2024 年 41 巻 4 号 p. 634-641
Hysterical symptoms, commonly referred to as functional neurological disorder, encompass various neurological manifestations not explainable by current neurology frameworks, suggesting involvement of psychogenic mechanisms. On the other hand, advances in neurophysiological anatomy have revealed that beyond the traditionally identified primary motor cortex (pyramidal tract), once regarded as the final output pathway, other essential output pathways have been functionally verified, such as the cortico–reticulospinal tract. Currently, motor output from the brain to the spinal cord should be considered through dual pathways. In this review, we elucidate hysterical symptoms through the prospective of a new functional brain anatomy paradigm that integrates motor output with dual pathways. Most hysterical motor symptoms can be attributed to disorders affecting the premotor cortex and supplementary motor area–reticulospinal tract. Since this cortico–reticular spinal tract is bilaterally innervated, symptoms arise from bilateral brain lesions. Bilateral abnormalities within this pathway are frequently identified through techniques such as 123I–IMP–SPECT or diffusion tensor imaging. In addition, the function of the reticular formation is considered to correlate with symptoms observed in PNES (psychogenic non–epileptic seizure), including impaired consciousness, tonic seizures of internal muscles, abnormalities in blood pressure and breathing, hypersensitivity to sound and light, as well as hyperalgesia. The origin of hysterical symptoms is primarily attributed to disorders involving the reticular formation and cortico–reticulospinal tract, caused by bilateral diffuse brain damage. Most hysterical symptoms could be explained through adept application of the new neurophysiological model, which delineates motor output into dual pathways. To comprehend complex brain symptoms, neurologists require an update of functional neurophysiological models.
