Gate-tunable frequency combs in graphene-nitride microresonators.

Optical frequency combs, which emit pulses of light at discrete, equally spaced frequencies, are cornerstones of modern-day frequency metrology, precision spectroscopy, astronomical observations, ultrafast optics and quantum information1-7. Chip-scale frequency combs, based on the Kerr and Raman nonlinearities in monolithic microresonators with ultrahigh quality factors8-10, have recently led to progress in optical clockwork and observations of temporal cavity solitons11-14. But the chromatic dispersion within a laser cavity, which determines the comb formation15,16, is usually difficult to tune with an electric field, whether in microcavities or fibre cavities. Such electrically dynamic control could bridge optical frequency combs and optoelectronics, enabling diverse comb outputs in one resonator with fast and convenient tunability. Arising from its exceptional Fermi-Dirac tunability and ultrafast carrier mobility17-19, graphene has a complex optical dispersion determined by its optical conductivity, which can be tuned through a gate voltage20,21. This has brought about optoelectronic advances such as modulators22,23, photodetectors 24 and controllable plasmonics25,26. Here we demonstrate the gated intracavity tunability of graphene-based optical frequency combs, by coupling the gate-tunable optical conductivity to a silicon nitride photonic microresonator, thus modulating its second- and higher-order chromatic dispersions by altering the Fermi level. Preserving cavity quality factors up to 106 in the graphene-based comb, we implement a dual-layer ion-gel-gated transistor to tune the Fermi level of graphene across the range 0.45-0.65 electronvolts, under single-volt-level control. We use this to produce charge-tunable primary comb lines from 2.3 terahertz to 7.2 terahertz, coherent Kerr frequency combs, controllable Cherenkov radiation and controllable soliton states, all in a single microcavity. We further demonstrate voltage-tunable transitions from periodic soliton crystals to crystals with defects, mapped by our ultrafast second-harmonic optical autocorrelation. This heterogeneous graphene microcavity, which combines single-atomic-layer nanoscience and ultrafast optoelectronics, will help to improve our understanding of dynamical frequency combs and ultrafast optics.

Signatures of nearly compensated magnetism and spin glass behavior in highly frustrated ß-Mn-type Mn50Fe25+xAl25-x Heusler alloys.

The present study examines the effect of Fe/Al concentration on the structural and magnetic properties of Mn-rich Mn50Fe25+xAl25-x (x = 5, 10, 15) Heusler alloys through x-ray diffraction, temperature- and field-dependent DC magnetization, thermoremanent magnetization, magnetic memory effect, AC susceptibility measurements, and DFT calculations. The samples crystallize in a cubic ß-Mn structure. The trend shows a reduction in lattice parameters (unit cell volume) with the increasing Fe proportion. These alloys exhibit strong antiferromagnetic interactions with large frustration parameters, indicating the presence of competing magnetic interactions. The DC magnetization data reveal spin glass-like features with a peak at spin glass freezing temperature (Tf). The observation of bifurcation in temperature-dependent zero-field-cooled and field-cooled magnetization curves, exponential dependence of the temperature variation of remanence and coercivity, magnetic relaxation, and magnetic memory effect below Tf support the spin-glass character of these alloys. The frequency dependence of Tf is also examined in the context of dynamic scaling laws, such as the Vogel-Fulcher law and critical slowing down model, which further supports the presence of spin glass behavior. In the theoretical DFT calculations, the electronic structure is found to be metallic and similar for both spin projections. Moreover, the antiferromagnetic arrangement of the magnetic moments, in line with the experimental observations, is stabilized by exchange interactions, resulting in an almost compensated total magnetic moment of 0.02-0.38 µB/f.u. This is probably caused by the frustrated structure and non-stoichiometric compositions of Mn50Fe25+xAl25-x.

Clinical analysis of surgical outcome of 89 patients having large cerebral arteriovenous malformations.

OBJECTIVE: The article analyzes the clinical features, morphological characteristics, surgical subtleties and long-term outcome of surgery in 89 cases of 'large' sized AVMs. MATERIALS AND METHODS: During the period 2004 to 2022, 89 cases of 'large' arteriovenous malformations were operated in the neurosurgery departments of the authors. Large AVMs were defined as those that were more than 4 cm on either lateral or antero-posterior view of digital subtraction angiogram. The factors that determined the extent of surgical difficulties included site and eloquence of the area, number of feeding vascular territories and draining veins, degree and rate of flow, presence of flow-related aneurysms, and the physical nature of the arteriovenous malformation. RESULTS: There were 59 males and 30 females and the average age was 32 years. Headache, giddiness and convulsions were the common presenting complaints. Six patients were unconscious after surgery. Of these, five patients died in the immediate post-operative period and one patient gradually recovered. Additionally, seven patients developed unilateral limb weakness that included hemiplegia (4 patients) and hemiparesis (3 patients) following surgery. Clinical follow-up ranged from 6 months to 18 years (average 43 months). All surviving patients are leading normal and essentially symptom free life and have recovered from their symptoms of headache, convulsions and giddiness. CONCLUSIONS: Large AVMs are amenable to 'curative' surgery with 'acceptable' results. The surgery can be challenging and appropriate case selection that is based on the surgeons experience is vital and decisive.

Assessment of the Dentinal Surface Adaptation Efficacy of Different Obturation Systems with Bioceramic Sealer: A Scanning Electron Microscope Study.

AIM: Aim of this study was to evaluate the dentinal surface adaptation effectiveness of different obturation methods with bioceramic sealer. MATERIALS AND METHODS: Sixty recently removed human permanent premolars of the mandible having a solitary, straight as well as completely produced root were chosen on the basis of clinical/radiographic evaluation. The coronal parts of the premolars were subjected to sectioning at the cementoenamel junction (CEJ) with the aid of a water-cooled diamond disk. The regular access opening was done, following which the working length was visually estimated by deducting 1 mm from the length of a 10 size K-file (Dentsply, OK, USA) at the apex. Subsequent to preparing the radicular canal, the premolar specimens were randomly allocated to one of the following three groups. Group I: Lateral compaction (LC) technique; group II: Warm vertical compaction (WVC) technique; and group III: Thermafil obturation technique. Following obturation, the samples were subjected to sectioning in the horizontal direction at three dissimilar points as follows: First at the cervical third, then at the middle, and at the apical third employing a minitom under water irrigation to put off overheating. Internal spaces amid the radicular dentin as well as the obturating agents were appraised with the use of a scanning electron microscope (SEM). RESULTS: Intragroup analysis showed that higher gaps were noted at the coronal level (2.30 ± 0.04), in pursuit by middle part (1.12 ± 0.02) and apical third (0.70 ± 0.02) for the LC method. With the WVC procedure, higher gaps were situated in the coronal level (1.96 ± 0.07), again in pursuit by middle part (1.02 ± 0.02) and apical third (0.86 ± 0.04). Even with the Thermafil obturation method, higher gaps were noted at the coronal level (0.92 ± 0.10), in pursuit by middle part (0.67 ± 0.05) and apical third (0.57 ± 0.01). No statistically significant difference was noted within the group. Upon intergroup comparative assessment of dentinal surface adaptation with dissimilar obturation systems at coronal, middle and apical thirds, there was a statistically noteworthy disparity amid the groups (p <0.001). CONCLUSION: This research arrived at a conclusion that the most superior dentinal adaptation of bioceramic sealer was procured when the Thermafil obturation method was employed for obturating the root canals compared to the WVC technique as well as the LC technique. CLINICAL SIGNIFICANCE: Numerous endodontic substances have been promoted for obturating the root canal areas. Majority of the methods use a core substance, in addition to a sealer. Despite the type of core agent, a sealer indispensable to each technique offers a fluid-tight sealing. The oral physicians' comprehension of the characteristics of the endodontic sealer plus method used, enhances the therapeutic effect.

New-onset diabetes mellitus with COVID-19: Coincidence or cause.

Diabetes mellitus (DM) was noted as the commonest comorbidity in the coronavirus disease 2019 (COVID-19) which contributed to worse prognosis in these patients. In some cases, we also noted new-onset DM detected during hospitalization for symptomatic COVID disease. We describe three such cases, where the patients presented with severe symptomatic hyperglycemia and ketoacidosis in two and hyperosmolality in one of them. Antibody to GAD-65 was negative and varying degrees of C-peptide secretion was noted after recovery in them. There was no clinical or biochemical evidence of exocrine pancreatic involvement noted during acute presentation or after the recovery. This interesting phenomenon of coexisting DM in symptomatic COVID-19 requires further studies to differentiate between coincidence or causation.

Patient-specific 3-dimensionally printed models for neurosurgical planning and education.

OBJECTIVE: Advances in 3-dimensional (3D) printing technology permit the rapid creation of detailed anatomical models. Integration of this technology into neurosurgical practice is still in its nascence, however. One potential application is to create models depicting neurosurgical pathology. The goal of this study was to assess the clinical value of patient-specific 3D printed models for neurosurgical planning and education. METHODS: The authors created life-sized, patient-specific models for 4 preoperative cases. Three of the cases involved adults (2 patients with petroclival meningioma and 1 with trigeminal neuralgia) and the remaining case involved a pediatric patient with craniopharyngioma. Models were derived from routine clinical imaging sequences and manufactured using commercially available software and hardware. RESULTS: Life-sized, 3D printed models depicting bony, vascular, and neural pathology relevant to each case were successfully manufactured. A variety of commercially available software and hardware were used to create and print each model from radiological sequences. The models for the adult cases were printed in separate pieces, which had to be painted by hand, and could be disassembled for detailed study, while the model for the pediatric case was printed as a single piece in separate-colored resins and could not be disassembled for study. Two of the models were used for patient education, and all were used for presurgical planning by the surgeon. CONCLUSIONS: Patient-specific 3D printed models are useful to neurosurgical practice. They may be used as a visualization aid for surgeons and patients, or for education of trainees.

Quasi-phase-matched multispectral Kerr frequency comb.

We study a new type of Kerr frequency comb where the momentum conservation law is fulfilled by azimuthal modulation of the waveguide dispersion. The concept can expand the parametric range in which a Kerr frequency comb is obtained. In a good agreement with the theoretical analysis, we demonstrate a multispectral Kerr frequency comb covering important fiber-optic communication bands. Comb coherence and absence of a sub-comb offset are confirmed by continuous-wave heterodyne beat note and amplitude noise spectra measurements. The device can be used for achieving broadband optical frequency synthesizers and high-capacity coherent communication.

Advanced diffusion MRI fiber tracking in neurosurgical and neurodegenerative disorders and neuroanatomical studies: A review.

Diffusion MRI enabled in vivo microstructural imaging of the fiber tracts in the brain resulting in its application in a wide range of settings, including in neurological and neurosurgical disorders. Conventional approaches such as diffusion tensor imaging (DTI) have been shown to have limited applications due to the crossing fiber problem and the susceptibility of their quantitative indices to partial volume effects. To overcome these limitations, the recent focus has shifted to the advanced acquisition methods and their related analytical approaches. Advanced white matter imaging techniques provide superior qualitative data in terms of demonstration of multiple crossing fibers in their spatial orientation in a three dimensional manner in the brain. In this review paper, we discuss the advancements in diffusion MRI and introduce their roles. Using examples, we demonstrate the role of advanced diffusion MRI-based fiber tracking in neuroanatomical studies. Results from its preliminary application in the evaluation of intracranial space occupying lesions, including with respect to future directions for prognostication, are also presented. Building upon the previous DTI studies assessing white matter disease in Huntington's disease and Amyotrophic lateral sclerosis; we also discuss approaches which have led to encouraging preliminary results towards developing an imaging biomarker for these conditions.

Modified super twisting control for robust trajectory tracking and hovering of quadrotor.

This paper proposes a novel controller design using adaptation based modified super twisting control to facilitate trajectory tracking and hovering maneuvers for the quadrotor. The controller gains of the existing modified super twisting control require bounds on the disturbance for trajectory tracking and hovering of the quadrotor. In this paper, the controller gains are adapted using the proposed dynamic adaptation law without knowing the actual disturbance or their upper bounds. The controller is designed within a nonlinear framework without performing linearization of quadrotor dynamics, which enables the proposed controller to remain effective even when the states deviate significantly from their nominal values. The performance of trajectory tracking and hovering of the quadrotor in the presence of disturbance is demonstrated using numerical simulations. In order to assess the effectiveness of the controller, the performance of the adaptation based modified super twisting control is compared to the existing modified super twisting control, and the proposed controller outperforms the existing one.

P T -symmetric KdV solutions and their algebraic extension with zero-width resonances.

A class of complex breather and soliton solutions to both KdV and mKdV equations are identified with a Pöschl-Teller type P T -symmetric potential. However, these solutions represent only the unbroken- P T phase owing to their isospectrality to an infinite potential well in the complex plane having real spectra. To obtain the broken- P T phase, an extension of the potential satisfying the s l 2 , R potential algebra is mandatory that additionally supports non-trivial zero-width resonances.

Lumbar parafacetal cyst-spinal segmental instability is the cause and stabilization is the treatment: A clinical report of eight surgically-treated patients.

Objective: The authors report the results of "only-fixation" of the affected spinal segment without any decompression of the bones or soft tissue or manipulation of the cyst wall or contents in eight cases having lumbar parafacetal cyst (LPFC). This surgical strategy was based on the concept that LPFCs are secondary to spinal instability, has a protective or adaptive role, and is reversible following stabilization. Materials and Methods: During the period from January 2018 to January 2023, eight consecutive patients having LPFC were surgically treated. There were 5 males and 3 females, and their ages ranged from 48 to 72 years (average 63 years). Seven patients had a single cyst and one patient had multiple cysts. The patients presented with symptoms classically attributed to lumbar canal stenosis. Apart from the cyst-affected spinal segment, degenerative alterations were observed in adjoining spinal segments in six out of seven patients having a single cyst. All patients underwent "only fixation" of the unstable spinal segments without any kind of bone or soft-tissue resection and without any manipulation or handling of the cyst wall or contents. Results: During the follow-up period that ranged from 12 to 57 months (average 29 months), all patients improved from their symptoms. The recovery was observed in the immediate postoperative period and was lasting. Conclusions: LPFCs are one of the several secondary alterations observed in spinal degeneration. Identification of unstable spinal segments and their fixation constitutes rational treatment of lumbar parafacetal cysts. Direct handling and resection of cysts are unnecessary.

Microsurgical Resection of Trigeminal Schwannoma Through Transorbital Approach: 2-Dimensional Operative Video.

We present the case of an asymptomatic 34-year-old woman who was found to have an incidental left trigeminal schwannoma.1,2 Owing to the rapid increase in size on imaging, an atypical finding for this type of lesion,3 as well as the risk of cranial nerve involvement and need for tissue diagnosis, the patient underwent a microsurgical left transorbital approach with lateral orbitotomy to resect the lesion.4,5 Piecemeal resection was performed, and the internal contents of the cavernous sinus were preserved. Ultimately, gross total resection was achieved with no residual disease identified on postoperative imaging. No new neurologic deficits were noted after surgery. The technical considerations for the transorbital approach and the literature review on the outcomes for middle fossa lesions accessed by a lateral orbitotomy are reviewed.6-10 The patient consented to the procedure and to the publication of her images. Institutional Review Board approval was deemed unnecessary due to the retrospective, case-report nature of this work.

Comprehensive Profiling of Secreted Factors in the Cerebrospinal Fluid of Moyamoya Disease Patients.

Moyamoya disease (MMD) is characterized by progressive occlusion of the intracranial internal carotid arteries, leading to ischemic and hemorrhagic events. Significant clinical differences exist between ischemic and hemorrhagic MMD. To understand the molecular profiles in the cerebrospinal fluid (CSF) of MMD patients, we investigated 62 secreted factors in both MMD subtypes (ischemic and hemorrhagic) and examined their relationship with preoperative perfusion status, the extent of postoperative angiographic revascularization, and functional outcomes. Intraoperative CSF was collected from 32 control and 71 MMD patients (37 ischemic and 34 hemorrhagic). Multiplex Luminex assay analysis showed that 41 molecules were significantly elevated in both MMD subtypes when compared to controls, including platelet-derived growth factor-BB (PDGF-BB), plasminogen activator inhibitor 1 (PAI-1), and intercellular adhesion molecule 1 (ICAM1) (p < 0.001). Many of these secreted proteins have not been previously reported in MMD, including interleukins (IL-2, IL-4, IL-5, IL-7, IL-8, IL-9, IL-17, IL-18, IL-22, and IL-23) and C-X-C motif chemokines (CXCL1 and CXCL9). Pathway analysis indicated that both MMD subtypes exhibited similar cellular/molecular functions and pathways, including cellular activation, migration, and inflammatory response. While neuroinflammation and dendritic cell pathways were activated in MMD patients, lipid signaling pathways involving nuclear receptors, peroxisome proliferator-activated receptor (PPAR), and liver X receptors (LXR)/retinoid X receptors (RXR) signaling were inhibited. IL-13 and IL-2 were negatively correlated with preoperative cerebral perfusion status, while 7 factors were positively correlated with the extent of postoperative revascularization. These elevated cytokines, chemokines, and growth factors in CSF may contribute to the pathogenesis of MMD and represent potential future therapeutic targets.

Expanded endoscopic endonasal approach for resection of residual parasellar growth hormone-secreting pituitary adenoma in a patient with kissing internal carotid arteries: Technical nuances.

Background: Growth hormone (GH)--secreting pituitary adenomas can be aggressive and difficult to manage. Surgical resection for GH-secreting tumors remains the gold standard with increasing use of expanded endoscopic endonasal (EEA) techniques. Certain anatomical considerations make postsurgical biochemical remission challenging. Case Description: We describe the case of a 43-year-old male presenting with acromegaly after a lack of biochemical remission from a previous surgery. Resection of the residual tumor invading the retrogenu compartment of the cavernous sinus was challenging for several reasons: (a) its location adjacent to the right parasellar horizontal internal carotid artery (ICA) with involvement of the medial wall, (b) the large kissing bilateral ICAs reducing the intercarotid distance, and (c) potential scar tissue. EEA was undertaken with key surgical steps, including wide bilateral sphenoidotomies, right middle clinoidectomy to access the clinoidal ICA and the retrogenu compartment, identification of the top of the paraclival ICA by drilling across the sella floor, division of the sellar floor dura to increase the intercarotid distance and transcavernous mobilization of medial wall, and the tumor capsule away from the horizontal parasellar ICA and across to the diaphragm and pituitary gland. Postoperatively, biochemical remission was achieved with no new endocrine deficits. Conclusion: These surgical nuances permit biochemical remission in complex revisional cases with acromegaly.

Spatio-temporal breather dynamics in microcomb soliton crystals.

Solitons, the distinct balance between nonlinearity and dispersion, provide a route toward ultrafast electromagnetic pulse shaping, high-harmonic generation, real-time image processing, and RF photonic communications. Here we uniquely explore and observe the spatio-temporal breather dynamics of optical soliton crystals in frequency microcombs, examining spatial breathers, chaos transitions, and dynamical deterministic switching - in nonlinear measurements and theory. To understand the breather solitons, we describe their dynamical routes and two example transitional maps of the ensemble spatial breathers, with and without chaos initiation. We elucidate the physical mechanisms of the breather dynamics in the soliton crystal microcombs, in the interaction plane limit cycles and in the domain-wall understanding with parity symmetry breaking from third-order dispersion. We present maps of the accessible nonlinear regions, the breather frequency dependences on third-order dispersion and avoided-mode crossing strengths, and the transition between the collective breather spatio-temporal states. Our range of measurements matches well with our first-principles theory and nonlinear modeling. To image these soliton ensembles and their breathers, we further constructed panoramic temporal imaging for simultaneous fast- and slow-axis two-dimensional mapping of the breathers. In the phase-differential sampling, we present two-dimensional evolution maps of soliton crystal breathers, including with defects, in both stable breathers and breathers with drift. Our fundamental studies contribute to the understanding of nonlinear dynamics in soliton crystal complexes, their spatio-temporal dependences, and their stability-existence zones.

Use of robot-guided stereotactic placement of intracerebral electrodes for investigation of focal epilepsy: initial experience in the UK.

We describe the operative technique and our preliminary experience with use of the Renishaw neuromate(®) stereotactic robot to implant depth electrodes for investigation of focal epilepsy in the UK. Conventional electrocorticography involving a craniotomy and implantation of grids of electrodes directly onto the brain surface is invasive and carries a high risk of major complications such as acute subdural haematoma and infection. Robot-guided depth electrodes implantation for stereotactic electroencephalography is a less invasive technique that allows accurate implantation of multiple deep brain electrodes along predefined trajectories, and has not been associated with any major surgical complications in our initial experience.

Novel use of narrow paddle electrodes for occipital nerve stimulation--technical note.

OBJECTIVES: Occipital nerve stimulation (ONS), an established treatment for medically intractable headache syndromes, has lead migration rates quoted up to 24%. In a series of patients with ideal characteristics for this treatment modality, we describe an operative technique for ONS involving the novel use of narrow paddle electrodes: "S8 Lamitrode" (St. Jude Medical [SJM], St. Paul, MN, USA). MATERIALS AND METHODS: Five patients (occipital neuralgia [ON] = 4; chronic migraine [CM] = 1) were treated with ONS between 2010 and 2011. All patients had a successful trial of peripheral neurostimulation (Algotec Ltd, Crawley, UK) therapy. Operative technique involved the use of a park-bench position, allowing simultaneous exposure of the occipital and infraclavicular regions. Through a retromastoid/occipital incision just beneath the external occipital protruberance, exposing the extrafascial plane, the S8 Lamitrode is implanted to intersect both greater occipital nerves for bilateral pain or unilateral greater and lesser occipital nerves for unilateral ON or with significant component of the pain relating to the lesser occipital nerve. RESULTS: Over the median follow-up of 12 months, there were no episodes of lead migration or revision. There also was significant improvement in symptoms in all patients. CONCLUSIONS: This is the first reported use of S8 Lamitrode electrode for ONS. This narrow electrode is suited for this role leading to minimal trauma during surgical placement, facilitates resolution of problems with lead migration, and optimizes effect with stimulation focused more in direction of the occipital nerves without skin involvement. To date, the SJM Genesis neurostimulation system, with percutaneous electrodes only, is CE mark approved in Europe for peripheral nerve stimulation of the occipital nerves for the management of pain and disability for patients diagnosed with intractable CM. Further developments and studies are required for better devices to suit ONS, thereby avoiding frequently encountered problems and which may clarify the role of paddle leads in ONS.

Prevalence, clinical presentation, management of pituitary tumour and its complications among elderly population in Mumbai, India.

Pituitary tumour is not typically thought of as an elderly patient's condition. Hence, we examined all cases of confirmed or suspected pituitary tumour diagnosed in a tertiary hospitals at Mumbai, India during May 2015 and May 2023 among patients over the age of 70 to evaluate the prevalence, clinical presentation, management, complications in elderly patients with a pituitary tumour. After the age of 70 years, 16% people having pituitary tumour were observed. The volume of fossa was statistically greater in elderly patients. The duration of follow up was statistically longer in younger controls. The visual defects observed in elderly group were greater than young patients. Pituitary adenomas in old patients can be treated with trans-sphenoidal-adenomectomy. However, the proportion is lower than younger controls. Data shows that post-operative radiotherapy was more commonly observed in old patients with pituitary adenoma than younger controls.

Subtemporal Approach and Its Infratentorial Extension: Review and a Comparative Analysis of Different Techniques.

Introduction Surgical resection of lesions occupying the incisural space is challenging. In a comparative fashion, we aimed to describe the anatomy and surgical approaches to the tentorial incisura and to the rostral brainstem via the intradural subtemporal approach and its infratentorial extensions. Methods Six fresh human head specimens (12 sides) were prepared for the microscopic dissection of the tentorial incisura using the intradural subtemporal approach and its infratentorial extensions. Endoscope was used to examine the anatomy of the region inadequately exposed with the microscope. Image-guided navigation was used to confirm bony structures visualized around the petrous apex. Results Standard subtemporal approach provides surgical access to the supratentorial brainstem above the pontomesencephalic sulcus and to the lateral surface of the cerebral peduncle. The linear or triangular tentorial divisions can provide access to the infratentorial space below the pontomesencephalic sulcus. The triangular tentorial flap in comparison with the linear incision obstructs the exposure of anterior incisural space and of the prepontine cistern. Visualization of the brainstem below the trigeminal nerve can be achieved by the anterior petrosectomy. Conclusion Infratentorial extension of the intradural subtemporal approach is technically demanding due to critical neurovascular structures and a relatively narrow corridor. In-depth anatomical knowledge is essential for the selection of the appropriate operative approach and safe surgical resections of lesions.

Expanded Endoscopic Endonasal Transtuberculum Approach for Resection of Germ Cell Tumor.

We present the case of a 16-year-old with short stature, fatigue, memory impairment, and pituitary gland failure. Imaging and cerebrospinal fluid (CSF) studies supported the diagnosis of a suprasellar nongerminomatous germ cell tumor with no clear radiologic disease in the spine; however, a single atypical cell was present in the CSF. After a period of external drainage via an Ommaya device, he was treated with chemotherapy, followed by craniospinal radiation. Three months post completion of chemoradiotherapy, he had ongoing residual macroscopic enhancing disease anatomically located in the basal third ventricle and intimately related to pituitary stalk and basal thalamoperforators. In order to maximize his chance of progression-free survival, a decision was made to surgically resect the lesion via an expanded endoscopic endonasal approach with planned stalk sacrifice because of the known pituitary gland failure. In Video 1, the technical nuances underpinning the use of an expanded endoscopic endonasal transtuberculum transchiasmatic sulcus approach to resect the adherent lesion in a postradiated field in its entirety are presented. We emphasize the strategies for perforator preservation including thalamoperforators and superior hypophyseal arteries to avoid ischemic injury and visual dysfunction, respectively. Postoperative scans demonstrated gross total resection without any ischemic injury. The patient was discharged without any neurologic deficit, visual dysfunction, or CSF leak.