Risk factors of high fluid absorption in patients treated with mini-PCNL: a single-center prospective study.

BACKGROUND: The factors influencing fluid absorption in mini-percutaneous nephrolithotripsy (mini-PCNL) are still unknown. We aim to investigate the factors that influence irrigation fluid absorption during mini-PCNL. METHODS: A total of 94 patients who underwent mini-PCNL were included in this prospective study. The endoscopic surgical monitoring system (ESMS) was used to measure the volume of irrigation fluid absorbed during the procedure. Irrigating time, the total volume of irrigation fluid, stone size, S.T.O.N.E. score, hemoglobin, electrolyte levels, and postoperative complications were recorded. RESULTS: A significant correlation was observed between fluid absorption and the presence of postoperative fever, and based on this phenomenon, patients were divided into low and high fluid absorption groups. The serum creatinine level in the high fluid absorption group was significantly high (7 vs. 16.5, p = 0.02). Significant differences were observed between the low and high fluid absorption groups in terms of mean stone size (21.70 mm vs. 26.78 mm), presence of stone burden ≥ 800 mm2 (4% vs. 23%), S.T.O.N.E. score > 8 (4% vs. 38%), the fluid used > 18,596 ml (19% vs. 78%), irrigation time (55.61 min vs. 91.28 min), and perfusion rate (24% vs. 45%) (all p < 0.05). The rates of postoperative fever and SIRS in the high fluid absorption group were significantly high (p < 0.05). CONCLUSIONS: Mean stone size, presence of stone burden ≥ 800 mm2, S.T.O.N.E. score > 8, the fluid used > 18596 mL, irrigation time, and perfusion rate are risk factors of intraoperative fluid absorption in mini-PCNL.

Written language preservation in glioma patients undergoing awake surgery: The value of tailored intra-operative assessment.

Written language is increasingly important, as contemporary society strongly relies on text-based communication. Nonetheless, in neurosurgical practice, language preservation has classically focused on spoken language. The current study aimed to evaluate the potential role of intra-operative assessments in the preservation of written language skills in glioma patients undergoing awake surgery. It is the first feasibility study to use a standardized and detailed Written language battery in glioma patients undergoing awakening surgery. Reading and spelling were assessed pre- and post-operatively in eleven patients. Intra-operatively, 7 cases underwent written language assessment in addition to spoken object naming. Results show that reading and spelling deficits may arise before and after glioma surgery and that written language may be differently affected than spoken language. In our case series, task-specific preservation of function was obtained in all cases when a specific written language skill was monitored intra-operatively. However, the benefits of intra-operative testing did not always generalize, and non-monitored written language tasks may not be preserved. Hence, when a specific written language skill needs to be preserved, to facilitate return to work and maintain quality of life, results indicate that intra-operative assessment of that skill is advised. An illustrative case report demonstrates how profile analyses can be used pre-operatively to identify cognitive components at risk and intra-operatively to preserve written language abilities in clinical practice.

Effect of nociception level index-guided intra-operative analgesia on early postoperative pain and opioid consumption: a systematic review and meta-analysis.

Acute postoperative pain remains a critical treatment priority and has prompted a search for technologies and techniques to assist with intra-operative analgesic monitoring and management. Anaesthetists traditionally rely on clinical judgement to guide intra-operative analgesia, but several emerging technologies such as the nociception level index herald the possibility of routine intra-operative analgesia monitoring. However, the impact of devices like nociception level index on postoperative outcomes has not been proven. We undertook a systematic review and meta-analysis of articles which compared nociception level index-guided analgesia to standard care. The primary outcomes were pain intensity and opioid consumption during the first 60-120 min after surgery. Secondary outcomes were the incidence of postoperative nausea and vomiting and duration of stay in the post-anaesthesia care unit. Ten studies, collectively including 662 patients and published between 2019 and 2023, met inclusion criteria for both the qualitative systematic review and quantitative meta-analysis. Risk of methodological bias was generally low or unclear, and six studies reported a significant conflict of interest relevant to their findings. Our meta-analysis was performed using a random-effects model. It found statistically significant benefits of nociception level index-guided analgesia for early postoperative pain (mean (95%CI) difference -0.46 (-0.88 to -0.03) on an 11-point scale, p = 0.03), and opioid requirement (mean (95%CI) difference -1.04 (-1.94 to -0.15) mg intravenous morphine equivalent, p = 0.02). Our meta-analysis of the current literature finds that nociception level index-guided analgesia statistically significantly reduces reported postoperative pain intensity and opioid consumption but fails to show clinically relevant outcomes. We found no evidence that nociception level index-guided analgesia affected postoperative nausea and vomiting nor duration of stay in the post-anaesthesia care unit.

Feasibility, Safety and Reliability of Surgeon-Directed Transcranial Motor Evoked Potentials Monitoring in Scoliosis Surgery.

(1) Background: Neuromonitoring is essential in corrective surgery for scoliosis. Our aim was to assess the feasibility, safety and reliability of "surgeon-directed" intraoperative monitoring transcranial motor evoked potentials (MEP) of patients. (2) Methods: A retrospective single-center study of a cohort of 190 scoliosis surgeries, monitored by NIM ECLIPSE (Medtronic), between 2017 and 2021. Girls (144) and boys (46) (mean age of 15 years) were included. There were 149 idiopathic and 41 secondary scoliosis. The monitoring consisted of stimulating the primary motor cortex to record the MEP with muscular recording on the thenar, vastus lateralis, tibialis anterior and adductor hallucis muscles. (3) Results: The monitoring data was usable in 180 cases (94.7%), with 178 true negatives, no false negatives and one false positive. There was one true positive case. The predictive negative value was 100%. The monitoring data was unusable in 10 cases (i.e., three idiopathic and seven secondary scoliosis). (4) Conclusions: Simplified transcranial MEP monitoring known as "surgeon-directed module" is usable, safety and reliable in surgery for moderate scoliosis. It is feasible in 95% of cases with a negative predictive value of 100%.

Intramedullary Tuberculoma of the Conus Medularis in an Immunocompetent Young Adult with no Pulmonary Tuberculosis, the Challenges of Diagnosis and Management: A Case Report and Review of Literature.

Background and Objective: Intramedullary tuberculoma (IMT) of the conus medullaris is an extremely rare tumour that constitutes a diagnostic and management challenge in a resource-limited setting. We report a case of conus medullaris, IMT in a young immunocompetent, patient with no prior clinical features of pulmonary or extra-pulmonary tuberculosis. Case Summary: The patient presented with six months history of progressive and persistent mid back pain and slight weakness of both lower limbs of 3 months duration. Physical examination revealed a well-nourished man with power of 3/5 and hyperreflexia on both lower limbs. Chest radiograph and other investigations for tuberculosis were negative. Magnetic resonance imaging (MRI) of the lumbosacral spine showed fusiform expansion of the conus medullaris, with a well circumscribed, ring enhancing, intramedullary mass straddle between T12 and L1. Patient had gross total resection with no intraoperative monitoring assistance and no post-operative worsening of neurological function. Histology showed granulomatous lesion with central caseation in keeping with a tuberculoma. Patient was commenced on post-operative anti-tuberculous therapy with physiotherapy, with full motor recovery at six months post-surgical intervention and anti-tuberculous therapy. Conclusion: Intramedullary tuberculoma can be considered as one of the differential diagnoses of intradural, intramedullary tumour of the conus, even in immunocompetent individual with no clinical features of tuberculosis.

Measuring and evaluating standardization of scrub nurse instrument table setups: a multi-center study.

OBJECTIVES: In-depth knowledge about surgical processes is a crucial prerequisite for future systems in operating rooms and the advancement of standards and patient safety in surgery. A holistic approach is required, but research in the field of surgical instrument tables, standardized instrument setups and involved personnel, such as nurses, is sparse in general. The goal of this study is to evaluate whether there is an existing standard within clinics for an instrument table setup. We also evaluate to which extent it is known to the personnel and whether it is accepted. MATERIALS AND METHODS: The study makes use of the Nosco Trainer, a scrub nurse training and simulation system developed to analyze various aspects of the workplace of scrub nurses. The system contains a virtual instrument table, which is used to perform and record instrument table setups. We introduce a metric which delivers a measurable score for the similarity of surgical instrument table setups. The study is complemented with a questionnaire covering related aspects. RESULTS: Fifteen scrub nurses of the Otolaryngology departments at three clinics in Germany and Switzerland performed a table setup for a Functional Endoscopic Sinus Surgery intervention and completed the questionnaire. The analysis of the developed metric with a leave one out cross-validation correctly allocated 14 of the 15 participants to their clinic. DISCUSSION: In contrast to the identified similarities of table setups within clinics with the collected data, only a third of the participants confirmed in the questionnaire that there is an existing table setup standard for Functional Endoscopic Sinus Surgery interventions in their facility, but almost three quarters would support a written standard and acknowledge its possible benefits for trainees and new entrants in the operating room. CONCLUSIONS: The structured analysis of the surgical instrument table using a data-driven metric for comparison is a novel approach to gain deeper knowledge about intra-operative processes. The insights can contribute to patient safety by improving the workflow between surgeon and scrub nurse and also open the way for goal-oriented standardization.

Intra-operative neurophysiological mapping to identify distorted functional anatomy of the 4th ventricle in a 5-month-old infant.

BACKGROUND: Neurophysiological brainstem mapping techniques facilitate the intra-operative localisation of cranial nerve nuclei amidst distorted anatomy. Neurophysiological recording in young infants can be limited due to immature myelination and synaptogenesis, as well as an increased sensitivity to anaesthetic agents. CASE REPORT: A 5-month-old boy was diagnosed with a cystic brainstem lesion located dorsally within the pons and upper medulla. An open surgical biopsy was undertaken via a posterior fossa craniotomy, revealing a grossly distorted fourth ventricular floor. Intra-operative neurophysiological mapping produced oculomotor, facial, glossopharyngeal and vagal muscle responses allowing a deviated functional midline to be identified. Direct stimulation was used to identify an area in the floor of the fourth ventricle eliciting no cranial nerve responses and allow safe entry into the tumour cavity and biopsy. Transcranial motor evoked responses (TcMEPs), short-latency somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) were all successfully recorded throughout the procedure, despite the use of halogenated gaseous anaesthesia. CONCLUSIONS: We describe the use of brainstem mapping techniques for identification of a distorted midline on the floor of the 4th ventricle in an infant, with reproducible recordings of intra-operative TcMEPs, SSEPs and BAEPs.

The clinical role of transesophageal echocardiography during transvenous lead extraction.

BACKGROUND: Transesophageal echocardiography (TEE) is commonly used during cardiothoracic procedures. TEE has also become standard during transvenous lead extraction (TLE) procedures, but its effect and role have not been optimally defined. The goal of this study is to identify how TEE was used during TLE at our institute and review its utility. METHODS: We retrospectively reviewed high-risk patients undergoing TLE, for whom more complications during extraction procedures, from June 2012 to September 2020. The patients were divided into TEE group and non-TEE group according to real-time TEE monitoring. We compared the rate of procedural success, complications between two groups and concluded the clinical utility of TEE during TLE. RESULTS: A total of 195 patients were included (105 in TEE group vs 90 in non-TEE group), the rate of procedure success (97.8% vs 96.5%, p = 0.41) and complications during extraction (8.6% vs 12.2%, p = 0.40, major complication 5.7% vs 12.2%, p = 0.11, minor complication 2.9% vs 0%, p = 0.30) were comparable. In TEE group, 12 patients (11.4%) received following benefits: altering surgical plans, guiding subsequent therapy strategies, and rapidly diagnosing complications, moreover no complications occurred from TEE. CONCLUSIONS: This study demonstrates that real-time monitoring by TEE cannot change the rate of procedural success and complication during TLE; however, TEE provides valuable information to instruct clinical therapy and improves the safety of TLE.

Feasibility and diagnostic accuracy of intra-operative monitoring of motor evoked potentials in children <2 years of age undergoing tethered cord surgery: results in 100 children.

OBJECTIVE: This study documents the monitorability using different anesthesia regimes and accuracy of muscle motor evoked potentials (mMEPs) in children ≤2 years of age undergoing tethered cord surgery (TCS). METHODS: Intraoperative mMEP monitoring was attempted in 100 consecutive children, ≤2 years of age, undergoing TCS. MEP monitoring was done under 4 different anesthetic regimes: (Total intravenous anesthesia (TIVA); balanced anesthesia with sevoflurane and ketamine; balanced anesthesia with isoflurane and ketamine; and balanced anesthesia with sevoflurane). Factors analyzed for their effect on monitorability were: age, neurological deficits, type of anesthesia, and the number of pulses used for stimulation. RESULTS: Baseline mMEPs were obtained in 87% children. Monitorability of mMEPs was similar in children ≤1 year and 1-2 years of age (85.7% and 87.5%). In multivariate analysis, anesthesia regime was the only significant factor predicting presence of baseline mMEPs. Children undergoing TIVA (p=0.02) or balanced anesthesia with a combination of propofol, sevoflurane, and ketamine (p=0.05) were most likely to have baseline mMEPs. mMEPs had a sensitivity of 97.4%, specificity of 96.4%, negative predictive value of 98.2% and accuracy of 96.8%. CONCLUSIONS: Baseline mMEPs were obtained in >85% of children ≤2 years of age including those who had motor deficits. TIVA and balanced anesthesia with sevoflurane and ketamine are ideal for mMEP monitoring. mMEPs have a high accuracy although, false positive and false negative results can occasionally be experienced.

Last Electrically Well: Intraoperative Neurophysiological Monitoring for Identification and Triage of Large Vessel Occlusions.

INTRODUCTION: Intra-operative stroke (IOS) is associated with poor clinical outcome as detection is often delayed and time of symptom onset or patient's last known well (LKW) is uncertain. Intra-operative neurophysiological monitoring (IONM) is uniquely capable of detecting onset of neurological dysfunction in anesthetized patients, thereby precisely defining time last electrically well (LEW). This novel parameter may aid in the detection of large vessel occlusion (LVO) and prompt treatment with endovascular thrombectomy (EVT). METHODS: We performed a retrospective analysis of a prospectively maintained AIS and LVO database from May 2018-August 2019. Inclusion criteria required any surgical procedure under general anesthesia (GA) utilizing EEG (electroencephalography) and/or SSEP (somatosensory evoked potentials) monitoring with development of intraoperative focal persistent changes using predefined alarm criteria and who were considered for EVT. RESULT: Five cases were identified. LKW to closure time ranged from 66 to 321 minutes, while LEW to closure time ranged from 43 to 174 min. All LVOs were in the anterior circulation. Angiography was not pursued in two cases due to large established infarct (both patients expired in the hospital). EVT was pursued in two cases with successful recanalization and spontaneous recanalization was noted in one patient (mRS 0-3 at 90 days was achieved in all 3 cases). CONCLUSIONS: This study demonstrates that significant IONM changes can accurately identify patients with an acute LVO in the operative setting. Given the challenges of recognizing peri-operative stroke, LEW may be an appropriate surrogate to quickly identify and treat IOS.

Intra-Operative Hypotension is a Risk Factor for Post-operative Silent Brain Ischaemia in Patients With Pre-operative Hypertension Undergoing Carotid Endarterectomy.

OBJECTIVE: Intra-operative haemodynamic instability during carotid endarterectomy (CEA) has been associated with an increased risk of procedural stroke. Diffusion weighted imaging (DWI) lesions have been proposed as a surrogate marker for peri-operative silent cerebral ischaemia. This study aimed to investigate the relationship between peri-operative blood pressure (BP) and presence of post-operative DWI lesions in patients undergoing CEA. METHODS: A retrospective analysis was performed based on patients with symptomatic CEA included in the MRI substudy of the International Carotid Stenting Study. Relative intra-operative hypotension was defined as a decrease of intra-operative systolic BP ≥ 20% compared with pre-operative ('baseline') BP, absolute hypotension was defined as a drop in systolic BP < 80  mmHg. The primary endpoint was the presence of any new DWI lesions on post-operative MRI (DWI positive). The occurrence and duration of intra-operative hypotension was compared between DWI positive and DWI negative patients as was the magnitude of the difference between pre- and intra-operative BP. RESULTS: Fifty-five patients with symptomatic CEA were included, of whom eight were DWI positive. DWI positive patients had a significantly higher baseline systolic (186 ± 31 vs. 158 ± 27 mmHg, p = .011) and diastolic BP (95 ± 15 vs. 84 ± 13 mmHg, p = .046) compared with DWI negative patients. Other pre-operative characteristics did not differ. Relative intra-operative hypotension compared with baseline occurred in 53/55 patients (median duration 34 min; range 0-174). Duration of hypotension did not differ significantly between the groups (p = .088). Mean systolic intra-operative BP compared with baseline revealed a larger drop in BP (-37 ± 29 mmHg) in DWI positive compared with DWI negative patients (-14 ± 26 mmHg, p = .024). Absolute intra-operative systolic BP values did not differ between the groups. CONCLUSION: In this exploratory study, high pre-operative BP and a larger drop of intra-operative BP were associated with peri-procedural cerebral ischaemia as documented with DWI. These results call for confirmation in an adequately sized prospective study, as they suggest important consequences for peri-operative haemodynamic management in carotid revascularisation.

The determination of real fluid requirements in laparoscopic resection of pheochromocytoma using minimally invasive hemodynamic monitoring: a prospectively designed trial.

BACKGROUND: Hemodynamic instability is frequently observed during adrenalectomy for pheochromocytoma (PCC). Guidelines recommend liberal preoperative volume administration. However, it is unclear whether fluid deficiency or vasoplegia causes shifting hemodynamics and whether minimally invasive hemodynamic monitoring with esophageal Doppler (EDM) can help visualize intraoperative changes avoiding volume overload and complications. METHODS: Ten patients with biochemically verified PCC and five patients with hormonally inactive adrenal tumors (HIAT; control group) were treated following a strict protocol. During laparoscopic adrenalectomy, goal-directed fluid therapy was performed using EDM. Hemodynamic and biochemical data were documented. The primary outcome variables were fluid requirement and hemodynamic parameters. RESULTS: Applying EDM, total intraoperative fluid administration was slightly higher in PCC patients than in patients with HIAT (2100 ± 516 vs. 1550 ± 622 ml, p = 0.097; 12.9 ± 4.8 vs. 8.3 ± 0.7 ml kg-1 h-1, p = 0.014). Hemodynamics varied considerably within the PCC group and was associated with type and level of secreted catecholamines. Arterial blood pressure and systemic vascular resistance index reached their minimum in the 10-min period after resection of PCC. Without liberal fluid administration, an increase in cardiac index was observed in both groups comparing baseline measurements to end of surgery. This increase was statistically significant only in PCC patients (PCC: 2.31 vs. 3.15 l min-1 m-2, p = 0.005; HIAT: 2.08 vs. 2.56 l min-1 m-2, p = 0.225). CONCLUSIONS: As vasoplegia, but not hypovolemia, was documented after tumor resection, there is no evidence that PCC patients profit from liberal fluid administration during laparoscopic adrenalectomy. To avoid volume overload, noninvasive techniques such as EDM should be routinely used to visualize the variable intraoperative course. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT01425710.

Direct cortical stimulation with cylindrical depth electrodes in the interhemispheric fissure for leg motor evoked potential monitoring.

OBJECTIVE: To evaluate cylindrical depth electrodes in the interhemispheric fissure as an alternative to subdural strip electrodes for direct cortical stimulation (DCS) leg motor evoked potential (MEP) monitoring. METHODS: A cylindrical depth electrode was positioned in the interhemispheric fissure of 37 patients who underwent supratentorial brain surgery. Leg sensory and motor cortices were localized by highest tibial nerve somatosensory evoked potential amplitude and lowest DCS leg MEP threshold; the lowest-threshold electrode was then used for DCS leg MEP monitoring. RESULTS: Intraoperative leg MEPs were obtained from all the patients in the series. The mean intensity applied for leg MEP monitoring with the cylindrical depth electrode was 15.2 ± 4.0 mA. No complications secondary to neurophysiological monitoring were detected. CONCLUSIONS: Lower extremity MEPs were consistently recorded using a multi-contact cylindrical depth electrode in the interhemispheric fissure by DCS. SIGNIFICANCE: Cylindrical depth electrodes may be a safe and effective alternative for DCS in the interhemispheric fissure, where subdural strips are difficult to place.

Cardiac output monitoring with thermodilution pulse-contour analysis vs. non-invasive pulse-contour analysis.

Intravenous fluid boluses guided by changes in stroke volume improve some outcomes after major surgery, but invasive measurments may limit use. From October 2016 to May 2018, we compared the agreement and trending ability of a photoplethysmographic device (Clearsight) with a PiCCO, calibrated by thermodilution, for haemodynamic variables in 20 adults undergoing major elective surgery. We analysed 4519 measurement pairs, including before and after 68 boluses of 250 ml crystalloid. The bias and precision of stroke volume measurement by Clearsight were -0.89 ± 4.78 ml compared with the invasive pulse-contour cardiac output device. The coefficient of agreement for stroke volume variation after fluid boluses between the two devices was 0.79 ('strong'). Fluid boluses that increased stroke volume by ≥ 10% increased mean absolute volume (SD) and mean percentage (SD) stroke volume measurements similarly for the invasive pulse-contour cardiac output and Clearsight devices: 9 (4) ml vs. 8 (4) ml and 16% (8%) vs. 15% (10%), respectively, p > 0.05. The non-invasive Clearsight pulse-contour analysis was similar to an invasive pulse-contour device in measuring absolute and changing stroke volumes during major surgery.

Investigating the utility of intraoperative neurophysiological monitoring for anterior cervical discectomy and fusion: analysis of over 140,000 cases from the National (Nationwide) Inpatient Sample data set.

OBJECTIVE: Intraoperative neurophysiological monitoring (IONM) is a useful adjunct in spine surgery, with proven benefit in scoliosis-correction surgery. However, its utility for anterior cervical discectomy and fusion (ACDF) is unclear, as there are few head-to-head comparisons of ACDF outcomes with and without the use of IONM. The authors sought to evaluate the impact of IONM on the safety and cost of ACDF. METHODS: This was a retrospective analysis of data from the National (Nationwide) Inpatient Sample of the Healthcare Cost and Utilization Project from 2009 to 2013. Patients with a primary procedure code for ACDF were identified, and diagnosis codes were searched to identify cases with postoperative neurological complications. The authors performed univariate and multivariate logistic regression for postoperative neurological complications with use of IONM as the independent variable; additional covariates included age, sex, surgical indication, multilevel fusion, Charlson Comorbidity Index (CCI) score, and admission type. They also conducted propensity score matching in a 1:1 ratio (nearest neighbor) with the use of IONM as the treatment indicator and the aforementioned variables as covariates. In the propensity score-matched cohort, they compared neurological complications, length of stay (LOS), and hospital charges (in US dollars). RESULTS: A total of 141,007 ACDF operations were identified. IONM was used in 9540 cases (6.8%). No significant association was found between neurological complications and use of IONM on univariate analysis (OR 0.80, p = 0.39) or multivariate regression (OR 0.82, p = 0.45). By contrast, age ≥ 65 years, multilevel fusion, CCI score > 0, and a nonelective admission were associated with greater incidence of neurological complication. The propensity score-matched cohort consisted of 18,760 patients who underwent ACDF with (n = 9380) or without (n = 9380) IONM. Rates of neurological complication were comparable between IONM and non-IONM (0.17% vs 0.22%, p = 0.41) groups. IONM and non-IONM groups had a comparable proportion of patients with LOS ≥ 2 days (19% vs 18%, p = 0.15). The use of IONM was associated with an additional $6843 (p < 0.01) in hospital charges. CONCLUSIONS: The use of IONM was not associated with a reduced rate of neurological complications following ACDF. Limitations of the data source precluded a specific assessment of the effectiveness of IONM in preventing neurological complications in patients with more complex pathology (i.e., ossification of the posterior longitudinal ligament or cervical deformity).

Anesthetic considerations for stereotactic electroencephalography implantation.

The refractory seizures have significant impact on the quality of life and increase long term neurologic and non-neurologic complications. Implantation of Stereotactic Electroencephalography (SEEG) leads is one of the newer surgical techniques intended to localize seizure foci with higher accuracy than the conventional methods. Most of the commonly utilized anesthetic agents depress EEG waveforms affecting intra operative monitoring during these surgeries. Hence, the anesthetic goals include a stable induction and maintenance with agents which have minimal effect on EEG. This article discusses the peri-operative considerations of multiple anti-epileptic medications, recent advances in anesthetic management, and important post-operative concerns.

Electrophysiological Evidence of the Basilar-Membrane Travelling Wave and Frequency Place Coding of Sound in Cochlear Implant Recipients.

AIM: To obtain direct evidence for the cochlear travelling wave in humans by performing electrocochleography from within the cochlea in subjects implanted with an auditory prosthesis. BACKGROUND: Sound induces a travelling wave that propagates along the basilar membrane, exhibiting cochleotopic tuning with a frequency-dependent phase delay. To date, evoked potentials and psychophysical experiments have supported the presence of the travelling wave in humans, but direct measurements have not been made. METHODS: Electrical potentials in response to rarefaction and condensation acoustic tone bursts were recorded from multiple sites along the human cochlea, directly from a cochlear implant electrode during, and immediately after, its insertion. These recordings were made from individuals with residual hearing. RESULTS: Electrocochleography was recorded from 11 intracochlear electrodes in 7 ears from 6 subjects, with detectable responses on all electrodes in 5 ears. Cochleotopic tuning and frequency-dependent phase delay of the cochlear microphonic were demonstrated. The response latencies were slightly shorter than those anticipated which we attribute to the subjects' hearing loss. CONCLUSIONS: Direct evidence for the travelling wave was observed. Electrocochleography from cochlear implant electrodes provides site-specific information on hair cell and neural function of the cochlea with potential diagnostic value.

Pedicle screw position changing policy for nerve injury problems during screw insertion on thoracolumbar compression fractures.

INTRODUCTION: Intraoperative neurophysiologic monitoring (IONM) had important role related to the complications in spinal surgery. Somatosensory Evoked Potential (SSEP), Transcranial electric Muscle Evoked Potentials (tceMEPs), and free run EMG are parameters used to asses functional integrity of the nervous system during surgical procedures. Once warning signal was recognized, surgeon have to make a precise decision to overcome that problem. PRESENTATION OF CASE: We present a 47-year old male with back pain due to compression fracture of thoracic vertebra T12 and lumbar vertebrae L1. While stabilizing through the posterior approach on the T11 and 12 as well as L2 and L3, the SSEP monitor showed 50% reduction in the waveform as the pedicle screw was inserted at the left side of T12. The instrumentation was changed into vertebra thoracal T10, T11, and vertebrae lumbar L2, L3. The SSEP normalized and post operatively pain decreased. After surgery there was no neurological deficit. DISCUSSION: Acute trauma as a result of spine instrumentation may provoke significant edema, with mass effect causing neurophysiological dysfunction. Administration of intravenous steroid would do at this stage, followed by constant infusion for following 24-48h, may help ameliorating the mass effect and improving the neurologic outcome. Alternatively, immediate pedicle screw changing policy showed absolute recovery of nerve injury. CONCLUSION: Insertion of pedicle screw in spinal surgery has a risk of complication that could be treated by pedicle screw changing policy.

[Selective and non-invasive monitoring of the posterior columns and pyramidal tract during surgery of the spine and spinal cord]. / Monitorage non invasif et sélectif des cordons postérieurs et de la voie pyramidale pendant les chirurgies du rachis et de la moelle épinière.

For intra-operative neurophysiological monitoring during spine and spinal cord surgery, the challenge is to detect, in real-time, the occurrence of neurological impairment at onset in order to remedy the problem as quickly as possible before it becomes definitely acquired and irreversible. The past three decades were marked by considerable technical progress. Feasibility and reliability have now reached a very high level. A multimodal approach combining simultaneous monitoring of somatosensory and motor pathways has enabled a considerable decline in the rate of false negatives reported in the 80s when somatosensory evoked potentials (SSEP) were monitored alone. Several methods of monitoring are described in the literature. Combining transcranial electric stimulation of muscle motor evoked potentials (mMEP) and cortical SSEP allows non-invasive and selective monitoring of the posterior columns and pyramidal tract. One of the most widely used techniques internationally backed by a broad consensus within the International Society of Intra-operative Neurophysiology (ISIN), this technique remains exceptional in French-speaking countries. We expose here the methodological aspects for the readers of La Revue Neurologique.

[Contribution of neuromonitoring to the safety of tracheal extubation after total thyroidectomy. Prospective study with needle electrodes]. / Contribución de la neuroestimulación a la seguridad en la extubación traqueal tras tiroidectomía total. Estudio prospectivo con electrodos de aguja.

INTRODUCTION AND OBJECTIVES: Bilateral laryngeal paralysis cause serious respiratory complications. In thyroid surgery, neuromonitoring helps in identifying the recurrent laryngeal nerve, reports on its functioning at the end of surgery, supports decision making, and may reduce the risk of bilateral paralysis. Our objective was to estimate the influence of neuromonitoring in operative strategy and extubation safety in total thyroidectomy. METHODS: A non-randomized prospective study was conducted on 210 patients undergoing total thyroidectomy (420 laryngeal nerves stimulated included). We collected qualitative neuromonitoring variables (presence or absence of final signal after stimulation of the vagus nerve), and postoperative indirect laryngoscopy (normal motility or paralysis), performed until 3rd day after the surgery. RESULTS: The accuracy of the test was 99.5% (95% CI 98.3 to 99.9). The positive predictive value was 100% (95% CI 99.1 to 100), which showed the high ability of neuromonitoring to predict paralysis in case of loss of signal, and the negative predictive value was 99.5% (95% CI 98.3 to 99.9), which indicated its predictive capacity for normal motility when there is a normal signal. CONCLUSIONS: In our group of patients, recurrent laryngeal nerve monitoring was useful in total thyroidectomy as it provided information on the prognosis of laryngeal motility, and helped in making decisions during surgery when there was signal loss. Due to the risk of serious respiratory complications due to bilateral recurrent laryngeal nerve paralysis, we opted for the performing of the 2-stage total thyroidectomy in case of signal loss in the first lobectomy. Thereby, neuromonitoring contributed to the safety of the airway in tracheal extubation, aiding in the prevention of a possible bilateral laryngeal paralysis.