Abstracts

Rationale: Diagnosis of episodes resembling a first epileptic seizure (FES) is not always easy. It is estimated that a misdiagnosis of epilepsy in adults occurs in approximately 25-75% of patients. Establishing an incorrect diagnosis affects health and quality of life of patients. We describe epidemiology, clinical and paraclinical characteristics and identify variables that could help in the correct diagnosis in patients with suspicion of FES. Methods: We included adult patients with suspicion of FES who were sent to electroencephalographic study (EEG). We describe demographic characteristics, clinical manifestations, EEG, brain image (BI) and final diagnosis. We analyzed the three most common diagnoses to identify variables useful for diagnosis. Results: We identified 95 patients with EEG and diagnosis of probable FES. Of these, 60% were initially evaluated in an outpatient way, 22% hospitalized, 15% in emergency room, and 3% in IUC. 65% were women, mean age 47.5 18 years. 9% had a family history of epilepsy, febrile seizures in 5%, head trauma in 14%, alcohol in 12%, syncope in 6%, diabetes mellitus in 21%, cardiovascular diseases in 24%, renal failure in 8%, stroke in 10%, AIDS and cancer in 6%. 56% had partial seizures and 44% generalized seizures. Clinical manifestations were motor activity in 47%, loss of alertness in 24%, fainted in 4%, psychiatric symptoms in 12 %, blurred vision in 9%, sensory symptoms in 6%, dizziness and anxiety in 1%. Neurological examination was normal in 70%. BI was performed in 85%, 60% were abnormal with focal lesion in 61%, diffuse lesion in 6%, and unspecified lesion in 33%. EEG was abnormal in 35%, 33% had diffuse slowing, focal epileptiform activity in 30%, focal slowing in 27%, and nonspecific activity in 9%. Epilepsy was diagnosed in 26%, 24% had non-epileptic seizures, syncope in 21%, undetermined cause in 11%, movement disorder and migraine in 8%, stroke in 5%, and sleep disorder in 3%. Statistical significance for diagnosis of syncope was reached for blurred vision; BI with focal lesion, and EEG with focal epileptiform activity were important for epilepsy; a clinical episode with duration >5 min was for non-epileptic seizures (p <0.05). See table. Conclusion: In probable FES there is a heterogeneous range of differential diagnoses. We found, as the main diagnosis: epilepsy and non-epileptic seizures, similar to described in literature. In >50% BI were abnormal, being the most common finding: focal lesion. The abnormal findings in EEG were generalized slowing and focal epileptiform activity. Variables important to guide the diagnosis were blurred vision for syncope, abnormal EEG and BI for epilepsy, and duration of episode for non-epileptic seizure. In the suspicion of FES the assessment should be based on appropriate clinical history, physical examination and paraclinical data to avoid misdiagnosis.