Impact of diagnostic delay on seizure outcome in newly diagnosed focal epilepsy

OBJECTIVE: In the current study, we aimed to assess the diagnostic delay and the impact of diagnostic delay on seizure outcome in a cohort of newly diagnosed patients with focal epilepsy. METHODS: The study material was compiled from eight clinical antiseizure medication monotherapy trials conducted at Kuopio Epilepsy Center during 1995‐2016. We analyzed the time from first seizure to diagnosis, the number of seizures before diagnosis, and the response to treatment at five years. RESULTS: Of the 176 patients (age range 15‐75 years) in the cohort, 135 (77%) had had more than two seizures before treatment. The majority of these (79 patients, 45%) had had three to ten seizures. Median number of all seizures before diagnosis was 5 (range 2‐2000). Focal aware seizures and focal impaired awareness seizures were more frequent than focal to bilateral tonic‐clonic seizures; median number 45 (range 2‐2000), 11 (range 2‐220), and 3 (range 2‐30), respectively (P < .001). Median delay was 12 months (range 0‐362). Diagnostic delay alone did not correlate with the treatment response at five years. However, an increasing number of seizures before diagnosis indicated a worse seizure outcome (P < .001). SIGNIFICANCE: This study shows that patients with focal epilepsy experience significant delays in diagnosis even in developed countries, especially with seizure types other than tonic‐clonic seizures. In these cases, a long delay in diagnosis alone might not affect the long‐term outcome. However, when accompanied with recurrent seizures misinterpreted by the patient or healthcare providers, the effect of such delay on prognosis can be considerable.