Transsylvian and trans-Heschl's gyrus approach for a left posterior insular lesion and functional analyses of the left Heschl's gyrus: illustrative case.

BACKGROUND: A common surgical approach for dominant insular lesions is to make a surgical corridor in asymptomatic cortices based on functional mapping. However, the surgical approach is difficult for posterior insular lesions in a dominant hemisphere because the posterior parts of the perisylvian cortices usually have verbal functions. OBSERVATIONS: We present the case of a 40-year-old male whose magnetic resonance images revealed the presence of contrast-enhancing lesions in the left posterior insula. Our surgical approach was to split the sylvian fissure as widely as possible, and partially resect Heschl's gyrus if the cortical mapping was negative for language tests. Because Heschl's gyrus did not have verbal functions, the gyrus was used as a surgical corridor. It was wide enough for the removal of the lesion; however, because intraoperative pathological diagnosis eliminated the possibility of brain tumors, further resection was discontinued. The tissues were histologically diagnosed as tuberculomas. Antituberculosis drugs were administered, and the residual lesions finally disappeared. According to the neurophysiological tests, the patient showed temporary impairment of auditory detection, but the low scores of these tests improved. LESSONS: The transsylvian and trans-Heschl's gyrus approach can be a novel surgical option for excising dominant posterior insular lesions.

Evaluating diploic vein blood flow using time-resolved whole-head computed tomography angiography and determining the positional relationship between typical craniotomy approaches and diploic veins in patients with meningioma.

BACKGROUND: Diploic veins may act as collateral venous pathways in cases of meningioma with venous sinus invasion. Diploic vein blood flow should be preoperatively evaluated to consider preserving the veins. In this study, we evaluated the use of time-resolved whole-head computed tomography angiography (4D-CTA)-which is less patient-intensive than digital subtraction angiography (DSA)-for assessing diploic vein blood flow and the positional relationship between typical craniotomy approaches and diploic veins. METHODS: We retrospectively examined 231 patients who underwent surgery for intracranial meningioma. We performed contrast-enhanced magnetic resonance imaging (MRI) to evaluate diploic vein pathways and compared the visualization rates of diploic vein blood flow assessed using 4D-CTA and DSA. Subsequently, we evaluated the rates of the diploic veins transected during craniotomy by comparing the pre- and postoperative contrast-enhanced MRI. RESULTS: The diagnostic performance of 4D-CTA was assessed in 45 patients. Of the 320 diploic veins identified in these patients, blood flow in 70 (21.9%) diploic veins was identified by 4D-CTA and DSA, and both results were consistent. To assess the transection rates of the diploic veins, 150 patients were included. A trend towards a high transection rate of the diploic vein in the basal interhemispheric, frontotemporal, orbitozygomatic, combined transpetrosal, and convexity craniotomy approaches was observed. CONCLUSIONS: In patients with meningiomas, both 4D-CTA and DSA are useful in evaluating diploic vein blood flow. In meningiomas with venous sinus invasion, determining the extent of craniotomy after understanding the pathways and blood flow of diploic veins is recommended.

Intracranial phosphaturic mesenchymal tumors. A case report and review of literature.

Most osteomalacia-inducing tumors (OITs) are phosphaturic mesenchymal tumors (PMTs) that secrete fibroblast growth factor 23 (FGF23). These tumors usually occur in the bone and soft tissues, and intracranial OITs are rare. Therefore, intracranial OIT is difficult to diagnose and treat. This paper presents a case of intracranial OIT and shows a review of previous cases. A 45-year-old man underwent nasal cavity biopsy and treatment with active vitamin D3 and neutral phosphate for hypophosphatemia. Amplification of FGF23 mRNA level within the tumor was detected. Subsequently, the surgical specimen was diagnosed with a PMT and was considered the cause of the patient's osteomalacia. The patient was referred to a neurosurgery department for the excision of the intracranial tumor extending to the nasal cavity. After tumor removal, the serum levels of FGF23 and phosphorus were normalized as compared to preoperative those. The patient remains disease-free, without additional treatment, approximately 10 years after surgery, with no tumor recurrence. As per the literature, intracranial OITs usually occur in patients aged 8-69 years. Bone and muscle pain are major complaints. Approximately 60% of the patients reported previously had symptoms because of intracranial tumors. In some cases, it took several years to diagnose OIT after the onset of the osteomalacia symptoms. Laboratory data in such cases show hypophosphatemia and elevated FGF23 levels. Because FGF23 levels are associated with the severity of osteomalacia symptoms, total tumor resection is recommended. PMT and hemangiopericytoma (HPC) are histologically similar, but on immunochemistry, PMT is negative for signal transducer and activator of transcription 6 (STAT6), whereas HPC is positive. FGF23 amplification is seen in PMTs but not in HPCs. Therefore, the analysis of FGF23 and STAT6 was helpful in distinguishing PMTs from HPCs. In cases of hypophosphatemia and osteomalacia without a history of metabolic, renal, or malabsorptive diseases, the possibility of oncogenic osteomalacia should be considered.

Intraoperative Real-Time Near-Infrared Image-Guided Surgery to Identify Intracranial Meningiomas via Microscope.

Meningiomas are a common pathology in the central nervous system requiring complete surgical resection. However, in cases of recurrence and post-irradiation, accurate identification of tumor remnants and a dural tail under bright light remains challenging. We aimed to perform real-time intraoperative visualization of the meningioma and dural tail using a delayed-window indocyanine green (ICG) technique with microscopy. Fifteen patients with intracranial meningioma received 0.5 mg/kg ICG a few hours before observation during the surgery. We used near-infrared (NIR) fluorescence to identify the tumor location. NIR fluorescence could visualize meningiomas in 12 out of 15 cases. Near-infrared visualization during the surgery ranged from 1 to 4 h after the administration of ICG. The mean signal-to-background ratio (SBR) of the intracranial meningioma in delayed-window ICG (DWIG) was 3.3 ± 2.6. The ratio of gadolinium-enhanced T1 tumor signal to the brain (T1BR) (2.5 ± 0.9) was significantly correlated with the tumor SBR (p = 0.016). K trans , indicating blood-brain barrier permeability, was significantly correlated with tumor SBR (p < 0.0001) and T1BR (p = 0.013) on dynamic contrast-enhanced magnetic resonance imaging (MRI). DWIG demonstrated a sensitivity of 94%, specificity of 38%, positive predictive value (PPV) of 76%, and negative predictive value (NPV) of 75% for meningiomas. This is the first pilot study in which DWIG fluorescence-guided surgery was used to visualize meningioma and dural tail intraoperatively with microscopy. DWIG is comparable with second-window ICG in terms of mean SBR. Gadolinium-enhanced T1 tumor signal may predict NIR fluorescence of the intracranial meningioma. Blood-brain barrier permeability as shown by K trans on dynamic contrast-enhanced MRI can contribute to gadolinium enhancement on MRI and to ICG retention and tumor fluorescence by NIR.

Diploic veins as collateral venous pathways in patients with dural venous sinus invasion by meningiomas.

BACKGROUND: Although it is known that diploic veins frequently communicate with the dural venous sinuses, the role of diploic veins in patients with venous sinus invasion from meningiomas remains unknown. METHODS: We retrospectively examined the medical records of 159 patients who underwent their first craniotomies for intracranial meningiomas. Contrast-enhanced magnetic resonance imaging was used to evaluate diploic vein routes, and digital subtraction angiography (DSA) was used to evaluate diploic vein blood flow. When high blood flow was visualized concurrently with the venous sinuses, the veins were classified as of the "early type." Diploic vein routes were classified into five routes. RESULTS: DSA was performed in 110 patients, with 14 showing superior sagittal sinus (SSS) invasion (SSS group) and 23 showing non-SSS venous sinus invasion (non-SSS group). The proportion of early type diploic veins was significantly higher in the SSS group (27.1%) than in other patients (patients without venous sinus invasion, 2.1%; non-SSS, 4.3%) (p < 0.01). In patients not in the SSS group, diploic veins were sacrificed during craniotomy in 76 patients, including four patients with veins of the early type. No patients demonstrated new neurological deficits postoperatively. In the SSS group, diploic veins were sacrificed in all patients, and early type diploic veins were cut in five patients. Two of these five patients showed postoperative neurological deficits. CONCLUSIONS: In the SSS group, diploic veins may function as collateral venous pathways, and attention is recommended for their interruption. In patients without SSS invasion, diploic veins, even of the early type, can be sacrificed.

Demystifying White Matter Injury in the Unconscious Patients with Diffusion Tensor Imaging.

BACKGROUND: Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) provide a noninvasive window to study the neural connectivity and reconstruct the tracts. Detection of white matter injury (WMI) by DTT is a recent application being used in stroke, diffuse axonal injury, and neurodegenerative disorders. Fiber tracking in patients with brain hemorrhage can detect loss of fibers and anatomical disruption of the tracts, which can be useful in the prognostication of patient outcome. MATERIALS AND METHODS: DTI and fiber tracking was done in four patients admitted at Fujita Health University Banbuntane Hospital, Japan, with decreased consciousness following brain hemorrhage (3 patients with aneurysmal subarachnoid hemorrhage and one patient with bifrontal hemorrhage), and WMI was analyzed. We also reviewed the literature on tractography in patients with brain hemorrhage and its correlation with consciousness. RESULTS: We found significant frontal WMI in the form of thinning and anatomical disruption in all four cases. The frontal white matter tracts form an important component of the limbic system and ascending reticular activating system and frontal WMI correlated with the poor conscious level and cognitive dysfunction. Structural damage to the fiber tracts demonstrated as thinning, reduction in the volume or absence on tractography with corresponding reduction in the mean fractional anisotropy values in the frontal white matter of the affected side. CONCLUSION: DTI can be useful as a critical tool for revealing the anatomical basis for the cognitive dysfunction and unconsciousness and can be possibly used to prognosticate patient recovery. Early detection of WMI by DTI can also help in tailored rehabilitation. The authors believe that DTT could have a crucial role in the future for detecting structural changes which lead to cognitive dysfunction and further studies are needed to arrive at a specific protocol for detecting WMI.

Intradural versus Extradural Location of Paraclinoid Aneurysms: Preoperative Red Flag Markers.

BACKGROUND: Exact preoperative confirmation of the distal dural ring and intradural location of a paraclinoid internal carotid aneurysm has been an age old dilemma. This study was aimed at identifying anatomical landmarks in cases of paraclinoid aneurysms, which were relatively consistent, and would help in predicting the possibility of an extradural inaccessible location of these aneurysms for surgical clipping. METHODS: Ninety surgically managed unruptured paraclinoid aneurysms were retrospectively analyzed with preoperative computerized tomography. Axial relation of the aneurysm neck to the ophthalmic artery (OA), optic strut (OS), and anterior clinoid process (ACP) in terms of vertical distance and the direction of projection were analyzed and tabulated for all 90 cases. Intradural and extradural (inaccessible) aneurysms were compared. RESULTS: Seven out of the 8 inaccessible necks were medially directed and 1 was ventrally placed (P = 0.053). The OA level when compared to the neck had a positive correlation with inaccessible aneurysms for clipping (P = 0.002) The OS location above the level of the neck had significant correlation with inaccessibility of clipping and extradural location (P < 0.001). The tip of the ACP had no statistical significance with inaccessibility (P = 0.351). CONCLUSIONS: Medially projecting aneurysms with necks below the level of the OS and origin of the OA should be managed with a high index of suspicion and an alternate method of treatment should be sought. The relation of the neck to the ACP does not seem to have significant statistical bearing with decision making.

Surgical Management of Complex Middle Cerebral Artery Aneurysms: An Institutional Review.

BACKGROUND: Complex middle cerebral artery (MCA) aneurysms are defined as large (≥10 mm) or giant (≥25 mm) aneurysms with M2 branches arising from the aneurysm rather than M1 segments and usually require some form of reconstruction of the bifurcation. Their management is difficult and surgery is preferred over endovascular modalities because of their peculiar angioarchitecture and association with critical branch points or perforators. OBJECTIVES: The study was aimed at analyzing surgically managed complex MCA aneurysms and discussing characteristics not favorable for endovascular management, surgical nuances and clipping strategies, patient outcomes, and newer diagnostic modalities which help improve management. METHODS: Nine cases of surgically operated complex MCA aneurysms were identified from January 2017 to July 2019. The aneurysm characteristics, surgical nuances, clipping strategies, patient outcomes and points not favoring endovascular management were tabulated and analyzed. RESULTS: The mean maximum aneurysm diameter was 13.4 mm and the mean fundus/neck ratio was 1.6. The average microscope time was 124 min, and the most common method was clip reconstruction. The average number of clips used was 2.7 and the mean follow-up was 13 months. All patients have good postoperative outcome (Modified Rankin Score 0-2). The complete occlusion rate was 88.9% with one intraoperative voluntary residual sac which was coated. Computational fluid dynamic study results done preoperatively correlated with intraoperative findings. CONCLUSIONS: MCA aneurysms pose a significant challenge for endovascular treatment because of various factors such as luminal thrombi, complex angio-architecture, precarious branch/perforator locations, broad necks, and fusiform characteristics. Surgical management in experienced hands can tackle all these problems with an armamentarium of clipping techniques and bypass procedures.