Interictal and periictal headache in patients with epilepsy

Background and purpose: Interictal headache (IIH), and in particular migraine, is considered a relevant co-morbidity in epilepsy; however, available data are ambiguous. Periictal headache (PIH) displays a frequent ancillary burden to seizures, but identification of unequivocal predictors is still elusive. Methods: All patients (>= 18 years) with epilepsy or unprovoked seizures seen in a tertiary epilepsy outpatient clinic underwent a semi-structured interview regarding occurrence and characteristics of IIH and PIH. Clinical variables in patients with and without IIH and PIH and seizure types with and without PIH were compared. Results: Out of 201 patients, 56.2% reported headache, IIH occurred in 34.3% and 10.9% suffered from migraine. PIH was reported by 35.3%, occurring preictally in 16 and postictally in 61 cases. PIH character was migrainous in 26.8% and tension-type headache-like in 62%, mean severity was 6.1 +/- 2.2 cm. PIH was treated analgetically by less than 40% of patients, only 11% sought specific medical advice. Predictors were low age at epilepsy onset (OR 0.963, 95% CI 0.945-0.981, P < 0.0001), antiepileptic drug (AED) polytherapy (OR 1.943, 95% CI 1.046-3.612, P = 0.036) and generalized tonic-clonic seizures (P < 0.0001). Conclusions: In patients with epilepsy, IIH, and particularly migraine, is less common than expected, challenging the widely held concept of co-morbidity of the two conditions. PIH is frequent, severe and undertreated. Predictors include low age at epilepsy onset, AED polytherapy and tonic-clonic generalized seizures. Physicians should ask for PIH and offer specific analgesic treatment. To confirm these findings, future studies with a prospective approach implementing a headache and seizure diary should be performed.