Structural lesions of the frontal lobe. Manifestations, classification, and prognosis

Newer imaging methods, particularly MRI, are recognizing increasing numbers of frontal static and progressive lesions in patients in whom recurrent seizures are the presenting and only symptoms. Surgical results in terms of controlling frontal seizures are improving and becoming comparable to those achieved in the temporal lobe. The results following removal of discrete frontal lesions are superior to those with more diffuse lesions or without demonstrable lesions. Stereotaxic surgery and microsurgical techniques are allowing safer excisions from formerly inaccessible areas or adjacent to areas of essential function. These advances have increased the number of candidates who benefit from successful frontal lobe surgery. The types of clinical seizures in patients with discrete local frontal lesions usually conform with five of the seven anatomically named seizure types described in the 1989 International Classification of Epilepsies and Epileptic Syndromes (supplemental motor seizures, anterior frontopolar region, dorsolateral, and motor cortex). Too few cases with discrete lesions were found with sufficiently detailed seizure descriptions of possible orbitofrontal and cingulate origin to allow separate categorizations. In those cases symptoms and signs, such as autonomic, mood and affect, gestural automatisms, and versive movements preceding the automatisms, did not seem to differentiate orbitofrontal and anterior cingulate lesion cases from each other or from those in other areas of the anterior third of the frontal lobe.