First seizure while driving: Clinical features and prognosis

Patients with epilepsy are ineligible to drive until seizure free for an appropriate period given the risk of a seizure-related motor vehicle accident. Driving restrictions also apply to patients after their first-ever seizure. However, it is unclear whether a longer period of non-driving is required if the first seizure occurred while driving. The association of a seizure with driving may have been by chance or due to a specific factor or trigger increasing the likelihood of a seizure. More data is required to inform driving restrictions.

This study was based on prospectively collected data of consecutive adults with a first-ever seizure seen at a hospital-based first seizure clinic between 2000 and 2015. We examined the clinical, EEG and imaging features of patients who were eligible to drive, comparing patients with their first seizure while driving (FSWD) to those who had an awake first seizure at other times (FSOT) to explore possible differences clinical features and likelihood of seizure recurrence, evaluated using survival analysis.

57 patients with a FSWD were compared to 1335 patients with FSOT. 80 % of FSWD resulted in loss of control of the vehicle, 64 % with a crash and almost half of patients sustaining an injury. Fifty of 57 FSWD were related to an unprovoked first seizure. FSWD patients had a higher cumulative likelihood of having a second seizure than FSOT patients (50.1 % vs 36.2 % at 1 year, 57.9 % vs 41.7 % at 2 years and 65.1 % vs 47.8 % at 5 years; p = 0.003), with the conditional risk of seizure recurrence only falling consistently below 2.5 %/month at twelve months after the first seizure. Independent predictors of seizure recurrence on multivariable analysis were epileptogenic lesion on imaging, unprovoked (vs acute symptomatic) first seizure, epileptiform abnormality on EEG, focal seizure; and for those with unprovoked first seizure, FSWD and higher Rankin score were also predictors.

First seizure whilst driving is an independent predictor of seizure recurrence for unprovoked seizures, supporting a longer period of seizure freedom before returning to driving.