Multimodality intraoperative neuromonitoring in extreme lateral interbody fusion. Transcranial electrical stimulation as indispensable rearview.

PURPOSE: To optimize intraoperative neuromonitoring during extreme lateral interbody fusion (XLIF) by adding transcranial electrical stimulation with motor evoked potential (TESMEP) to previously described monitoring using spontaneous EMG (sEMG) and peripheral stimulation (triggered EMG: tEMG). METHODS: Twenty-three patients with degenerative lumbar scoliosis had XLIF procedures and were monitored using sEMG, tEMG and TESMEP. Spontaneous and triggered muscle activity, and the MEP of 5 ipsilateral leg muscles, 2 contralateral leg muscles and 1 arm muscle were monitored. RESULTS: During XLIF surgery decreased MEP amplitudes were measured in 9 patients and in 6 patients sEMG was documented. In 4 patients, both events were described. In 30 % of the cases (n = 7), the MEP amplitude decreased immediately after breaking of the table and even before skin incision. After reduction of the table break, the MEP amplitudes recovered to baseline. In two patients, the MEP amplitude deteriorated during distraction of the psoas with the retractor, while no events were reported using sEMG and tEMG. Repositioning of the retractor led to recovery of the MEP. CONCLUSIONS: Monitoring the complete nervous system during an XLIF procedure is found to be helpful since nerve roots, lumbar plexus as well as the intradural neural structures may be at risk. TESMEP has additional value to sEMG and tEMG during XLIF procedure: (1) it informed about otherwise unnoticed events, and (2) it confirmed and added information to events measured using sEMG.

First experiences with the use of intraoperative 3D-RX for wrist surgery.

With the use of conventional C-arm fluoroscopy for hand surgery, suboptimal positioning of implants, K-wires, insufficient reconstructions and joint incongruities frequently remain unrevealed We prospectively compared the performance of the surgeon interpreted from conventional methods (2D fluoroscopy and direct visual and physical inspection) versus 3D imaging as well as the occurrence of revision surgeries based on post-op radiological findings. Twenty-four intraoperative findings based on 2D fluoroscopy and findings on direct visual and physical inspections were compared with intraoperatively acquired 3D-RX scans by means of a questionnaire. Moreover, record was kept of revision surgery (minimal three months follow up) for all patients treated with the aid of 3D-RX. A clear difference in findings was observed between the performance based on fluoroscopy and direct visual and physical inspection and that based on intraoperative 3D-RX for hand surgery (p < 0.05). Post-operative radiological examinations revealed that none of the 56 patients treated with the aid of 3D-RX needed revision surgery. Intraoperative 3D-RX provides information for the hand surgeon that is additional to the information acquired with conventional fluoroscopy. Intraoperative 3D-RX provides well defined images of the positioning of osteosynthesis material, of the spatial orientation of carpals, and of reconstruction of the wrist joint.

Extensor pollicis longus rerouting for thumb-in-palm deformity in cerebral palsy: a biomechanical analysis.

Extensor pollicis longus rerouting is a common procedure to improve thumb abduction in thumb-in-palm deformity seen with spastic cerebral palsy. In 1985, Manske redirected the extensor pollicis longus tendon in this procedure through the first extensor compartment. They also proposed an alternative subcutaneous route around the extensor pollicis brevis and abductor pollicis longus tendons proximal to the extensor compartment. In this study, we performed a three-dimensional analysis of thumb motion on 11 cadaver arms with the subcutaneous route and the first extensor compartment route. We found that with the two different routing methods, the mean difference in thumb radial abduction and retropulsion (0° or 6°, respectively) was very small. Such differences are unlikely to have clinical relevance. We were unable to find significant differences in the motion range of the thumb after these rerouting techniques or sites of insertion. Our biomechanical data support the simpler subcutaneous route.

In vivo experiments with tracheostoma tissue connector prototypes.

In cancer patients who have undergone total surgical removal of the larynx, ideally voice rehabilitation should be performed using a shunt valve (placed in a fistula of the tracheo-esophageal wall) and a tracheostoma valve (TSV) to enable hands-free tracheo-esophageal speech. A tracheostoma is created by suturing the trachea into the lower anterior part of the neck, and a TSV is a device that can be placed at the stoma. Unfortunately, many patients are unable to use a TSV, mainly due to fixation difficulties. To improve the fixation of the TSV, tracheostoma tissue connector (TS-TC) prototypes have been designed. Prototype 1 consisted of a titanium ring, inner diameter 30 mm, with a circular polypropylene mesh glued to it with silicone adhesive. Four holes had been drilled into the ring for the insertion of sub- and percutaneous screws. Prototype 2 consisted of a silicone rubber ring, inner diameter 30 mm, combined with polypropylene mesh and four titanium inserts that functioned as a base plate for the insertion of sub- and percutaneous screws. In adult female goats a tracheostoma was created and the prototypes were implanted. After 6 weeks of subcutaneous implantation, percutaneous screws were inserted. After twelve weeks, the experiment was terminated and the implants with the surrounding tissues were processed and examined histologically. The clinical appearance during weeks 7-12 varied from very poor to relatively good. Histologically, the implants showed a uniform inflammatory response. We found that all the tissue surrounding the screws showed signs of epithelial down growth. It was concluded that the two-stage implantation procedure of our prototype TS-TCs in this animal model was unsuccessful. Additional research efforts are necessary to improve tissue immobilization and to devise reliable fixation systems for TSVs.

The Saanen goat as an animal model for post-laryngectomy research: practical implications.

A modern way of voice rehabilitation after total laryngectomy includes the use of shunt valves and tracheostoma valves. Problems of fixation to the surrounding tissue are a major drawback in the use of the shunt valve, heat and moisture exchange (HME) filters and, especially, the tracheostoma valve. To solve these problems different tissue connectors were developed. The main objective was to test the feasibility of these prototypes in a new animal model. Here we discuss the results, problems and complications of the selected Saanen goat model. In this prospective laboratory study, 19 healthy adult female Saanen goats (Capra hircus) were used and observed post-surgically for 12 weeks. Selection criteria such as comparable anatomy to humans and easy handling were used for animal model development. Also a literature search using the Medline and the ISI Web of Science databases was performed. The anatomy of the Saanen goat was investigated in a separate postmortem study. Surgery consisted of a laryngotracheal separation and implantation of a tracheo-oesophageal and tracheostoma tissue connector with fibrin tissue glue. Postoperative care consisted of frequent stoma care, monitoring appetite, weight, vital signs and administration of antibiotics, analgesics and mucolytic agents. All animals survived the surgical procedure. However, postoperative care was extensive, labour intensive and was accompanied by several complications. Eleven animals died spontaneously before the end of the experiment. The tracheostoma tissue connector caused signs of local infection in all cases. There was no evidence of infection around the tracheo-oesophageal tissue connector in 18 cases. It was concluded that the use of goats in this tracheostoma model was associated with major complications and should, therefore, only be used for short-term experiments with intensive care. Additional research is needed to see if clinical application of the tissue connectors is possible in the future.

The Nijmegen decision tool for chronic low back pain. Development of a clinical decision tool for secondary or tertiary spine care specialists.

BACKGROUND: In Western Europe, low back pain has the greatest burden of all diseases. When back pain persists, different medical specialists are involved and a lack of consensus exists among these specialists for medical decision-making in Chronic Low Back Pain (CLBP). OBJECTIVE: To develop a decision tool for secondary or tertiary spine care specialists to decide which patients with CLBP should be seen by a spine surgeon or by other non-surgical medical specialists. METHODS: A Delphi study was performed to identify indicators predicting the outcome of interventions. In the preparatory stage evidence from international guidelines and literature were summarized. Eligible studies were reviews and longitudinal studies. Inclusion criteria: surgical or non-surgical interventions and persistence of complaints, CLBP-patients aged 18-65 years, reported baseline measures of predictive indicators, and one or more reported outcomes had to assess functional status, quality of life, pain intensity, employment status or a composite score. Subsequently, a three-round Delphi procedure, to reach consensus on candidate indicators, was performed among a multidisciplinary panel of 29 CLBP-professionals (>five years CLBP-experience). The pre-set threshold for general agreement was ≥70%. The final indicator set was used to develop a clinical decision tool. RESULTS: A draft list with 53 candidate indicators (38 with conclusive evidence and 15 with inconclusive evidence) was included for the Delphi study. Consensus was reached to include 47 indicators. A first version of the decision tool was developed, consisting of a web-based screening questionnaire and a provisional decision algorithm. CONCLUSIONS: This is the first clinical decision tool based on current scientific evidence and formal multidisciplinary consensus that helps referring the patient for consultation to a spine surgeon or a non-surgical spine care specialist. We expect that this tool considerably helps in clinical decision-making spine care, thereby improving efficient use of scarce sources and the outcomes of spinal interventions.

Quantitative microdialysis using modified ultraslow microdialysis: direct rapid and reliable determination of free brain concentrations with the MetaQuant technique.

The only method to quantify free extracellular levels of drugs in the brain of living animals is microdialysis. However, quantitative microdialysis has been hampered by methodological issues for decades. The problems arise from the need to establish the in vivo recovery for appropriate quantitation. In dealing with these issues the "dynamic no-net-flux" (DNNF) method seemed to be the experimental method of choice. Major disadvantages were, however, the need for a very high degree of bioanalytical precision and accuracy and the need for a large number of animals. Moreover, today we know that the experimental data are not always straightforward. To improve robustness and practicality of quantitative microdialysis sampling we modified the ultraslow microdialysis approach. Ultraslow microdialysis uses very low microdialysis flow rates (<200 nl/min) which increase recovery (both in vivo and in vitro) to over 90%. However, new practical issues arise when attempting to work with these flow rates. The resulting very low volumes and long lag times make this method very impractical for general application. In the modified version, addition of a carrier flow after the dialysis process has been completed, which negates the problems of long lag times and low volumes. The resulting dilution of the dialysis sample concentration can simply be mathematically corrected. In the current study we measured the free brain levels of two CNS compounds using the classic DNNF and the new modified ultraslow dialysis method. Modified ultraslow microdialysis was shown to generate robust data with the use of only small numbers of rats. The method is a promising tool for common straightforward screening of blood-brain barrier penetration of compounds into the brain.

Experimental results of the tracheoesophageal tissue connector for improved fixation of shunt valves in laryngectomized patients.

BACKGROUND: After total laryngectomy and voice rehabilitation using a tracheoesophageal shunt valve, patients often have valve-related complications such as leakage. To solve these problems, a tracheoesophageal tissue connector (TE-TC) was devised to serve as an interface between the patient's tissue (trachea and esophagus) and the shunt valve. METHODS: The TE-TC is a permucosal connection constructed from a titanium ring (filled with a silicon rubber plug) combined with polypropylene or titanium mesh. After implantation in adult goats for 12 weeks the implants were submitted to histologic investigation. RESULTS: Firm implant fixation was achieved. In nearly all (18/19), no signs of infection of the implant were seen; 11 of 19 animals died before the end of the experiment owing to complications not related to the implant. CONCLUSIONS: The TE-TC is a new device with potential in the solution for fixation-related problems in tracheoesophageal voice rehabilitation.

In vitro assessment of the unloading and perfusion capacities of the PUCA II and the IABP.

The PUCA II pump is a minimally invasive intra-arterial left ventricular assist device that can be used as an alternative for the intra-aortic balloon pump (IABP). In this study, we assessed the cardiac unloading and organ perfusion capacities of both PUCA II and IABP in an in vitro set up, consisting of a heart simulator and a silicone arterial tree, mimicking anatomical geometry and flow distribution. The IABP was positioned in the descending aorta, while the PUCA II was tested both in 'trans-aortic' and 'abdominal' positions. All devices were driven by the same Arrow AutoCat IABP driver at different pump rates. Apart from flow, arterial pressure and pulse pressure, we also calculated haemodynamic indices for myocardial oxygen supply and demand. The 'abdominal' PUCA II assist and the IABP both provide mild unloading of the heart, and a limited improvement of arterial pressure and flow. The 'trans-aortic' PUCA II assist greatly enhances flow and pressure, but does not unload the heart properly in the tested configuration.