Classification of headache disorders

Previous headaches presented by these patients were classified according to the third edition of the International Classification of Headache Disorders (ICHD-3) (17).

Headaches were classified as being associated with COVID-19 if they fulfilled criteria A to C1 for ‘Headache attributed to systemic viral infection' (9.2.2) (17).

The phenotypes of headaches associated with COVID-19 headache were classified as follows:

Migraine phenotype: Headaches that fulfilled criteria B to D for migraine without aura (1.1). Headaches that did not meet criterion B because they lasted more than 72 hours were also considered.

Tension-type headache phenotype: Headaches that fulfilled criteria B to D for tension-type headache (2.1). Headaches that did not meet criterion B because they lasted more than 7 days were also considered.

Cough headache phenotype: Headaches that fulfilled criteria B to D for cough headache (4.1). Those headaches that were aggravated only after coughing were not classified as cough headache (17).