It has been hypothesized that the human brain has less redundancy than animals, but the structural evidence has not been identified to confirm this claim. Here, we report three redundancy circuits of the commissural pathways in primate brains, namely the orbitofrontal, temporal, and occipital redundancy circuits of the anterior commissure and corpus callosum. Each redundancy circuit has two distinctly separated routes connecting a common pair of cortical regions. We mapped their trajectories in human and rhesus macaque brains using individual and population‐averaged tractography. The dissection results confirmed the existence of these redundancy circuits connecting the orbitofrontal lobe, amygdala, and visual cortex. The volume analysis showed a significant reduction in the orbitofrontal and occipital redundancy circuits of the human brain, whereas the temporal redundancy circuit had a substantial organizational difference between the human and rhesus macaque. Our results support the hypothesis that the human brain has less redundancy in the commissural pathways than that of the rhesus macaque brain. Further studies are needed to explore its neuropathological implications.

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BACKGROUND Many approaches are used for midline anterior cranial fossa meningioma resection. In the subfrontal approach, the anterior superior sagittal sinus (SSS) is commonly ligated to release the anterior falx. The transbasal approach allows access to the origin of the anterior SSS, allowing for maximum venous preservation. OBJECTIVE To investigate variations in the first and second veins draining into the SSS. METHODS We performed stepwise dissections for a transbasal level 1 approach on 8 anatomic specimens. We visualized the first and second veins draining into the sinus and measured the distance from the foramen cecum to these veins. We also measured the orbital bar height to determine the length of sagittal sinus that could be preserved with orbital bar removal. RESULTS The distance between the foramen cecum and the first vein ranged from 4 to 36 mm while the distance to the second vein ranged from 6 to 48 mm. The mean orbital bar height was 26.4 mm. Based on these measurements, with a traditional bicoronal craniotomy without orbital bar removal, 81% of first veins and 58% of second veins would be sacrificed. CONCLUSION A supraorbital bar or nasofrontal osteotomy, part of the transbasal skull base approach, is helpful to preserve the first and second veins when ligating the anterior SSS. Based on this study, it may be difficult to preserve these veins without orbital bar removal. Preservation of these veins may be of clinical importance when approaching midline anterior fossa pathologies.

The single feature of all malformations in cortical development is the clinical association with epilepsy. It has been proven that Sox-1 expression is essential during neurodevelopment and it is reported that Sox-1 knockout mice present spontaneous generalized seizures. Particularly in cerebellum, Sox-1 plays a key role in the Bergmann´s glia (BG) function, which allows the correct function of the Purkinje cells (PC). The targets of PC are the dentate and interpositus nuclei, which form the main cerebellar efferents involved in the physiopathology of epilepsy. Here we present the Sox-1 expression in cerebellum of rats during electric amygdala-kindling. We obtained seizures and once they had 3, 15 and 45 electric stimuli, the animals were sacrificed; the cerebellum was processed for inmunohistochemistry and Western blot analysis was performed to determine Sox-1 expression. Liquid chromatography was performed to examine gammaaminobutyric acid (GABA) and glutamate concentration. According to the literature, a progressive increase was observed in the electrographic and behavioral parameters. We found that Sox-1 expression in 15 and 45-stimuli groups had a statistically significant decrease as compared with controls, while the 3-stimuli group was similar to the control group. The concentration of glutamate was increased in rats with 45 stimuli. We can conclude that Sox-1 expression decreases as the number of seizures increases, and this is probably due to an altered glutamate regulation by a dysfunctional BG. In this way, we can suggest this mechanism as a one possible explanation of how the cerebellum participates in the pathophysiology of epilepsy.

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Background High-flow skull base dural defects are associated with an increased risk of postoperative cerebrospinal fluid (CSF) leaks. Objective This study aimed to identify the risk factors for persistent postoperative CSF leak after endoscopic endonasal surgery (EES) and determine the ideal reconstruction strategy after initial failed repair. Methods Patients with CSF leak after intradural EES between October 2000 and February 2017 were identified. Cases with persistent CSF leak were compared with patients with similar pathologic diagnosis without a persistent leak to identify additional risk factors. Results Two hundred and twenty-three out of 3,232 patients developed postoperative CSF leak. Persistent leaks requiring more than one postoperative repair occurred in 7/223 patients (3.1%). All seven had undergone intradural approach to the posterior fossa for resection of recurrent/residual clival chordomas. This group was matched with 25 patients with recurrent/residual clival chordoma who underwent EES without postoperative CSF leak (control group). Age, gender, history of diabetes, smoking, or radiotherapy were not statistically different between the groups. Obesity (body mass index > 30) was significantly more common in the group with persistent leak (86%) compared with controls (36%) (p = 0.02). All patients with a persistent CSF leak developed meningitis (p = 0.001). Five patients with persistent leak required a pericranial flap to achieve definitive repair. Conclusion Multiple recurrent CSF leak after EES primarily occurs following resection of recurrent/residual posterior fossa chordoma. Obesity is a major risk factor and meningitis is universal with persistent leak. Flap necrosis may play a role in the development of persistent CSF leaks, and the use of secondary vascularized flaps, specifically extracranial–pericranial flaps, should be considered as an early rescue option in obese patients.

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