Is the Patient State Index a reliable parameter as guide to anaesthesiology in cranial neurosurgery? A first intraoperative study and a literature review.

BACKGROUND: Patient State Index (PSI) and Suppression Ratio (SR) are two indices calculated by quantitative analysis of EEG used to estimate the depth of anaesthesia but their validation in neurosurgery must be done. Our aim was to investigate the congruity PSI and SR with raw EEG monitoring in neurosurgery. METHODS: We included 34 patients undergoing elective cranial neurosurgery. Each patient was monitored by a SedLine device (PSI and SR) and by raw EEG. To appraise the agreement between PSI, SR and EEG Suppr%, Bland-Altman analysis was used. We also correlated the PSI and SR recorded at different times during surgery to the degree of suppression of the raw EEG data by Spearman's rank correlation coefficient. For a comparison with previous data we made an international literature review according to PRISMA protocol. RESULTS: At all recording times, we found that there is a strong agreement between PSI and raw EEG. We also found a significant correlation for both PSI and SR with the EEG suppression percentage (p < 0.05), but with a broad dispersion of the individual values within the confidence interval. CONCLUSION: The Masimo SedLine processed EEG monitoring system can be used as a guide in the anaesthetic management of patients during elective cranial neurosurgery, but the anaesthesiologist must be aware that previous correlations between PSI and SR with the suppression percentage may not always be valid in all individual patients. The use of an extended visual raw EEG evaluated by an expert electroencephalographer might help to provide better guidance.

Intraoperative Mapping of the Sensory Root of the Trigeminal Nerve in Patients with Pontocerebellar Angle Pathology.

OBJECTIVE: The aim of the present study was to determine the position of the 3 sensory branches of the trigeminal nerve in the preganglionic tract using intraoperative neurophysiological mapping. METHODS: We included consecutive adult patients who underwent neurosurgical treatment of cerebellopontine angle lesions. The trigeminal nerve was antidromically stimulated at 3 sites along its circumference with different stimulus intensities at a distance of ≤1 cm from the brainstem. The sensory nerve action potentials (SNAPs) were recorded from each main trigeminal branch (V1 [ophthalmic branch], V2 [maxillary branch], and V3 [mandibular branch]). RESULTS: We analyzed 13 patients. The stimulation points at which we obtained the greatest number of congruous and exclusive SNAPs (SNAPs only on the stimulated branch) was the stimulation point for V3 (20.7%). The stimulation intensity at which we obtained the highest number of congruent and exclusive SNAPs with the stimulated branch was 0.5 mA. CONCLUSIONS: Using our recording conditions, trigeminal stimulation is a reliable technique for mapping the V3 and V1 branches using an intensity not exceeding 0.5. However, reliable identification of the fibers of V2 is more difficult. Stimulation of the trigeminal nerve can be a reliable technique to identify the V3 and V1 branches if rhizotomy of these branches is necessary.

Feasibility of Intraoperative Visual Evoked Potential Monitoring by Cortical Strip Electrodes in Patients During Brain Surgery: A Preliminary Study.

OBJECTIVE: The role of visual evoked potentials (VEPs) monitoring during neurosurgical procedure in patient remains unclear. The purpose of our study was to determine the feasibility of intraoperative VEP recording using a strip cortical electrode during surgical resection of intracranial lesions. METHODS: In this prospective, monocentric, observational study, we enrolled consecutive patients undergoing neurosurgical procedure for intracranial lesions. After dural opening, a cortical strip was positioned on the lateral occipital surface. Flash VEPs were continuously recorded using both subdermal corkscrew electrodes and strip electrodes. An electroretinogram was also recorded to guarantee delivery of adequate flash stimuli to the retina. RESULTS: We included 10 patients affected by different intracranial lesions. Flash VEPs were recorded using subdermal corkscrew electrodes in all patients except 1 in whom they were never identified during the recording. Flash VEPs were recorded using strip electrodes in all patients and showed a polyphasic morphology with a significantly larger amplitude compared with that of flash VEPs measured using subdermal corkscrew electrodes. No patient reported worsened postoperative vision and a >50% decrease in the VEPs amplitude was never registered. CONCLUSIONS: We have reported for the first time in the literature that VEP monitoring during a neurosurgical procedure is feasible via a cortical strip located on the occipital surface. The technique demonstrated greater stability and a larger amplitude compared with recordings with scalp electrodes, facilitating identification of any changes. Studies with more patients are needed to assess the clinical reliability of the technique.

How the work of respiratory physiotherapists changes the tracheostomy management and decannulation in a NICU department: an Italian experience.

Tracheotomy is a clinical procedure that is often necessary though not without complications, hence the need for appropriate and timely decannulation. The inclusion of trained respiratory physiotherapists (RPT) in the staff and the use of shared protocols could help the team to manage the patient with tracheotomy cannula. The objective of this study was to describe the difference in the rate of decannulation and clinical outcomes of tracheostomized patients admitted to a NeuroIntensive Care Unit (NICU) team after the inclusion of a group of physiotherapists specialized in respiratory physiotherapy and a new phoniatric protocol. It is a 6-year retrospective study, in which two periods of 3 years each were compared: in the first period (P1: September 2013-August 2016) physiotherapists were called to treat NICU patients on a consultative basis (2 hours/day for 5 days a week); in the second period (P2: September 2016-August 2019) two full-time respiratory physiotherapists were present on the ward (7 hours/day, 6/7 days/week). In P2 period, a decannulation protocol was used. Patients who had undergone a tracheotomy procedure and who were alive at the time of discharge were retrospectively evaluated. We described the number of decannulations, the length of stay in NICU and decannulation time; the diagnosis of decannulated patients and the number of deaths. 928 total patients were analysed: 468 in P1, 460 in P2. Total length of stay or number of deaths did not change significantly between the two periods, while the number of decannulated patients before the discharge was higher in P2 143 (64%), compared with P1 79 (36%) p<0.001. More patients with neurological pathologies involving possible swallowing disorders, such as cerebral haemorrhage, head trauma and stroke, have been successfully decannulated in P2 than in P1 (120 patients in P2 vs 54 in P1). A multidisciplinary approach, including respiratory physiotherapist, dedicated to tracheostomy management, decannulation and early mobilization in NICU is safe, feasible and seems to improve the number of severe patients decannulated, even if no change was observed in NICU length of stay or deaths. Further studies must confirm our results in other ICU settings.

Amplitude Instability of Somatosensory Evoked Potentials as an Indicator of Delayed Cerebral Ischemia in a Case of Subarachnoid Hemorrhage.

We describe a 55-year-old male patient with a subarachnoid hemorrhage (SAH) as a result of left middle cerebral artery (MCA) aneurysm rupture, who underwent continuous electroencephalogram (EEG) and somatosensory evoked potential (cEEG-SEP) monitoring that showed an unusual SEP trend pattern. EEG was continuously recorded, and SEPs following stimulation of median nerves were recorded every 50 minutes, with the amplitude and latency of the cortical components automatically trended. An increase in intracranial pressure required a left decompressive craniectomy. cEEG-SEP monitoring was started on day 7, which showed a prolonged (24 hours) instability of SEPs in the left hemisphere. During this phase, left MCA vasospasm was demonstrated by transcranial Doppler (TCD), and computed tomography perfusion (CTP) showed a temporo-parieto-occipital ischemic penumbra. Following intravascular treatment, hypoperfusion and the amplitude of cortical SEPs improved. In our case, a prolonged phase of SEP amplitude instability during vasospasm in SAH correlated with a phase of ischemic penumbra, as demonstrated by CTP. In SAH, SEP instability during continuous monitoring is a pattern of alert that can allow treatments capable of avoiding irreversible neurological deterioration.

Efficacy of lacosamide on seizures and myoclonus in a patient with epilepsia partialis continua.

A 39-year-old male with epilepsia partialis continua, refractory to first- and second-line antiepileptic drugs, is described. Lacosamide produced a progressive antiepileptic effect on Jacksonian motor seizures and subsequently on positive myoclonus, which developed into negative myoclonus before complete resolution. Our report confirms the efficacy of lacosamide on focal motor refractory status epilepticus and documents a unique effect of lacosamide on seizure semiology.

Cooperative patient general anesthesia (Co.Pa.Ge.A.): the new anesthetic technique for neurological monitoring of the "cooperative" patient during endovascular treatment of elective brain arteriovenous malformations with Onyx18.

BACKGROUND: An anesthetic technique, which allows for neurological monitoring as well as continuous and safe monitoring of the airways with orotracheal intubation (cooperative patient general anesthesia [Co.Pa.Ge.A.]) has been described in patients undergoing elective thromboendoarterectomy surgery. The aim of this paper is to evaluate the effectiveness and the safety of Co.Pa.Ge.A. during scheduled endovascular treatments of brain arteriovenous malformations with a polymeric embolization agent, Onyx18. METHODS: Ten patients (3 F, 7 M; median age: 33.5±6.0 y, range: 20 to 39 y, American Society of Anesthesiologists class I to II) underwent endovascular embolization of brain arteriovenous malformations located in an eloquent area. Remifentanil was administered i.v. until an anesthetic target level was reached which allowed the anesthesiologists and the neuroradiologists to perform neurological monitoring during the entire procedure. The degree of patient satisfaction was evaluated based on a questionnaire administered the day after the procedure. RESULTS: Co.Pa.Ge.A. was successfully performed on all of the patients. No intraprocedural or postprocedural adverse events occurred. Hemodynamic stability was maintained in 5 cases with Remifentanil alone, in 2 cases with Remifentanil and Clonidine and in 1 case with Remifentanil and Nimodipine. CONCLUSIONS: At the moment and to the best of our knowledge, this is the first report in the medical literature on this new anesthetic technique in interventional neuroradiology. Co.Pa.Ge.A. can be considered a safe, effective, and satisfactory technique characterized by hemodynamic stability and good control of the respiratory pattern, offering the possibility to perform real-time neurological monitoring and easy conversion to general anesthesia in case of intraprocedural complications or anesthetic necessity.