Nitin Manohara

Intraoperative electroencephalography (EEG) is increasingly used to monitor the depth of anesthesia and a range of other perioperative indications. While processed EEG indices offer a convenient numerical representation, exclusive reliance on these values can obscure clinically significant findings. Discordance between the numerical index and the raw EEG or density spectral array (DSA) may arise due to artifacts, patient-specific neurophysiology, or pharmacologic effects. This article highlights common sources of such discordance, illustrated through clinical examples, and emphasizes the importance of integrating raw EEG interpretation and DSA analysis into routine intraoperative monitoring.

Vagal nerve stimulator (VNS) generator replacements continue to increase given the various indications of the device since its FDA approval in 1997. VNS generator replacements are usually safe and serious cardiac complications are not typically encountered during VNS generator replacement surgeries. We present a rare case of VNS generator replacement complicated by asystole and laryngospasm while exploring the plausible factors contributing to these events in our patient. The general recommendations to prevent and manage VNS therapy-related complications in the perioperative setting are described along with the safety strategies specific to VNS generator replacement procedures.

Perioperative anesthetic, surgical and critical careinterventions can affect brain physiology and overall brain health. The clinical utility of electroencephalogram (EEG) monitoring in anesthesia and intensive care settings is multifaceted, offering critical insights into the level of consciousness and depth of anesthesia, facilitating the titration of anesthetic doses, and enabling the detection of ischemic events and epileptic activity. Additionally, EEG monitoring can aid in predicting perioperative neurocognitive disorders, assessing the impact of systemic insults on cerebral function, and informing neuroprognostication. This review provides a comprehensive overview of the fundamental principles of electroencephalography, including the foundations of processed and quantitative electroencephalography. It further explores the characteristic EEG signatures associated wtih anesthetic drugs, the interpretation of the EEG data during anesthesia, and the broader clinical benefits and applications of EEG monitoring in both anesthetic practice and intensive care environments.

Multimodal intraoperative neurophysiological monitoring (IONM) is highly valuable in scoliosis surgeries for monitoring spinal cord function, particularly during instrumentation. Accurate timing of baseline recordings of TcMEP and SSEP is crucial, as any changes observed during surgery and instrumentation are compared to these baseline recordings. However, the impact of ultrasound-guided erector spinae block (USG-ESPB) on SSEP and TcMEP is not well-studied in scoliosis surgery. In this report, we present two cases of scoliosis surgery where bilateral two-level USG-ESPB using different concentrations of ropivacaine (0.375% and 0.2%) resulted in a transient and significant deterioration of TcMEP, occurring 3 minutes after the block and lasting for 20 minutes. Remarkably, SSEPs remained unchanged during this period. These findings suggest that USG-ESPB may produce TcMEP changes, highlighting the importance of carefully considering the timing of baseline TcMEP acquisition in scoliosis surgery.

This retrospective study was conducted on 581 awake craniotomy (AC) cases by a single neurosurgeon to identify risk factors for intraoperative seizures (IOS) during elective resection or biopsy of a space-occupying brain lesion. This study identified a low incidence (5%) of IOS during AC. Most seizures (93%) were focal in nature and did not limit planned intraoperative stimulation mapping. The frontal location of the tumor and intraoperative dexmedetomidine use were independently associated with IOS in the multivariable analysis. The association between dexmedetomidine and intraoperative seizures needs to be evaluated in larger randomized controlled trials.

This study was conducted on 18 good-grade subarachnoid haemorrhage (SAH) patients in the interventional neuroradiology suite with digital subtraction angiography to study the vasodilatory effects of sevoflurane and propofol anaesthesia on the major cerebral vessels during endovascular coiling. This study confirms the cerebral vasodilatory effect of inhalational anaesthetic - sevoflurane compared to propofol, and this may be important in choosing the most appropriate anaesthetic regimen while anaesthetising such cases.

Delirium in postoperative and critical care patients is a serious issue associated with many adverse effects like cognitive dysfunction, increased hospital stay, and mortality. This systematic review and meta-analysis confirms the beneficial effects of dexmedetomidine in preventing delirium in critical and postoperative patients.

This novel prospective observational study shows that noninvasive tests like computed tomography (CT) grade more than 2, optic nerve sheath diameter measured with ultrasound of greater than 0.63 centimeters and ratio of low frequency to high ratio (LF/HF) of more than 1.8 with heart rate variability monitor can be good predictors of intraoperative brain bulge. This indirectly predicts raised ICP and brain odema that an anesthesiologist may face intraoperatively in elective supratentorial tumour surgery. These noninvasive methods could help anaesthesiologists predict and prepare for tight brain situations that they may encounter intraoperatively in supratentorial elective surgeries.

This is a secondary analysis of the landmark RESCUE ICP trial with outcome analysis again done at an extended time window of 24 months. This study reconfirms the findings of the RESCUE ICP trial at this extended time window. Trial registry details: ISRCTN66202560.