An FP’s guide to caring for patients with seizure and epilepsy

Is it really a first-time seizure? A “first,” usually dramatic, generalized tonic-clonic seizure that triggers the diagnostic work-up may not be the very first seizure. Evidence suggests that many patients have experienced prior undiagnosed seizures. Subtle prior events often missed include episodes of deja vu, transient feelings of fear or unusual smells, speech difficulties, staring spells, or myoclonic jerks.¹ A routine EEG to record epileptiform discharges and a high-resolution brain MRI to rule out any intracranial pathology are indicated. However, if the EEG indicates a primary generalized (as opposed to focal-onset) epilepsy, a brain MRI may not be needed. If a routine EEG is unrevealing, long-term video-EEG monitoring may be needed to detect an abnormality.

Accuracy of EEG and MRI. Following a first unprovoked seizure, routine EEG to detect epileptiform discharges in adults has yielded a sensitivity of 17.3% and specificity of 94.7%. In evaluating children, these values are 57.8% and 69.6%, respectively.⁶ If results are equivocal, a 24-hour EEG can increase the likelihood of detecting epileptiform discharges to 89% of patients.⁷ Brain MRI may detect an abnormality in 12% to 14% of patients with newly diagnosed epilepsy, and in up to 80% of those with recurrent seizures.⁸ In confirming hippocampus sclerosis, MRI has demonstrated a sensitivity of 93% and specificity of 86%.⁹

When to treat a first-time seizure. Available data and prediction models identify risk factors that would help determine whether to start an antiseizure medication after a first unprovoked seizure: abnormal EEG with particular epileptiform activity, abnormal neurologic exam, abnormal computerized tomography or MRI results, nocturnal seizure, focal seizure, or family history of seizures. In the absence of such risk factors, chances of further unprovoked seizures are not high enough to justify treatment with antiseizure medications. However, if a second unprovoked seizure were to occur, that would meet the definition of epilepsy, and treatment is indicated due to the high risk for further seizures.^10,11

Epilepsy diagnosis

The International League Against Epilepsy (ILAE) previously defined epilepsy as 2 unprovoked seizures more than 24 hours apart. However, a more recent ILAE task force modified this definition: even a single unprovoked seizure would be enough to diagnose epilepsy if there is high probability of further seizures—eg, in the presence of definitive epileptiform discharges on EEG or presence of a brain tumor or a remote brain insult on imaging, since such conditions induce an enduring predisposition to generate epileptic seizures. ² Also, a single unprovoked seizure is enough to diagnose epilepsy if it is part of an epileptic syndrome such as juvenile myoclonic epilepsy. Further, a time limit was added to the definition—ie, epilepsy is considered resolved if a patient remains seizure free for 10 years without use of antiseizure medications during the past 5 years. However, given the multitude of variables and evidence, the task force acknowledged the need for individualized considerations. ²

Seizure classification

Classification of seizure type is based on the site of seizure onset and its spread pattern—ie, focal, generalized, or unknown onset.

Continue to: Focal-onset seizures