Contact laser-assisted neuroendoscopy can be performed safely by using pretreated 'black' fibre tips: experimental data

Locally Concentrated Deep Eutectic Liquids Electrolytes for Low-Polarization Aluminum Metal Batteries

Low-cost and nontoxic deep eutectic liquid electrolytes (DELEs), such as [AlCl3]1.3[Urea] (AU), are promising for rechargeable non-aqueous aluminum metal batteries (AMBs). However, their high viscosity and sluggish ion transport at room temperature lead to high cell polarization and low specific capacity, limiting their practical application. Herein, non-solvating 1,2-difluorobenzene (dFBn) is proposed as a co-solvent of DELEs using AU as model to construct a locally concentrated deep eutectic liquid electrolyte (LC-DELE). dFBn effectively improves the fluidity and ion transport without affecting the ionic dynamics in the electrolyte. Moreover, dFBn also modifies the solid electrolyte interphase growing on the aluminum metal anodes and reduces the interfacial resistance. As a result, the lifespan of Al/Al cells is improved from 210 to 2000 h, and the cell polarization is reduced from 0.36 to 0.14 V at 1.0 mA cm-2. The rate performance of Al-graphite cells is greatly improved with a polarization reduction of 0.15 and 0.74 V at 0.1 and 1 A g-1, respectively. The initial discharge capacity of Al-sulfur cells is improved from 94 to 1640 mAh g-1. This work provides a feasible solution to the high polarization of AMBs employing DELEs and a new path to high-performance low-cost AMBs.

Weak biophoton emission after laser surgery application in soft tissues: Analysis of the optical features

Nowadays, laser scalpels are commonly used in surgery, replacing the traditional surgical scalpels for several applications involving cutting or ablating living biological tissue. Laser scalpels are generally used to concentrate light energy in a very small-sized area; light energy is then converted in heat by the tissues. In other cases, the fiber glass tip of the laser scalpel is heated to high temperature and used to cut the tissues. Depending on the temperature reached in the irradiated area, different effects are visible in the tissues. In this study, we report the discovery and characterization of the light emitted by soft mammalian biological tissues from seconds to hours after laser surgery application. A laser diode (with hot fiber glass tip) working at 808 nm and commercially available for medical and dentistry applications was used. The irradiated tissues (red meat, chicken breast and fat) showed light emission in the visible range, well detectable with a commercial charge coupled device (CCD) camera. The time decay of the light emission, the laser power effects and the spectral features in the range 500 to 840 nm in the different tissues are here reported.

Two-Micron Continuous-Wave Laser-Assisted Neuroendoscopy: Clinical Experience of Two Institutions in 524 Procedures

OBJECTIVE

To present the clinical experience of 2 neurosurgical centers with the use of a 2-micron continuous-wave laser (2μ-cwL) system as standard tool in neuroendoscopic procedures and to discuss the safety and efficacy of this system.

METHODS

In total, 469 patients underwent neuroendoscopic procedures using 2μ-cwL between September 2009 and January 2015. All patient data were retrospectively reviewed. In total, 241 (51%) patients were children and 228 (49%) adults. Mean age was 27.5 years (range: 3 days to 83 years). Intraoperative ultrasonography or neuronavigation were used to guide ventricular or cyst puncture and for intraventricular or intracystic orientation if necessary.

RESULTS

A total of 524 neuroendoscopic procedures using 2μ-cwL were performed. Laser-assisted endoscopic third ventriculostomy was the most common procedure in 302 (64%) patients. Cyst fenestration was performed in 124 (26%), septostomy in 45, tumor biopsy in 41, tumor resection in 8, and choroid plexus coagulation in 3 patients. There was no intraoperative complication directly attributable to the use of laser and an overall procedural complication rate of 4.8%.

CONCLUSIONS

This large series of 2μ-cwL as a routine tool in neuroendoscopic procedures demonstrates that 2μ-cwL is safe for endoscopic third ventriculostomy, septostomy, cyst fenestration, and intraventricular tumor biopsy or resection. As a cutting and coagulation tool, it combines the action of mechanical tools like forceps, balloons, and scissors plus those of electric tools. It therefore renders neuroendoscopic procedures more straightforward with a minimum need to change tools.

Thulium laser-assisted endoscopic third ventriculostomy: Determining safe laser settings using in vitro model and 2 year follow-up results in 106 patients

BACKGROUND AND OBJECTIVE

Endoscopic third ventriculostomy is used to treat hydrocephalus. Different laser wavelengths have been proposed for laser-assisted endoscopic third ventriculostomies over the last decades. The aim of this study was to evaluate Thulium laser endoscopic third ventriculostomy heat penetration in the surrounding environment of the floor of the third ventricle in an in vitro setting with visualization of thermal distribution. Subsequently 106 Thulium laser endoscopic third ventriculostomy procedures were retrospectively analyzed to demonstrate safety.

METHODS

The in vitro visualization was based on the color Schlieren method. The heat penetration was measured beneath a tissue phantom of the floor of the third ventricle with a fiber of 365 μm in diameter at different energy settings; 1.0W (956 J/cm2 ), 2.0W (1,912 J/cm2 ), 4.0W (3,824 J/cm2 ), and 7.0W (6,692 J/cm2 ), with a pulse duration of 1.0 second. All experiments were repeated five times. In addition, 106 Thulium laser endoscopic third ventriculostomy procedures between 2005 and 2015 were retrospectively analysed for etiology, sex, complications, and laser parameters.

RESULTS

In the energy settings from 1.0 to 4.0 W, heat penetration depth beneath the phantom of the third ventricle did not exceed 1.5 mm. The heat penetration depth at 7 W, exceeded 6 mm. The clinical overall success rate was 80% at the 2-year follow-up study. Complications occurred in 5% of the procedures. In none of the 106 investigated clinical patients bleeding or damage to the basilar artery was encountered due to Thulium laser ablation.

CONCLUSIONS

The in vitro experiments show that under 4.0W the situation is considered safe, due to low penetration of heat, thus the chance of accidentally damaging critical structures like the basilar artery is very small. The clinical results show that the Thulium laser did not cause any bleeding of the basilar artery, and is a safe technique for laser endoscopic third ventriculostomy. Lasers Surg. Med. © 2017 Wiley Periodicals, Inc.

Application of a flexible CO2 laser fiber for neurosurgery: laser-tissue interactions

Object

The CO2 laser has an excellent profile for use in neurosurgery. Its high absorption in water results in low thermal spread, sparing adjacent tissue. Use of this laser has been limited to line-of-sight applications because no solid fiber optic cables could transmit its wavelength. Flexible photonic bandgap fiber technology enables delivery of CO2 laser energy through a flexible fiber easily manipulated in a handheld device. The authors examined and compared the first use of this CO2 laser fiber to conventional methods for incising neural tissue.

Methods

Carbon dioxide laser energy was delivered in pulsed or continuous wave settings for different power settings, exposure times, and distances to cortical tissue of 6 anesthetized swine. Effects of CO2 energy on the tissue were compared with bipolar cautery using a standard pial incision technique, and with scalpel incisions without cautery. Tissue was processed for histological analysis (using H & E, silver staining, and glial fibrillary acidic protein immunohistochemistry) and scanning electron microscopy, and lesion measurements were made.

Results

Light microscopy and scanning electron microscopy revealed laser incisions of consistent shape, with central craters surrounded by limited zones of desiccated and edematous tissue. Increased laser power resulted in deeper but not significantly wider incisions. Bipolar cautery lesions showed desiccated and edematous zones but did not incise the pia, and width increased more than depth with higher power. Incisions made without using cautery produced hemorrhage but minimal adjacent tissue damage.

Conclusions

The photonic bandgap fiber CO2 laser produced reliable cortical incisions, adjustable over a range of settings, with minimal adjacent thermal tissue damage. Ease of application under the microscope suggests this laser system has reached true practicality for neurosurgery.

LASER-ASSISTED ENDOSCOPIC THIRD VENTRICULOSTOMY

OBJECTIVE

Endoscopic third ventriculostomy is a well-known surgical option in the treatment of noncommunicating hydrocephalus. We studied complications and long-term success in 202 patients to demonstrate the safety and efficacy of laser-assisted endoscopic third ventriculostomy (LA-ETV) using a unique “black” fiber tip/diode laser combination for controlled tissue ablation.

METHODS

We studied 213 LA-ETVs, which were performed in 202 patients. Patients' ages ranged from 2 days to 83 years (mean age, 27 yr). The mean follow-up period for all patients was 2.7 years (range, 2 d to 12 yr). Hydrocephalus was caused by aqueductal stenosis in 65 patients, tumors in 67 patients, hemorrhages in 24 patients, myelomeningoceles in 20 patients, cysts in 15 patients, and other causes in 11 patients. The long-term effectiveness of LA-ETV was studied with Kaplan-Meier analysis.

RESULTS

Technically successful LA-ETVs were accomplished in 196 of the 202 patients (97%). The overall success rate for a functional LA-ETV was 68% at the 2-year follow-up evaluation. LA-ETV was more effective in patients aged 1 year and older (70% success rate) than in younger patients (59% success rate). Success rates were greater in patients with aqueductal stenosis or tumors as compared to other etiologies. Complications occurred in 22 procedures (10.3%). Only one patient (0.5%) experienced a major complication. No surgical mortalities or laser-related complications occurred.

CONCLUSION

This study demonstrates that LA-ETV is a safe and effective procedure that is comparable to other techniques for ETV. LA-ETV is most effective in patients aged 1 year and older and in patients with aqueductal stenosis and tumors, with a low major complication rate.

First experiences with a 2.0-μm near infrared laser system for neuroendoscopy

Nd:YAG, argon and diode lasers have been used in neurosurgical procedures including neuroendoscopy. However, many neurosurgeons are reluctant to use these lasers because of their inappropriate wavelength and uncontrollable tissue interaction, which has the potential to cause serious complications. Recently, a 2.0-microm near infrared laser with adequate wavelength and minimal tissue penetration became available. This laser was developed for endoscopic neurosurgical procedures. It is the aim of the study to report the initial experiences with this laser in neuroendoscopic procedures. We have performed 43 laser-assisted neuroendoscopic procedures [multicompartmental congenital, posthaemorrhagic or postinfectious hydrocephalus (n = 17), tumour biopsies (n = 6), rescue of fixed and allocated ventricular catheters (n = 2), endoscopic third ventriculostomy (ETV, n = 17) and aqueductoplasty (n = 1)] in 41 patients aged between 3 months and 80 years. The laser beam was delivered through a 365-microm bare silica fibre introduced through the working channel of a rigid endoscope. It was used for the opening of cysts, perforating the third ventricular floor, and for coagulation prior to and after biopsy. The therapeutic goals [creating unhindered cerebrospinal fluid (CSF) flow between cysts, ventricles and cisterns, sufficient tissue samples for histopathological diagnosis and catheter rescue] were achieved in 40 patients by the first and in 2 patients by a second neuroendoscopic operation. In one child, a CSF shunt was later required despite patency of the created stoma proven by magnetic resonance imaging (MRI). In another patient ETV was abandoned due to a tiny third ventricle. There was neither mortality nor transient or permanent morbidity. The authors conclude that the use of the 2.0-microm near infrared laser enables safe and effective procedures in neuroendoscopy.

Imaging techniques for research and education of thermal and mechanical interactions of lasers with biological and model tissues

A setup based on color Schlieren techniques has been developed to study the interaction of energy sources, such as lasers, with biological tissues. This imaging technique enables real-time visualization of dynamic temperature gradients with high spatial and temporal resolution within a transparent tissue model. High-speed imaging techniques were combined in the setup to capture mechanical phenomena such as explosive vapor, cavitation bubbles, and shock waves. The imaging technique is especially used for qualitative studies because it is complex to obtain quantitative data by relating the colors in the images to temperatures. By positioning thermocouples in the field of view, temperature figures can be added in the image for correlation to colored areas induced by the temperature gradients. The color Schlieren setup was successfully used for various studies to obtain a better understanding of interaction of various laser, rf, and ultrasound devices used in medicine. The results contributed to the safety and the optimal settings of various medical treatments. Although the interaction of energy sources is simulated in model tissue, the video clips have proven to be of great value for educating researchers, surgeons, nurses, and students to obtain a better understanding of the mechanism of action during patient treatment.

Endoscopic third ventriculostomy in the treatment of hydrocephalus in pediatric patients

Advances in surgical instrumentation and technique have lead to an extensive use of endoscopic third ventriculostomy in the management of pediatric hydrocephalus. The aim of this work was to point out the leading aspects related to this technique. After a review of the history, which is now almost one century last, the analysis of the endoscopic ventricular anatomy is aimed to detail normal findings and possible anatomic variations which might influence the correct conclusion of the procedure. The overview of modern endoscopic instrumentation helps to understand the technical improvements that have contributed to significantly reduce the operative invasiveness. Indications are analysed from a pathogenetic standpoint with the intent to better understand the results reported in the literature. A further part of the paper is dedicated to the neuroradiological and clinical means of outcome evaluation, which are still a matter of debate. Finally a review of transient and permanent surgical complications is performed looking at their occurrence in different hydrocephalus etiologies.

Laser-assisted endoscopic third ventriculostomy for obstructive hydrocephalus: technique and results in a series of 40 consecutive cases

BACKGROUND AND OBJECTIVES

To report a case series of endoscopic third ventriculostomy (ETV) using laser in 40 consecutive patients with obstructive hydrocephalus.

STUDY DESIGN/MATERIALS AND METHODS

Under stereotactic and endoscopic guidance, multiple perforations in the ventricular floor using a 1.32 microm neodymium-yttrium/aluminum/garnet (Nd-YAG) or a 0.805 microm diode laser unit and removal of intervening coagulated tissue ensued with a 4-6 mm opening between third ventricle and basilar cisterns.

RESULTS

The procedure could be completed in all cases. A transient complication occurred in five cases. In 39 patients (mean follow-up 28 months), 31 (79%) had a favorable outcome. Failure occurred in six patients, requiring permanent shunting leading to complete recovery, and two patients remained in a poor clinical status despite ETV.

CONCLUSIONS

Laser-assisted ETV is a safe and efficient procedure for the treatment of obstructive hydrocephalus. Laser is advantageous in cases of distorted anatomy and may reduce technical failures.

Use of lasers in Barrett's esophagus

Lasers are used in the management of Barrett's esophagus for specific tasks. First is for the ablation of non-dysplastic and dysplastic Barrett's as part of an aggressive, minimally invasive, yet unproven preventive interventional strategy for both low-risk and high-risk of progression subgroups. Secondly is for potentially curative treatment of early mucosal cancers (Tis and T1mN0M0). Finally, lasers are used for palliation of dysphagia for advanced tumors. The first two laser uses should be considered experimental and undertaken in the setting of an institutionally approved research protocol. Paramount to the success of ablation of dysplastic and early cancerous Barrett's is careful selection of patients by meticulous video endoscopic inspection of the mucosa, use of high frequency and dedicated endosonography (to uncover unsuspected tumors that penetrate the submucosa or involve lymph nodes that cannot be targeted by laser treatment), and experienced GI pathologists. Lasers can also play an important adjuvant role in the management of dysphagia for advanced cancers: however, the specific patients' characteristics for this group of patients is currently not well-defined in this era of easily placed expandable metallic stents.