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Motor and sensory mapping of the frontal and occipital lobes
R P Lesser1, S Arroyo, N Crone
1Department of Neurology, The Johns Hopkins University School of Medicine, and the Zanvyl Krieger Mind/Brain Institute, Baltimore, Maryland, USA.
Abstract:
In patients with intractable epilepsy, surgical resections are performed with the primary goal of improving seizure control. The risk is that the resections may also remove tissues crucial for normal activities. The goal of surgical planning is therefore to determine as accurately as possible the regions of seizure onset and the regions controlling important functions, so that one can determine what to remove and what to leave in place. Clinical functional localization has been performed using cortical stimulation for over half a century, using both intraoperative and extraoperative methods. Signal averaging also has been widely used. More recently, techniques based on analysis of EEG in the frequency domain have shown promise. The methods appear to accurately indicate the function of the region assessed but do not necessarily predict functional consequences of resection. We review these methods, their indications, and the results obtained by their use.
Insights
Surgical planning for epilepsy aims to control seizures while preserving function. Accurate localization of seizure onset and critical brain areas is essential for successful surgical resection, minimizing neurological deficits.
Area of Science:
- Neurosurgery
- Epileptology
- Neurophysiology
Background:
- Intractable epilepsy often requires surgical resection to improve seizure control.
- Surgical interventions risk removing brain tissue essential for normal function.
- Accurate identification of seizure onset zones and functional areas is critical for surgical planning.
Purpose of the Study:
- To review methods for clinical functional localization in epilepsy surgery.
- To assess the indications and outcomes of various localization techniques.
- To highlight the importance of balancing seizure control with functional preservation.
Main Methods:
- Review of established techniques including cortical stimulation (intraoperative and extraoperative) and signal averaging.
- Exploration of newer methods like electroencephalography (EEG) frequency domain analysis.
- Evaluation of the accuracy of these methods in indicating regional function.
Main Results:
- Cortical stimulation and signal averaging have been used for decades in functional localization.
- Frequency domain analysis of EEG shows promise for accurate functional assessment.
- Current methods accurately indicate regional function but may not predict post-resection functional deficits.
Conclusions:
- Effective epilepsy surgery necessitates precise localization of both epileptogenic zones and critical functional areas.
- A range of neurophysiological techniques exist to aid surgical planning.
- Further refinement of methods is needed to better predict functional outcomes after resection.