Clinical Implications

Abstract

Accurate localization of central fissure is important in patients undergoing surgery in regions adjacent to somatosensory and motor cortex to prevent disabling and permanent neurological deficits like severe paresis. The correct identification of primary motor cortex, somatosensory cortex, and central fissure cannot be reliably made by visual inspection of the cortical surface due to large inter-patient variability in the configuration of gyri and surface vasculature [5, 378]. Wood et al. [378] systematically reviewed cortical anatomy in 46 neurosurgical patients who were evaluated with SEPs on ECoG for localization of cortical hand area. These authors could not observe a consistent pattern concerning morphology of sulci, gyri, and overlying vasculature. While the central sulcus often made a characteristic bend in the region of the hand area, it sometimes did not, and similar bends were seen on both pre- and postcentral sulci. Furthermore, large lesions may displace common anatomical landmarks and cause tissue compression and brain edema which makes identification of sulci virtually impossible. Thus, no surface clues exist how to approach subcortical lesions which implies risk to injure the primary motor and somatosensory regions [149]. Even if there exist surface clues about the location of a subcortical lesion, it is important to know the spatial relationship of this lesion to functionally important brain areas [149]. MRI scans, intraoperative ultrasound [60], and CT guided stereotaxy [169] can be used to localize the surface area overlying a subcortical lesion and their combined use with neurophysiologic techniques should increase the safety of removing lesions from the vicinity of central sulcus [149].