Factors affecting the extent of resection and neurological outcomes following transopercular resection of insular gliomas.

BACKGROUND: Surgical resection of insular gliomas is a challenge. TO resection is considered more versatile and has lower risk of vascular damage. In this study, we aimed to understand the factors that affect resection rates, ischemic changes and neurological outcomes and studied the utility of IONM in patients who underwent TO resection for IGs. METHODS: Retrospective analysis of 66 patients with IG who underwent TO resection was performed. RESULTS: Radical resection was possible in 39% patients. Involvement of zone II and the absence of contrast enhancement predicted lower resection rate. Persistent deficit rate was 10.9%. Although dominant lobe tumors increased immediate deficit and fronto-orbital operculum involvement reduced prolonged deficit rate, no tumor related factor showed significant association with persistent deficits. 45% of patients developed a postoperative infarct, 53% of whom developed deficits. Most affected vascular territory was lenticulostriate (39%). MEP changes were observed in 9/57 patients. 67% of stable TcMEPs and 74.5% of stable strip MEPs did not develop any postoperative motor deficits. Long-term deficits were seen in 3 and 6% patients with stable TcMEP and strip MEPs respectively. In contrast, 25% and 50% of patients with reversible strip MEP and Tc MEP changes respectively had persistent motor deficits. DWI changes were clinically more relevant when accompanied by MEP changes intraoperatively, with persistent deficit rates three times greater when MEP changes occurred than when MEPs were stable. CONCLUSION: Radical resection can be achieved in large, multizone IGs, with reasonable outcomes using TO approach and multimodal intraoperative strategy with IONM.

Utility of Multimodal Intraoperative Neuromonitoring for Excision of Filum Terminale Ependymoma in Close Proximity to Conus.

Myxopapillary ependymoma are well circumscribed tumours arising mainly from conus medullaris (CM) and filum terminale (FT), typically presenting at median age of 39 years.1 Owing to its aggressive clinical behaviour including cerebrospinal fluid dissemination and local recurrence, it is classified as grade 2 in World Health Organisation Central Nervous System 5 Classification.2 Gross total resection without capsular violation is critical, as subtotal resection is associated with local recurrence.3 The FT comprises intradural filum terminale (iFT) and extradural filum terminalecomponents with iFT extending from the inferior tip of the CM to coccyx.4 The iFT-CM junction is a transitional zone; with neural tissue being incrementally replaced by fibrous tissue of filum, gradually converging to a pure nonneural FT.5 Achieving gross total resection is challenging for intramedullary FT myxopapillary ependymoma in proximity to conus, necessitating neuromonitoring to preserve vital CM functions. We present a case of 33-year-old male with 6 months of nocturnal back pain and bilateral lower limb without neurological deficits. Preoperative MRI revealed a T2 hyperintense, heterogeneously contrast enhancing intradural extramedullary mass at L1 vertebral level.

A Nationwide Survey to Assess the Practices and Patterns of Use of Intraoperative Nerve Monitoring During Thyroid Surgery Among Surgeons in India.

There is still equipoise for the routine use of intraoperative nerve monitoring (IONM) for thyroid surgeries; however, some surgeons tend to use it for various reasons. In our study, we did a national survey to assess the patterns and practice of the use of IONM among surgeons during thyroid surgery in India. A questionnaire survey was sent to surgeons (head and neck surgical oncologists, general surgical oncologists, endocrine surgeons and otolaryngologists) in different zones in India via email, and their responses were analysed. One hundred and one responses were received. The majority of the respondents were head and neck surgical oncologists (n = 56, 55.4%). Forty-three (42.6%) respondents used IONM during thyroid surgeries in this survey. Surgeons with ≤ 15 years of experience performing thyroid surgeries (p = 0.02) and surgeons performing > 50 thyroid surgeries also tended to use IONM. Mostly IONM was used for surgeries on thyroid malignancies (p = 0.016). The respondents used IONM for more than one reason such as medicolegal purposes and surgeon comfort among others. IONM was most often used during redo surgeries (n = 46, 45.5%) and in patients with already one fixed cord (n = 39, 38.6%). The majority felt IONM was not cost-effective (n = 53, 52.5%). The use of IONM during thyroid surgery in our survey was nearly 43%. It was used mostly for surgery for thyroid malignancies, and it was found to be used for more than one reason and indications such as redo surgeries (most commonly). Supplementary Information: The online version contains supplementary material available at 10.1007/s13193-023-01818-5.

Tumor location and neurocognitive function-Unravelling the association and identifying relevant anatomical substrates in intra-axial brain tumors.

Background: Neurocognitive function is a key outcome indicator of therapy in brain tumors. Understanding the underlying anatomical substrates involved in domain function and the pathophysiological basis of dysfunction can help ameliorate the effects of therapy and tailor directed rehabilitative strategies. Methods: Hundred adult diffuse gliomas were co-registered onto a common demographic-specific brain template to create tumor localization maps. Voxel-based lesion symptom (VLSM) technique was used to assign an association between individual voxels and neuropsychological dysfunction in various domains (attention and executive function (A & EF), language, memory, visuospatial/constructive abilities, and visuomotor speed). The probability maps thus generated were further co-registered to cortical and subcortical atlases. A permutation-based statistical testing method was used to evaluate the statistically and clinically significant anatomical parcels associated with domain dysfunction and to create heat maps. Results: Neurocognition was affected in a high proportion of subjects (93%), with A & EF and memory being the most affected domains. Left-sided networks were implicated in patients with A & EF, memory, and language deficits with the perisylvian white matter tracts being the most common across domains. Visuospatial dysfunction was associated with lesions involving the right perisylvian cortical regions, whereas deficits in visuomotor speed were associated with lesions involving primary visual and motor output pathways. Conclusions: Significant baseline neurocognitive deficits are prevalent in gliomas. These are multidomain and the perisylvian network especially on the left side seems to be very important, being implicated in dysfunction of many domains.

Baseline neurocognitive dysfunction is ubiquitous in intrinsic brain tumors- results from a large Indian cohort of patients and analysis of factors associated with domain-specific dysfunction.

Background: Neurocognitive function (NCF) before surgery is an important marker of baseline performance in patients with brain tumors. Increasingly, neurocognitive deficits (NCD) have been demonstrated in a high proportion of patients. Selection bias (patient, tumor, and surgical procedure related) may influence the prevalence and type of domains involved in patients with gliomas. Methods: We evaluated baseline NCF in a consecutive cohort of intra-axial tumors in Indian patients (n = 142). A comprehensive battery evaluating five domains - attention & executive function (EF), memory, language, visuospatial function and visuomotor abilities was used. Deficits were categorized as severe and mild-moderate. Factors associated with severe NCD were evaluated. Results: Severe NCD was present in 90% of the patients, 70% of them having affection of at least 2 domains. Attention-EF, memory and visuomotor speed were most affected. 132 underwent surgery (69 awake, 63 under general anesthesia - GA). The awake cohort had younger patients with lower grade gliomas and more left sided tumors. Multi-domain dysfunction was seen almost equally in awake/GA groups as well as left/right sided tumors. On multivariate analysis, older age, lower educational status and larger tumor volume adversely affected NCF in many of the domains. Only language dysfunction was location specific (temporal lobe tumors) though not laterality (left/right) specific. Conclusions: NCD were seen in a large majority of cases before surgery, including those undergoing awake surgery. Language may be affected even in tumors in the non-dominant hemisphere. Attention-EF and memory are most affected and need to be factored in while assessing patient performance intraoperatively during awake surgery as well as tailoring rehabilitative measures subsequently.

Transopercular Approach to Resection of Dominant Hemisphere Diffuse Insular Glioma Using Multimodal Intraoperative Strategy with Awake Mapping.

Background: Deep location as well as relation to major vascular structures and eloquent brain areas make insular glioma resection challenging. Transsylvian and transopercular approaches have been described for resection of these tumors. Objective: We illustrate the anatomical relations of a dominant hemisphere insular glioma and present the video demonstrating the step-wise resection of the same via frontal transopercular approach. Surgical Procedure: A 27-year-old lady with dominant hemisphere insular glioma underwent awake surgery through a transopercular approach with cortical and subcortical mapping using direct electrical stimulation for resection of the same. Result: Gross total resection of left insular glioma was achieved without any fresh postoperative deficits. Conclusion: Awake transopercular approach with intraoperative motor, language, and neuropsychological monitoring helps achieve maximum safe resection of insular glioma in the dominant cerebral hemisphere.

Importance of Intraoperative Neuromonitoring Parameters in Predicting Temporary Recurrent Laryngeal Nerve Palsy Following Thyroid Surgery for Malignancy.

Recurrent laryngeal nerve (RLN) palsy is one of the feared complications following thyroid surgery. Intraoperative neuromonitoring (IONM) has been used as an adjunct to reduce this complication. In the present study, we attempted to evaluate the IONM parameters such as latency, current requirement, and baseline amplitude that could predict temporary RLN palsy along with factors that could influence these parameters during thyroid surgery. This was a retrospective study of patients who underwent hemi, total, or completion thyroidectomy for cancer at our institute between June 1, 2017 to May 31, 2019 in whom IONM was used during surgery. The study consisted of 84 consecutive patients with 138 nerves at risk. The RLN palsy rate in our study was 5% (n = 7). Patients with low baseline amplitude and/or requiring higher current to maintain normal baseline amplitude were often associated with temporary RLN palsy. In the multivariate analysis, age > 40 years (p = 0.001, OR = 4.14) influenced the baseline EMG amplitude the most. The intraoperative current management was influenced by advanced pT stage (p = 0.001, OR = 2.87), and structural nerve injury (p = 0.001, OR = 3.15). Patients with low baseline amplitude and/or requiring higher current to maintain normal baseline amplitude were often associated with temporary RLN palsy. Factors such as age, pT stage, and structural nerve injury influenced the IONM stimulation and recording parameters.

Seeing Is Not Believing: Intraoperative Nerve Monitoring (IONM) in the Thyroid Surgery.

Ensuring the integrity of the recurrent laryngeal nerve (RLN), the external branch of superior laryngeal nerve (EBSLN) and preservation of normal voice are the prime 'functional' goals of thyroid surgery. More in-depth knowledge of neuronal mechanisms has revealed that anatomical integrity does not always translate into functional integrity. Despite meticulous dissection, neural injuries are not always predictable or visually evident. Intraoperative nerve monitoring (IONM) is designed to aid in nerve identification and early detection of functional impairment. With the evolution of technique, intermittent monitoring has given way to continuous-IONM. Over the years, IONM gathered both support and flak. Despite numerous randomised studies, systematic reviews, and meta-analyses, there still prevails a state of clinical equipoise concerning the utility of IONM and its cost-effectiveness. This article inspects the true usefulness of IONM, elaborates on the optimal way to practice it, and presents a critical literature review.

Risk factors predisposing for recurrent laryngeal nerve palsy following thyroid malignancy surgery: experience from a tertiary oncology centre.

BACKGROUND: Postoperative recurrent laryngeal nerve (RLN) palsy is one of the major morbidities encountered after thyroid surgery. The risk further increases when surgery is performed for thyroid malignancies. METHODOLOGY: A retrospective study of patients who underwent hemi, total or completion thyroidectomy at our institute between June 2017 to May 2019 were analyzed. We assessed factors that predisposed to the development of RLN palsy. RESULTS: The study comprised of 228 patients. A total of 400 nerves were at risk. The RLN palsy rate was 6.8% (n = 27). On univariate and multivariate analysis, the risk of RLN palsy was seen most with pT4a tumor (OR = 8.5), gross extra-thyroidal extension (ETE) (OR = 3.5) and tracheo-esophageal groove (TEG) (OR = 2.8) involvement, followed by aggressive histopathology, and central compartment node positivity. CONCLUSION: pT4a tumors, gross ETE, and TEG involvement were the leading causes predisposing for the development of RLN palsy in our series.

The effects of propofol and isoflurane on intraoperative motor evoked potentials during spinal cord tumour removal surgery - A prospective randomised trial.

BACKGROUND AND AIMS: Transcranial electrical stimulation (TES) elicited intraoperative motor evoked potentials (iMEPs), are suppressed by most anaesthetic agents. This prospective randomised study was carried out to compare the effects of Isoflurane and Propofol on iMEPs during surgery for spinal cord tumours. METHODS: A total of 110 patients were randomly divided into two groups. In group P, anaesthesia was maintained with intravenous propofol (6.6 ± 1.5 mg/kg/hr) and in group I anaesthesia was maintained with isoflurane (0.8 ± 0.1% minimal alveolar concentration (MAC). An Oxygen- air mixture (FiO2-0.3) was used in both groups. TES-iMEPs were recorded from tibialis anterior, quadriceps, soleus and external anal sphincter muscles in 60 of 90 patients. Statistical analysis was performed with Pearson correlation and Paired 't' tests. RESULTS: Successful baseline iMEPs were recorded in 74% of patients in Group P and in 50% of patients in Group I. Age and duration of symptoms influenced the elicitation of baseline iMEPs under isoflurane (r = -0.71, -0.66 respectively, P < 0.01) as compared to propofol (r = -0.60, -0.50 respectively, P < 0.01). The mean stimulus strength required to elicit the baseline iMEPs were lesser in propofol (205 ± 55Volts) as compared to isoflurane (274 ± 60 Volts). Suppression of the iMEP responses was less under propofol (7.3%) as compared to isoflurane anaesthesia (11.3%) in patients with no preoperative neurological deficits. CONCLUSION: iMEPs are better maintained under propofol anaesthesia (6-8 mg/kg/hr) when compared with isoflurane (0.7-0.9 MAC). in patients undergoing surgery for excision of spinal cord tumours.

Time-Dependent Bidirectional Neuroprotection by Adenosine 2A Receptor in Experimental Traumatic Brain Injury.

BACKGROUND: Traumatic brain injury (TBI) results in both focal and diffuse brain pathological features that become severely exacerbated after the initial injury. Owing to this disease complexity, no effective therapeutic measure has yet been devised aimed directly at these pathological processes. We developed a clinically relevant model of TBI and tested the bidirectional neuroprotective role of adenosine 2A receptors (A2ARs) at different times. METHODS: Wistar rats were divided into 4 treatment groups (sham, TBI, A2AR agonist [CGS-21680], and A2AR antagonist [SCH-58261]) and 4 post-TBI intervals (15 minutes and 1, 12, and 24 hours). A2AR agonist and antagonist effects were tested by the neurological functional score (NFS) and levels of cyclic adenosine monophosphate, interleukin-1ß, oxidative stress antioxidant markers, and caspase-3. RESULTS: The A2AR agonist-treated group showed significant NFS improvement at 15 minutes and 1 hour after TBI compared with the TBI group. However, no improvement was observed at 12 and 24 hours. The A2AR antagonists resulted in no NFS improvement at 15 minutes and 1 hour, and significant improvement observed at 12 and 24 hours. Significant neuroprotective effect with an A2AR agonist were observed with cyclic adenosine monophosphate, interleukin-1ß, oxidative stress markers, catalase, and caspase-3 levels at 15 minutes and 1 hour after TBI. The A2AR antagonist showed no effect at these intervals but showed a protective effect at 12 and 24 hours after TBI. CONCLUSIONS: The A2AR agonist showed a beneficial neuroprotective effect at the early stages after TBI, and the A2AR antagonist showed a benefit at the later stages after TBI. These findings suggest that A2AR agonists and antagonists should be used in accordance with the point at which the TBI occurred.

Combined Motor Evoked Potential Monitoring and Subcortical Dynamic Mapping in Motor Eloquent Tumors Allows Safer and Extended Resections.

BACKGROUND: Subcortical motor mapping is crucial to ensure preservation of motor tracts during resections of tumors. Continuous dynamic mapping using a modified monopolar suction probe is a novel and effective way of achieving this goal. We describe our experience using this technique. METHODS: Forty patients were operated on between June 2017 and February 2018. Transcranial electric stimulation (TES) and direct cortical strip (DCS) motor evoked potentials (MEPs) were monitored. Subcortical stimulation (SCS) mapping was attempted in all cases by adapting the technique using a monopolar suction stimulator. Neurologic outcomes and extent of resection were analyzed. RESULTS: Motor fibers were between 0 and 7.6 mm away from the tumor boundaries in 26 patients. TES MEP were monitored in all patients. DCS MEPs were attempted in 31 and successfully monitored in 26 patients. SCS using the monopolar suction probe worked in all patients except one. SCS elicited no responses at 15-mA motor thresholds in 16 patients. The motor threshold ranged from 3 to 10 mA in the remainder. Overall, MEP changes were noted in 5 patients. Ten patients experienced neurologic worsening (6 transient, 3 prolonged, and 1 delayed). There was no permanent deficit at 3 months. DCS MEPs predicted neurologic worsening better than did TES MEPs. Radical resections were achieved in 68%. Neuromonitoring inputs resulted in premature termination of resection in 14 patients (35%). Radical resections (near-total resections) were still achieved in 8 of the 14 patients. CONCLUSIONS: Continuous dynamic subcortical mapping is a reliable method to map the motor tracts. This process is crucial to correctly identify truly eloquent tumors and tailor the surgical procedure as per planned goals, maximizing the resections with acceptable morbidity.

Continuous Dynamic Subcortical Mapping Using a Suction Monopolar Device in a Child: Case Report and Technical Note.

Extent of resection is a very important prognostic marker in adult and pediatric brain tumors. Therefore, radical resections confer an oncological benefit. Resection of intra-axial tumors in proximity to eloquent regions requires intraoperative mapping and monitoring. Continuous subcortical mapping using a suction monopolar device has been recently described for adult tumors. This allows a real-time dynamic mapping of the advancing resection cavity walls, synchronized with the surgeon's actions during resection. We describe the application of this technique in a child who presented with a rapidly increasing right parietal mass. It was resected using this dynamic mapping technique. This is the first such report of its use in a pediatric brain tumor. We also review the relevant literature briefly.

Influence of Tumor Location and Other Variables on Predictive Value of Intraoperative myogenic Motor-Evoked Potentials in Spinal Cord Tumor Surgery.

OBJECTIVE: To study the influence of tumor location (cervical vs. thoracic; extramedullary vs. intramedullary) on predictive value of intraoperative myogenic motor-evoked potentials (iMEP) changes in patients undergoing surgery for spinal cord tumors. METHODS: Three hundred patients retrospective data (91 intramedullary) and 209 (intradural extramedullary) with successful iMEP recordings were analyzed. Responses to transcranial electrical stimulation were recorded from the lower limb muscles. Preoperative clinical variables, iMEPs changes, and postoperative neurologic deficits were noted. Associations between categorical variables and outcome were analyzed with the Fisher exact test. RESULTS: Of the 300 patients 28 (9.3%) had significant intraoperative worsening of iMEPs. New postoperative deficits occurred in 23 of these 28 patients. False-positive decreases in iMEPs were observed in 5 patients. There was a significant association between changes in iMEP and postoperative new motor deficits (P ≤ 0.0001). Multivariate analysis showed that patients with changes in iMEP undergoing surgery for thoracic segment tumors, with longer duration of symptoms (>12 months) and older age (≥21.5 years) were more likely to suffer postoperative neurological decline (odds ratio 4.1, P ≤ 0.001 and odds ratio 5.4 P ≤ 0.0001, respectively). The sensitivity of iMEPs was 100% and specificity 98.2%. The positive and negative predictive values were 82% and 100%; however, the sensitivity and specificity is similar in thoracic intramedullary (TIM) (n = 53) and cervical intramedullary tumors (n = 38) (both were 100% and 97%). The positive predictive value was significantly greater for TIM tumors (93% vs. 50%). CONCLUSIONS: A strong association was observed between worsening of iMEPs and postoperative new neurological deficits in patients with TIM tumor.

Oxidative stress-associated hypertension in surgically induced brain injury patients: effects of ß-blocker and angiotensin-converting enzyme inhibitor.

BACKGROUND: Postoperative hypertension is a common problem in patients undergoing surgical procedures, and the modification of this response could result in improved surgical outcome. Although it is recognized that the incidence of postoperative hypertension is higher in neurosurgical procedures, mechanisms behind this are not well understood. Oxidative stress is an important component of brain injury, and free radicals can influence blood pressure by a number of mechanisms. This study examined the effect of pretreatment with antihypertensive agents on postoperative hypertension in patients undergoing neurosurgery for supratentorial brain tumors and the role of oxidative stress in the process. METHODS: Forty-nine consecutive patients who underwent surgery for supratentorial brain tumors were divided in to three groups (control, Tab. Glucose; atenolol; and lisinopril groups). Blood was drawn at three time points (1 d before the surgery, at the time of dura opening, and at the time of extubation). Hemodynamic parameters in all three groups and levels of malondialdehyde, protein carbonyl content, nitrate, and α-tocopherol in serum at various time points were analyzed. RESULTS: The results showed that perioperative hemodynamic changes were highly associated with oxidative stress parameters in all the three groups. It was seen that atenolol and lisinopril significantly decreased levels of malondialdehyde, protein carbonyl content, and nitrate in the intraoperative period (P < 0.05), an effect which continued postoperatively. CONCLUSIONS: The results demonstrate that pretreatment with ß-receptor blocker (atenolol) or angiotensin-converting enzyme inhibitor (lisinopril) reduces postoperative hypertension in patients undergoing neurosurgery, and inhibition of oxidative stress may be a potential mechanism for this effect.

Factors predicting the feasibility of monitoring lower-limb muscle motor evoked potentials in patients undergoing excision of spinal cord tumors.

OBJECT: This prospective study on intraoperative muscle motor evoked potentials (MMEPs) from lower-limb muscles in patients undergoing surgery for spinal cord tumors was performed to: 1) determine preoperative clinical features that could predict successful recording of lower-limb MMEPs; 2) determine the muscle in the lower limb from which MMEPs could be most consistently obtained; 3) assess the need to monitor more than 1 muscle per limb; and 4) determine the effect of a successful baseline MMEP recording on early postoperative motor outcome. METHODS: Of 115 consecutive patients undergoing surgery for spinal cord tumors, 110 were included in this study (44 intramedullary and 66 intradural extramedullary tumors). Muscle MEPs were generated using transcranial electrical stimulation under controlled anesthesia and were recorded from the tibialis anterior, quadriceps, soleus, and external anal sphincter muscles bilaterally. The effect of age (≤ 20 or > 20 years old), location of the tumor (intramedullary or extramedullary), segmental location of the tumor (cervical, thoracic, or lumbar), duration of symptoms (≤ 12 or > 12 months), preoperative functional grade (Nurick Grades 0-3 or 4-5), and muscle power (Medical Research Council Grades 0/5-3/5 or 4/5-5/5) on the success rate of obtaining MMEPs was studied using multiple regression analysis. The effect of the ability to monitor MMEPs on motor outcome at discharge from the hospital was also analyzed. RESULTS: The overall success rate for obtaining baseline lower-limb MMEPs was 68.2% (75 of 110 patients). Eighty-nine percent of patients with Nurick Grades 0-3 had successful MMEP recordings. Muscle MEPs could not be obtained in any patient in whom muscle power was 2/5 or less, but were obtained from 91.4% of patients with muscle power of 4/5 or more. Analysis showed that only preoperative Nurick grade (p ≤ 0.0001) and muscle power (p < 0.0001) were significant predictors of the likelihood of obtaining MMEPs. Responses were most consistently obtained from the tibialis anterior muscle (68%), but in the other 32% MMEPs could not be recorded from the tibialis anterior but could be recorded from another muscle. The ability to monitor MMEPs was associated with better motor outcome at discharge from the hospital (p = 0.052). CONCLUSIONS: The likelihood of obtaining lower-limb MMEPs is significantly greater in patients with better functional grades and higher motor power. Muscle MEPs are most consistently obtained from the tibialis anterior muscle but other muscles should also be monitored to optimize the chances of obtaining MMEP responses from the lower limbs.