Surgical treatment of tumors of the supplementary motor area

Abstract

Background. The supplementary motor area is a part of the medial frontal cortex, that is located just anterior to the primary motor cortex entirely within the interhemispheric fissure. This area belongs traditionally to the secondary motor cortex and perhaps it is the least studied motor region of the brain. While functions and symptoms of a damage to the primary motor and the premotor cortex areas have been well known and described for a long time, study of the supplementary motor area has been limited to fundamental neuroimaging and electrophysiological researches, and a practical side of the issue and clinical significance of this region remained outside the interest of researchers.Aim. To present the anatomical and functional features of the supplementary motor area, the clinical symptoms of its lesion, to analyze all the data available today and aspects of surgical treatment of tumors in this region.Materials and methods. A search in scientific databases (PubMed, etc.) led to the selection and analysis of sixty-two literary sources. The review is mainly devoted to the aspects and risk factors of surgical treatment of pathologies localized in this region.Results. According to its anatomical and functional characteristics, the supplementary motor area is a heterogeneous region - it has two separate subregions in it. In addition to the motor function of the supplementary motor area, its role has also been reliably established in the implementation of working memory processes, language, perceptual, cognitive and other functions. Such a number of functions performed by the supplementary motor area is associated with numerous neural connections of this area. For example, the frontal aslant tract has been described recently, and it connects medial part of the superior frontal gyrus with the pars opercularis of the inferior frontal gyrus. This tract, apparently, is associated with the implementation of language function in the dominant hemisphere and function of working memory in the non-dominant hemisphere.When the supplementary motor area is affected, various neurological motor and speech symptoms can occur, in particular, the supplementary motor area syndrome, which is characterized by the development of akinetic mutism in patients and, in most cases, is completely reversible within a few days or months. Among all pathologies in this area, tumors are most common, especially gliomas, which can also manifest themselves with various clinical symptoms both in the preoperative and postoperative periods.Conclusion. Critically important preoperative planning, informing the patient about the spatio-temporal picture of the predicted postoperative clinical disorders and the timing of rehabilitation are critically important. It is recommended to use methods of intraoperative neuronavigation, as well as intraoperative neurophysiological monitoring. It is necessary to further study the supplementary motor area and the peculiarities of its surgery in order to standardize approaches to the treatment of pathologies.