Intraoperative vs. Postoperative Side-Effects-Thresholds During Pallidal and Thalamic DBS

Background: It is currently unknown whether results from intraoperative test stimulation of two types of Deep Brain Stimulation (DBS), either during awake pallidal (GPi) or thalamic (Vim), are comparable to the results generated by chronic stimulation through the definitive lead.Objective: To determine whether side-effects-thresholds from intraoperative test stimulation are indicative of postoperative stimulation findings.Methods: Records of consecutive patients who received GPi or Vim were analyzed. Thresholds for the induction of either capsular or non-capsular side-effects were compared at matched depths and at group-level.Results: Records of fifty-two patients were analyzed (20 GPis, 75 Vims). The induction of side-effects was not significantly different between intraoperative and postoperative assessments at matched depths, although a large variability was observed (capsular: GPi DBS: p = 0.79; Vim DBS: p = 0.68); non-capsular: GPi DBS: p = 0.20; and Vim DBS: p = 0.35). Linear mixed-effect models revealed no differences between intraoperative and postoperative assessments, although the Vim had significantly lower thresholds (capsular side-effects p = 0.01, non-capsular side-effects p < 0.01). Unpaired survival analyses demonstrated lower intraoperative than postoperative thresholds for capsular side-effects in patients under GPi DBS (p = 0.01), while higher intraoperative thresholds for non-capsular side-effects in patients under Vim DBS (p = 0.01).Conclusion: There were no significant differences between intraoperative and postoperative assessments of GPi and Vim DBS, although thresholds cannot be directly extrapolated at an individual level due to high variability.

Persistence of secondary hyperparathyroidism after parathyroidectomy in a patient with chronic kidney disease: a case report

This is a clinical case of surgical treatment of persistence of secondary hyperparathyroidism (SHPT) in a patient with chronic kidney disease after previous parathyroidectomy. Programmed hemodialysis started in 2014, and in 2016 SHPT was diagnosed. In November 2018, indications for surgical treatment were presented in one of the clinics. According to scintigraphy, an increase in the functional activity of all four parathyroid glands (PTG) was observed, according to ultrasound data, the localization of the right lower, left upper and lower PTG was established. Removal of 3x PTG was performed without revision of the thymus horns (11.2018), while in the postoperative period, an adequate decrease in parathyroid hormone was not observed. After additional examination, according to ultrasound, scintigraphy and computer tomography of the neck with intravenous enhancement, it was found that both lower PTGs are located in the upper horns of the thymus. In July 2020, a repeated surgical intervention was performed in the volume of the right lower and left lower parathyroidectomy with a positive intraoperative test. Remission of SHPT was achieved. At present, no consensus has been reached on the extent of surgery for SHPT, since no statistically significant differences were found in the incidence of persistence / recurrence of SHPT. A complete assessment of the results of preoperative imaging techniques is required when planning surgery. Intraoperative monitoring of parathyroid hormone is an effective technique for assessing the radicality of surgical treatment.

Electromyography as an intraoperative test to assess the quality of nerve anastomosis – experimental study on rats

BackgroundMany factors contribute to successful nerve reconstruction. The correct technique of anastomosis is one of the key elements that determine the final result of a surgery. The aim of this study is to examine how useful an electromyography (EMG) can be as an objective intraoperative anastomosis assessment method.MethodsThe study material included 12 rats. Before the surgery, the function of the sciatic nerve was tested using hind paw prints. Then, both nerves were cut. The left nerve was sutured side-to-side, and the right nerve was sutured end-to-end. Intraoperative electromyography was performed. After 4 weeks, the rats were reassessed using the hind paw print analysis and electromyography.ResultsAn analysis of left and right hind paw prints did not reveal any significant differences between the length of the steps, the spread of the digits in the paws, or the deviation of a paw. The width of the steps also did not change.Electromyography revealed that immediately after a nerve anastomosis (as well as 4 weeks after the surgery), better nerve conduction was observed through an end-to-end anastomosis. Four weeks after the surgery, better nerve conduction was seen distally to the end-to-end anastomosis.ConclusionsThe results indicate that in acute nerve injuries intraoperative electromyography may be useful to obtain unbiased information on whether the nerve anastomosis has been performed correctly – for example, in limb replantation.When assessing a nerve during a procedure, EMG should be first performed distally to the anastomosis (the part of the nerve leading to muscle fibers) and then proximally to the anastomosis (the proximal part of the nerve). Similar EMG results can be interpreted as a correct nerve anastomosis.The function of the distal part of the nerve and the muscle remains intact if the neuromuscular transmission is sustained.

Intraoperative test stimulation versus stereotactic accuracy as a surgical end point: a comparison of essential tremor outcomes after ventral intermediate nucleus deep brain stimulation

OBJECTIVEVentral intermediate nucleus deep brain stimulation (DBS) for essential tremor is traditionally performed with intraoperative test stimulation and conscious sedation, without general anesthesia (GA). Recently, the authors reported retrospective data on 17 patients undergoing DBS after induction of GA with standardized anatomical coordinates on T1-weighted MRI sequences used for indirect targeting. Here, they compare prospectively collected data from essential tremor patients undergoing DBS both with GA and without GA (non-GA).METHODSClinical outcomes were prospectively collected at baseline and 3-month follow-up for patients undergoing DBS surgery performed by a single surgeon. Stereotactic, euclidean, and radial errors of lead placement were calculated. Functional (activities of daily living), quality of life (Quality of Life in Essential Tremor [QUEST] questionnaire), and tremor severity outcomes were compared between groups.RESULTSFifty-six patients underwent surgery: 16 without GA (24 electrodes) and 40 with GA (66 electrodes). The mean baseline functional scores and QUEST summary indices were not different between groups (p = 0.91 and p = 0.59, respectively). Non-GA and GA groups did not differ significantly regarding mean postoperative percentages of functional improvement (non-GA, 47.9% vs GA, 48.1%; p = 0.96) or QUEST summary indices (non-GA, 79.9% vs GA, 74.8%; p = 0.50). Accuracy was comparable between groups (mean radial error 0.9 ± 0.3 mm for non-GA and 0.9 ± 0.4 mm for GA patients) (p = 0.75). The mean euclidean error was also similar between groups (non-GA, 1.1 ± 0.6 mm vs GA, 1.2 ± 0.5 mm; p = 0.92). No patient had an intraoperative complication, and the number of postoperative complications was not different between groups (non-GA, n = 1 vs GA, n = 10; p = 0.16).CONCLUSIONSDBS performed with the patient under GA to treat essential tremor is as safe and effective as traditional DBS surgery with intraoperative test stimulation while the patient is under conscious sedation without GA.

Decision Making in Surgery for Nonsaccular Posterior Inferior Cerebellar Artery Aneurysms With Special Reference to Intraoperative Assessment of Collateral Blood Flow and Neurophysiological Function

BACKGROUND Posterior inferior cerebellar artery (PICA) aneurysms represent a challenging pathology. PICA sacrifice is often necessary, due to the high proportion of nonsaccular aneurysms that can be found in this location. Several treatments are available, but the infrequency of these aneurysms and the increasing number of endovascular techniques have limited the development of a standardized algorithm for cases in which open surgery is indicated. OBJECTIVE We present our series of nonsaccular PICA aneurysms, in the attempt to define an algorithm for their surgical management. METHODS We retrospectively reviewed the operation database, identifying patients harboring nonsaccular PICA aneurysms who were surgically treated at our institution from 2007 to 2016. RESULTS During a 9-yr period, 17 patients harboring 18 nonsaccular PICA aneurysms were surgically treated at our institution. Fourteen (7.7%) aneurysms were located within the proximal PICA (including those located at the vertebral artery–PICA junction), and 4 were located distally. We performed PICA revascularization in 8 (57.1%) cases of proximal aneurysms (n = 4, PICA–PICA bypass; n = 4, occipital artery–PICA bypass). We based our decision whether to perform bypass on intraoperative test occlusion with indocyanine green (ICG) videoangiography and neurophysiological monitoring. In no cases, bypass was necessary for distal aneurysms. CONCLUSION For nonsaccular PICA aneurysms, in which vessel occlusion is often necessary, it is possible to adopt a selective use of revascularization techniques. Intraoperative occlusion test with ICG videoangiography and neurophysiological monitoring provides reliable indications, allowing real-time assessment of collateral circulation.