This chapter describes the dynamics of the evolving frontal syndrome. The first factor was the pathological weakening of higher inhibition processes, and the replacement of preliminary analytical-synthetic activity with impulsive attempts at problem solving. The second possible factor accounting for intellectual disorder, inactivity and the pathological inertness of established stereotypes, could accompany lesions of the frontal lobes localized to different areas. The chapter focuses on the precise impact of a gradually evolving injury to the different systems of the frontal areas on the syndrome's development, and examines the emerging intellectual disturbances in the case of one and the same patient, observed at successive stages of the disease. It discusses the cases of a patient slow growing intercerebral tumor in the right frontal lobe required its resection, after which the tumor spread to the left frontal lobe and partially destroyed it.