Pick's Disease

PICK'S DISEASE (Pick), described by the author under the name "circumscribed senile atrophy of the brain," is characterized primarily by focal symptoms that develop gradually in the absence of strokes and relate for the most part to the left temporal lobe syndrome. Especially characteristic are amnestic aphasia, echolalia, and Wernicke's transcortical sensory aphasia. With extreme impoverishment of spontaneous speech, patients repeat words spoken by others well. In other cases, alexia, paragraphia, and apractic and asymbolic disorders are observed, which already relate to the lower parietal syndrome. Finally, in some cases, Pick described peculiar visual disorders in the form of so-called "apperceptive blindness," in which there are no gross visual impairments, but the patient at times does not perceive visual sensations and behaves as if blind, while at other moments vision is restored, with visual functions seemingly activated under the influence of the simultaneous action of other stimuli (e.g., olfactory). On the part of the psyche, progressive dementia, mood changes, and often sharp apathy (elements of the frontal syndrome) are noted, sometimes with short-term states of confusion. A tendency of patients toward aimless wandering (at the beginning of the disease) is quite characteristic. The course of the disease is slow. Death occurs in a state of marasmus. The etiology of the disease is unclear; there are no indications of the influence of any exogenous factors; the significance of heredity also still requires proof. People of advanced age fall ill, women about 3 times more often than men. Differential diagnosis is especially difficult when distinguishing it from cerebral arteriosclerosis, which can also produce focal symptoms analogous to those observed in Pick's disease, as well as dementia and marasmus. However, in arteriosclerosis, focal phenomena are established for the most part after strokes and, in any case, not so slowly and gradually. Alzheimer's disease differs from the Pick form by a more rapid decay and the predominance of severe motor disorders (contractures, paresis of cranial nerves, epileptiform seizures, etc.). Syphilis of the brain can be distinguished from Pick's disease by the presence of serological reactions and the onset of focal symptoms in connection with strokes. Over 40 anatomically verified cases have been described to date. Upon pathological-anatomical examination of Pick's disease, local circumscribed atrophy of the cortex and white matter of the cerebrum is noted, which is noticeable even macroscopically. Primarily, the prefrontal and temporal regions are affected, then sometimes the lower parietal, and in some cases the occipital lobes. Of other areas of the brain, involvement of the caudate nucleus and the thalamus was most often noted. The mentioned foci of local atrophy correspond to clinical symptoms (temporal, frontal, lower parietal syndromes), which makes it possible to precisely localize the disorders observed in this disease. Microscopic data indicate the presence in the atrophic foci of a parenchymatous-degenerative process and the predominant involvement of the II and III layers of the cortex. In the nerve cells, swelling, destruction of fibrils and chromatin substance, and argentophilic granules and globules (very characteristic of this disease) are noted. At the same time, proliferation of glia occurs, with the growth of glial fibers, rather than the multiplication of cells, being in the foreground. Nerve fibers are also sharply affected: changes in axial cylinders and myelin decay are observed. Furthermore, a large quantity of decay products and pigment is confirmed in the affected foci. Drusen, which are characteristic of senile dementia, and Alzheimer's fibrillary changes are usually absent in Pick's disease (with the exception, primarily, of cases with atypical localization in the occipital lobes). Changes in the mesodermal tissue, in particular the vessels, are not observed to any sharp degree. The indicated anatomical data, and especially the absence of changes specific to senile dementia, give most authors at the present time grounds to consider the Pick form an independent disease, and not atypical senile dementia, as Pick himself believed. On the other hand, however, it is possible that not all cases described under this name are homogeneous. Some of them (with the presence of drusen, etc.) apparently still relate to atypical senile dementia. A combination of Pick's disease with arteriosclerosis is also possible. In general, many authors are inclined to consider vascular changes, which impair (less grossly than in ordinary arteriosclerosis) the nutrition of the brain tissue, as a very important factor in the development of Pick's disease, which determines the focality of the disease. Other authors (including Pick) explain the selective focality of the lesions by a functional moment that causes the wear and tear of specific areas of the cortex. It is characteristic that in Pick's disease, the association systems and phylogenetically new areas of the cortex, which are the primary possession of the human brain, are mainly affected.