Pedicle Screw Instrumentation of the Cervicothoracic Junction in the Sitting Position using CT-guided Navigation: Application and Technical Aspects.

BACKGROUND: We evaluate the feasibility and potential advantages of spinal CT navigation in the placement of pedicle screws at the cervicothoracic junction in the sitting position to counteract the anatomy-related limitations of 2D fluoroscopy. METHODS: We retrospectively analyze the data from 15 patients who underwent CT-based navigation-guided placement of a total of 36 pedicle screws at the cervicothoracic junction in the sitting position. RESULTS: CT-based spinal navigation is a useful method in increasing accuracy of pedicle screw instrumentation in the sitting position, successfully counteracting the anatomy-related limitations of 2D fluoroscopy at the cervicothoracic junction. CONCLUSION: CT-based navigation-guided placement of pedicle screws at the cervicothoracic junction in the sitting position proved to be an accurate, safe, and user-friendly method.

Small doses of epinephrine prolong the recovery from a rocuronium-induced neuromuscular block: a case report.

BACKGROUND: During anaesthesia it is not uncommon to administer epinephrine in patients blocked by non-depolarizing muscle relaxants. However, there are few reports on possible interaction of epinephrine with neuromuscular transmission in humans. CASE PRESENTATION: An otherwise healthy 74-yr-old man underwent transurethral resection of a benign prostatic hyperplasia under total intravenous anaesthesia. Because of repeated drop in heart rate and blood pressure the patient received in total three bolus of epinephrine 5 µg, respectively. Each time this small dose of epinephrine intensified a rocuronium-induced neuromuscular block verified by acceleromygraphy. Further anaesthetic course was uneventful. CONCLUSIONS: In this case reported here small doses of intravenously administered epinephrine markedly prolonged a rocuronium-induced neuromuscular block. Given the widely used co-administration of epinephrine and muscle relaxants possible adrenergic interference with neuromuscular transmission would have implications for daily anaesthetic practice.

Intraoperative continuous cerebral microcirculation measurement in patients with aneurysmal subarachnoid hemorrhage: preliminary data on the early administration of magnesium sulfate.

BACKGROUND: In patients with subarachnoid hemorrhage (SAH), vasospasm remains one of the major complications. The application of intravenous magnesium sulfate (MgSO4) has been under discussion to prevent cerebral ischemia. Our aim was to examine the impact of early MgSO4 administration on local cerebral microcirculation during microsurgical clipping of SAH-related aneurysms. METHODS: The non-invasive laser-Doppler spectrophotometry system "Oxygen-to-See (O2C)" was used in 14 consecutive patients (11 female, 3 male, median age 56.5±9.7 yrs) with aneurysmatic SAH. A subdural probe measured capillary venous oxygenation (SO2), relative hemoglobin content (rHb), blood cell velocity (velo) and blood flow (flow) in 7 mm tissue depth. Data samples were recorded as baseline immediately before intraoperative application of MgSO4 10% 50 mg/kg body weight and 10 min thereafter. The continuous MgSO4 infusion rate depended on blood pressure (mean arterial pressure > 60-65 mmHg) and lasted a maximum of 60 min. RESULTS: MgSO4 was administered 2.8 (min. 1.6, max. 15.5) hours after onset of symptoms. Median flow increased significantly by 20.8% (5-68%, p = 0.001). Velo increased 4.9% (1-17%), rHb decreased 1.5% (3-34%) and SO2 decreased 9.4% (8-38%) by trend compared to the baseline values. FiO2 correlated positively with velo (rs = 0.712, p = 0.004), whereas arterial HCO3 correlated negatively with SO2 (rs = -0.599, p = 0.024). Of 14 patients, 2 had symptomatic vasospasm. CONCLUSIONS: Our data suggest an increased cerebral blood flow after early intraoperative administration of MgSO4 in patients with SAH. Using a non-invasive laser-Doppler spectrophotometry system, this technique is feasible for continuous real-time monitoring of cerebral microcirculation. TRIAL REGISTRATION: DRKS (German Clinical Trial Registry), DRKS00013047 , retrospectively registered on September 21st, 2017.

Intraoperative Vascular Neuromonitoring in Patients with Subarachnoid Hemorrhage: A Pilot Study Using Combined Laser-Doppler Spectrophotometry.

BACKGROUND: Intraoperative monitoring of cerebral microcirculation in patients with subarachnoid hemorrhage (SAH) may predict the postoperative neurologic outcome. In this pilot study, we examined the value of a novel noninvasive real-time measurement technique for detecting changes in local microcirculation. METHODS: We used the O2C (Oxygen to see) laser-Doppler spectrophotometry system in 14 patients with Hunt & Hess grade 2-5 SAH who underwent microsurgical cerebral aneurysm clipping. A subdural probe recorded capillary venous oxygenation (SO2), relative hemoglobin concentration, blood cell velocity, and blood flow at a tissue depth of 7 mm. Data were recorded immediately before dural closure. We also recorded somatosensory evoked potentials (SEPs) with median and tibial nerve stimulation. Results were compared with neurologic performance, as measured on the modified Rankin Scale, at the day of discharge from the hospital and 12 months thereafter. RESULTS: Patient functional outcomes after discharge and 12 months were correlated with pathological decreased flow and increased SO2 values. In 6 of 8 patients, microcirculatory monitoring parameters indicated ischemia during surgery, as shown by electrophysiological SEP changes and infarction detected on the postoperative computed tomography (CT) scan. Pathological SEP results correlated closely with infarct demarcation as seen on CT. CONCLUSIONS: Our results indicate the potential benefit of intraoperative combined laser-Doppler flowmetry and spectrophotometry for predicting postoperative clinical outcomes in this small patient sample. Larger-cohort testing is needed to verify our findings and show the possible merits of this novel method.

Intravenous theophylline is the most effective intervention to prolong EEG seizure duration in patients undergoing electroconvulsive therapy.

BACKGROUND: Seizure duration in electroconvulsive therapy (ECT) is positively related with patients' outcome. This study sought to investigate the impact of anesthetic management on seizure duration, and the impact of selected drugs (theophylline, remifentanil, S-ketamine) on seizure duration. METHODS: Retrospective analysis of all patients undergoing ECT at our institution from January 2011 to April 2012 was performed based on electronic medical chart and review of existing quality improvement data. Patient data (N = 78), including gender, age, height, weight, and administered drugs, energy levels, and electroencephalic seizure duration were analyzed. Statistical analysis was performed using a generalized linear model. RESULTS: A total of 78 patients (male = 39, female = 39, age 51 ± 12 years) were included. Average number of session was 10 ± 6 (1-30). In our patient population, theophylline administration was the only parameter, which significantly prolonged seizure duration, whereas S-ketamine, remifentanil, thiopental, age, sex, session or energy level had no significant effect. CONCLUSION: Theophylline can be a useful adjunct for patients with inadequate seizure duration. If there is a concomitant beneficial effect on patients' outcome needs to be investigated in further studies.

Combined Laser-Doppler Flowmetry and Spectrophotometry: Feasibility Study of a Novel Device for Monitoring Local Cortical Microcirculation during Aneurysm Surgery.

Background Monitoring of cortical cerebral perfusion is essential, especially in neurovascular surgery. Study Aims To test a novel noninvasive laser-Doppler flowmetry and spectrophotometry device for feasibility during elective cerebral aneurysm surgery. Material and Methods In this prospective single-institution nonrandomized trial, we studied local cerebral microcirculation using the noninvasive laser-Doppler spectrophotometer "Oxygen-to-see" (O2C) in 20 consecutive patients (15 female, 5 male; median age: 60.5 ± 11.7 years) who were operated on for incidental cerebral aneurysms. Capillary-venous oxygenation (oxygen saturation ["SO2"]), postcapillary venous filling pressures (relative hemoglobin content ["rHb"]), blood cell velocity ("velo"), and blood flow ("flow") were measured in 7-mm tissue depth using a subdural fiberoptic probe. Results Representative recordings were acquired immediately after dural opening over a median time span of 88 ± 21.8 seconds (range: 60-128 seconds) before surgical manipulation. Baseline values (median ± 2 standard deviations) of brain perfusion as measured with the O2C device were SO2, 39 ± 16.6%; rHb, 53 ± 18.6 arbitrary units (AU); velo, 60 ± 20.4 AU; and flow, 311 ± 72.8 AU. Placement of the self-retaining retractor led to a decrease in SO2 of 17% ± 29% (p < .05) and flow of 10% ± 11% (p < .01); rHb increased by 18% ± 20% (p < .01), and velo remained unchanged. Retractor removal caused the opposite with an increased flow of 10% ± 7% (p < 0.001) and velo (3% ± 6%, p = 0.11), but a decrease in SO2 of 24% ± 33% (p = 0.09) and rHb of 12% ± 20% (p =0.18). No neurologic or surgical complications occurred. Conclusion Using this novel noninvasive system, we were able to measure local cerebral microcirculation during aneurysm surgery. Our data indicate that this device is able to detect changes during routine neurosurgical maneuvers. Thus it may be useful for early detection of cerebral microcirculatory disturbances.

Anatomical location of the vocal cords in relation to cervical vertebrae: A new predictor of difficult laryngoscopy?

BACKGROUND: Several anatomical factors, such as prognathism, sex, short thyromental distance and others are known to make direct laryngoscopy difficult. OBJECTIVE: We investigated the hypothesis that the anatomical position of the vocal cords in relation to the cervical vertebrae correlates with difficult laryngoscopy. Existing MRI was used to identify the position of the vocal cords relative to the cervical spine in patients with and without difficult laryngoscopy. DESIGN: Observational study with adaptive enrichment. SETTING: University hospital. PATIENTS: A total of 142 adult patients, 91 with easy (Cormack-Lehane class 1 or 2) and 51 with difficult (Cormack-Lehane class 3 or 4) laryngoscopy. MAIN OUTCOME MEASURES: Position of the vocal cords relative to cervical vertebrae in patients with easy vs. difficult laryngoscopy. RESULTS: In patients with difficult laryngoscopy, we found a higher incidence of cranial position of the vocal cords in relation to the cervical spine compared with patients with easy laryngoscopy (P < 0.001). CONCLUSION: Anaesthesiologists should take advantage of existing imaging of the cervical spine when assessing the patient's airway.

Improved Postoperative Facial Nerve and Hearing Function in Retrosigmoid Vestibular Schwannoma Surgery Significantly Associated with Semisitting Position.

OBJECTIVE: The pros and cons of semisitting positioning (SSP) versus lateral, horizontal positioning (LP) during retrosigmoid vestibular schwannoma (VS) surgery, especially concerning postoperative cranial nerve and brain stem preservation, are under continuous discussion. METHODS: In a single-center retrospective cohort study, 30 VSs operated on in SSP compared with 30 operated on in LP with comparable demography were analyzed. During SSP surgery, transesophageal echocardiographic monitoring for venous air embolism was used continuously. Electrophysiologic cranial nerve monitoring was used in both groups. RESULTS: Length of surgery was significantly different between both groups: 183 minutes mean in SSP surgery versus 365 minutes mean in LP surgery (P = 0.0001). Postoperative rates of facial palsy and hearing loss were also significantly different. Six months postoperatively, 63% had normal facial nerve function after SSP surgery, whereas in LP surgery, 40% had no facial palsy (P = 0.02). Hearing preservation rate was also significantly different: 44% in SSP surgery compared with 14% in LP surgery who had preserved hearing (P = 0.006). Because of cerebrospinal fluid leaks, there were 3 operative revisions in the LP group (10%) and 1 (3.3%) in the SSP group. A clinically insignificant venous air embolism rate was found in 3.3% of patients (1/30) during SSP surgery. The neurologic outcome after 6 months was 1.2 on the Rankin Scale in the LP group and 1.0 in the SSP group, with zero mortality. CONCLUSIONS: SSP compared with LP surgery was associated with significantly shorter operation time and better facial and cochlear nerve function in VS surgery postoperatively, without differences in complication rates.

Catheter-based distal sciatic nerve block in patients with Charcot-Marie-Tooth disease.

BACKGROUND: The use of peripheral nerve blocks in patients with Charcot-Marie-Tooth (CMT) disease is scarcely reported; however, when performed it has proven to be effective for postoperative pain control. METHODS: A distal catheter-based sciatic nerve block for postoperative pain control was offered to 27 consecutive CMT patients scheduled for elective foot surgery. 18 of the 27 CMT patients consented to the offered sciatic nerve block. Localization of the sciatic nerve was guided by a nerve stimulator. The threshold current required to generate a motor response was assessed and a catheter inserted. Postoperative pain was assessed by recording the dose of analgesics to maintain visual analog score < 3 the next 48 hours. On demand patients received boluses of ropivacaine (2 mg/mL) via the catheter and/or analgesics in case of insufficient pain relief. Total postoperative ropivacaine dosage and analgesic consumption were recorded. About one year after the block patients were contacted to report their actual status by self-assessment. RESULTS: In 17 patients a catheter could be placed. In 7 patients placement of the catheter was difficult (several attempts, high electrical impedance). Patients with nerve block had lower analgesics consumption compared to patients without a block. Surprisingly, the 7 patients with "difficult" catheter-placement had the overall lowest ropivacaine and analgesics consumption compared to all other patients with or without peripheral block. No anesthesia related complications were reported by the questionnaire. CONCLUSIONS: In our small series catheter-based distal sciatic block within CMT patients had safely been used for pain relief up to three days. The infusion of local anesthetics via a catheter was not associated with any complication.

The sitting position in neurosurgery: indications, complications and results. a single institution experience of 600 cases.

BACKGROUND: The benefit of the sitting position for surgery of the posterior fossa and cervical spine is still a matter of controversy. In our study we analyzed the outcome after sitting position surgery at our institution. We compared the incidence of venous air embolism (VAE) as recognized with different monitoring techniques and the severity of complications. METHODS: We retrospectively analyzed 600 patients, who underwent surgery for different posterior fossa and cervical spine pathologies, respectively, in the sitting position at our institution from 1995 to 2011. Intraoperative monitoring for VAE included endtidal CO2 level, Doppler ultrasound or intraoperative transesophageal echocardiography (TEE). We defined VAE as a decrease of the endtidal CO2 levels by more than 4 mm Hg, a characteristic sound in the thoracic Doppler, or any sign of air in the TEE. RESULTS: We found an overall incidence of VAE in 19 % of all patients, whereas the rate of severe complications associated with VAE such as a decline of partial oxygen pressure (pO2) or a drop of blood pressure was only 3.3 % in all patients. Only three out of 600 operations had to be terminated because of non-controllable VAE (0.5 %). There was no mortality resulting from VAE in our series. We also found a difference in the incidence of VAE depending on the monitoring technique. The VAE rate as monitored with TEE was 25.6 % whereas the incidence of VAE in patients monitored with Doppler ultrasound was 9.4 %. The rate of a significant VAE was comparable in both methods 4.8 % vs. 1.2 %. All patients were preoperatively screened for persisting foramen ovale (PFO); 24 patients with clinically confirmed PFO were included in this series. There was no case of paradox air embolism. CONCLUSIONS: In our series, VAE was detected in 19 % of all patients in the sitting position. However, in only 0.5 % of cases a termination of the surgical procedure became necessary. In all other cases, the cause of air embolism could be found and eliminated during surgery. TEE was found to be the monitoring technique with the highest sensitivity. In our opinion, the sitting position is a safe positioning technique if TEE monitoring is used.

Postictal agitation after electroconvulsive therapy: incidence, severity, and propofol as a treatment option.

OBJECTIVES: Postictal agitation (PIA) after electroconvulsive therapy (ECT) is a major medical problem. This observational study investigated the incidence and severity of PIA and evaluated propofol as a treatment option in a patient population. METHODS: The study included 14 patients that underwent a series of ECTs performed either with or without an approximately 0.5-mg/kg propofol bolus after the end of an electroencephalography (EEG) seizure. Among other values, we documented PIA incidence and severity as rated by a simple score; orientation to person, time, place, and situation; transfer times to the postanesthesia care (PACU) and inpatient unit; nurses' and patients' rating of recovery period, and others and tested for significant differences. RESULTS: Five minutes after the end of ECT, the patients showed moderate to severe PIA in 8 of 37 ECT sessions. Incidence was significantly lower when patients had received propofol (3/37). Transfer time to the PACU was longer, but transfer time to the inpatient unit was shorter after administration of propofol. The recovery period was rated significantly better after propofol administration by nurses and patients. CONCLUSIONS: A single bolus of propofol administered after the end of the seizure reduced the incidence of post-ECT PIA. The PACU staff and patients rated the emergence period significantly better when propofol was administered.

Anaesthetic management in patients with Duchenne muscular dystrophy undergoing orthopaedic surgery: a review of 232 cases.

CONTEXT: Patients with Duchenne muscular dystrophy are at increased risk of some anaesthesia-related hazards such as rhabdomyolysis, fever and hyperkalaemia. OBJECTIVES: To evaluate the management of anaesthesia in patients with Duchenne muscular dystrophy, including preoperative evaluation, intraoperative performance, critical events and postoperative care. DESIGN: We performed a retrospective case review study of anaesthesia in patients with Duchenne muscular dystrophy covering the period between April 2000 and December 2008. PATIENTS: 91 Duchenne patients undergoing 232 general anaesthetics for orthopaedic surgical interventions. SETTING: University hospital. RESULTS: Anaesthesia was performed using propofol, opioids and, if required, a non-depolarising muscle relaxant. Eight difficult direct laryngoscopies were reported. All patients undergoing spinal fusion surgery received transfusion of homologous blood products and required postoperative invasive ventilatory support for an average of 19 h. There was no severe anaesthesia-related complication and no case of unexplained fever or rhabdomyolysis. CONCLUSION: This retrospective survey confirms clinical experience that total intravenous anaesthesia can be used safely in Duchenne patients without major concern. Further prospective studies are necessary to establish evidence-based clinical guidelines for daily practice.

Transient increase of plasma concentrations of amyloid ß peptides after electroconvulsive therapy.

BACKGROUND: Electroconvulsive therapy (ECT) is applied to effectively treat depressive episodes, and it can be considered an ideal model of generalized seizures induced and performed under precisely controllable conditions. OBJECTIVE: We hypothesize that ECT causes a transiently increased blood-brain barrier permeability. METHODS: We measured plasma concentrations of amyloid ß (Aß) peptides: 1-42, 1-40, x-42, and x-40 before ECT, within 30 minutes after 2, and 24 hours after ECT treatment in 33-36 sessions of n=13 different patients. RESULTS: We observed a significant increase of the plasma concentrations of all four peptides within 30 minutes after the ECT, followed by the normalization of the peptides concentrations 2 hours after the ECT. CONCLUSION: Different physiologic phenomena may be responsible for the transient increase of the Aß peptides concentrations in plasma shortly after ECT session, and further studies are necessary to explain these mechanisms. For example, decreased integrity of the blood-brain barrier permeability, an increased release from neurons due to their activation or increased release from peripheral sources, like thrombocytes or muscles, or a combination of different factors must be taken into consideration.

Increased spike frequency during general anesthesia with etomidate for magnetoencephalography in patients with focal epilepsies.

OBJECTIVE: Magnetoencephalography (MEG) is used for focus localization in presurgical evaluation of patients with focal epilepsies. In this proof-of-concept study, general anesthesia with etomidate was used to improve effectiveness of MEG-recordings. METHODS: MEG-recordings of six patients with focal epilepsy were performed before and after application of etomidate. Spike frequency and localization accuracy of MEG with general anesthesia were compared with spontaneous MEG. RESULTS: After application of etomidate, an increase in spike frequency occurred in all patients, and movement artifacts were prevented. In one patient, spikes could only be detected by invasive EEG but not by MEG. The results were in accordance with spontaneous MEG or presurgical hypotheses about localizations of neocortical foci in three patients. Dipole localizations were distributed over fronto-temporal areas in three patients with ipsilateral temporo-mesial focus hypotheses. CONCLUSIONS: Etomidate ameliorated spike yield and stopped movement artifacts during MEG recordings in patients with focal epilepsy. Localization results were especially accurate in patients with neocortical epilepsy. SIGNIFICANCE: These results could facilitate larger studies on the usefulness and safety of general anesthesia with etomidate that record and localize epileptic activity in patients with focal epilepsy by MEG.

Influence of disease progression on the neuromuscular blocking effect of mivacurium in children and adolescents with Duchenne muscular dystrophy.

BACKGROUND: Studies with nondepolarizing neuromuscular blocking agents showed a delayed onset and prolonged recovery in patients with Duchenne muscular dystrophy. The objective of this study was to investigate if these alterations depend on disease progression. METHODS: The authors studied 11 children (6-9 yr) with moderate Duchenne muscular dystrophy, 11 adolescents (12-16 yr) with advanced Duchenne muscular dystrophy, and 2 age-matched control groups of 8 patients each (5-9 and 10-17 yr). Anesthesia was performed with propofol and remifentanil. Patients received a single intravenous dose of 0.2 mg/kg mivacurium. Neuromuscular transmission was monitored by acceleromyography. The time course of neuromuscular blockade was characterized by the onset time and the times to different levels of recovery. RESULTS: Onset and duration of neuromuscular blockade were significantly prolonged in adolescent Duchenne muscular dystrophy patients (onset time, 4.0 min; recovery index, 12.3 min; median), as compared with Duchenne muscular dystrophy children (onset time, 2.3 min; recovery index, 6.8 min), and also as compared with young controls (onset time, 2.0 min; recovery index, 4.4 min) and adolescent controls (onset time, 2.5 min; recovery index, 4.8 min). Within the Duchenne muscular dystrophy patients, onset time and recovery index increased significantly with age. In the control group, age had no effect. CONCLUSIONS: The neuromuscular blocking effects of mivacurium showed a significant age dependency in Duchenne muscular dystrophy patients, which was most probably caused by the progression of the disease.

Pharmacodynamic modelling of rocuronium in adolescents with Duchenne muscular dystrophy.

BACKGROUND AND OBJECTIVE: Studies with rocuronium showed a delayed onset and prolonged recovery in patients with Duchenne muscular dystrophy (DMD). The objective of this study was to identify the pharmacokinetic and/or pharmacodynamic origin of these alterations. METHODS: Twenty-five male patients (15 with DMD, 10 controls, aged 10-18 years) were studied. Patients were anaesthetized with propofol and sufentanil. Neuromuscular transmission was monitored by acceleromyography. Patients received a single intravenous dose of 0.3 mg kg(-1) rocuronium. In five patients of the DMD group, pharmacokinetic modelling was performed from arterial rocuronium concentrations. The time course of neuromuscular block was analysed with a sigmoid E(max) model including an effect compartment. RESULTS: The pharmacokinetics of rocuronium in DMD patients were Vc 63 +/- 14 ml kg(-1), Cl 3.0 +/- 1.0 ml min(-1) kg(-1), half-lives 2.0 +/- 0.6, 20 +/- 10 and 129 +/- 98 min, SE. For both the DMD and the control group, the time course of neuromuscular block could be described by a sigmoid E(max) model using the estimated pharmacokinetic parameters of the DMD group. In patients with DMD, the equilibration between the central and effect compartment was significantly slower (T(1/2)ke0: 9.7 +/- 0.3 vs. 1.3 +/- 0.1 min) and the EC(50) was significantly smaller (512 +/- 20 vs. 1170 +/- 64 ng ml(-1)), whereas the ED(50) was 0.16 +/- 0.02 mg kg(-1) in both groups. CONCLUSION: The pharmacodynamics of rocuronium were significantly altered in patients with DMD, whereas the pharmacokinetics seemed to be similar to those in healthy adults. Patients with DMD were more sensitive with respect to effect site concentration but not with respect to dose.