Indian Neurosurgeons at the Forefront: A Comprehensive Exploration of their Pioneering Contributions to Neuroendoscopy.

This article delves into the profound impact of Indian neurosurgeons on the expansive canvas of neuroendoscopy. By scrutinizing their trailblazing research, innovations, new surgical techniques, and relentless dedication to education and training, we aim to unravel the intricacies of their influence on a global scale. The review, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, conducts a comprehensive analysis of the literature related to neuroendoscopy contributed by Indian neurosurgeons. The exploration covers a spectrum of achievements, ranging from pioneering research and innovations to complication avoidance, neuroendoscopic training, and global recognition. Despite challenges, Indian neurosurgeons continue to lead the way in shaping the future of neuroendoscopy, ensuring better patient outcomes and improved quality of life. Many Indian neurosurgeons have contributed significantly to the development of neuroendoscopy in India. Prof. YR Yadav's contributions stand significant in the form of research articles and publications on almost all subjects on neuroendoscopy, the textbook on neuroendoscopy, popularizing neuroendoscopy by starting the first university-certified neuroendoscopy fellowship training program in India, describing many innovative techniques/first report of endoscopic techniques and conducting regular endoscopic workshops in his institutions and other major cities of India.

Neuroendoscopic transventricular transchoroidal approach for access to the posterior zone of the third ventricle or pineal region.

The endoscopic transventricular transchoroidal approach facilitates entry into the posterior part of the third ventricle, allowing a visualization field from the foramen of Monro to the pineal region through this anatomical corridor. Combined surgery to treat the target lesion and possible endoscopic third ventriculostomy (ETV) can be performed through a single burr hole. A detailed description of this surgical technique is given, and a series of cases from our center is presented. This retrospective study included patients with lesions in the pineal region or posterior zone of the third ventricle who underwent surgery between 2004 and 2022 in our center for tumor biopsy or endoscopic cyst fenestration. In nine cases, the transchoroidal approach was performed. Demographic and clinical variables were collected: sex, age at diagnosis, clinical presentation, characteristics of the lesion, pathological diagnosis, characteristics of the procedure, complications, subsequent treatments, evolution, follow-up time, and degree of success of the endoscopic procedure. The mean and range of the quantitative variables and frequency of the qualitative variables were analyzed, together with the statistical significance (p < 0.05). Surgical planning was carried out by performing a preoperative MRI, calculating the ideal entry point and trajectory for each case. The preoperative planning of the surgical technique is described in detail. Of our sample, 55.6% were women, with a mean age of 35 years (7-78). The most common clinical presentation was intracranial hypertension (55.6%), with or without a focus. Eight patients presented hydrocephalus at diagnosis. The most frequent procedure was endoscopic biopsy with ETV (66.7%). The pathological diagnosis varied widely. Procedure-related complications included one case of self-limited bleeding of the choroidal fissure at its opening and one intraventricular hemorrhage due to tumor bleeding in the postoperative period. Non-procedure-related complications comprised two ETV failures and one case of systemic infection, while late complications included one case of disease progression and one case of radionecrosis. Four patients died, one due to poor neurological evolution after post-surgical tumor bleeding and three due to causes unrelated to the procedure. The rest of the patients had a favorable evolution and were asymptomatic or stable. The transchoroidal approach through a single burr hole is a feasible and safe option for access to the posterior part of the third ventricle. Proper planning of each case is necessary to avoid complications.

Use of Dyna-computed tomography-assisted neuroendoscopic hematoma evacuation in the treatment of hypertensive intracerebral hemorrhage.

The purpose of this study was to evaluate and summarize the technical characteristics and clinical efficacy of using Dyna-computed tomography (CT)-assisted neuroendoscopic hematoma evacuation to treat hypertensive intracerebral hemorrhage (HICH). We treated 42 consecutive patients with HICH who underwent neuroendoscopic hematoma evacuation in our department from March 1, 2020, to May 31, 2022. Patients were divided into two groups: Dyna-CT-assisted neuroendoscopic group (n = 18) and neuroendoscopic group (n = 24). Retrospective data, treatment efficacy, and outcomes were collected and compared between these two groups. The operative time in the Dyna-CT-assisted neuroendoscopic group was significantly shorter than the operative time in the neuroendoscopic group (mean time 131.6 ± 13.51 vs. 156.6 ± 19.25 min, P < 0.001). Dyna-CT-assisted neuroendoscopic group had significantly less intraoperative blood loss than the neuroendoscopic group (46.94 ± 10.42 vs. 106.46 ± 23.25, P = 0.003). Meanwhile, patients who underwent Dyna-CT-assisted neuroendoscopic had a comparable hematoma clearance rate to those who underwent neuroendoscopic (89.36 ± 7.31 vs. 68.87 ± 19.44%, P = 0.006). The incidence of complications in the Dyna-CT-assisted neuroendoscopic group (5.5%) was lower than in the neuroendoscopic group (12.5%), but the difference was not statistically significant (P = 0.129). Patients who underwent Dyna-CT-assisted neuroendoscopic hematoma evacuation had better 6-month functional outcomes, and the difference was significant (P = 0.004). Furthermore, multivariable analysis showed that younger age, smaller hematoma volume, and Dyna-CT-assisted neuroendoscopic were predictors of favorable 6-month outcomes in HICH patients. In the treatment of HICH, Dyna-CT-assisted hematoma evacuation appears to be safer and more effective than neuroendoscopic hematoma evacuation. Dyna-CT-assisted neuroendoscopic hematoma evacuation in hybrid operating rooms may improve the clinical effect and outcomes of patients with HICH.

Neuroendoscopy: history, endoscopes, and instrumentation.

INTRODUCTION: Endoscopy was first employed in the surgical treatment of neurosurgical diseases early in the twentieth century, but did not become an established practice for a long time, mainly because of poor technology and clinical results. After a slow re-appearance in the 1980s, the 1990s saw an explosion of techniques and instrumentation. Continuing technological improvement has led to further expansion of surgical techniques and indications for use of neuroendoscopy. DISCUSSION: The expansion of ventricular endoscopy has led to significant understanding of CSF disorders. Aqueduct stenosis as cause of hydrocephalus and arachnoid cysts are an example of pathologies, the concept and understanding of which now is considerably enhanced, due to the application of neuroendoscopy in their treatment. Management of loculated hydrocephalus has been facilitated considerably with the use of the endoscope. The concepts of aqueductoplasty, septostomy, and foraminoplasty of the foramina of Monro and Magendie emerged, which were previously unknown. Skull base surgery, especially surgery for craniopharyngioma, has seen dramatic improvement in results with the use of the endoscope. Coupling of the endoscope with neuronavigation has expanded technical capabilities even further. Overall, we can do a lot more with the endoscope now in comparison to 30 years ago. CONCLUSION: We should always remember that the endoscope is only a tool. Its use has indications and limitations related to its design and our ability to extract the maximum, in the context of its shortcomings. Further technological advances will push surgical frontiers even more in years to come.

Isolated entrapment of the lateral ventricle after neuroendoscopic resection of colloid cysts: single - center experience and management.

BACKGROUND: A minimally invasive option of colloid cyst surgical treatment is endoscopic resection, well validated in various reports and clinical practice. A rare complication of the surgical treatment, previously reported only once in literature, is the entrapment of the lateral ventricle. In this study we aim to outline our experience in the management of this occurrence, hypothesizing possible etiopathogenetic causes. METHODS: Among patients who underwent neuroendoscopic resection for a colloid cysts at our Institution between 2013 and 2022, cases who developed a postoperative lateral ventricle entrapment were retrospectively reviewed and included. Clinical history, imaging and treatment were reported. RESULTS: Among 34 patients treated for a colloid cysts, two (5.9 %) patients developed an ipsilateral ventricular entrapment with dilation from two to five months after the resection. Both patients were substantially asymptomatic and neurologically intact, and therefore treated conservatively. One case underwent complete spontaneous radiological resolution one month later, and the other one has remained neurological asymptomatic at follow-up. CONCLUSIONS: Isolated asymptomatic ventricular entrapment with significant dilation after endoscopic colloid cyst resection is a rare occurrence which can be plausibly caused by scar tissue at the level of the foramen of Monro. Because they can have an indolent course with spontaneous resolution, conservative treatment is a viable option, with strict radiological and clinical follow - up. Given the rarity of the occurrence, further studies with larger cohorts are warranted to confirm the etiopathogenetic hypothesis and validate the clinical management.

The Roof of the 4th Ventricle Seen From Inside: Endoscopic Anatomic Illustration-A Case Series.

BACKGROUND: The anatomy of the roof of the fourth ventricle has been illustrated in many laboratory investigations, but in vivo reports of the roof anatomy and its variants are still lacking. OBJECTIVE: To describe the topographical anatomy of the roof of the fourth ventricle explored through a transaqueductal approach that overcomes cerebrospinal fluid depletion, displaying in vivo anatomic images possibly quite close to normal physiological conditions. METHODS: We critically reviewed the intraoperative video recordings of our 838 neuroendoscopic procedures, selecting 27 cases of transaqueductal navigation that provided good quality image details of the anatomy of the roof of the fourth ventricle. Twenty-six patients affected by different forms of hydrocephalus were therefore categorized into three groups: Group A: blockage of the aqueduct-aqueductoplasty, Group B: communicating hydrocephalus, and Group C: tetraventricular obstructive hydrocephalus. RESULTS: Group A has shown what the roof of a normal fourth ventricle really looks like albeit the structures seemed overcrowded because of the narrow space. Images from groups B and C paradoxically allowed a more distinct identification of the roof structures flattened by ventricular dilation, making them more comparable with the topography traced on the laboratory microsurgical studies. CONCLUSION: Endoscopic in vivo videos and images provided a novel anatomic view and an in vivo redefinition of the real topography of the roof of the fourth ventricle. The relevant role of cerebrospinal fluid was defined and outlined, as well as the effects of hydrocephalic dilation on some structures on the roof of the fourth ventricle.

A ventricular catheter that migrated into the fourth ventricle successfully removed using a neuroendoscope.

BACKGROUND: In order to remove a foreign body in the ventricle, such as a ventricular drainage catheter, craniotomy and corticotomy are required to access the ventricle. A case in which a catheter in the 4th ventricle was safely removed with a flexible neuroendoscope is reported. CASE DESCRIPTION: A 47-year-old man underwent coil embolization and ventricular drainage for subarachnoid hemorrhage. 10 days after the operation, he tore off the ventricular drainage catheter and the catheter remained intracranially. The tip of the catheter was in the 4th ventricle and the operation to remove remaining catheter with a neuroendoscope was performed. Using a neuroendoscope, we could remove the catheter safely and did not detect the complications. CONCLUSION: To date, there have been no reports of cases in which a drainage catheter in the ventricle was removed using a flexible endoscope. This case suggests that a flexible endoscope is useful for removing a foreign body from the ventricle less invasively.

Management of severe intraoperative hemorrhage during intraventricular neuroendoscopic procedures: the dry field technique.

OBJECTIVE: Neuroendoscopic procedures inside the ventricular system always bear the risk for an unexpected intraoperative hemorrhage with potentially devastating consequences. The authors present here their experience, and a stage-to-stage guide for the endoscopic management of intraoperative hemorrhages. METHODS: A step-by-step guide for the management to gain control of and stop the bleeding is described including a grading system. More advanced techniques are presented in cases examples. CONCLUSION: Most of intraoperative hemorrhages can be controlled by constant irrigation and coagulation. More advanced techniques can be applied quickly and easily to ensure control of the hemorrhages and avoid the need for a microsurgical conversion.

A Single Vertebral Surgical Approach for Spinal Extradural Meningeal Cysts Spanning Multiple Vertebral Segments by Auxiliary Neuroendoscope.

BACKGROUND: Spinal extradural meningeal cysts (SEMCs) are rare lesions, especially those spanning multiple vertebral segments, and the surgical strategy has remained controversial. In the present study, we have described the outcomes of 4 patients with SEMCs treated with dural defect repair alone assisted by neuroendoscopy. METHODS: From January 2018 to January 2020, 4 patients with SEMCs spanning multiple vertebral segments had undergone single-vertebral laminectomy or hemilaminectomy. RESULTS: The SEMCs in all 4 patients had spanned multiple vertebral segments, from T11 to L2. Using magnetic resonance imaging, the location of the dural defect was predicted correctly for 3 patients. Single-vertebral laminectomy was used in 2 patients and single-vertebral hemilaminectomy in 2 patients. Intraoperatively, the entire cyst, including the upper pole, lower pole, and middle segment of the cyst, was explored using neuroendoscopy. In each patient, only 1 dural defect was found, which had been located in the middle segment of the cyst (T12-L1). All cyst dural defects had been sutured under a microscope. In all cases, the cyst wall was not removed. Postoperatively, the symptoms for all the patients had improved significantly, and subsequent magnetic resonance imaging studies showed obvious cyst regression. During the follow-up period of 15-44 months, no recurrence was observed. CONCLUSIONS: For SEMCs spanning multiple vertebral segments, dural defect repair without cyst wall resection through single-vertebral hemilaminectomy or laminectomy can be effective. Intraoperative neuroendoscopy can assist, not only in finding the dural defect, but also in avoiding the omission of multiple dural defects as much as possible.

Outcome of Initial 3 Years of Cranial Endoscopy at DG Khan Medical College and Teaching Hospital, Dera Ghazi Khan.

OBJECTIVE: With the evolution of surgical approaches, endoscopic skull base surgery has emerged as a suitable alternative to many other invasive methods. The aim of this study was to investigate the efficacy and outcome of cranial endoscopy in treating various neurosurgical intracranial pathologies in terms of procedural success and complications. METHODS: This observational, prospective case series was conducted at the Department of Neurosurgery of DG Khan Medical College from November 2017 to October 2020. The study enrolled 74 patients with indications for cranial neuroendoscopy. Clinical examination was performed, and a detailed history of the disease was obtained. Follow-up was conducted in the outpatient department. The collected data were analyzed using statistical analysis software. RESULTS: Of 77 procedures performed, endoscopic third ventriculostomy, arachnoid cyst fenestration, septostomy, colloid cyst excision, endoscopic assisted ventricular catheter placement, and intraventricular tumor biopsy were performed in 53.3%, 18.2%, 10.4%, 7.8%, 6.5%, and 3.9% of patients. Aqueductal stenosis was identified as the most common cause of obstructive hydrocephalus. Seizures and cerebrospinal fluid leaks were the most commonly reported complications (12% and 8.1%, respectively). The observed mortality rate was 2.7%. CONCLUSIONS: Neuroendoscopic surgery has become safe and effective, as surgeon experience and learning have lowered the risk of complications, and offers a low-cost alternative intervention.

Neuroendoscopic surgery in neonates - indication and results over a 10-year practice.

PURPOSE: Neuroendoscopic procedures for treatment of term and preterm newborn infants, such as endoscopic lavage for posthemorrhagic hydrocephalus, are gaining popularity despite sparse data. This single-institution report compiles all neuroendoscopic surgical procedures performed in neonates during a 10-year period. METHODS: Charts and electronic records were reviewed of all consecutive newborns who underwent a neuroendoscopic procedure before reaching a postmenstrual age of 44 weeks between 09/2010 and 09/2020. Available documentation was reviewed regarding the performed neuroendoscopic procedure, course of disease, complications, and all re-operations throughout the first year of life. RESULTS: During the 10-year study period, 116 infants (median gestational age at birth: 29 1/7 weeks) underwent a total of 153 neuroendoscopic procedures (median postmenstrual age at surgery: 35 0/7 weeks). The most common indication at the time of the neuroendoscopic procedures (n = 153) was intraventricular hemorrhage (IVH, n = 119), intraventricular infection (n = 15), congenital malformation (n = 8), isolated 4th ventricle (n = 7), multiloculated hydrocephalus (n = 3), and tumor (n = 1). Thirty-eight of 116 children (32.8%) underwent 43 operative revisions after 153 neuroendoscopic procedure (28.1%). Observed complications requiring surgical revision were secondary infection (n = 11), CSF fistula (n = 9), shunt dysfunction (n = 8), failure of ETV (n = 6), among others. 72 children (62%) of 116 children required permanent CSF diversion via a shunt. The respective shunt rates per diagnosis were 47 of 80 (58.8%) for previously untreated IVH, 11 of 13 (84.6%) for intraventricular infection. Shunt survival rate for the first year of life was 74% for the whole cohort. CONCLUSION: The experience with this large cohort of neonates demonstrates the feasibility of neuroendoscopic technique for the treatment of posthemorrhagic or postinfectious hydrocephalus. Rate and type of complications after neuroendoscopic procedures were within the expected range. Assessing the potential long-term benefits of neuroendoscopic techniques has to await results of ongoing studies.

Rigid versus flexible neuroendoscopy: a systematic review and meta-analysis of endoscopic third ventriculostomy for the management of pediatric hydrocephalus.

OBJECTIVE: Endoscopic third ventriculostomy (ETV), with or without choroid plexus cauterization (±CPC), is a technique used for the treatment of pediatric hydrocephalus. Rigid or flexible neuroendoscopy can be used, but few studies directly compare the two techniques. Here, the authors sought to compare these methods in treating pediatric hydrocephalus. METHODS: A systematic MEDLINE search was conducted using combinations of keywords: "flexible," "rigid," "endoscope/endoscopic," "ETV," and "hydrocephalus." Inclusion criteria were as follows: English-language studies with patients 2 years of age and younger who had undergone ETV±CPC using rigid or flexible endoscopy for hydrocephalus. The primary outcome was ETV success (i.e., without the need for further CSF diversion procedures). Secondary outcomes included ETV-related and other complications. Statistical significance was determined via independent t-tests and Mood's median tests. RESULTS: Forty-eight articles met the study inclusion criteria: 37 involving rigid endoscopy, 10 involving flexible endoscopy, and 1 propensity scored-matched comparison. A cumulative 560 patients had undergone 578 rigid ETV±CPC, and 661 patients had undergone 672 flexible ETV±CPC. The flexible endoscopy cohort had a significantly lower average age at the time of the procedure (0.33 vs 0.53 years, p = 0.001) and a lower preoperatively predicted ETV success score (median 40, IQR 32.5-57.5 vs 62.5, IQR 50-70; p = 0.033). Average ETV success rates in the rigid versus flexible groups were 54.98% and 59.65% (p = 0.63), respectively. ETV-related complication rates did not differ significantly at 0.63% for flexible endoscopy and 3.46% for rigid endoscopy (p = 0.30). There was no significant difference in ETV success or complication rate in comparing ETV, ETV+CPC, and ETV with other concurrent procedures. CONCLUSIONS: Despite the lower expected ETV success scores for patients treated with flexible endoscopy, the authors found similar ETV success and complication rates for ETV±CPC with flexible versus rigid endoscopy, as reported in the literature. Further direct comparison between the techniques is necessary.

[Application of Neuroendoscope and Exoscope for Glioma Surgery].

The recent progress of neuroendoscopy and exoscopy has yielded new strategies in neurosurgery, especially in glioma surgery. Neuroendoscopic port surgery makes it possible to remove deep-seated gliomas with minimal invasiveness. In port surgery, it is important to control tumor bleeding during intratumoral removal. As exoscopic systems have high flexibility of the video camera position, the surgical approach can be selected with various visual axes, which is difficult when using microscopic systems. Considering the characteristics of exoscopes, exoscopic surgery can be applied for the removal of superficial gliomas, and exoscopes are useful for glioma resection under awake craniotomy. However, there are outstanding tasks to improve surgical devices for neuroendoscopic surgery. The video quality and deep lighting of exoscopes are insufficient for general usage. Moreover, there are few training courses available for these surgical techniques. In the near future, based on these developments, neuroendoscopic and exoscopic surgeries may become more common treatments.

TROPHY registry - status report.

INTRODUCTION: The TROPHY registry has been established to conduct an international multicenter prospective data collection on the surgical management of neonatal intraventricular hemorrhage (IVH)-related hydrocephalus to possibly contribute to future guidelines. The registry allows comparing the techniques established to treat hydrocephalus, such as external ventricular drainage (EVD), ventricular access device (VAD), ventricular subgaleal shunt (VSGS), and neuroendoscopic lavage (NEL). This first status report of the registry presents the results of the standard of care survey of participating centers assessed upon online registration. METHODS: On the standard of treatment forms, each center indicated the institutional protocol of interventions performed for neonatal post-hemorrhagic hydrocephalus (nPHH) for a time period of 2 years (Y1 and Y2) before starting the active participation in the registry. In addition, the amount of patients enrolled so far and allocated to a treatment approach are reported. RESULTS: According to the standard of treatment forms completed by 56 registered centers, fewer EVDs (Y1 55% Y2 46%) were used while more centers have implemented NEL (Y1 39%; Y2 52%) to treat nPHH. VAD (Y1 66%; Y2 66%) and VSGS (Y1 42%; Y2 41%) were used at a consistent rate during the 2 years. The majority of the centers used at least two different techniques to treat nPHH (43%), while 27% used only one technique, 21% used three, and 7% used even four different techniques. Patient data of 110 infants treated surgically between 9/2018 and 2/2021 (13% EVD, 15% VAD, 30% VSGS, and 43% NEL) were contributed by 29 centers. CONCLUSIONS: Our results emphasize the varying strategies used for the treatment of nPHH. The international TROPHY registry has entered into a phase of growing patient recruitment. Further evaluation will be performed and published according to the registry protocol.

Neuroendoscopic training in neurosurgery: a simple and feasible model for neurosurgical education.

BACKGROUND: The development of high levels of technical competence and excellent decision-making skills are key goals of all neurosurgical residency training programs. This acquisition of technical skills is becoming increasingly difficult due to many factors including less exposure to operative cases, demand for more time and cost-effective practices, and resident work hour restrictions. We describe a step-by-step method for how to build a low-cost and feasible model that allows residents to improve their neuroendoscopic skills. METHODS: The bell pepper-based model was developed as an endoscopic training model. Using continuous irrigation, several hands-on procedures were proposed under direct endoscopic visualization. Endoscope setup, endoscopic third ventriculostomy, septostomy, and tumor biopsy procedures were simulated and video recorded for further edition and analysis. RESULTS: The model can be setup in less than 15 min with minimal cost and infrastructure requirements. A single model allows simulation of all the exercises described above. The model allows exposure to the camera skills, instrument handling, and hand-eye coordination inherent to most neuroendoscopic procedures. CONCLUSION: Minimal infrastructure requirements, simplicity, and easily setup models provide a proper environment for regular training. The bell pepper-based model is inexpensive, widely available, and a feasible model for routine training. Neurosurgery residents may benefit from the use of this model to accelerate their learning curve and familiarize themselves with the neuroendoscopic core principles in a risk-free environment without time or resource constraints.

Benefits of Endoscopic Sheath in Intraventricular Neuroendoscopy: Technical Note.

BACKGROUND: The usefulness of the endoscopic sheath is underreported in the literature. OBJECTIVE AND METHODS: To explain the use of an endoscopic sheath and to highlight its benefits. RESULTS: In addition to protecting the surrounding brain parenchyma when inserting the endoscope, the endoscopic sheath is a very useful tool to retract neurovascular structures, achieve hemostasis, and create adequate working space within narrow ventricles. The sheath can be moved within the ventricular system, and the endoscope can be moved independently within the sheath. These movements represent all the advantages of the endoscopic sheath. CONCLUSIONS: We used an endoscopic sheath in ∼ 300 intraventricular neuroendoscopic procedures and consider the sheath an essential part of a ventriculoscopic system. Proper use of the sheath can help avoid or manage endoscopic complications.

Single-Surgeon in Vivo Experience with the Zeiss QEVO Microinspection Tool: An Analysis of Its Use for Extending the Reach of Operative Visualization.

The operating microscope is a foundational tool in modern neurosurgery. Operating microscopes serve increasingly as the lynchpin for highly sophisticated visualization platforms incorporating many complementary technologies. The Zeiss QEVO microinspection tool is a 45-degree viewing endoscopic instrument integrated into the Zeiss KINEVO 900 operating microscope (Carl Zeiss AG, Oberkochen, Germany). The QEVO tool enables surgeons to "look around the corners" of the surgical field to optimize visualization within tight operative corridors. In this article, we document our experience using the QEVO microinspection tool in a series of complex cranial neurosurgery procedures. This report focuses on the handling, visualization, and overall utility of the QEVO tool for achieving optimal visualization in deep cranial corridors.

Cardiorespiratory synchronisation and systolic blood pressure correlation of peripheral arterial stiffness during endoscopic thoracic sympathectomy.

Muscle sympathetic nerve activity (MSNA) is known as an effective measure to evaluate peripheral sympathetic activity; however, it requires invasive measurement with the microneurography method. In contrast, peripheral arterial stiffness affected by MSNA is a measure that allows non-invasive evaluation of mechanical changes of arterial elasticity. This paper aims to clarify the features of peripheral arterial stiffness to determine whether it inherits MSNA features towards non-invasive evaluation of its activity. To this end, we propose a method to estimate peripheral arterial stiffness [Formula: see text] at a high sampling rate. Power spectral analysis of the estimated [Formula: see text] was then performed on data acquired from 15 patients ([Formula: see text] years) who underwent endoscopic thoracic sympathectomy. We examined whether [Formula: see text] exhibited the features of MSNA where its frequency components synchronise with heart and respiration rates and correlates with the low-frequency component of systolic blood pressure. Regression analysis revealed that the local peak frequency in the range of heartbeat frequency highly correlate with the heart rate ([Formula: see text], [Formula: see text]) where the regression slope was approximately 1 and intercept was approximately 0. Frequency analysis then found spectral peaks of [Formula: see text] approximately 0.2 Hz that correspond to the respiratory cycle. Finally, cross power spectral analysis showed a significant magnitude squared coherence between [Formula: see text] and systolic blood pressure in the frequency band from 0.04 to 0.2 Hz. These results indicate that [Formula: see text] inherits the features observed in MSNA that require invasive measurements, and thus [Formula: see text] can be an effective non-invasive substitution for MSNA measure.

Effect of endoscope flexibility on tissue dissection profile assessed with pulsed water jet device: ensuring safety, efficacy, and handling of thin devices for neuroendoscopic surgery.

OBJECTIVE: We developed an actuator-driven pulsed water jet device (ADPJ) for flexible neuroendoscopy to achieve effective tissue dissection with vasculature preservation. Although flexibility is a strong advantage for minimally invasiveness, the effect of the ductile curvature on the dissection profiles remains unknown. The purpose of this study was to clarify the impact of the curvature change of the ADPJ connecting tube on the dissection safety and efficacy. RESULTS: Three ADPJ connecting tubes with different inner diameters (1.0, 0.75, 0.5 mm) were used to dissect the brain phantom. They were bent at 3 angles: 0°, 60°, and 120°. The dissection profiles were evaluated using the mean depth and coefficient of variation (CV) for efficacy and safety, respectively.The larger inner diameter connecting tube dissected more deeply. The dissection depth was not changed regardless of the curvature degree in each tube. There was no significant difference in CVs regardless of inner diameter and curvature. The ductile curvature of the flexible neuroendoscope did not affect the efficacy and safety of the ADPJ dissection profile. Among the numerous instruments, tube-formed devices, including suction and injecting devices such as ADPJ, can be used safely and effectively without flexibility-related limitations.