Anterior Perforated Substance Research Articles

Laser interstitial thermal therapy for deep-seated perivascular brain tumors is not associated with distal ischemia.

Laser interstitial thermal therapy (LITT) is a minimally invasive cytoreductive treatment option for brain tumors with a risk of vascular injury from catheter placement or thermal energy. This may be of concern with deep-seated tumors that have surrounding end-artery perforators and critical microvasculature. The purpose of this study was to assess the risk of distal ischemia following LITT for deep-seated perivascular brain tumors. A retrospective review of a multi-institution database was used to identify patients who underwent LITT between 2013 and 2022 for tumors located within the insula, thalamus, basal ganglia, and anterior perforated substance. Demographic, clinical and volumetric tumor characteristics were collected. The primary outcome was radiographic evidence of distal ischemia on post-ablation magnetic resonance imaging (MRI). 61 LITT ablations for deep-seated perivascular brain tumors were performed. Of the tumors treated, 24 (39%) were low-grade gliomas, 32 (52%) were high-grade gliomas, and 5 (8%) were metastatic. The principal location included 31 (51%) insular, 14 (23%) thalamic, 13 (21%) basal ganglia, and 3 (5%) anterior perforated substance tumors. The average tumor size was 19.6 cm3 with a mean ablation volume of 11.1cm3. The median extent of ablation was 92% (IQR 30%, 100%). Two patients developed symptomatic intracerebral hemorrhage after LITT. No patient had radiographic evidence of distal ischemia on post-operative diffusion weighted imaging. We demonstrate that LITT for deep-seated perivascular brain tumors has minimal ischemic risks and is a feasible cytoreductive treatment option for otherwise difficult to access intracranial tumors.

The clinical, radiological, and surgical characteristics of anterior perforated substance glioma: a retrospective study

BackgroundTo explore the clinical, radiological, and surgical characteristics of anterior perforated substance (APS) gliomas.MethodsTwenty patients with APS glioma who were treated with surgery between March 2019 and January 2022 from Tiantan hospital were retrospectively reviewed. The clinical, histological and radiological data were collected.ResultsTwenty patients, including 7 males (55%) and 13 females (45%), with a mean age at diagnosis of 37.9 years (range, 28–53 years) underwent operative intervention for APS. Headaches and dizziness were the most common preoperative symptoms in the majority patients (14, 70%). Based on radiological features of MRI, the APS was classified into two subtypes, type A and type B. Seven patients (40%) in type A indicated a clear tumor margin, while 13 patients (60%) in type B showed an ill-defined margin. The surgical approach including frontal, temporal, and coronal frontal incisions for type A and type B tumors, respectively. Three patients in type A received total resection, while one patient in type B were total resected. Pathologically, 12 cases (60%, 12/20) were diagnosed as astrocytoma and 8 cases (20%, 8/20) were oligodendroglioma. Meanwhile, 17 cases (85%, 17/20) had MGMT promotor methylation.ConclusionIn this study, we performed the first systematic research of patients with APS glioma. Most of patients with APS presented headaches and dizziness symptoms. The APS glioma was further divided into two major radiological subtypes with relevant different surgical approaches. The APS glioma in type A were more likely to receive total resection.

The anterior perforated substance (APS) revisited: Commented anatomical and imagenological views.

Since 2002, when we published our article about the anterior perforated substance (APS), the knowledge about the region has grown enormously. To make a better description of the anatomy of the zone with new dissection material added to the previous, to sustain the anatomical analysis of the MRI employing the SPACE sequence, interacting with our imagenology colleagues. Especially, we aim to identify and topographically localize by MRI the principal structures in APS-substantia innominata (SI). The presentation follows various steps: (1) location and boundaries of the zone and its neighboring areas; (2) schematic description of the region with simple outlines; (3) cursory revision of the SI and its three systems; (4) serial images of the dissections of the zone and its vessels, illustrated and completed when possible, by MRI images of a voluntary experimental subject (ES). With this method, we could expose most of the structures of the region anatomically and imagenologically. The zone can be approached for dissection with magnification and the habitual microsurgical instruments with satisfactory results. We think that fibers in this region should be followed by other anatomical methods in addition to tractography. The principal structures of ventral striopallidum and extended amygdala (EA) can be identified with the SPACE sequence. The amygdala and the basal ganglion of Meynert (BGM) are easily confused because of their similar signal. Anatomical clues can orient the clinician about the different clusters of the BGM in MRI. The dissection requires a previous knowledge of the zone and a good amount of patience. The APS is a little space where concentrate essential vessels for the telencephalon, "en passage" or perforating, and neural structures of relevant functional import. From anatomical and MRI points of view, both neural and vascular structures follow a harmonious and topographically describable plan. The SPACE MRI sequence has proved to be a useful tool for identifying different structures in this area as the striatopallidal and EA. Anatomical knowledge of the fibers helps in the search of clusters of the basal ganglion.

Abstract 109: Endonasal Endoscopic Approach Associated Cerebral Vasospasm and Management: A Case Report

Introduction Endoscopic endonasal approach(EEA) techniques have been increasingly utilized and have been associated with development of cerebrospinal fluid(CSF) leak, meningitis, diabetes insipidus post‐operatively. Cerebral vasospasm following EEA has rarely been described. Here, we describe the clinical course and management of a patient who underwent EEA for encephalocele repair whose course was complicated by postoperative subarachnoid hemorrhage(SAH) and cerebral vasospasm. Methods n/a Results Case Presentation: 40 year old female with past medical history significant for cerebral venous sinus stent on aspirin, CSF rhinorrhea secondary to right nasal encephalocele s/p endoscopic transnasal transethmoidal repair with nasoseptal flap reconstruction and lumbar drain placement eleven days prior presented with speech difficulties and right sided weakness. On exam, patient was noted to have mild right hemiparesis and expressive aphasia. MRI brain showed subacute infarcts in left greater than right frontal lobes, corpus collosum and right anterior perforated substance. MRA head demonstrated multifocal arterial stenosis. In light of postoperative CT head showing SAH in the basilar, perimesencephalic, prepontine cisterns, interhemispheric fissure and right frontal sulci as well as intraventricular hemorrhage in fourth ventricle, her presentation was thought to be secondary to cerebral vasospasm in the setting of postoperative SAH. She was treated with intravenous hydration, permissive hypertension with head of bed in flat position and transferred for further evaluation. On arrival, she continued have mild right hemiparesis and aphasia. Repeat CTA head/neck and CT perfusion showed severe stenosis of bilateral M1 segments and left greater than right A1 segments as well as ischemic penumbra in left ACA/MCA watershed territory. Diagnostic cerebral angiogram showed bilateral severe A1 stenosis and mild to moderate bilateral M1 and supraclinoid ICA stenosis which improved with intra‐arterial verapamil. She was started on nimodipine. Systolic blood pressure was augmented with vasopressors for goal of 150‐180mmHg. Daily TCDs were followed. She developed worsening right leg weakness following day, thus she was taken for repeat diagnostic cerebral angiogram during which time she was re‐administered intra‐arterial verapamil with improvement in vasospasm. After the second treatment, she had improvement in speech and motor strength. Systolic blood pressure goal was gradually normalized. She was noted to have incidental left internal jugular (IJ) vein thrombosis for which anticoagulation was held in the setting of recent neurosurgical procedure and SAH. Workup for vasculitis and hypercoagulability was unrevealing. Lumbar puncture demonstrated 13 WBC/cu mm with lymphocytic predominance(90%), 23 RBC/cu mm, glucose 89mg/dl, protein 30mg/dl. CSF cultures were negative. Pleocytosis in CSF was attributed to recent neurosurgical procedure. Her neurological exam improved to baseline on hospital day(HD) 9.On HD12, she was found to have left common femoral deep venous thrombus in addition to the left IJ thrombus. Anticoagulation with low dose heparin infusion was started which was transitioned to apixaban on discharge. She was discharged home on HD20. Conclusion We report a case of EEA associated with severe multifocal cerebral vasospasm secondary to postoperative SAH that was successfully treated with induced hypertension, oral nimodipine and intra‐arterial verapamil as an adjunct therapy with an excellent outcome.

Transanterior Limiting Sulcus of the Insula Approach: Novel Surgical Approach to the Ventral Striatum Region

Lesions in the ventral striatum region (above the anterior perforated substance) are a challenge for neurosurgeons due to their direct relationship with the lenticulostriate arteries, which difficult the surgical access. The standard approaches for this region include thefollowing: 1) transfrontal approach, 2) transanterior perforating substance approach, 3) transcallosal transventricular approach, and 4) pterional transsylvian-transinsular route. In this study, we aimed to describe a novel anatomical approach through the anterior limiting sulcus of the insula in order to access the ventral striatum. We reviewed the literature and performed a detailed dissection of this region by using Klingler's technique with brain specimens injected with silicone, paying special attention to the white fibers and lenticulostriate arteries, and provided a description of an illustrative case of a cavernous malformation. Neuroanatomical dissections showed that the lenticulostriate arteries had an inverted C-shaped anterior concavity, leaving less significant vascular relationships in the depth of the anterior limiting sulcus of the insula. In the case we described, the cavernous malformation was completely resected and the patient was discharged without any neurological deficits. The transanterior limiting sulcus of the insula approach to the ventral striatum offers a safe access route for selected cases and can be performed on the basis of anatomical references. Three-dimensional understanding of the intrinsic brain architecture and its relationships with vascular structures in this specific area is important and can be acquired mainly through laboratory training.

Recurrent insular low-grade gliomas: factors guiding the decision to reoperate.

Reoperation has been established as an effective therapeutic strategy in recurrent diffuse low-grade gliomas (LGGs). Insular gliomas represent a specific surgical challenge because of the surrounding vascular and functional structures. The aim of this study was to investigate the main clinicoradiological factors guiding the decision to reoperate on recurrent insular LGGs (ILGGs). In this retrospective consecutive series, the authors screened all patients operated on for an ILGG in their institution who further presented with a tumor regrowth without the development of contrast enhancement. They compared patients who were subsequently offered a reoperation under awake mapping at recurrence or who underwent reoperation after adjuvant treatment had reduced the volume of the initial tumor recurrence (with a proven pathological diagnosis of LGG after the second surgery) to patients who were not selected for a reoperation. The first group (reoperated group; n = 20) included all recurrent ILGG patients who underwent second resection, and the second group (nonreoperated group; n = 60) included patients who did not undergo reoperation but underwent adjuvant oncological treatment. Factors significantly associated with reoperation were extent of resection (EOR) at first surgery (91.9% vs 89.7%, p = 0.014), residual tumor volume (9.5 ± 7.1 mL [range 0-30 mL] vs 6.3 ± 7.3 mL [range 0-30 mL], p = 0.02) at first surgery and left temporopolar infiltration at the time of tumor recurrence (Liebermeister statistical analysis, 4293 voxels survived false discovery rate correction with p < 0.05; maximal z-statistic = 6.50). Infiltration of the anterior perforated substance at tumor recurrence was significantly anticorrelated to reoperation (179 voxels survived false discovery rate correction with p < 0.05; minimal z-statistic = -4.33). The mean EOR was 83.7% at reoperation with a 90% survival rate at last follow-up (9.3 ± 3.8 years), low postsurgical morbidity (Karnofsky Performance Status score ≥ 80 in 95% of patients), a high rate of postoperative professional resumption (95%), and seizure control in 57.1% of patients. In selected patients with recurrent ILGG without radiographic evidence of malignant transformation, reoperation with intraoperative awake mapping is associated with favorable oncological outcomes and a low postsurgical morbidity. A greater EOR and a lower residual tumor volume at first surgery were significantly associated with reoperation. Patients who benefited from a second surgery typically had a recurrent pattern within cortical areas (such as the temporopolar region), while other patients typically presented with a deeper infiltrative pattern within the anterior perforated substance and the surrounding white matter pathways. Such original findings may be helpful to select the optimal indications of reoperation in recurrent ILGG.

Usefulness of Orbitocranial Approach in Neck Clipping of Aneurysms Arising from Middle Cerebral Artery Proximal to the Limen Insulae: A Case Series

Neck clipping of the aneurysms arising from the middle cerebral artery (MCA) proximal to the limen insulae is often difficult because of difficulties in securing a bright and wide operative field to observe the aneurysms and surrounding structures, such as the anterior perforated substance, lenticulostriate arteries, and early frontal branch. Our objective was to determine the usefulness of the orbitocranial approach in neck clipping of the aneurysms arising from the MCA proximal to the limen insulae. This prospective study included 7 patients who underwent neck clipping of aneurysms arising from the MCA proximal to the limen insulae through the orbitocranial approach. In addition to conventional pterional craniotomy, the superiolateral orbital rim was resected with a 1-piece fashion. Its procedures, complications, and outcomes were reviewed. Removal of the superolateral orbital rim facilitated a bright and wide observation from the skull base side. It was much easier to identify the anterior perforated substance, lenticulostriate arteries, and early frontal branch around the aneurysm through the orbitocranial approach than through the conventional pterional approach. Neck clipping could be performed completely and safely in all cases. The orbitocranial approach to aneurysms arising from the MCA proximal to the limen insulae provides us a bright and wide operative field compared with the conventional pterional approach, which is useful to secure complete and safe neck clipping by avoiding cerebral contusion and unexpected obstruction of the early frontal branch.

Practical microscopic neuroanatomy of the limbic system and basal forebrain identifiable on clinical 3T MRI.

Microscopic neuroanatomy of limbic system and basal forebrain on MRI is complex and is a terra incognita for many radiologists, clinicians, and neuroscientists. Interestingly, most of the important structures/at least anatomical regions containing these structures demonstrable on cadaveric and surgical dissections can be identified on clinical MRI, with 3T being much better than 1.5T. This article teaches the practical MRI identification of these structures which will greatly help in evaluating complex ailments like temporal lobe epilepsy, Alzheimer dementia, and other neuropsychiatric disorders. This knowledge will also aid in accurate reporting of tumor spread along the white matter fasciculi in the temporal stem/basal forebrain region. Limbic system includes the mesial temporal structures and their connections, piriform cortex including "area tempestas," and the septal area comprising of subcallosal area and paraterminal gyrus. Basal forebrain includes structures like substantia innominata with basal nucleus of Meynert, diagonal gyrus/diagonal band of Broca, and nucleus accumbens lying in between the anterior perforated substance inferiorly and the anterior commissure superiorly.

Avoiding vascular complications in insular glioma surgery - Amicrosurgical anatomy study and critical reflections regarding intraoperative findings.

IntroductionVascular lesions in insular glioma surgery can severely impact patients' quality of life. This study aims to present the results of our dissections and authors’ reflections on the insular vascular anatomy.Matherials and MethodsThe insular vascularization was examined using ×3 to ×40 magnification in 20 cadaveric cerebral hemispheres in which the arteries and veins had been perfused with colored silicone.ResultsIn insular gliomas, this individualization of the anatomical structures is rarely possible, as the gyri are swollen by the tumor and lose their individuality. In the transsylvian approaches, the anatomical parameters for delimiting the insula in tumors are best provided by the superior and inferior circular sulci. The branches of the MCA are easily identified in the transcortical approach, but only at the end of the surgery after the tumor is resected.). One of the factors under-discussed in the literature is the involvement of the lenticulostriate arteries by the medial part of the tumor. In our experience of 52 patients (article submitted to publishing), LSTa were founded to be involved by the tumor in 13 cases. In 39 patients, there was no involvement of the LSTa, which allowed a more aggressive resection. Early preoperative identification of the anterior perforated substance on the MRI and its proximity to the tumor may help determine the route of the LSTa over the medial tumor boundaries.DiscussionOur reflections introduced our imaging and anatomical concept regarding LSTa in insular glioma surgery. Accurate identification of origin, route, and distribution of the LSTa is pivotal to surgical success, especially in the lateral group. The anatomical knowledge of their path directly impacts the extent of tumor resection and functional preservation.ConclusionKnowledge of microsurgical anatomy, brain mapping, and surgical experience counts a lot in this type of surgery, creating a reasonable procedure flowchart to be taken intraoperatively.

Optic Tract as an Upper Limit in Amygdalectomy: Microsurgical Study.

In surgeries involving resection of the amygdala, despite clear relations established with the medial, lateral, anterior, posterior, and inferior segments, the upper limit remains controversial. The optic tract (OT) has been anatomically considered as a good landmark immediately inferior to the striatopallidal region. This anatomic structure has barely been explored by microsurgical study, generating uncertainty about the exact relationship with the surrounding structures. To describe the OT in its entire length through microsurgical study, showing its superior, inferior, medial, and lateral relationships and highlighting its value as a landmark in superior amygdala resection. Microsurgical anatomic dissection of the OT, from its origin in the chiasm to the lateral geniculate nucleus was performed in 8 alcohol-fixed human hemispheres, showing its different segments and relations. Photographs were taken from different angles to facilitate surgical orientation. We performed a dissection of the OT, showing its position relative to caudate and hippocampal formations. We exposed the structures related to the OT superiorly (striatopallidal region and superior caudate fasciculus), inferiorly (head of the hippocampus, amygdala, anterior choroidal artery, perforating artery branch of the anterior choroidal artery, terminal stria, and basal vein), medially (internal capsule and midbrain), and laterally (temporal stem [uncinate and inferior fronto-occipital fascicle], anterior perforated substance, and superior caudate fasciculus). To date, there is a paucity of articles describing the anatomy of the OT from a neurosurgery perspective. In this study, we describe the microsurgical anatomic path of the OT, as a reliable upper limit landmark for amygdala resection.

Tractography of the stria terminalis in the human brain.

The aim of this study was to investigate the trajectory of the stria terminalis and develop a protocol for mapping the stria terminalis using multi-shell diffusion images based tractography. The stria terminalis was reconstructed by combining one region of interest at the amygdala with another region of interest at the bed nucleus of stria terminalis. In addition, one region of avoidance was placed on the fornix at the interventricular foramen and another was set at the anterior perforated substance. The fiber-tracking protocol was tested in a Human Connectome Project-842 template, 35 healthy subjects from Massachusetts General Hospital, and 20 healthy subjects from the Human Connectome Project using generalized q-sampling imaging based tractography. The stria terminalis was reconstructed in the Human Connectome Project-842 template, 35 Massachusetts General Hospital healthy subjects, and 20 Human Connectome Project healthy subjects with our protocol. The stria terminalis originated from the amygdala and traveled parallel to the fornix. Then, the stria terminalis followed a C-shaped trajectory around the inferior, posterior, and dorsal surfaces of the thalamus before projecting to the bed nucleus of stria terminalis between the thalamus and caudate nucleus. There were no significant differences in the quantitative anisotropy and fractional anisotropy values between the left and right stria terminalis. The stria terminalis was accurately visualized across subjects using multi-shell diffusion images through generalized q-sampling imaging based tractography. This method could be an important tool for the reconstruction and evaluation of the stria terminalis in various neurological disorders. One Sentence Summary The visualization of the stria terminalis through the multi-shell diffusion images using generalized q-sampling imaging based tractography.

Enigmatic Neural Pathways: Potentiating Viral Neuroinvasion Into the CNS.

Enigmatic Neural Pathways: Potentiating Viral Neuroinvasion Into the CNS.

Challenging Giant Insular Gliomas With Brain Mapping: Evaluation of Neurosurgical, Neurological, Neuropsychological, and Quality of Life Results in a Large Mono-Institutional Series.

ObjectiveGiant insular tumors are commonly not amenable to complete resection and are associated with a high postoperative morbidity rate. Transcortical approach and brain mapping techniques allow to identify peri-insular functional networks and, with neurophysiological monitoring, to reduce vascular-associated insults. Cognitive functions to be mapped are still under debate, and the analysis of the functional risk of surgery is currently limited to neurological examination. This work aimed to investigate the neurosurgical outcome (extent of resection, EOR) and functional impact of giant insular gliomas resection, focusing on neuropsychological and Quality of Life (QoL) outcomes.MethodsIn our retrospective analysis, we included all patients admitted in a five-year period with a radiological diagnosis of giant insular glioma. A transcortical approach was adopted in all cases. Resections were pursued up to functional boundaries defined intraoperatively by brain mapping techniques. We examined clinical, radiological, and intra-operative factors possibly affecting EOR and postoperative neurological, neuropsychological, and Quality of Life (QoL) outcomes.ResultsWe finally enrolled 95 patients in the analysis. Mean EOR was 92.3%. A Gross Total Resection (GTR) was obtained in 70 cases (73.7%). Five patients reported permanent morbidity (aphasia in 3, 3.2%, and superior quadrantanopia in 2, 2.1%). Suboptimal EOR associated with poor seizures control postoperatively. Extensive intraoperative mapping (inclusive of cognitive, visual, and haptic functions) decreased long-term neurological, neuropsychological, and QoL morbidity and increased EOR. Tumor infiltration of deep perforators (vessels arising either medial to lenticulostriate arteries through the anterior perforated substance or from the anterior choroidal artery) associated with a higher chance of postoperative ischemia in consonant areas, with the persistence of new-onset motor deficits 1-month post-op, and with minor EOR. Ischemic insults in eloquent sites represented the leading factor for long-term neurological and neuropsychological morbidity.ConclusionIn giant insular gliomas, the use of a transcortical approach with extensive brain mapping under awake anesthesia ensures broad insular exposure and extension of the surgical resection preserving patients’ functional integrity. The relation between tumor mass and deep perforators predicts perioperative ischemic insults, the most relevant risk factor for long-term and permanent postoperative morbidity.

Anterior perforated substance region aneurysms: review of a series treated with microsurgical technique.

Aneurysms arising from the distal carotid, proximal A1, and proximal M1 that project posteriorly and superiorly toward the anterior perforated substance (APS) are rare. Their open surgical treatment is particularly difficult due to poorly visualized origin of the aneurysm and the abundance of surrounding perforators. We sought to analyze the anatomical and clinical characteristics of APS aneurysms and discuss surgical nuances that can optimize visualization, complete neck clip obliteration, and preservation of adjacent perforators. Thirty-two patients with 36 APS aneurysms were surgically treated between November 2000 and September 2017. Patients were prospectively enrolled in a cerebral aneurysm database and their clinical, imaging, and surgical records were retrospectively reviewed. Twenty-seven aneurysms originated from the distal ICA, 7 from the proximal A1, and 2 from the proximal M1; 15 patients presented with subarachnoid hemorrhage. Careful intraoperative dissection revealed 4 aneurysms originating at the takeoff of a perforator; another 25 had at least 1 adherent perforator. All aneurysms were clipped except for one that was trapped. Postoperatively, 3 patients had radiographic infarctions in perforator territory with only 1 developing delayed clinical hemiparesis. Good outcome (modified Rankin Scale, 0-2) was achieved in 28 patients (88%). APS aneurysms present a challenging subset of aneurysms due to their complex anatomical relationship with surrounding perforators. These should be identified on preoperative imaging based on location and projection. Successful microsurgical clipping relies on optimization of the surgical view, meticulous clip reconstruction, preservation of all perforators, and electrophysiological monitoring to minimize ischemic complication.

Микрохирургическая анатомия артерий переднего продырявленного вещества головного мозга человека

Aim of study. To specify the peculiarities in spatial arrangement of arterial branches in the area of anterior perforated substance. Material and methods. The work was carried out using brain material of 25 people of both genders from the archive of the Department of Anatomy at the FSBEI HE Ryazan State Medical University MOH RF. In order to verify the arteries before formaldehyde fi xation of brain, their injection with gelatine solution was performed. Th e peculiarities in origin of central arteries from the internal carotid artery, middle cerebral artery, anterior cerebral artery as well as their calibres and quantity were examined. Results. The study has shown that the spatial arrangement of the perforating arteries in the anterior perforated substance depends on the particular site of origin. Th e origins of arterial branches flowing through the anterior perforated substance are the internal carotid artery, anterior cerebral artery, middle cerebral artery and anterior choroidal artery. Perforating branches originating from the internal carotid artery were registered in both hemispheres in 98 % of the cases. Unilateral (left ) absence of branches originating from the C4 segment was only noted in one case. The largest quantity of arteries originated from M1 segment of the middle cerebral artery. Th erewith, the majority of the branches belonged to the lateral group exceeding the quantity of such branches in the medial group by 2.3 times on average. Th ereat, the quantity of branches in each group showed no valid diff erence in relation to the side of the body. Conclusion. Knowledge of the anatomy of the anterior perforated substance, the peculiarities in spatial arrangement of the branches of middle cerebral artery and the anterior choroidal artery is important and is of interest for clinicians from the perspective of diagnosis and timely treatment of cerebral tumours and aneurisms of its arterial ring

Morphological evaluation of the distal medial striate artery. A study with cadaveric material.

Objective: To evaluate the morphology of the distal medial striated artery, taking into account biometric variables useful for clinical and surgical management. Methods: A descriptive transversal study was performed with a sample of brains, who underwent autopsy at the Institute of Legal Medicine and Forensic Sciences of Bucaramanga-Colombia, which were evaluated using the perfusion technique of vascular structures with polyester resin.Results: The distal medial striated artery was presented in 1.4% and 4.2% duplicated in the right and left hemispheres respectively. Agenesis was presented in 2.8% in the left hemisphere. Its origin was 44.6% of the anterior cerebral artery junction site with the anterior communicating artery and was observed in 6 cases (4.2%) presented with a common trunk with the orbitofrontal artery. The main qualitative finding was the sinuous trajectory that was observed in 57.7% on the right side and 45.1% in the left hemisphere. Also, an important alteration found at the biometric analysis was hypoplasia that could be related to the decreased blood supply to the basal nuclei. The diameter was 0.5 ± 0.2 mm and its total length was 20.3 ± 4.1 mm.Conclusions: The topographical knowledge of this structure determines the vulnerability of its morphology because it can complicate surgical procedures performed in the anterior segment of the arterial circle of the brain. Besides, the observed collateral circulation contributes to the blood supply and the perfect functionality of the subcortical nervous structures.

Atypical Virchow-Robin Spaces Mimicking Cystic Primary Brain Tumor – Clinical Report and Literature Review

AbstractThe Virchow-Robin spaces (VRSs), which are often incidentally observed in modern structural neuroimaging examinations, are small cystic cavities that usually surround the small arteries and arterioles at the level of basal ganglia, the anterior perforated substance and the thalamic-mesencephalic junction. Typically, they have similar physicochemical characteristics to cerebral spinal fluid (CSF) and there is no contrast enhancement on brain CT and MRI images. Its real meaning is unknown, although some contemporary studies have suggested that it might be related to certain traumatic brain injury or several other central nervous system (CNS) disorders, as degenerative diseases. Occasionally, some wide and atypical VRS may be mistaken for primary cystic brain tumors, especially in the context of large and symptomatic lesions, multiple clustered cysts, cortical lesions and if there is adjacent reactive gliosis. The present paper reports four patients who were affected by atypical VRS mimicking brain tumors that required imaging follow-up or even a biopsy to confirm the diagnosis or to indicate the correct approach. Although it is not so unusual, one of them occurred concomitantly and adjacent to a diffuse glioma (co-deleted 1p19q, WHO-GII).

The Posterior Perforated Substance: A Brain Mystery Wrapped in an Enigma.

There is a dearth of published information on the posterior perforated substance as compared to the anterior perforated substance. We managed to glean facts about the posterior perforated substance that can serve as a landmark for surgical operations in the adjacent regions of the midbrain and the vessels passing through it. Moreover, the posterior perforated substance contains the interpeduncular nucleus responsible for the mental state of the individual. 1) To describe the topography of the blood vessels supplying the posterior perforated substance area from the surgical point of view; 2) to investigate the functions of the interpeduncular nucleus. We assembled and analyzed results from source databases by Elsevier, NCBI MedLine, Scopus, Scholar. Google and Embase. Each article was studied in detail for practically useful information about the posterior perforated substance. The P1-segment perforating branches of the posterior cerebral artery supply the posterior perforated substance. This area is especially vulnerable in the case of vascular pathologies. The posterior communicating artery can block the surgeon's view and impede maneuverability of the tool in the area of the posterior perforated substance, which may be addressed using the separation technique, which can lead to positive results. In addition, the medial habenula-interpeduncular nucleus in the posterior perforated substance is associated with various addictions and psychiatric conditions. The posterior perforated substance area is of great interest for surgical interventions. Future studies of the interpeduncular nucleus anticipate the development of drugs to affect different types of dependencies and some mental diseases.

Surgical Technique and Outcome of Extensive Frontal Lobectomy for Treatment of Intracable Non-lesional Frontal Lobe Epilepsy.

Although extensive frontal lobectomy (eFL) is a common surgical procedure for intractable frontal lobe epilepsy (FLE), there have been very few reports regarding surgical techniques for eFL. This article provides step-by-step descriptions of our surgical technique for non-lesional FLE. Sixteen patients undergoing eFL were included in this study. The goals were to maximize gray matter removal, including the orbital gyrus and subcallosal area, and to spare the primary motor and premotor cortexes and anterior perforated substance. The eFL consists of three steps: (1) positioning, craniotomy, and exposure; (2) lateral frontal lobe resection; and (3), resection of the rectus gyrus and orbital gyrus. Resection ahead of bregma allows preservation of motor and premotor area function. To remove the orbital gyrus preserving anterior perforated substance, it is essential to visualize the olfactory trigone beneath the pia. It is important to observe the surface of the contralateral medial frontal lobe for complete removal of the subcallosal area of the frontal lobe. Thirteen patients (81.25%) became seizure-free and three patients (18.75%) continued to have seizures. None of the patients showed any complications. The eFL is a good surgical technique for the treatment of intractable non-lesional FLE. For treatment of epilepsy by eFL, it is important to resect the non-eloquent area of the frontal lobe as much as possible with preservation of the eloquent cortex.

A White Matter Fiber Microdissection Study of the Anterior Perforated Substance and the Basal Forebrain: A Gateway to the Basal Ganglia?

Studies detailing the anatomy of the basal forebrain (BF) from a neurosurgical perspective are missing. To describe the anatomy of the BF and of the anterior perforated substance (APS), the BF emphasizing surgical useful anatomical relationship between surface landmarks and deep structures. White matter fiber microdissection was performed on 5 brain specimens to analyze the topographic anatomy of the APS and expose layer-by-layer fiber tracts and nuclei of the BF. The APS, as identified anatomically, surgically, and neuroradiologically, has clear borders measured 23.3 ±3.4 mm (19-27) in the mediolateral and 12.5±1.2 mm (11-14) in the anteroposterior directions. A detailed stratigraphy of the BF was performed from the APS up to basal ganglia and thalamus allowing identification and dissection of the main components of the BF (septum, nucleus accumbens, amygdala, innominate substance) and its white matter tracts (band of Broca, extracapsular thalamic peduncle, ventral amygdalohypothalamic fibers). The olfactory trigone together with diagonal gyrus and the APS proper is a relevant superficial landmark for the basal ganglia (inferior to the nucleus accumbens, lateral to the caudate head, and medial to the lentiform nucleus). The findings in our study supplement available anatomic knowledge of APS and BF, providing reliable landmarks for precise topographic diagnosis of BF lesions and for intraoperative orientation. Surgically relevant relationships between surface and deep anatomic structures are highlighted offering thus a contribution to neurosurgeons willing to perform surgery in this delicate area.