatments that may improve patient outcomes are being evaluated, because to date, treatment has been empirical and based on the predominant pain phenotype.
In any case, most doctors currently treat post–COVID-19 headache on the basis of how similar the symptoms are to those of other primary headaches. “Given the impact that headache has on patients’ quality of life, there’s a pressing need for controlled studies on possible treatments and their effectiveness,” noted Patricia Pozo Rosich, MD, PhD, one of the coauthors of the study.
“We at the Spanish Society of Neurology truly believe that if these patients were to have this symptom correctly addressed from the start, they could avoid many of the problems that arise in the situation becoming chronic,” she concluded.
Dr. García Azorín and Dr. Rodríguez Vico disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.