Hematoma expansion unrelated to rebleeding in ruptured anterior cerebral artery aneurysms treated by early endovascular embolization

Background: Whether hematoma expansion after aneurysmal rupture is always a sign of rerupture remains unclear. Hence, the present study aimed to assess the incidence and risk factors of hematoma expansion unrelated to aneurysmal rerupture after endovascular embolization for ruptured cerebral aneurysms. Methods: We included patients who underwent endovascular embolization for ruptured cerebral aneurysms within 48 h after onset at our institution between January 2009 and February 2014. The medical records of 70 consecutive patients were reviewed and analyzed retrospectively. Results: Hematoma expansion unrelated to aneurysmal rerupture occurred in 7 (10%) of 70 patients. Interestingly, four of seven patients had distal anterior cerebral artery (ACA) aneurysms. The interval from onset to aneurysm coiling was shorter in patients with hematoma expansion than in those without (P = 0.040). Conclusion: Early embolization of ruptured ACA aneurysms might increase the risk of hematoma expansion unrelated to aneurysmal rerupture because the procedures were conducted under systemic anticoagulation. It would be better to refer the patient for direct clipping if the patient has a distal ACA aneurysm with parenchymal hematoma at interhemispheric fissure. Delayed coil embolization, which means around 12–18 h delayed, might be another option for ruptured distal ACA aneurysms to prevent hematoma expansion.

Utility of a novel exoscope, ORBEYE, in gravity-assisted brain retraction surgery for midline lesions of the brain

Background: Midline brain lesions, such as falx meningioma, arteriovenous malformations, and cavernous malformations, are usually approached from the ipsilateral interhemispheric fissure. To this end, patients are positioned laterally with the ipsilateral side up. However, some studies have reported the usefulness of gravity-assisted brain retraction surgery, in which patients are placed laterally with the ipsilateral side down or up, enabling surgeons to approach the lesions through the ipsilateral side or through a contralateral interhemispheric fissure, respectively. This surgery requires less brain retraction. However, when using an operative microscope, performing this surgery requires the surgeon to operate in an awkward position. A recently developed high-definition (4K-HD) 3-D exoscope system, ORBEYE, can improve the surgeon’s posture while performing gravity-assisted brain retraction surgery. Methods: We report five cases with midline brain tumors managed by resectioning with gravity-assisted brain retraction surgery using ORBEYE. We also performed an ergonomic analysis of gravity-assisted brain retraction surgery with a craniotomy model and a neuronavigation system. Results: Gravity-assisted brain retraction surgery to the midline brain tumors was successfully performed for all five patients, using ORBEYE, without any postoperative neurological deficit. Conclusion: Gravity-assisted brain retraction surgery to the midline brain lesions using ORBEYE is feasible, and ORBEYE is ergonomically more favorable than a microscope. ORBEYE has the potential to generalize neurosurgical approaches considered difficult due to the surgeon’s awkward position, such as gravity-assisted brain retraction surgery.

Resection of a recurrent pineal region teratoma via a posterior interhemispheric transcallosal approach

The authors describe the unusual case of a 6-year-old boy presenting with decorticate posturing, diminished hearing, and an inability to open his eyes, despite being verbally responsive. He underwent a posterior interhemispheric transcallosal intervenous approach for resection of a pineal region mature teratoma, which recurred 2 years postoperatively. This video demonstrates his initial surgery and reresection, illustrating the value of this approach for more complex lesions that involve the internal cerebral veins (ICVs). At the time of recurrence, microsurgical dissection of the scarred interhemispheric fissure was required to facilitate removal of the multifocal recurrent teratoma, resulting in gross-total resection. The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2134.

Cranial imaging in children with malnutrition aged 6 to 60 months

Background: India has 57 million or more than a third of the world's 146 million undernourished children. Protein energy malnutrition is associated with cerebral atrophy 2 which may be detrimental to intellectual development. The aim and objective of this stusy was to study the changes in the brain by cranial imaging in children with malnutrition aged 6 months to 5 years and to correlate these changes with severity of malnutrition.Methods: It was a hospital based prospective study done in Bal Chikitsalay, Maharana Bhupal government hospital, Udaipur during the study period July 2015 to July 2016. Total 120 children were enrolled, out of which 80 were severely malnourished, 20 were moderately malnourished and 20 normally nourished children undergoing neuroimaging for some other reason taken as controls. All the cases were subjected to CT scan and the following parameters were noted. Central atrophy was evaluated by bifrontal index (BFR) and bicaudate index (BCR). Cortical atrophy was evaluated by width of sylvian fissure (SFW) and widening of interhemispheric fissure (IHD). These parameters were then compared with the severity of malnutrition and among controls. Data was analysed with standard software of biostatics using parametric tests, Pearson’s correlation analysis, ANOVA test and student’s t test.Results: On an average 80% of SAM and 10% of MAM had various degree of cerebral atrophy while none of the controls showed significant degree of cerebral atrophy.Conclusions: Effect of malnutrition on brain can be objectively assessed by CT indices, BFR, BCR, SFW and IHD to define the degree of cerebral atrophy in the malnourished population.

Hybrid Fluoroscopic and Neurophysiological Targeting of Responsive Neurostimulation of the Rolandic Cortex

BACKGROUND Precise targeting of cortical surface electrodes to epileptogenic regions defined by anatomic and electrophysiological guideposts remains a surgical challenge during implantation of responsive neurostimulation (RNS) devices. OBJECTIVE To describe a hybrid fluoroscopic and neurophysiological technique for targeting of subdural cortical surface electrodes to anatomic regions with limited direct visualization, such as the interhemispheric fissure. METHODS Intraoperative two-dimensional (2D) fluoroscopy was used to colocalize and align an electrode for permanent device implantation with a temporary in Situ electrode placed for extraoperative seizure mapping. Intraoperative phase reversal mapping technique was performed to distinguish primary somatosensory and motor cortex. RESULTS We applied these techniques to optimize placement of an interhemispheric strip electrode connected to a responsive neurostimulator system for detection and treatment of seizures arising from a large perirolandic cortical malformation. Intraoperative neuromonitoring (IONM) phase reversal technique facilitated neuroanatomic mapping and electrode placement. CONCLUSION In challenging-to-access anatomic regions, fluoroscopy and intraoperative neurophysiology can be employed to augment targeting of neuromodulation electrodes to the site of seizure onset zone or specific neurophysiological biomarkers of clinical interest while minimizing brain retraction.

DRAXIN regulates interhemispheric fissure remodelling to influence the extent of corpus callosum formation

Corpus callosum dysgenesis (CCD) is a congenital disorder that incorporates either partial or complete absence of the largest cerebral commissure. Remodelling of the interhemispheric fissure (IHF) provides a substrate for callosal axons to cross between hemispheres, and its failure is the main cause of complete CCD. However, it is unclear whether defects in this process could give rise to the heterogeneity of expressivity and phenotypes seen in human cases of CCD. We identify incomplete IHF remodelling as the key structural correlate for the range of callosal abnormalities in inbred and outcrossed BTBR mouse strains, as well as in humans with partial CCD. We identify an eight base-pair deletion in Draxin and misregulated astroglial and leptomeningeal proliferation as genetic and cellular factors for variable IHF remodelling and CCD in BTBR strains. These findings support a model where genetic events determine corpus callosum structure by influencing leptomeningeal-astroglial interactions at the IHF.

DCC regulates astroglial development essential for telencephalic morphogenesis and corpus callosum formation

The forebrain hemispheres are predominantly separated during embryogenesis by the interhemispheric fissure (IHF). Radial astroglia remodel the IHF to form a continuous substrate between the hemispheres for midline crossing of the corpus callosum (CC) and hippocampal commissure (HC). DCC and NTN1 are molecules that have an evolutionarily conserved function in commissural axon guidance. The CC and HC are absent in Dcc and Ntn1 knockout mice, while other commissures are only partially affected, suggesting an additional aetiology in forebrain commissure formation. Here, we find that these molecules play a critical role in regulating astroglial development and IHF remodelling during CC and HC formation. Human subjects with DCC mutations display disrupted IHF remodelling associated with CC and HC malformations. Thus, axon guidance molecules such as DCC and NTN1 first regulate the formation of a midline substrate for dorsal commissures prior to their role in regulating axonal growth and guidance across it.

Endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach for microsurgical resection of vermian arteriovenous malformation: operative video and technical nuances

In this illustrative video, the authors demonstrate resection of a superior vermian arteriovenous malformation (AVM) using the endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach. Lateral positioning allows for gravity-assisted access to the interhemispheric fissure without retractors. The parieto-occipital trajectory is useful in patients who have a steep tentorial angle and avoids manipulation of the occipital lobe and visual cortex. In addition, the authors utilize an angled endoscope, which allows full inspection of the resection bed after AVM removal to visualize areas hidden from the microsurgical view to minimize the chance of residual disease in a deep corridor with multiple visual obstructions.The video can be found here: https://youtu.be/hk9nIIdtqbI