Pathologic physiology of cerebral dysfunction

Clinically, disorders of the central nervous system are expressed as dysfunction and are ordinarily classified as “organic” or “functional” syndromes. The former may be due to interference with the supply of carbohydrate or oxygen to the brain, to abnormalities of cerebral enzyme activity, or to disordered energy utilization or mediation of interneuronal impulses. Such disturbances, which are associated with or consist of anatomical, biochemical or physiological abnormalities, have not been demonstrated in the case of the “functional” disorders. Nevertheless, the nature of the “functional” syndromes suggests impaired integration of neuronal activity, which may be related to abnormal neurohumoral intersynaptic transmission. The subject of chemical mediators in the central nervous system has only recently been studied intensively and is as yet but incompletely understood. It is probable, although by no means conclusively established, that most of the currently available neuropharmacologic agents—ataractics, “psychic energizers” and psychotomimetics—act upon or substitute for the neurohumoral mediators and thereby alter cerebral energy utilization. It is this latter factor which in the final analysis may be responsible for the outward manifestations of central nervous system activity, whether normal or organically or “functionally” abnormal. Hence, it should not be surprising that the etiology of disturbances in cerebral energy utilization may be difficult or impossible to identify as “organic” or “functional” on the basis of symptomatology alone. Indeed, it is the consensus that even normal mental activity is closely associated with an organic substrate; it seems an entirely reasonable corollary that the “functional” cerebral disorders are probably related to an organic, at least physiological disturbance, however obscure.