Unilateral abnormality of initial motor-evoked potential in the upper limb detected during lumbar spine surgery: a case report.

BACKGROUND: We present a case with abnormal findings of initial motor-evoked potential (MEP) in the left upper limb after prone positioning during lumbar spine surgery. CASE PRESENTATION: A 71-year-old man with bilateral lower extremity numbness without a history of preexisting motor weakness underwent L3-5 spinal fenestration. Initial MEP monitoring after prone positioning revealed markedly prolonged latency and lower amplitude in the left abductor pollicis brevis (APB). Because the left upper limb somatosensory-evoked potentials had normal values, a position-related impending peripheral nerve injury located between the neck and the forearm was excluded. Postoperative examination revealed that MEP abnormality in the left APB was caused by carpal tunnel syndrome. CONCLUSIONS: Abnormal initial MEP from the upper limb was unexpectedly detected after prone positioning during lumbar spine surgery. The condition was caused by preexisting carpal tunnel syndrome.

Motor-evoked potential monitoring from urinary sphincter muscle during pediatric untethering surgery: a case series.

PURPOSE: Postoperative urinary dysfunction following untethering surgery for spinal lipoma is devastating. To assess urinary function, we invented a pediatric urinary catheter equipped with electrodes for the direct transurethral recording of myogenic potential from the external urethral sphincter (EUS). This paper presents two cases in which urinary function was monitored intraoperatively by recording of motor-evoked potential (MEP) from EUS during untethering surgery in children. METHODS: Two children (aged 2 and 6 years) were included in this study. One patient had no preoperative neurological dysfunction, while the other had frequent urination and urinary incontinence. A pair of surface electrodes was attached to a silicone rubber urethral catheter (6 or 8 Fr; diameter, 2 or 2.6 mm). The MEP from the EUS was recorded to assess the function of the centrifugal tract from the motor cortex to the pudendal nerve. RESULTS: Baseline MEP waveforms from the EUS were successfully recorded with latency and amplitude of 39.5 ms and 66 µV in patient 1 and 39.0 ms and 113 µV in patient 2, respectively. A significant decrease in amplitude was not observed during surgery in the two cases. No new urinary dysfunction and complications associated with the urinary catheter-equipped electrodes developed postoperatively. CONCLUSION: Using an electrode-equipped urinary catheter, monitoring of MEP from the EUS could be applicable during untethering surgery in pediatric patients.

Application of laser speckle flowgraphy to evaluate cerebral perfusion after carotid endarterectomy.

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) is devastating, and postoperative monitoring of cerebral perfusion is essential to prevent CHS. We report two cases of successful measurement of ocular blood flow using laser speckle flowgraphy (LSFG) for bedside assessment of the changes in cerebral perfusion after CEA. An 18.7% (case 1) and 47.7% (case 2) increase in ocular blood flow were measured postoperatively using LSFG compared with the baseline. LSFG might be applicable to evaluate cerebral perfusion after CEA.

Transurethral electrical stimulation for intraoperative bulbocavernosus reflex monitoring during spine surgery in females.

OBJECTIVE: Intraoperative bulbocavernosus reflex (BCR) monitoring is more difficult in females than in males. This study was designed to compare the feasibility of transurethral electrical stimulation BCR (tu-BCR) monitoring with that of conventional BCR (c-BCR) monitoring during spine surgery in females. METHODS: Twenty-four females were included. For stimulation in c-BCR monitoring, a pair of surface electrodes was placed on the genitals (cathode/anode: clitoris/adjacent labium). For stimulation in tu-BCR monitoring, a urethral catheter attached to a pair of electrodes was inserted into the urethra. BCRs were recorded from the external anal sphincter after a single train of four stimulation pulses. RESULTS: There was no postoperative urinary tract injury associated with urethral catheter insertion for tu-BCR. Tu-BCR monitoring had a significantly higher success rate of baseline recording than c-BCR monitoring (87.5% vs 66.7%, respectively, p = 0.028). The specificities of tu-BCR and c-BCR monitoring were 100% and 87.2%, respectively. The sensitivity was not calculated because no patients had postoperative urinary or bowel dysfunction. CONCLUSIONS: Our data indicate that tu-BCR monitoring improved the success rate of baseline recording and specificity during spine surgery in females. SIGNIFICANCE: Tu-BCR monitoring was more reliable than c-BCR monitoring during spine surgery in females.

Accuracy and Trending Ability of Cardiac Index Measured by the CNAP System in Patients Undergoing Abdominal Aortic Aneurysm Surgery.

OBJECTIVES: The CNAP system is a noninvasive monitor that provides a continuous arterial pressure waveform using an inflatable finger cuff. The authors hypothesized that dramatic changes in systemic vascular resistance index during abdominal aortic aneurysm (AAA) surgery might affect the accuracy of noninvasive pulse contour monitors. The aim of this study was to evaluate the accuracy and trending ability of cardiac index derived by the CNAP system (CICN) in patients undergoing AAA surgery. DESIGN: Prospective clinical study. SETTING: Cardiac surgery operating room in a single cardiovascular center. PARTICIPANTS: Twenty patients who underwent elective AAA surgery. INTERVENTIONS: CICN and cardiac index measured using 3-dimensional images (CI3D) were determined simultaneously at 8 points during the surgery. At aortic clamping and unclamping, the authors tested the trending ability of CICN using 4-quadrant plot analysis and polar plot analysis. MEASUREMENTS AND MAIN RESULTS: The authors found a wide limit of agreement between CICN and CI3D (percentage error: 85.0%). The cubic splines, which show the relationship between systemic vascular resistance index and percentage CI discrepancy [(CICN-CI3D)/CI3D], were sloped positively. Four-quadrant plot analysis showed poor trending ability for CICN at both aortic clamping and unclamping (concordance rate: 29.4% and 57.9%, respectively). In the polar plot analysis, the concordance rates at aortic clamping and unclamping were 15.0% and 35.0%, respectively. CONCLUSIONS: CICN is not interchangeable with CI3D in patients undergoing AAA surgery. The trending ability for CICN at aortic clamping and unclamping was below the acceptable limit. These inaccuracies might be secondary to the high systemic vascular resistance index during AAA surgery.

Non-Destructive Detection of Tea Leaf Chlorophyll Content Using Hyperspectral Reflectance and Machine Learning Algorithms.

Tea trees are kept in shaded locations to increase their chlorophyll content, which influences green tea quality. Therefore, monitoring change in chlorophyll content under low light conditions is important for managing tea trees and producing high-quality green tea. Hyperspectral remote sensing is one of the most frequently used methods for estimating chlorophyll content. Numerous studies based on data collected under relatively low-stress conditions and many hyperspectral indices and radiative transfer models show that shade-grown tea performs poorly. The performance of four machine learning algorithms-random forest, support vector machine, deep belief nets, and kernel-based extreme learning machine (KELM)-in evaluating data collected from tea leaves cultivated under different shade treatments was tested. KELM performed best with a root-mean-square error of 8.94 ± 3.05 µg cm-2 and performance to deviation values from 1.70 to 8.04 for the test data. These results suggest that a combination of hyperspectral reflectance and KELM has the potential to trace changes in the chlorophyll content of shaded tea leaves.