Two cases of SMA syndrome after neurosurgical injury to the frontal aslant tract

Supplementary motor area (SMA) syndrome is characterised by transient disturbance in volitional movement and speech production which classically occurs after injury to the medial premotor area. We present two cases of SMA syndrome following isolated surgical injury to the frontal aslant tract (FAT) with the SMA intact. The first case occurred after resection of a left frontal operculum tumour. The second case occurred after a transcortical approach to a ventricular neurocytoma. The clinical picture and fMRI activation patterns during recovery were typical for SMA syndrome and support the theory that the FAT is a critical bundle in the SMA complex function.

Frontal aslant tract in the non-dominant hemisphere: A systematic review of anatomy, functions, and surgical applications

Knowledge of both the spatial organization and functions of white-matter fiber tracts is steadily increasing. We report here the anatomy and functions of the frontal aslant tract (FAT) in the non-dominant hemisphere (usually the right hemisphere). Despite the structural symmetry between the right and left FAT, these two tracts seem to display functional asymmetry, with several brain functions in common, but others, such as visuospatial and social cognition, music processing, shifting attention or working memory, more exclusively associated with the right FAT. Further studies are required to determine whether damage to the right FAT causes permanent cognitive impairment. Such studies will constitute the best means of testing whether this tract is a critical pathway that must be taken into account during neurosurgical procedures and the essential tasks to be incorporated into intraoperative monitoring during awake craniotomy.

The Frontal Aslant Tract: A Systematic Review for Neurosurgical Applications

The frontal aslant tract (FAT) is a recently identified white matter tract connecting the supplementary motor complex and lateral superior frontal gyrus to the inferior frontal gyrus. Advancements in neuroimaging and refinements to anatomical dissection techniques of the human brain white matter contributed to the recent description of the FAT anatomical and functional connectivity and its role in the pathogenesis of several neurological, psychiatric, and neurosurgical disorders. Through the application of diffusion tractography and intraoperative electrical brain stimulation, the FAT was shown to have a role in speech and language functions (verbal fluency, initiation and inhibition of speech, sentence production, and lexical decision), working memory, visual–motor activities, orofacial movements, social community tasks, attention, and music processing. Microstructural alterations of the FAT have also been associated with neurological disorders, such as primary progressive aphasia, post-stroke aphasia, stuttering, Foix–Chavany–Marie syndrome, social communication deficit in autism spectrum disorders, and attention–deficit hyperactivity disorder. We provide a systematic review of the current literature about the FAT anatomical connectivity and functional roles. Specifically, the aim of the present study relies on providing an overview for practical neurosurgical applications for the pre-operative, intra-operative, and post-operative assessment of patients with brain tumors located around and within the FAT. Moreover, some useful tests are suggested for the neurosurgical evaluation of FAT integrity to plan a safer surgery and to reduce post-operative deficits.

Combined Decompressive Hemicraniectomy and Port-Based Minimally Invasive Parafascicular Surgery for the Treatment of Subcortical Intracerebral Hemorrhage: Case Series, Technical Note, and Review of Literature

BACKGROUND

Intracerebral hemorrhage (ICH) is a neurosurgical emergency. Combined decompressive hemicraniectomy (DHC) and minimally invasive parafascicular surgery (MIPS) may provide a practical method of managing subcortical ICH.

OBJECTIVE

1) To present a case series of combined DHC-MIPS for the treatment of subcortical-based ICH; 2) to describe technical nuances of DHC-MIPS; and 3) to provide a literature overview of MIPS for ICH.

METHODS

The following inclusion criteria were used: 1) Glasgow Coma Scale (GCS) score <3-4; 2) admission within 6 hours of onset; 3) increased intracranial pressure caused by hemorrhage; 4) patient unresponsive to medical management; 5) hemorrhage >30 cm³; 6) subcortical location; and 7) midline shift (mm). Before DHC, sulcal cannulation used the following coordinates: intersection of tragus-frontal bone and midpoint of midpupillary line and midline; coronal suture: 3-4 cm posterior to this point).

RESULTS

Three patients were selected: a 62-year old woman, a 45-year old woman, and a 36-year-old man. GCS and ICH scores on admission were 7 and 3, 3 and 4, and 3 and 4, respectively. ICH was located in left basal ganglia in patients 1 and 3 and right basal ganglia in patient 2, all with intraventricular extension. ICH volume was 81.7, 68.2, and 42.3 cm³, respectively. The postoperative GCS score was 11, 10, and 6, respectively. There were no intraoperative complications or mortalities. Evacuation was within 15 minutes in all patients. The modified Rankin Scale score was 3, 4, and 5, respectively, with semi-independence in case 1.

CONCLUSIONS

Combined DHC-MIPS, with the use of craniometric points, can provide a unique and simple surgical option for the management of subcortical ICH.

Minimally invasive trans-sulcal parafascicular surgical resection of cerebral tumors: translating anatomy to early clinical experience

The minimally invasive port-based trans-sulcal parafascicular surgical corridor (TPSC) has incrementally evolved to provide a safe, feasible, and effective alternative to access subcortical and intraventricular pathologies. A detailed anatomical foundation is important in mitigating cortical and white matter tract injury with this corridor. Thus, the aims of this study are (1) to provide a detailed anatomical construct and overview of TPSCs and (2) to translate an anatomical framework to early clinical experience. Based on regional anatomical constraints, suitable parafascicular entry points were identified and described. Fiber tracts at both minimal and increased risks for each corridor were analyzed. TPSC-managed cases for metastatic or primary brain tumors were retrospectively reviewed. Adult patients 18 years or older with Karnofsky Performance Status (KPS) ≥ 70 were included. Subcortical brain metastases between 2 and 6 cm or primary brain tumors between 2 and 5 cm were included. Patient-specific corridors and trajectories were determined using MRI-tractography. Anatomy: The following TPSCs were described and translated to clinical practice: superior frontal, inferior frontal, inferior temporal, intraparietal, and postcentral sulci. Clinical: Eleven patients (5 males, 6 females) were included (mean age = 52 years). Seven tumors were metastatic, and 4 were primary. Gross total, near total, and subtotal resection was achieved in 7, 3, and 1 patient(s), respectively. Three patients developed intraoperative complications; all recovered from their intraoperative deficits and returned to baseline in 30 days. A detailed TPSC anatomical framework is critical in conducting safe and effective port-based surgical access. This review may represent one of the few early translational TPSC studies bridging anatomical data to clinical subcortical and intraventricular surgical practice.