Dorsal root ganglion stimulator-A targeted therapy for post-herpetic neuralgia: The Middle East Experience

BACKGROUND

Post herpetic neuralgia (PHN) is a chronic neuropathic pain syndrome which presents after an episode of herpes zoster caused by the reactivation of varicella zoster virus. Conservative treatment starts with pharmacological measures using Anti-epileptics and Antidepressants. Some patients also respond well to epidural steroid injections too, but the effect is usually short lasting. Dorsal Root Ganglion Stimulator (DRG-S) has recently been suggested as a new treatment modality for PHN due to its selective targeting of the pathophysiologic focus.

CASE SERIES

We are reporting three cases, who were suffering from neuropathic pain after an episode of herpes zoster. Pain and pain related suffering scores were high, even with multiple antiepileptics and opioid medications. They underwent DRG-S implant and appreciated more than 50% reduction of their pain score, meaningful reduction in the dose of medications along with significant improvement of their general well being measured using Generalized Anxiety Disorder Questionnaire (GAD-7), pain disability index (PDI), and 9 Question Patient Health Questionnaire (PHQ-9). To our knowledge this is the first report on DRG stimulator from the Middle East Region.

CONCLUSION

DRG-S has potential to be a preferable treatment option in patients with refractory PHN and acts as a specific targeted therapy in the treatment of these patients.

Enhanced Thermoelectric Performance in the SrTi0.85Nb0.15O3 Oxide Nanocomposite with Fe2O3-Functionalized Graphene

Doped SrTiO3 is considered one of the potential thermoelectric (TE) candidates but its TE figure of merit, ZT needs to be improved for practical application of electricity generation from high-grade waste-heat. In the present work, enhanced TE performance has been realized for SrTi0.85Nb0.15O3 (STN) perovskite adopting the strategy of composite formation with Fe2O3-functionalized graphene (FGR). We have achieved a maximum electrical conductivity of 1.4 × 105 S m-1 for 1 wt % FGR added to STN, which is around 1185% larger than that of pristine STN. The presence of FGR in the STN matrix acts as a mobility booster of electrons, overcoming the effect of Anderson localization of electrons, which impedes the electron transport in STN. This is evident from the order of magnitude increase in weighted mobility of STN after FGR addition. Furthermore, the incorporation of FGR causes about a 34% decrease in the lattice thermal conductivity. The Debye-Callaway model demonstrates that the phonon-phonon Umklapp scattering is primarily responsible for reduced thermal conductivity. The presence of FGR sheets along the grain boundaries of STN, Fe2O3 nanoparticles, and lattice imperfections gives rise to the glass-like temperature-independent phonon mean-free-path, especially above Debye temperature. The maximum ZT ∼ 0.57 has been obtained at 947 K for the 1 wt % FGR sample, which is around 420% higher than that of pristine STN. Furthermore, we have fabricated a prototype of a four-legged n-type TE module, demonstrating one of the highest power outputs of 18 mW among reported oxide thermoelectrics.

Enhanced Thermoelectric Performance of Rare-Earth-Free n-Type Oxide Perovskite Composite with Graphene Analogous 2D MXene

Here, the first experimental demonstration on the effect of incorporating new generation 2D material, MXene, on the thermoelectric performance of rare-earth-free oxide perovskite is reported. The charge localization phenomenon is predominant in the electron transport of doped SrTiO₃ perovskites, which deters from achieving a higher thermoelectric power factor in these oxides. In this work, it is shown that incorporating Ti₃ C₂ T_x MXene in a matrix of SrTi_0.85 Nb_0.15 O₃ (STN) facilitates the delocalization of electrons resulting in better than single-crystal-like electron mobility in polycrystalline composites. A 1851% increase in electrical conductivity and a 1000% enhancement in power factor are attained. Besides, anharmonicity caused by MXene in the STN matrix has led to enhanced Umklapp scattering giving rise to lower lattice thermal conductivity. Hence, 700% ZT enhancement is achieved in this composite. Further, a prototype of thermoelectric generator (TEG) using only n-type STN + MXene is fabricated and a power output of 38 mW is obtained, which is higher than the reported values for oxide TEG.

Designing rare earth-free high entropy oxides with a tungsten bronze structure for thermoelectric applications

In recent years, forming high entropy oxides has emerged as one of the promising approaches to designing oxide thermoelectrics. Entropy engineering is an excellent strategy to improve thermoelectric performance by minimizing the thermal conductivity arising from enhanced multi-phonon scattering. In the present work, we have successfully synthesized a rare-earth-free single phase solid solution of novel high entropy niobate (Sr_0.2Ba_0.2Li_0.2K_0.2Na_0.2)Nb₂O₆, with a tungsten bronze structure. This is the first report on the thermoelectric properties of high entropy tungsten bronze-type structures. We have obtained a maximum Seebeck coefficient of -370 μV K^-1 at 1150 K, which is the highest among tungsten bronze-type oxide thermoelectrics. The minimum thermal conductivity of 0.8 W m^-1 K^-1 is obtained at 330 K, which is so far the lowest reported value among rare-earth-free high entropy oxide thermoelectrics. This synergistic combination of large Seebeck and record low thermal conductivity gives rise to a maximum ZT of 0.23 which is so far the highest among rare-earth free high entropy oxide-based thermoelectrics.

Two-Stage Resection of a Giant Trigeminal Schwannoma in a Non-Neurofibromatosis Type 2 Pediatric Patient: A Case Report, Systematic Review, and Intraoperative Video

BACKGROUND

Trigeminal schwannoma is an uncommon tumor in pediatric patients. Several surgical approaches have been described in the literature.

METHODS

The case of an 11-year-old boy with a giant dumbbell-shaped trigeminal schwannoma removed through a 2-stage approach was presented with an intraoperative video. Using PubMed and Scopus, the literature on trigeminal schwannoma in pediatric patients was searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

RESULTS

The search strategy yielded 312 titles, of which 13 were included in the review. Cases of trigeminal schwannoma were described, with a highly variable clinical presentation and anatomical arrangement in cranial fossae. Two-stage approaches were reported, although most studies described single-stage approaches. Common postoperative outcomes were a range of disturbances of cranial nerve V.

CONCLUSIONS

The surgical approach varies based on the tumor conformation. However, a 2-stage pterional subtemporal and semisitting retrosigmoid approach is a safe, practical, and effective strategy for the removal of dumbbell-shaped trigeminal schwannoma in a pediatric patient.

Low Lattice Thermal Conductivity in a Wider Temperature Range for Biphasic-Quaternary (Ti,V)CoSb Half-Heusler Alloys

Intrinsically high lattice thermal conductivity has remained a major bottleneck for achieving a high thermoelectric figure of merit (zT) in state-of-the-art ternary half-Heusler (HH) alloys. In this work, we report a stable n-type biphasic-quaternary (Ti,V)CoSb HH alloy with a low lattice thermal conductivity κ_L ≈ 2 W m^-1 K^-1 within a wide temperature range (300-873 K), which is comparable to the reported nanostructured HH alloys. A solid-state transformation driven by spinodal decomposition upon annealing is observed in Ti_0.5V_0.5CoSb HH alloy, which remarkably enhances phonon scattering, while electrical properties correlate well with the altering electronic band structure and valence electron count (VEC). A maximum zT ≈ 0.4 (±0.05) at 873 K was attained by substantial lowering of κ_L and synergistic enhancement of the power factor. We perform first-principles density functional theory calculations to investigate the structure, stability, electronic structure, and transport properties of the synthesized alloy, which rationalize the reduction in the lattice thermal conductivity to the increase in anharmonicity due to the alloying. This study upholds the new possibilities of finding biphasic-quaternary HH compositions with intrinsically reduced κ_L for prospective thermoelectric applications.

Enhanced Thermoelectric Performance in Oxide Composites of La and Nb Codoped SrTiO3 by Using Graphite as the Electron Mobility Booster

Inherent insulating nature of oxides makes it challenging for use in thermoelectric applications that warrant reasonable electrical conductivity. In the present work, we have used graphite (G) to improve the electron transport in La_0.07Sr_0.93Ti_0.93Nb_0.07O₃ (LSTN) by making composites. Graphite acts as the electron momentum booster in the LSTN matrix, which otherwise suffers from Anderson localization of electrons, causing an order of magnitude increase in weighted mobility and electrical conductivity. As a result, the thermoelectric power factor increases more than 6 times due to graphite incorporation in LSTN. Furthermore, the lattice thermal conductivity is suppressed due to enhanced Umklapp scattering, as derived from the Debye-Callaway model. Hence, we have recorded ∼423% increment in the figure of merit (ZT) in LSTN + G composites. The maximum ZT obtained is 0.68 at 980 K for the LSTN with 1 wt % graphite composite. Furthermore, we have fabricated a four-legged n-type thermoelectric power generator demonstrating a milliwatt level power output, which hitherto remained unattainable for oxide thermoelectrics.

Temperature-dependent excitonic emission characteristics of lead-free inorganic double perovskites and their third-order optical nonlinearities

We report temperature-dependent photoluminescence (PL) in the temperature range between 77 K and 300 K, and room temperature nonlinear optical (NLO) properties of solution processed lead-free Cs₂NaBiI₆ (CNBI) and Cs₂KBiI₆ (CKBI) perovskite films. The de-convolution analysis of temperature-dependent PL spectra showed thermal quenching behavior of free-exciton (FX) emission, an unusual blue-shift of PL emission, and line broadening with increasing temperature as a consequence of strong exciton-phonon interaction. The nonlinear refractive index (n₂) and nonlinear absorption coefficient (β) of both the CNBI and CKBI films are determined using a closed aperture (CA) and open aperture (OA) Z-scan technique, respectively. Both the CNBI and CKBI perovskites exhibited features of saturable absorption (SA) with β ∼ -6.23 × 10^-12 cm W^-1, and -1.14× 10^-12 cm W^-1, respectively. The CA measurements depicted a self-defocusing effect in both the samples with n₂ values ∼-1.06 × 10^-14 cm² W^-1 and -1.337× 10^-14 cm² W^-1, respectively. With such emission and NLO characteristics, CNBI and CKBI perovskite films can be used for designing eco-friendly optoelectronic and NLO devices.

Endoscopic-assisted resection of vestibular schwannomas in high-riding jugular bulb

The present surgical video demonstrates safe opening of the internal auditory canal (IAC) during vestibular schwannoma surgery via a retrosigmoid approach in the sitting position. Resection of the intrameatal portion of a tumor is important for progression-free survival. Preoperative thin-sliced CT revealed a high-riding jugular bulb obscuring the trajectory. After dural opening, the IAC was approached anteriorly and superiorly. The posterior margin of IAC drilling was above the Tubingen line. Drilling was performed under continuous jugular compression. The vein was pushed down to augment visibility. An angled endoscope was helpful. IAC can be drilled safely in a high-riding jugular bulb with the technique mentioned in the video. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2198.

Use of Temporary Rod and Intraoperative Neuroimaging for Correction of Adolescent Idiopathic Scoliosis: 2-Dimensional Operative Video

Adolescent idiopathic scoliosis (AIS) is an abnormal lateral curvature of the spine that arises during the pubescent growth spurt. AIS mainly affects females in the age group of 10 to 16 yr, with a prevalence of about 1% to 3% in the at-risk population.1 Treatment options vary depending on disease presentation and severity. Mild curvature mainly requires periodic observation for disease progression, whereas more moderate curvature can necessitate bracing or corrective surgery.2 Here, we present the use of a temporary rod and neuroimaging for the correction of Lenke type 1 spinal curvature in an AIS patient. An inferior facetectomy is performed, and a Lenke probe is used for entry into the pedicle and vertebral body. The channel is sounded before and after tapping to check for adequate walls prior to insertion of the pedicle screw. The ARTIS pheno is brought into the field, which uses fluoroscopy to create a 3-dimensional (3D) representation of the instrumentation within the spine. A temporary rod is placed in the concavity, and a combination of corrective techniques, including a rod roll, apical translation, and reduction, is performed to bring up the concavity, derotate the spine, and translate the spine. The permanent rod is then placed in the convexity, and compression is performed to bring down the scapular prominence. The temporary rod is then removed, and a final rod is placed to complete the 3D correction. The patient consented to the procedure, and an informed written consent was obtained from the patient to use her photographs and video recordings for publication.

The analysis of charge transport mechanism in mixed ionic electronic conductor composite of Sr2TiCoO6double perovskite with yttria stabilized zirconia

In this investigation, the ionic conduction mechanism in mixed ionic electronic conductors composites of Sr₂TiCoO₆/YSZ has been studied with the help of universal dynamic response. 3 mol% and 8 mol% yttria stabilized ZrO₂have been mixed with Sr₂TiCoO₆(STC) double perovskite in 1:1 ratio to prepare STC/3YSZ and STC/8YSZ composites via solid-state reaction route. AC Impedance spectroscopy has been carried out to examine the charge transport mechanism, which has been modeled using the microstructural networks of resistors and capacitors. Grain boundaries are more resistive and capacitive compared to the bulk. Modulus spectroscopy analysis demonstrates the non-Debye character of conductivity relaxation with frequency. Complex frequency-dependent AC conductivity is found to obey Almond West power law and reveals that ion migration occurs through the correlated hopping mechanism. Further, the DC conductivity and relaxation time have been found to follow the Barton Nakajima and Namikawa relation, which is correlated with AC to DC conduction. The time-temperature superposition principle has been used to explain the conductivity scaling in the intermediate frequency range. At low temperatures, the ions are localized in the asymmetric potential well, while at high temperatures, hopping behavior starts dominating. Further Kramers-Kronig transformation connects the dielectric strength with conductivity relaxation and verifies the impedance data.

Effect of B-site cation ordering on high temperature thermoelectric behavior of Ba x Sr2-x TiFeO6 double perovskites

Here, we have reported the detailed structural analysis in correlation with thermoelectric properties of Ba doped Sr₂TiFeO₆ (BSTF) double perovskites in the temperature range from 300 K to 1100 K. BSTF compositions exhibit single phase cubic structure with [Formula: see text] crystal symmetry from room temperature to 523 K and also at temperature beyond 923K. Rietveld refinement of high temperature XRD data suggests the coexistence of two cubic phases with [Formula: see text] space group having same composition in the intermediate temperature region. Correlation of the phase-fraction with electrical conductivity data posits the possibility of high temperature cubic phase being conductive compared to the insulator-like cubic phase observed at room temperature. The experimental analysis alone seems insufficient to explain the conductivity behavior demonstrating semiconductor [Formula: see text] to metal like [Formula: see text] transition. Hence DFT framework has been adopted for computational analysis coupled with the Boltzmann transport equations to understand their thermoelectric properties based on the electronic restructuring occurred due to octahedral arrangements in these double perovskites. It has been shown that clustering of FeO₆ octahedra may lead to the formation of a conduction path in the cubic phase of BSTF, which induces metallic behavior in these double perovskites.

An International Radiosurgery Research Foundation Multicenter Retrospective Study of Gamma Ventral Capsulotomy for Obsessive Compulsive Disorder

BACKGROUND

Obsessive compulsive disorder (OCD) across its full spectrum of severity is a psychiatric illness affecting ∼2% to 3% of the general population and results in significant functional impairment. There are few large patient series regarding Gamma ventral capsulotomy (GVC).

OBJECTIVE

To evaluate clinical outcomes of severe medically refractory OCD treated with GVC.

METHODS

This is an international, multicenter, retrospective cohort study. Forty patients with pre-GVC Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores ≥ 24 (indicating severe OCD) were included. GVC was performed with 1 or 2 isocenters with a median maximum dose of 135 Gy (range, 120-180 Gy). Patients were deemed "responders" to GVC if there was ≥35% reduction of follow-up Y-BOCS scores, and considered in remission if their Y-BOCS scores were ≤16. The median follow-up was 36 mo (range, 6-96 mo).

RESULTS

The median pre-SRS Y-BOCS score was 35 (range, 24-40). Eighteen patients (45%) were considered "responders," and 16 (40%) of them were in remission at their last follow-up. Nineteen patients (47.5%) remained stable with Y-BOCS of 33 (range, 26-36) following GVC, whereas 3 patients (7.5%) experienced worsening in Y-BOCS scores. Patients treated with 2 isocenters were more likely to have improvement in Y-BOCS score at 3 and 5 yr (P < .0005). Ten patients (25%) experienced post-GVC mood disturbance and neurological complications in 3 patients (7.5%). One patient developed radiation necrosis with edema that improved with steroids.

CONCLUSION

GVC serves as a reasonable treatment strategy for severe medical refractory OCD. Patients treated with 2 isocenters were more likely to have substantial improvement in OCD.

Use of Pheno Room, Augmented Reality, and 3-Rod Technique for 3-Dimensional Correction of Adolescent Idiopathic Scoliosis

This is a surgical video that showcases the surgical repair of a young male patient with idiopathic scoliosis in a hybrid operating room with the utilization of a new imaging modality Advanced Radar Target Identification System (ARTIS) PHENO (Siemens Medical Solutions, Pennsylvania, USA) and augmented reality (Video 1). A 17-year-old male patient with idiopathic scoliosis underwent scoliosis repair in a hybrid operating room with segment reality surgical planning. The use of augmented reality helped in visualization of proper screw trajectory, and the use of ARTIS PHENO helped in identification of correct screw placement and rod fixation. Intraoperative use of new imaging modalities as augmented reality imaging and ARTIS PHENO can decrease surgical complication and time.

Surgical correction of proximal junctional kyphosis

This 3D video showcases the surgical techniques for patients with proximal junctional kyphosis. The surgical repair for patients with proximal junctional kyphosis is an individualized approach depending on patient history and imaging with adequate surgical measurements. This video will shed light on two cases with proximal junctional kyphosis and the method taken for their repair. The first case is of an 11-year-old female known to have osteogenesis imperfecta and status post T5–L3 posterior spinal fusion with segmental instrumentation. The patient underwent change of older instruments and scoliosis repair, with full correction on postoperative x-ray. The second patient is a 16-year-old male known to have cerebral palsy and kyphoscoliosis status post spinal fusion. The patient underwent scoliosis repair surgery with replacement of old instrumentation and scoliosis correction.

The video can be found here: https://youtu.be/f5iLwqbU26Q.

Vascular Transposition of the Superior Cerebellar Artery Using a Fenestrated Clip and Fibrin Glue in Trigeminal Neuralgia: 2-Dimensional Operative Video

This is the case of an 86-yr-old gentleman who presented with left facial pain exacerbated by eating, drinking, chewing, and shaving (distribution: V2, V3). The patient was diagnosed with trigeminal neuralgia and was refractory to medications. Imaging showed a superior cerebellar artery (SCA) loop adjacent to the trigeminal nerve root entry zone and a decision to perform a microvascular decompression of the fifth nerve was presented to the patient. After patient informed consent was obtained, a standard 3 cm × 3 cm retrosigmoid craniotomy was performed with the patient in a supine head turned position and in reverse Trendelenburg. The arachnoid bands tethering the SCA to the trigeminal nerve were sharply divided. A slit was then made in the tentorium and a 3 mm fenestrated clip was then used to secure the transposed SCA away from the trigeminal nerve. The SCA proximal to this was slightly patulous in its course so a small amount of a fibrin glue was also used to secure the more proximal SCA to the tentorium. The patient was symptom-free postoperatively and no longer required medical therapy. Additionally, imaging was consistent with adequate separation of the nerve from adjacent vessels.1-5

Role of GO and r-GO in resistance switching behavior of bilayer TiO2 based RRAM

Graphene-based resistance random access memory devices (RRAMs) have shown promise as a suitable replacement for flash memories, owing to their fast switching speed, low programming voltage, better scalability and great reliability. Furthermore, recent research works have shown bi-layer RRAM devices exhibiting better performance along the same parameters, where titania is one of the most commonly used materials. In the present work, we have studied the resistance switching behavior in a bi-layer RRAM device structure of TiO₂ with graphene oxide (GO) and reduced graphene oxide (rGO). Switching mechanism in these devices has been investigated by detailed experimental characterization in conjunction with a finite element modeling (FEM) simulation. A dual conical conductive filament has been used in the present work, based on the modeling of the electroforming process carried out by FEM. It has been demonstrated that for the GO/TiO₂ based hybrid RRAM device structure, GO acts as an active filament formation layer, whereas in the rGO/TiO₂ bi-layer structure, rGO acts as a mere electrode.

Novel Use of Pipeline Stent Device After Inadvertent Microcatheter Rupture During Arteriovenous Fistula Embolization

BACKGROUND

Onyx, a liquid embolic agent, is the mainstay of embolization treatment of arteriovenous malformation or arteriovenous fistula. Microcatheter retention in an embolic cast is a well-known complication. Rupture of catheter with spillage of onyx is a rare phenomenon but can lead to potential occlusion of the parent vessel.

METHODS

We describe a case in which a patient with ruptured arteriovenous fistula experienced rupture of a microcatheter at the proximal part and spillage of onyx on embolization. A Pipeline embolization device (PED) was successfully deployed, and onyx was jailed between the catheter and vessel wall at the third segment of the vertebral artery (V3 segment). A balloon angioplasty helped to complete the opening of the stent.

RESULTS

The procedure was uneventful, and the patient recovered well. Follow-up angiogram revealed patency of posterior circulation. The 6-month follow-up angiogram revealed a patent stent.

CONCLUSIONS

Microcatheter rupture and spillage of onyx during embolization of arteriovenous malformation/arteriovenous fistula is a potential complication, and management should be individualized. The unique close cell design of the PED was successfully used to avoid a potentially life-threatening occlusion of the vertebrobasilar system. To the best of our knowledge, we report for the first time this novel use of PED.

Far field superfocusing along with enhanced near field emission from hybrid spiral plasmonic lens inscribed with nano corrals slit diffractor

Here, we have numerically calculated electric field intensity and phase of the emission from various hybrid spiral plasmonic lenses (HSPL) in near field as well as in far-field. We have proposed a novel HSPL inscribed with nano corrals slit (NCS) and compared its focusing ability with other HSPLs inscribed with circular slit and circular grating. With the use of nano corrals slit, we have been able to improve light intensity in the far-field without compromising near-field intensity. Our NCS-HSPL outperforms other HSPLs and standalone SPL in near-field as well as far-field. We have also found that proposed circular slit diffractor is far more superior than previously reported circular grating diffractor. We have been able to extend the focal length of hybrid plasmonic lens upto 3 um and observed a two-fold increment in the far field intensity compared to existing spiral plasmonic lens even though size of focal spot remains same. Optical complex fields produced by NCS based HSPL can be used for various applications such as super resolution microscopy, nanolithography, bioimaging and sensing, angular momentum detectors, etc. Moreover, enhanced near-field intensity in conjunction with far-field superfocusing with reasonable focal length may lead to the development of novel multifunctional lab-on-chip devices.

Neuromodulation in intractable pain management: outcomes and predictors of revisions of spinal cord stimulators

OBJECTIVE Spinal cord stimulators (SCSs) appear to be safe and efficacious for chronic intractable back pain. Although there are many reports on percutaneous SCSs, there are very few studies on outcomes of paddle lead SCSs. In addition, the predictors of requirement for SCS revision have not been well established. Here, the authors review the outcome of a case series and attempt to identify the predictors of SCS revisions. METHODS The clinical and radiological information of 141 patients with intractable chronic pain who underwent SCS implantation within the past 20 years was retrospectively reviewed. Paddle lead SCSs were used in this series. Statistical analysis was conducted using Kaplan-Meier curves and Cox proportional-hazards regression. RESULTS Among 141 cases, 90 (64%) did not require any revision after SCS implantations. Removal of the SCS was required in 14 patients. The average pain score was significantly reduced (preimplantation score of 8 vs postimplantation score of 1.38; p < 0.0001). Younger age, male sex, obesity, a preimplantation pain score ≥ 8, and the presence of neuromuscular pain were identified as predictors of the overall requirement for SCS revision. However, only a preimplantation pain score ≥ 8 was identified as a predictor of early failure of the SCS. CONCLUSIONS Implantation of a paddle lead SCS is a relatively less invasive, safe, and effective procedure for patients with intractable back pain. Revision of the procedure depends on many factors, including younger age, male sex, associated neuromuscular pain, and severity of the pain. Therefore, patients with these factors, for whom implantation of an SCS is planned, should be closely followed for the possible requirement for revision.

Metal-like electrical conductivity in LaxSr2−xTiMoO6 oxides for high temperature thermoelectric power generation

Increasing electrical conductivity in oxides, which are inherently insulators, can be a potential route in developing oxide-based thermoelectric power generators with higher energy conversion efficiency.

Large change in thermopower with temperature driven p–n type conduction switching in environment friendly BaxSr2−xTi0.8Fe0.8Nb0.4O6 double perovskites

Temperature driven p–n type conduction switching in combination with colossal change in thermo-power in Ba_xSr_2−xTi_0.8Fe_0.8Nb_0.4O₆ (BSTFN) double perovskites.

Outcome of resection of WHO Grade II meningioma and correlation of pathological and radiological predictive factors for recurrence

This study investigated whether extent of surgical resection (Simpson and Shinshu grade) along with pathological and radiological factors influence the tumor control and recurrence-free survival (RFS) of patients with World Health Organization (WHO) grade II meningiomas. The clinical, radiological and surgical notes on the 59 patients with WHO grade II meningioma managed at our institution over 20years were retrospectively reviewed. In this study, median survival time was 41months. The overall recurrence rate in Simpson grades I and II resection was 31%. In grades III and IV, the overall recurrence rate was 73%, and this high recurrence rate in these groups was confined within 5years. In Cox regression analysis, combined data of grades (I and II)/complete resection showed a significant difference in RFS compared to grades (III and IV)/subtotal resection (p=0.0001). A similar trend of RFS (p=0.0001) was observed with the Shinshu grading system of resection. In addition, a Ki-67% marker for proliferation less than 15% (p=0.029), absence of certain radiological features including heterogeneous enhancement, cyst formation and peritumoral edema (p=0.006), and repeat surgery for recurrent meningioma was associated with better survival (p=0.014). However, radiosurgery did not have a beneficial role in the treatment of recurrence of atypical meningioma. The Simpson grading system is the primary predictor of recurrence of WHO grade II meningioma after resection. In addition, certain pathological and radiological features need to be considered as possible factors of recurrence after resection. Lastly, depending on the likely risks and surgical morbidity, repeat surgical resection should be performed for recurrent atypical meningioma.

Microsurgical decompression of tumor of a rare posterior third ventricular pathology

Of the posterior third ventricular tumors, a papillary tumor of the pineal gland is a rare entity that originates from specialized ependymoma of the subcommissural organ. In this video narration, we present a case of a 33-year-old male with headaches and recent cognitive decline due to a posterior third ventricular lesion. The patient underwent a posterior interhemispheric approach, and a gross-total decompression was achieved with no signs of recurrence in a 2-year follow-up period. With this case we highlight the microsurgical technique employed for decompressing tumors of the posterior third ventricular region with preservation of eloquent structures and draining veins. The video can be found here: https://youtu.be/o0WbyOqmtX0 .

Posterior interhemispheric approach and microsurgical resection of a pineal parenchymal neoplasm of intermediate differentiation

Owing to a deep-seated location and intricate venous anatomy, pathologies of the posterior third ventricular region pose formidable challenges to the operating neurosurgeon. In this video, we present a case of an elderly Caucasian female with a rare histological variant of a pineal parenchymal mass who presented with gait disturbances and worsening retro-orbital headache. Radiological and clinco-histopathological correlates of this rare tumor pathology having intermediate differentiation are highlighted. Briefly outlined are surgical pearls and strategies to minimize complications, as the tumor is approached through the posterior interhemispheric corridor, to achieve a gross-total decompression. The video can be found here: https://youtu.be/KXwclZ7Ei84 .

Environmentally friendly BaxSr2−xTiFeO6double perovskite with enhanced thermopower for high temperature thermoelectric power generation

SrTiO₃based double perovskites, BaxSr_2−xTiFeO₆(BSTF) compositions showed very large thermo-power (S) for the application of high temperature thermoelectric power generation.

Intraventricular Meningioma: Technical Nuances in Surgical Management

OBJECTIVE

Intraventricular meningiomas (IVMs) are rare tumors compared with intracranial meningiomas. Optimal surgical management of IVMs is controversial. The objective of this article was to review the outcomes and complications of meningiomas treated with various surgical approaches.

METHODS

We performed a retrospective review of 18 patients with IVMs who received different treatment strategies during the period 2000-2014. Of 18 patients, 17 underwent microsurgical resection, and 1 patient received Gamma Knife radiosurgery. The literature was reviewed to compare the present cohort with previously published series.

RESULTS

In our series, 12 (70%) patients underwent parieto-occipital craniotomy and a superior parietal gyrus approach, which was similar to procedures used in various series (74.4%) in the existing literature. Preoperatively, patients commonly presented with headache (65%) and neurologic deficits (70%). After surgical management, there was a significant reduction in symptoms, including headache (preoperative 65% vs. postoperative 6%, P = 0.0001), and neurologic deficits (preoperative 70% vs. postoperative 5.5%). Preoperatively, 2 patients experienced visual impairment, which was completely resolved after surgery. The Karnofsky performance scale was significantly improved after resection compared with before treatment (89 vs. 76, P = 0.003). In 4 patients with World Health Organization grade II tumor, redo surgery was required because of recurrence of tumor.

CONCLUSIONS

Based on a literature review and our experience, surgical approaches for patients with IVM vary according to size, location, and laterality of the meningioma. In addition, the growth pattern of the tumor (transependymal extension), vascular supply of the tumor, and brain function (particularly visual function) can affect surgical treatment and should be identified preoperatively.

Malignant nodular hidradenoma of scalp

Malignant nodular hidradenoma (MNH) is a rare tumor of sweat gland known by many names in the literature. Scalp is a known and yet uncommon site of occurrence. We describe two patients with scalp MNH with brain parenchymal invasion. Both tumors recurred in spite of total excision and radiotherapy.

Subcutaneous metastasis in medulloblastoma: A case report and review of literature

Extraneural metastasis (ENM) in patients with medulloblastoma is a rare but a well-described phenomenon, both in children and adults. Most of the ENM involve bone and bone marrow and rarely involve other solid organs. Subcutaneous and muscular metastasis is an extremely rare event, more so in children, with only two cases documented in the pediatric population. We describe a case of medulloblastoma with ENM in right masseter and subcutaneous plane along with concomitant central nervous system relapse, 4 years after the primary diagnosis, with a brief review of the literature.

Arteriovenous malformation associated with cyst in a child: Case report and review of literature

Cysts associated with arteriovenous malformations (AVMs) are either secondary to hemorrhage or after radiosurgery. Untreated and unruptured AVMs with large cysts are rare. We here describe a child with medial parietal AVM associated with cyst, without any history of hemorrhage or radiosurgery. Surgical excision led to cure for the patient.

Midline suboccipital osteoplastic craniotomy - 'cobra craniotomy'

BACKGROUND

Midline suboccipital craniotomy has been proposed as an alternative to conventional craniectomy for removal of posterior fossa tumors.

METHOD

We describe a modified technique for midline suboccipital osteoplastic craniotomy based on the atlantooccipital membrane for a 17-year-old boy with superior vermian astrocytoma. Osteoplastic craniotomy was performed safely in this patient.

RESULT

The presence of the turned down, attached bone flap did not interfere with surgery. Reattachment of the bone flap was easy and stable. This technique was not associated with additional risks.

CONCLUSION

Midline suboccipital osteoplastic craniotomy is a better option for superiorly placed midline posterior fossa tumor surgery.

Patched acts catalytically to suppress the activity of Smoothened

Mutations affecting the transmembrane proteins Patched (Ptc) or Smoothened (Smo) that trigger ligand-independent activity of the Hedgehog (Hh) signalling pathway are associated with human tumours such as basal cell carcinoma (BCC) and medulloblastoma. Despite extensive genetic studies demonstrating the importance of these receptor components in embryonic patterning and cancer, the mechanism by which Ptc regulates Smo is not understood. Here we report that Ptc and Smo are not significantly associated within Hh-responsive cells. Furthermore, we show that free Ptc (unbound by Hh) acts sub-stoichiometrically to suppress Smo activity and thus is critical in specifying the level of pathway activity. Patched is a twelve-transmembrane protein with homology to bacterial proton-driven transmembrane molecular transporters; we demonstrate that the function of Ptc is impaired by alterations of residues that are conserved in and required for function of these bacterial transporters. These results suggest that the Ptc tumour suppressor functions normally as a transmembrane molecular transporter, which acts indirectly to inhibit Smo activity, possibly through changes in distribution or concentration of a small molecule.

Patched acts catalytically to suppress the activity of Smoothened

Mutations affecting the transmembrane proteins Patched (Ptc) or Smoothened (Smo) that trigger ligand-independent activity of the Hedgehog (Hh) signalling pathway are associated with human tumours such as basal cell carcinoma (BCC) and medulloblastoma. Despite extensive genetic studies demonstrating the importance of these receptor components in embryonic patterning and cancer, the mechanism by which Ptc regulates Smo is not understood. Here we report that Ptc and Smo are not significantly associated within Hh-responsive cells. Furthermore, we show that free Ptc (unbound by Hh) acts sub-stoichiometrically to suppress Smo activity and thus is critical in specifying the level of pathway activity. Patched is a twelve-transmembrane protein with homology to bacterial proton-driven transmembrane molecular transporters; we demonstrate that the function of Ptc is impaired by alterations of residues that are conserved in and required for function of these bacterial transporters. These results suggest that the Ptc tumour suppressor functions normally as a transmembrane molecular transporter, which acts indirectly to inhibit Smo activity, possibly through changes in distribution or concentration of a small molecule.