Frontal System Syndromes

Abstract

Clinically, frontal lobe syndromes, frontal network syndromes, frontal systems syndromes, executive dysfunction, and metacognition have all been used to describe disorders of frontal lobes and their extended networks although they are not all synonymous. Anatomically they refer to those parts of the brain rostral to the central sulcus. However, because the frontal lobes network with every other part of the brain, strictly speaking, frontal network syndromes constitute the most accurate neurobiological depiction. The term, frontal network syndromes (FNS) emphasizes the universal connectivity of the frontal lobes with all other brain regions. For example, the stroke literature is replete with FNS that have been reported with discreet lesions outside the anatomical boundary of the frontal lobe, such as subcortical gray matter, subcortical white matter, with isolated lesions of the brainstem, cerebellum, temporal and parietal lobes [1–8]. For the purposes of simplification, five primary, core or elementary syndromes and numerous secondary syndromes may be delineated. Impairment in working memory, executive function, conation, inhibition, and emotional control may be regarded as the elementary deficits of FNS. In addition a number of secondary manifestations may be identified such as a wide array of behavioral abnormalities such as loss of social norms, imitation behavior, compulsions, and obsessions [9, 10]. Fig. 12.1.