Pharmacological Inhibition of Epidermal Growth Factor Receptor Prevents Intracranial Aneurysm Rupture by Reducing Endoplasmic Reticulum Stress.

BACKGROUND: Multiple pathways and factors are involved in the rupture of intracranial aneurysms. The EGFR (epidermal growth factor receptor) has been shown to mediate inflammatory vascular diseases, including atherosclerosis and aortic aneurysm. However, the role of EGFR in mediating intracranial aneurysm rupture and its underlying mechanisms have yet to be determined. Emerging evidence indicates that endoplasmic reticulum (ER) stress might be the link between EGFR activation and the resultant inflammation. ER stress is strongly implicated in inflammation and apoptosis of vascular smooth muscle cells, both of which are key components of the pathophysiology of aneurysm rupture. Therefore, we hypothesized that EGFR activation promotes aneurysmal rupture by inducing ER stress. METHODS: Using a preclinical mouse model of intracranial aneurysm, we examined the potential roles of EGFR and ER stress in developing aneurysmal rupture. RESULTS: Pharmacological inhibition of EGFR markedly decreased the rupture rate of intracranial aneurysms without altering the formation rate. EGFR inhibition also significantly reduced the mRNA (messenger RNA) expression levels of ER-stress markers and inflammatory cytokines in cerebral arteries. Similarly, ER-stress inhibition also significantly decreased the rupture rate. In contrast, ER-stress induction nullified the protective effect of EGFR inhibition on aneurysm rupture. CONCLUSIONS: Our data suggest that EGFR activation is an upstream event that contributes to aneurysm rupture via the induction of ER stress. Pharmacological inhibition of EGFR or downstream ER stress may be a promising therapeutic strategy for preventing aneurysm rupture and subarachnoid hemorrhage.

Vitamin D deficiency promotes intracranial aneurysm rupture.

Intracranial aneurysm rupture causes severe disability and high mortality. Epidemiological studies show a strong association between decreased vitamin D levels and an increase in aneurysm rupture. However, the causality and mechanism remain largely unknown. In this study, we tested whether vitamin D deficiency promotes aneurysm rupture and examined the underlying mechanism for the protective role of vitamin D against the development of aneurysm rupture utilizing a mouse model of intracranial aneurysm. Mice consuming a vitamin D-deficient diet had a higher rupture rate than mice with a regular diet. Vitamin D deficiency increased proinflammatory cytokines in the cerebral arteries. Concurrently, vitamin D receptor knockout mice had a higher rupture rate than the corresponding wild-type littermates. The vitamin D receptors on endothelial and vascular smooth muscle cells, but not on hematopoietic cells, mediated the effect of aneurysm rupture. Our results establish that vitamin D protects against the development of aneurysmal rupture through the vitamin D receptors on vascular endothelial and smooth muscle cells. Vitamin D supplementation may be a viable pharmacologic therapy for preventing aneurysm rupture.

Perivascular macrophages in cerebrovascular diseases.

Cerebrovascular diseases are a major cause of stroke and dementia, both requiring long-term care. These diseases involve multiple pathophysiologies, with mitochondrial dysfunction being a crucial contributor to the initiation of inflammation, apoptosis, and oxidative stress, resulting in injuries to neurovascular units that include neuronal cell death, endothelial cell death, glial activation, and blood-brain barrier disruption. To maintain brain homeostasis against these pathogenic conditions, brain immune cells, including border-associated macrophages and microglia, play significant roles as brain innate immunity cells in the pathophysiology of cerebrovascular injury. Although microglia have long been recognized as significant contributors to neuroinflammation, attention has recently shifted to border-associated macrophages, such as perivascular macrophages (PVMs), which have been studied based on their crucial roles in the brain. These cells are strategically positioned around the walls of brain vessels, where they mainly perform critical functions, such as perivascular drainage, cerebrovascular flexibility, phagocytic activity, antigen presentation, activation of inflammatory responses, and preservation of blood-brain barrier integrity. Although PVMs act as scavenger and surveillant cells under normal conditions, these cells exert harmful effects under pathological conditions. PVMs detect mitochondrial dysfunction in injured cells and implement pathological changes to regulate brain homeostasis. Therefore, PVMs are promising as they play a significant role in mitochondrial dysfunction and, in turn, disrupt the homeostatic condition. Herein, we summarize the significant roles of PVMs in cerebrovascular diseases, especially ischemic and hemorrhagic stroke and dementia, mainly in correlation with inflammation. A better understanding of the biology and pathobiology of PVMs may lead to new insights on and therapeutic strategies for cerebrovascular diseases.

Inhalational Anesthesia Reduced Transient Neurological Events After Revascularization Surgery for Moyamoya Disease.

BACKGROUND AND OBJECTIVES: The choice between inhalational and total intravenous anesthesia (TIVA) in revascularization surgery for Moyamoya disease (MMD) remains a topic of debate. Anesthesia methods have changed with the advent of new anesthetics. This study investigated whether modern anesthesia methods affected the development of neurological symptoms after revascularization surgery for MMD. METHODS: This single-center retrospective study included 63 adult patients (82 hemispheres) with MMD treated with direct and indirect bypass surgeries at our hospital between 2013 and 2022. Patients were divided into inhalational anesthesia (IA) and TIVA groups based on the anesthesia maintenance method. Baseline patient characteristics; postoperative neurological symptoms, including hyperperfusion syndrome, cerebral infarction, and transient neurological events (TNEs); and cortical hyperintensity belt (CHB) sign scores (5-point scale from 0 to 4) on postoperative magnetic resonance imaging were compared between the two groups. The operation methods, anesthetics, and intraoperative hemodynamic and ventilatory parameters were compared between patients with and without TNEs. RESULTS: The IA and TIVA groups comprised 39 and 43 hemispheres, respectively. The frequency of postoperative hyperperfusion syndrome and cerebral infarction did not differ between the groups, but the number of TNEs in the IA group (5/39; 13%) was significantly lower than that in the TIVA group (16/43; 37%). Multivariate logistic regression analysis revealed that TNEs were associated with TIVA (odds ratio, 3.91; 95% CI, 1.24-12.35; P = .02). The median [IQR] postoperative CHB sign score in the IA group (2 [1-3]) was significantly lower than that in the TIVA group (4 [3-4]). CONCLUSION: The IA group had fewer postoperative TNEs and lower CHB sign scores than the TIVA group. Although further studies are needed, this study provides insights into the prevention of TNEs with IA and reconsideration of the optimal anesthesia for MMD.

Pretreatment with Clodronate Improved Neurological Function by Preventing Reduction of Posthemorrhagic Cerebral Blood Flow in Experimental Subarachnoid Hemorrhage.

BACKGROUND: Brain perivascular macrophages (PVMs) are potential treatment targets for subarachnoid hemorrhage (SAH), and previous studies revealed that their depletion by clodronate (CLD) improved outcomes after experimental SAH. However, the underlying mechanisms are not well understood. Therefore, we investigated whether reducing PVMs by CLD pretreatment improves SAH prognosis by inhibiting posthemorrhagic impairment of cerebral blood flow (CBF). METHODS: In total, 80 male Sprague-Dawley rats received an intracerebroventricular injection of the vehicle (liposomes) or CLD. Subsequently, the rats were categorized into the prechiasmatic saline injection (sham) and blood injection (SAH) groups after 72 h. We assessed its effects on weak and severe SAH, which were induced by 200- and 300-µL arterial blood injections, respectively. In addition, neurological function at 72 h and CBF changes from before the intervention to 5 min after were assessed in rats after sham/SAH induction as the primary and secondary end points, respectively. RESULTS: CLD significantly reduced PVMs before SAH induction. Although pretreatment with CLD in the weak SAH group provided no additive effects on the primary end point, rats in the severe SAH group showed significant improvement in the rotarod test. In the severe SAH group, CLD inhibited acute reduction of CBF and tended to decrease hypoxia-inducible factor 1α expression. Furthermore, CLD reduced the number of PVMs in rats subjected to sham and SAH surgery, although no effects were observed in oxidative stress and inflammation. CONCLUSIONS: Our study proposes that pretreatment with CLD-targeting PVMs can improve the prognosis of severe SAH through a candidate mechanism of inhibition of posthemorrhagic CBF reduction.

A Consideration of Optimal Head Position in Transsylvian Selective Amygdalohippocampectomy.

Transsylvian selective amygdalohippocampectomy (TSA) is one of the predominant surgical options for drug-resistant mesial temporal lobe epilepsy. The purpose of this article is to highlight the unique features of TSA and determine the setting to perform safe and secure TSA with special reference to the optimal head position. TSA should be performed via a small surgical corridor in the temporal stem that contains functionally important fiber tracts, including the uncinate fasciculus, the inferior fronto-occipital fasciculus, and the optic radiation. Graphical simulations proposed that low-degree (<30°) head rotation had the advantage of sufficiently opening the surgical field in TSA and may help surgical procedures within the limited exposure of the medial temporal structures. Inspection of the surgical videos implied that the collapse of the inferior horn was prevented in low-degree rotation, probably because the deformation due to the brain shift was minimized in the medial temporal structures. A simulation also implied that chin-up position had the advantage of resecting the tail of the hippocampus in a straightforward manner. We suggest that the setting is optimized in TSA with low-degree rotation and chin-up head position.

Variations in the branching patterns of the anterior choroidal artery: an angiographic study with special reference to temporal lobe epilepsy surgery.

BACKGROUND: The preservation of the anterior choroidal artery (AChA) is essential for avoiding neurological sequelae after mesial temporal lobe epilepsy (mTLE) surgery. The purpose of this study is to reveal the anatomical variation in which the perforating branches arise from the plexal segment of the AChA by using a modern neuroimaging modality. METHODS: This study analyzed 3D rotational angiography (3DRA) images from 56 subjects. The AChA and perforating branches were visualized using slab MIP. We analyzed branching patterns, courses of the perforating arteries arising from the plexal segment of the AChA, and the anastomosis of the AChA with other cerebral arteries. RESULTS: The slab MIP applied to 3DRA visualized one or more perforating branches from the AChA in 92.9% of cases. The presence of perforating branches arising from the AChA plexal segment was 17.3%. Most of the branching points of plexal perforators were likely located in the operative field during hippocampal resection. The course of the AChA plexal perforators included the posterior limb of the internal capsule. Anastomosis with other cerebral arteries was visualized in 25% of the AChA with plexal perforators. CONCLUSIONS: 3DRA slab MIP was useful for visualizing the perforating branches of the AChA. Our results showed the possibility that surgical manipulation of the choroid plexus may cause infarction in the AChA territory. We suggest that the existence of the AChA plexal perforators should be recognized to further enhance the safety of hippocampal resection for mTLE.

Outcome of Superficial Temporal Artery-to-Middle Cerebral Artery Bypass in Appropriately Selected Patients with Acute Ischemic Stroke.

Background: Endovascular treatment is the preferred treatment for acute ischemic stroke (AIS) due to main artery steno-occlusive disease, but it has temporal and technical limitations. Moreover, there is no established treatment for progressive stroke. Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is sometimes considered as a treatment option. Objective: The objective of this paper is to review the treatment outcomes of patients with AIS undergoing urgent STA-MCA bypass. Methods and Material: This was a retrospective study including 32 patients diagnosed with AIS treated with urgent STA-MCA bypass at our facility. The patients had small infarct volumes and a large diffusion-perfusion mismatch. Results: New ischemic lesions in postoperative diffusion-weighted images were detected in 15 patients (46.9%), but only four (12.5%) developed paralysis. Hyperperfusion occurred in nine patients (28.1%), and five (15.6%) had bypass occlusion at 1 week. Delayed wound healing were found in four patients (12.5%). Neurological outcome was measured 3 months after onset: Manual Muscle Testing (MMT), 3-5 in 27 patients (84.4%); modified Rankin scale (mRS), 0-2 in 17 patients (53.1%); and 0-3 in 26 patients (81.3%). Prognosis was better in patients who underwent surgery after 24 h of stroke onset (mRS, 0-2 in 56.0% cases and 0-3 in 88.0% at 3 months). Statistical analyses revealed that MMT before surgery had a significant association with favorable outcomes (P = 0.041). Conclusions: Urgent STA-MCA bypass for progressive stroke may result in a good prognosis if the right patients are selected and may play an important role in cases treated 24 h after onset in whom endovascular treatment is ineffective.

Development of a New Image-Guided Neuronavigation System: Mixed-Reality Projection Mapping Is Accurate and Feasible.

BACKGROUND: Image-guided systems improve the safety, functional outcome, and overall survival of neurosurgery but require extensive equipment. OBJECTIVE: To develop an image-guided surgery system that combines the brain surface photographic texture (BSP-T) captured during surgery with 3-dimensional computer graphics (3DCG) using projection mapping. METHODS: Patients who underwent initial surgery with brain tumors were prospectively enrolled. The texture of the 3DCG (3DCG-T) was obtained from 3DCG under similar conditions as those when capturing the brain surface photographs. The position and orientation at the time of 3DCG-T acquisition were used as the reference. The correct position and orientation of the BSP-T were obtained by aligning the BSP-T with the 3DCG-T using normalized mutual information. The BSP-T was combined with and displayed on the 3DCG using projection mapping. This mixed-reality projection mapping (MRPM) was used prospectively in 15 patients (mean age 46.6 yr, 6 males). The difference between the centerlines of surface blood vessels on the BSP-T and 3DCG constituted the target registration error (TRE) and was measured in 16 fields of the craniotomy area. We also measured the time required for image processing. RESULTS: The TRE was measured at 158 locations in the 15 patients, with an average of 1.19 ± 0.14 mm (mean ± standard error). The average image processing time was 16.58 min. CONCLUSION: Our MRPM method does not require extensive equipment while presenting information of patients' anatomy together with medical images in the same coordinate system. It has the potential to improve patient safety.

Identification of the Facial Colliculus in Two-dimensional and Three-dimensional Images.

The facial colliculus (FC), an important landmark for planning a surgical approach to brainstem cavernous malformation (BCM), is a microstructure; therefore, it may be difficult to identify on magnetic resonance imaging (MRI). Three-dimensional (3D) images may improve the FC-identification certainty; hence, this study attempted to validate the FC-identification certainty between two-dimensional (2D) and 3D images of patients with a normal brainstem and those with BCM. In this retrospective study, we included 10 patients with a normal brainstem and 10 patients who underwent surgery for BCM. The region of the FC in 2D and 3D images was independently identified by three neurosurgeons, three times in each case, using the method for continuously distributed test results (0-100). The intra- and inter-rater reliability of the identification certainty were confirmed using the intraclass correlation coefficient (ICC). The FC-identification certainty for 2D and 3D images was compared using the Wilcoxon signed-rank test. The ICC (1,3) and ICC (3,3) in both groups ranged from 0.88 to 0.99; therefore, the intra- and inter-rater reliability were good. In both groups, the FC-identification certainty was significantly higher for 3D images than for 2D images (normal brainstem group; 82.4 vs. 61.5, P = .0020, BCM group; 40.2 vs. 24.6, P = .0059 for the unaffected side, 29.3 vs. 17.3, P = .0020 for the affected side). In the normal brainstem and BCM groups, 3D images had better FC-identification certainty. 3D images are effective for the identification of the FC.

Development of Innovative Neurosurgical Operation Support Method Using Mixed-Reality Computer Graphics.

BACKGROUND: In neurosurgery, it is important to inspect the spatial correspondence between the preoperative medical image (virtual space), and the intraoperative findings (real space) to improve the safety of the surgery. Navigation systems and related modalities have been reported as methods for matching this correspondence. However, because of the influence of the brain shift accompanying craniotomy, registration accuracy is reduced. In the present study, to overcome these issues, we developed a spatially accurate registration method of medical fusion 3-dimensional computer graphics and the intraoperative brain surface photograph, and its registration accuracy was measured. METHODS: The subjects included 16 patients with glioma. Nonrigid registration using the landmarks and thin-plate spline methods was performed for the fusion 3-dimensional computer graphics and the intraoperative brain surface photograph, termed mixed-reality computer graphics. Regarding the registration accuracy measurement, the target registration error was measured by two neurosurgeons, with 10 points for each case at the midpoint of the landmarks. RESULTS: The number of target registration error measurement points was 160 in the 16 cases. The target registration error was 0.72 ± 0.04 mm. Aligning the intraoperative brain surface photograph and the fusion 3-dimensional computer graphics required ∼10 minutes on average. The average number of landmarks used for alignment was 24.6. CONCLUSIONS: Mixed-reality computer graphics enabled highly precise spatial alignment between the real space and virtual space. Mixed-reality computer graphics have the potential to improve the safety of the surgery by allowing complementary observation of brain surface photographs and fusion 3-dimensional computer graphics.

Correlation of Inflow Velocity Ratio Detected by Phase Contrast Magnetic Resonance Angiography with the Bleb Color of Unruptured Intracranial Aneurysms.

BACKGROUND: Intraoperative rupture is the most fatal and catastrophic complication of surgery for unruptured intracranial aneurysms (UIAs); thus, it is extremely useful to predict reddish and thin-walled regions of the UIA before surgery. Although several studies have reported a relationship between the hemodynamic characteristics and intracranial aneurysm wall thickness, a consistent opinion is lacking. We aimed to investigate the relationship between objectively and quantitatively evaluated bleb wall color and hemodynamic characteristics using phase-contrast magnetic resonance angiography (PC-MRA). METHODS: Ten patients diagnosed with UIA who underwent surgical clipping and preoperative magnetic resonance imaging along with PC-MRA were included in this study. Bleb wall color was evaluated from an intraoperative video. Based on the Red (R), Green, and Blue values, bleb wall redness (modified R value; mR) was calculated and compared with the hemodynamic characteristics obtained from PC-MRA. RESULTS: The wall redness distribution of 18 blebs in 11 UIAs in 10 patients was analyzed. Bleb/neck inflow velocity ratio (Vb/Va: r = 0.66, P = 0.003) strongly correlated with mR, whereas bleb/neck inflow rate ratio (r = 0.58, P = 0.012) correlated moderately. Multivariate regression analysis revealed that only Vb/Va (P = 0.017) significantly correlated with mR. There was no correlation between wall shear stress and mR. CONCLUSIONS: The bleb redness of UIAs and Vb/Va, calculated using PC-MRA, showed a significantly greater correlation. Thus, it is possible to predict bleb thickness noninvasively before surgery. This will facilitate more detailed pre- and intraoperative strategies for clipping and coiling for safe surgery.

Retro-odontoid Pseudotumor: Two Cases of Intradural Ganglion Cysts Arising From the Odontoid Process with Syringobulbia.

BACKGROUND: Ganglion cysts mostly occur in the knuckles and wrists, but they rarely present in the odontoid process and can cause neurological symptoms by compressing the spinal cord. They are mostly localized in the epidural space, but may very rarely appear in the intradural space. There are no reports of cases of intradural ganglion cyst involving syringobulbia. CASE DESCRIPTION: We report the presentation and management of 2 cases of an intradural ganglion cyst of the odontoid process. Several treatment options for ganglion cysts of the odontoid process have been reported, such as rest and use of a neck collar, posterior decompression and fusion, and transoral anterior decompression. Because our 2 cases progressed rapidly and had severe neurological symptoms, surgical treatment was performed for rapid decompression and definitive pathological diagnosis. The mass was resected as much as possible using the lateral occipital fossa approach, and the operation was completed without dissection of the brain stem or manipulation of the syringobulbia. Postoperatively, neurological symptoms promptly improved, and the syringobulbia reduced. CONCLUSIONS: For intradural ganglion cysts with syringobulbia, we suggest relief of the compression by resection of the mass and treatment of the syringobulbia in 2 stages, if necessary, to avoid the risk of damage to the brainstem.

Interval between endoscopic surgery and decreased intracranial pressure related to putaminal hemorrhage prognosis.

BACKGROUND: Endoscopic evacuation of a putaminal hemorrhage is effective and minimally invasive; however, it may not result in sufficient brain decompression. While monitoring postoperative intracranial pressure (ICP) is likely useful, specific ICP data in patients with a putaminal hemorrhage are limited. The aim of this study was to determine the association between postoperative ICP and the prognosis of patients with putaminal hemorrhage after endoscopic surgery. METHODS: We retrospectively analyzed 24 consecutive patients with a putaminal hemorrhage in whom ICP monitoring after endoscopic surgery was performed. Clinical data regarding hematoma volume, evacuation rate, onset-to-treatment time, operation time, ICP max, ICP peak out time (T peak out), and neurological outcomes on discharge were investigated. RESULTS: From August 2011 to October 2015, 24 patients with a putaminal hemorrhage were analyzed. Consciousness on admission and hemorrhage volume were associated with poor outcomes after endoscopic surgery for putaminal hemorrhage. The hematoma volume, operation time, and evacuation rate of hemorrhage were correlated to early peak out of ICP. Furthermore, a T peak out ≤24 h was significantly associated with good neurological outcomes on discharge. CONCLUSIONS: Our data suggest that early peak out (≤24 h) of ICP after endoscopic surgery is predictive of a good prognosis following putaminal hemorrhage. Operation time and evacuation rate of hemorrhage could hasten peak out of ICP and improve outcomes in patients with a putaminal hemorrhage after endoscopic surgery.

De Novo Development of Moyamoya Disease after Stereotactic Radiosurgery for Brain Arteriovenous Malformation in a Patient With RNF213 p.Arg4810Lys (rs112735431).

BACKGROUND: Reports of cases diagnosed as Moyamoya disease (MMD) after stereotactic radiosurgery (SRS) for arteriovenous malformation (AVM) are extremely rare. In recent years, ring finger protein 213 (RNF213) has been identified as a susceptibility gene of MMD, but the mechanism by which MMD develops remains unclear. Those cases of de novo development of MMD may provide some clues to clarify the mechanism of progression of MMD. CASE DESCRIPTION: We report the case of de novo MMD that developed after SRS for AVM. This patient presented with a variant of the RNF213 gene. The intracranial internal carotid artery was not within the irradiation field; therefore it was obvious that the development of MMD was not caused by the direct effect of radiation in the current case study. Moreover, we demonstrated the decrease in velocity in the internal carotid artery prior to the development of MMD using phase-contrast magnetic resonance angiography. Previous studies demonstrated that progression of the pathological condition in the cerebral arteries in response to hemodynamic changes is enhanced in patients with RNF213 variants. CONCLUSIONS: Our findings indicate that the changes in the intracranial hemodynamics after SRS for AVM could trigger the de novo onset of MMD in patients with a genetic predisposition for the RNF213 variant.

Histological analysis of infiltrating macrophages in the cerebral aneurysm walls.

A series of recent evidences suggested activated macrophages have broadly two distinct forms that possess opposite functions for the process of inflammation: classically activated macrophages (M1/kill macrophages) and alternatively activated macrophages (M2/repair macrophages) according to their functions and expression markers. To elucidate what roles those two phenotypes of macrophages play in the evolution of cerebral aneurysm, the presence of macrophages inside the aneurysm walls was assessed with an immunohistochemical approach. The portions of the aneurysm domes deflated after neck clipping were utilized for the further histological examinations, including immunostainings with five antibodies to identify macrophage subpopulations. In this study, contrary to the previous reports, the following various ratios of subtypes were observed in the aneurysm walls: M1 > M2 (2 cases), M1 < M2 (2 cases), M1 = M2 (3 cases). While M1-like macrophages have been typically regarded as a main driver of the degenerating process, these surprisingly richer presences of M2-like macrophages in the aneurysm walls suggests that an unrecognized biological process might be in play in aneurysm development.

Palliative lumboperitoneal shunt for leptomeningeal metastasis-related hydrocephalus: A case series.

BACKGROUND: Leptomeningeal metastasis-related hydrocephalus causes distress to patients with end-stage cancer through headache and other symptoms by elevating intracranial pressure, thus reducing quality of life. Ventriculoperitoneal shunt has been used as a treatment option in palliative care. We review four cases of patients who underwent lumboperitoneal shunt for leptomeningeal metastasis-related hydrocephalus. CASES: All patients suffered from severe headache and nausea. The primary lesion was histologically diagnosed as lung adenocarcinoma in each case. The duration from diagnosis to onset of hydrocephalus symptoms ranged from 0 to 52 (mean 26) months. Cerebrospinal fluid pressure in every case was above the normal range due to high intracranial pressure. Case management: Conventional procedures for lumboperitoneal shunt were employed for all patients. Adjustable pressure valves were retrofitted into the shunt system. Case outcome: Three patients demonstrated significant improvement of clinical symptoms and quality of life after placement of lumboperitoneal shunts. In two cases, not only did performance status improve to independent daily activity but also comparatively long-term survival was achieved due to subsequent chemotherapies after surgery. No symptoms of peritoneal dissemination by floating cancer cells in cerebrospinal fluid were seen in any patients. CONCLUSION: Lumboperitoneal shunt appears to improve quality of life if the patient is suffering from symptoms of leptomeningeal metastasis-related hydrocephalus. Compared to ventriculoperitoneal shunt, lumboperitoneal shunt is less invasive and simpler, providing a suitable option for frail patients with end-stage cancer. Adjustable pressure shunt valves can cope with varying symptoms and ventricle sizes.

Delayed Development of Aneurysms Following Gamma Knife Surgery for Trigeminal Neuralgia: Report of 2 Cases.

BACKGROUND: Delayed development of intracranial aneurysms is an extremely rare complication of gamma knife surgery (GKS), with only 6 cases been reported to date. There are no reported cases after GKS performed to treat trigeminal neuralgia (TN). Of the 6 aforementioned cases, none referred to the natural history or pathophysiology of GKS-related intracranial aneurysm formation. CASE DESCRIPTION: We treated 2 patients with subarachnoid hemorrhage (SAH) resulting from rupture of an intracranial aneurysm that developed long after GKS. Case 1 involved a 77-year-old man who had undergone GKS to treat recurrent TN after microvascular decompression surgery. At 13 years after the GSK, he developed SAH from a ruptured left anterior inferior cerebellar artery in close vicinity to the left trigeminal nerve. He died from a premature rupture before intervention could be instituted. Case 2 involved a 72-year-old woman who developed SAH at 9 years after undergoing GKS for TN. A ruptured left superior cerebellar artery aneurysm was treated successfully with endovascular occlusion of the parent artery. She recovered well after the surgery, and was discharged to the rehabilitation hospital with a modified Rankin Scale score of 2. CONCLUSION: Long-term observations are necessary after GKS performed for TN owing to the possibility of formation of intracranial aneurysms near the irradiated region.

Olfactory auras caused by a very focal isolated epileptic network in the amygdala.

Epileptic olfactory auras manifesting as simple partial seizures are rare. We report a patient who presented with olfactory auras after hemorrhage from a cavernous angioma in the left mesial temporal region. His olfactory auras persisted 12 years after two surgeries for a cavernous angioma. Intracranial depth electrodes revealed a very focal isolated epileptogenic zone in the amygdala. Olfactory auras were successfully treated by focus resection.