Journal of Neurology & Neurophysiology

Knowledge of lateralizing and localizing value of seizure semiology (symptoms and signs) and other clinical findings is not only helpful, but also necessary in the management process of patients with focal epilepsy. The importance of these findings has specifically increased during the past three decades and with widespread use of surgery in the management of patients with refractory focal epilepsy. The advent of video-EEG monitoring has permitted careful analysis of semiologic features of seizures and their correlation with simultaneous EEG activities. The availability of new imaging and functional studies could be considered as a revolution in localization of the epileptogenic zone in patients with focal epilepsy [1].

One should consider that seizure semiology has several limitations in localizing and even lateralizing the seizure onset. Although, many semiologic features have high positive predictive values, none is perfect in determining the seizure onset or epileptogenic zones. Seizure semiology is sometimes dictated by the pathway of electrical seizure propagation [2] and can reflect only the symptomatogenic zone [3]. Therefore, video recordings of multiple seizures should be reviewed carefully to find as many useful semiologic features as possible. A seizure that is representative of the rest of the recorded seizures should be reviewed with the patient’s relatives to verify that habitual seizures have been captured and analyzed. It is noteworthy to mention that age and brain maturation has some effects on seizure semiology and ictal features are less conclusive in children with focal epilepsy [4]. Concordance between seizure semiology and EEG activity increases the value of localization process and judgment [2,5]. Furthermore, concordance of the above-mentioned findings with imaging, functional studies, and neuropsychological studies increase the reliability of the localization and / or lateralization of the seizure onset zone or epileptogenic zone significantly [6-10].

In the current concise review, a list of presumably well-documented lateralizing and localizing findings in focal epilepsies is prepared (Table 1-6). The purpose is to provide a complete and easy to use list of clinical findings, which are helpful in lateralization and localization of the epileptogenic zone in patients with focal epilepsy. This paper is designed as a practical tool for physicians, aiming to serve as a practical, problem-oriented reference. While, I include the correlated symptomatogenic zone and the possible mechanism in generating the finding in the context of a focal seizure, this paper emphasizes how to localize the epileptogenic zone according to any given specific finding. These findings are organized in a series of tables (Table 1-6). These tables are organized in a way, so that the reader can easily review the relevant information. I hope that this concise paper leads to improved patient care.

Table 1: Localizing semiologic findings pointing to the contralateral location (for the epileptogenic zone).

Table 2: Localizing semiologic findings pointing to the ipsilateral location (for the epileptogenic zone).

Table 3: Lateralizing semiologic findings pointing to the non-dominant hemisphere.

Table 4: Lateralizing semiologic findings pointing to the dominant hemisphere.

Table 5: Non-lateralizing semiologic findings in focal epilepsies.

Table 6: Lateralizing and localizing paraclinical findings in focal epilepsies.