Precentral gyrus
Central sulcus region
The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex.
see Brodmann area 4.
The middle frontal gyrus (MFG) often connects to the pre-central gyrus via a thin isthmus 1).
Several methods have been created to aid both neurosurgeons and neuroradiologists in precisely localizing the precentral gyrus. One of them consists of recognizing the intersection between the superior frontal sulcus and the precentral sulcus, being the motor hand area at the same sagittal plane on the precentral gyrus 2) 3).
The intersectional point between the superior frontal sulcus and precentral sulcus (**) is the invagination base of the knob on the precentral gyrus.
Hand “Knob”: The alpha motor neurons for hand motor function are located in the superior aspect of the prefrontal gyrus 4). On axial imaging, this appears as a knob-like protrusion (shaped like an inverted greek letter omega Ω) of the precentral gyrus projecting posterolaterally into the central sulcus 5). On sagittal imaging, it has a posteriorly projecting hook-like appearance and is even with the posterior limit of the Sylvian fissure 6).
The cortical representation for facial movement occurs in the motor strip along the lateral aspect (just above the most inferior opercular portion of the precentral gyrus).
Direct cortical stimulation studies and functional magnetic resonance imaging studies have demonstrated that the precentral gyrus lodges the motor primary cortex and the second curvature of the central sulcus, which corresponds to the knob-like form in the precentral gyrus, are specifically associated with contralateral motor hand skills.
Brain surface reformatted imaging improves the diagnostic accuracy of standard anatomical MR imaging for localizing superficial brain lesions in relation to the precentral gyrus. The complementary use of this technique with standard two-dimensional imaging is supported by the fast and simple postprocessing technique and may provide useful information for preoperative surgical planning 7).
Kim et al. reviewed 33 consecutive patients who experienced pharmacologically intractable epilepsy and underwent Precentral gyrus resection (PGR) with intraoperative cortical stimulation and mapping while under awake anesthesia. The etiological diagnoses were brain neoplasm in 26 patients (78.8%), cortical lesion in 4 (12.1%), and no lesion in 3 (9.1%). The mean follow-up period was 62.6 months (range, 12-146 months). All topographical analyses of the resected quadrant area were performed based on postoperative magnetic resonance images.
After PGR, 22 patients (66.7%) experienced neurological worsening, including 5 permanent deficits (15.2%) and 17 transient deficits (51.5%). Permanent deficits included 2 instances of weakness, 1 dysarthria, 1 dysesthesia, and 1 fine-movement disturbance of the hand. While the neurological risk for anterior lower quadrant PGR was 20.0% (1/5), the risk for posterior upper quadrant PGR was 100.0% (10/10). The anterior upper and posterior lower quadrant PGR caused neurological deteriorations in 60.0% (6/10) and 62.5% (5/8) of the patients, respectively. In a multivariate analysis, PGR of the posterior and upper quadrant sections were significant risk factors for post-PGR neurological deteriorations (P = .022 and 0.030, respectively).
The posterior upper quadrant of the precentral gyrus was vulnerable to post-resective neurological impairment 8).
Left precentral gyrus
Garcia Santos et al aimed to investigate whether magnetic resonance spectroscopy (MRS) metabolite ratios change in the precentral gyrus of patients with amyotrophic lateral sclerosis (ALS) after spinal cord surgical injection of bone marrow mononuclear cells, as well as their relationship with disability and survival and demonstrates that spinal cord injection of stem cells shows metabolic improvement in the brain that might be related to longer survival and less disability 9).