Lipid-Polymer Hybrid Nanoparticles Synthesized via Lipid-Based Surface Engineering for a robust drug delivery platform.

Herein, lipid-polymer core-shell hybrid nanoparticles composed of poly(D,L-lactic-co-glycolic acid) (PLGA)/lecithin (PLNs) were synthesized through lipid-based surface engineering. Lipids were absorbed onto the surface of the PLGA core to enhance the advantages of polymeric nanoparticles and liposomes. The amounts of lipids and encapsulation of the drug nicardipine hydrochloride (NCH) in the PLNs were studied. NCH-loaded PLNs (NCH-PLNs) were produced in high yield (66%) with a high encapsulation efficiency (92%) and a size of 176 nm. The mass of phosphorus (P) on the NCH-PLN surface was qualitatively and quantitatively investigated using X-ray fluorescence spectroscopy, and lecithin addition increased the P mass percentage due to the phosphate group (PO43-) in its structure. These data confirmed the lipid-based surface engineering of NCH-PLNs. The zeta potential of NCH-PLN exceeded -30 mV, ensuring colloidal stability, and preventing precipitation through electrostatic stabilization. In vitro, NCH was continuously and slowly released from NCH-PLNs over 16 days. Furthermore, PSVK1 cells exhibited high viability after treatment with NCH-PLNs, indicating favorable cytocompatibility. After comparing various mathematical equations of drug release kinetics, the data best fit the Korsmeyer-Peppas model with R2 values of 0.989, 0.990, and 0.982 for 1.0, 3.0, and 5.0 mg/mL lecithin, respectively. The release exponents obtained ranged from 0.480 to 0.505, suggesting anomalous transport release. Thus, NCH-PLNs have potential as a robust drug delivery platform for the controlled administration of NCH, particularly for vasodilation during neurosurgery.

Assessing the benefits of digital twins in neurosurgery: a systematic review.

Digital twins are virtual replicas of their physical counterparts, and can assist in delivering personalized surgical care. This PRISMA guideline-based systematic review evaluates current literature addressing the effectiveness and role of digital twins in many stages of neurosurgical management. The aim of this review is to provide a high-quality analysis of relevant, randomized controlled trials and observational studies addressing the neurosurgical applicability of a variety of digital twin technologies. Using pre-specified criteria, we evaluated 25 randomized controlled trials and observational studies on the applications of digital twins, including navigation, robotics, and image-guided neurosurgeries. All 25 studies compared these technologies against usual surgical approaches. Risk of bias analyses using the Cochrane risk of bias tool for randomized trials (Rob 2) found "low" risk of bias in the majority of studies (23/25). Overall, this systematic review shows that digital twin applications have the potential to be more effective than conventional neurosurgical approaches when applied to brain and spinal surgery. Moreover, the application of these novel technologies may also lead to fewer post-operative complications.

Comparison of standard and modified prone positioning for lateral lumbar spine fusion: a feasibility study to reduce lumbar plexus injury.

Single-prone-lateral (PL) positioning is a new technique that allows for simultaneous anterior and posterior lumbar spine surgery. However, there is a concern regarding the risk of lumbar plexus injury in PL positioning. This study compared the risk of lumbar plexus damage and the overall safety profile of a modified PL (mPL) position to the standard PL (sPL) position for lateral lumbar spine fusion surgery. A crossover soft cadaveric study was conducted with two raters examining the comparative outcomes of position A: sPL and position B: mPL. The mPL position differs from the sPL position in that the ipsilateral arm is placed at the side of the body rather than above the head. To assess positive results (no lumbar plexus injury) between positions A and B, a mixed effects logistic regression model was utilized. The odds ratio of a good result between positions B and A was also determined. The odds ratio of the favorable outcome between position B and A was 1.77, indicating significantly higher odds of a favorable outcome in the modified position B than in the control or position A. The mPL positioning outperformed the sPL positioning in terms of safety and efficacy for lateral lumbar spine fusion. The mPL positioning may reduce the risk of lumbar plexus injury by allowing for a more direct approach to the lumbar spine and by avoiding excessive stretching of the lumbar plexus.

Cefazolin Loaded Oxidized Regenerated Cellulose/Polycaprolactone Bilayered Composite for Use as Potential Antibacterial Dural Substitute.

Oxidized regenerated cellulose/polycaprolactone bilayered composite (ORC/PCL bilayered composite) was investigated for use as an antibacterial dural substitute. Cefazolin at the concentrations of 25, 50, 75 and 100 mg/mL was loaded in the ORC/PCL bilayered composite. Microstructure, density, thickness, tensile properties, cefazolin loading content, cefazolin releasing profile and antibacterial activity against S. aureus were measured. It was seen that the change in concentration of cefazolin loading affected the microstructure of the composite on the rough side, but not on the dense or smooth side. Cefazolin loaded ORC/PCL bilayered composite showed greater densities, but lower thickness, compared to those of drug unloaded composite. Tensile modulus was found to be greater and increased with increasing cefazolin loading, but tensile strength and strain at break were lower compared to the drug unloaded composite. In vitro cefazolin release in artificial cerebrospinal fluid (aCSF) consisted of initial burst release on day 1, followed by a constant small release of cefazolin. The antibacterial activity was observed to last for up to 4 days depending on the cefazolin loading. All these results suggested that ORC/PCL bilayered composite could be modified to serve as an antibiotic carrier for potential use as an antibacterial synthetic dura mater.

Endonasal endoscopic transsphenoidal approach robot prototype: A cadaveric trial.

BACKGROUND: The Endonasal Endoscopic Transsphenoidal Surgery (EETS) is a minimally invasive procedure to approach and remove pituitary tumors and other sellar lesions. The process causes less pain, faster recovery, and provides further minimal invasive access in critical cases. However, a slight deviation of tools from the target area can be fatal to the patients. The aim of this study is to design and develop a prototype robot to demonstrate neurosurgical robot-assisted EET approach. METHODS: The effectiveness of a prototype robot in executing a minimally invasive EET surgery was studied in 6 cadavers. The robot was associated with a multi-information integrated technique for surgery including QR code tracking. The robot was controlled and driven by the neurosurgeon. RESULTS: The standard procedure of EET was followed and the robot carried out the first stage of EET under the supervision of neurosurgeon. Finally, the sellar was reached by the neurosurgeon. The result was determined by qualitative analysis and was confirmed by the neurosurgeon. The time for the entire EET surgical procedure showed marked reduction compared to the traditional EET approach. CONCLUSION: The robot design was found to be technically feasible and hence can be used for assisting the EET procedure. The robot used was able to assist the neurosurgeon correctly to approach the sinus.

Autologous bone-marrow mononuclear stem cell therapy in patients with stroke: a meta-analysis of comparative studies.

BACKGROUND: There is a need to promote recovery after stroke with novel therapeutic interventions. Of them, bone-marrow mononuclear cell (BM-MNC) therapy offers promising outcomes in preclinical and clinical models. AIMS: To investigate the efficacy and safety of BM-MNCs versus traditional medical care of stroke patients. A meta-analysis was conducted involving controlled prospective studies and randomized clinical trials (RCTs) which investigated the changes in the scores of neurological functions (the National Institutes of Health Stroke Scale [NIHSS]), the indices of functional recovery (the Barthel Index [BI] and the modified Rankin scale [mRS]) at 3 and 6 month post-transplantation. A total of nine studies (five RCTs) recruited 469 stroke patients (65.5% males, 49.25% received the intervention). There were no significant differences in NIHSS, BI, or mRS scores after 3 months of follow-up. However, the BI indices of BM-MNCs-receiving patients improved significantly after 6 months (standardized mean difference = 1.17, 95% confidence interval, 0.23 to 2.10, P = 0.01) as compared to traditional treatment. The risk of mortality and adverse events and the proportion of patients with favorable outcomes (mRS ≤ 3) were similar in both groups. CONCLUSION: Both the BM-MNCs and medical stroke treatment have similar outcomes in terms of safety and short-term efficacy, while the effect of therapy is significant only after 6 months. More well-designed, large sized RCTs are needed to confirm the efficacy of stem cell therapy over long periods of follow-up.

In vivo evaluation of bilayer ORC/PCL composites in a rabbit model for using as a dural substitute.

OBJECTIVE: After a neurosurgical procedure, dural closure is commonly needed to prevent cerebrospinal fluids (CSF) leakage and to reduce the risk of complications, including infections and chronic inflammatory reactions. Although several dural substitutes have been developed, their manufacturing processes are complicated and costly and that many of them have been implicated in causing postoperative complications. This study aimed to assess the effectiveness and safety of new bilayer ORC/PCL composites in a rabbit model. METHODS: Two formulations of bilayer oxidized regenerated cellulose (ORC)/poly ε-caprolactone (PCL) knitted fabric-reinforced composites and an autologous graft (pericranium) were employed for dural closure in forty-five male rabbits. Systemic reaction and the local reaction of the samples were assessed and compared at one-, three- and six-months post-implantation by blood chemistry and gross, and microscopic assessment using hematoxylin-eosin and Masson's trichrome stains. RESULTS: No signs of CSF leakage or systemic infection were seen for all samples. All samples demonstrated minimal adhesion to adjacent tissues. The degree of host fibrous connective tissue ingrowth into both composites was comparable to that of the autologous group, but bone formation and osteoclast activities were significantly greater. Both composites progressively degraded over times and the residual thickness of the nonporous layer was 50% of the initial thickness at six months post-implantation. DISCUSSION: Bilayer ORC/PCL composites were successfully employed for dural closure in the rabbit model. They were biocompatible and could support dural regeneration comparable to that of the autologous group, but induced greater osteogenesis.

Performance evaluation of bilayer oxidized regenerated cellulose/poly ε-caprolactone knitted fabric-reinforced composites for dural substitution.

Ideally, alloplastic dural substitute should have functional properties resembling human dura mater and retain a watertight closure to prevent cerebrospinal leakage. Therefore, functional properties for successful dural closure application of newly developed bilayer oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites were studied and compared with human cadaveric dura mater and three commercial dural substitutes including two collagen matrices and one synthetic poly-L-lactide patch. It was found that oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites uniquely contained a bilayer structure consisting of micropores distributed within the relatively dense microstructure. Density, tensile properties and stitch tear strength of oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites were found to be closed to human cadaveric dura mater than those of dense-type and porous-type dural substitutes. Water tightness performance in both sutured and non-sutured forms of oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composites was slightly inferior to human cadaveric dura mater, but still better than those of commercial dural substitutes. This study revealed that oxidized regenerated cellulose knitted fabric/poly ε-caprolactone knitted fabric-reinforced composite showed better functional properties than typical dural substitutes and was found to be a good candidate for being employed as a dural substitute. The role and relationship of both microstructure and the type of materials on the functional properties and water tightness of the dural substitutes were also elucidated.

Anatomical Workspace Study of Endonasal Endoscopic Transsphenoidal Approach.

PURPOSE: To determine the workspace through an anatomical dimensional study of the skull base to further facilitate the design of the robot for endonasal endoscopic transsphenoidal (EET) surgery. METHODS: There were 120 cases having a paranasal sinus CT scan in the database. The internal volumes of the nasal cavities (NC), the volumes of the sphenoid sinuses (SS), and the distance between the anterior nasal spine and base of the sellar (d-ANS-BS) were measured. RESULTS: The Pearson correlation coefficient (PCC) between the relevant distances and the volumes of the right NC was 0.32; between the relevant distances and the volumes of the left NC was 0.43; and between the relevant distances and volumes of NC was 0.41; with a statistically significant difference (p < 0.001). All PCCs had a statistically significant meaningful difference (p < 0.05). CONCLUSION: The volume of NCs were significantly correlated with distances (p < 0.05). The safest and shortest distance to guide the robotic arm length in the EET approach could be represented by d-ANS-BS. This result was also used as primary information for further robotic design.

Analysis of Endonasal Endoscopic Transsphenoidal (EET) surgery pathway and workspace for path guiding robot design.

BACKGROUND: Endoscopic Endonasal Transsphenoidal Surgery (EETS) is the standard method to treat pituitary adenoma, tumor in the pituitary gland which would affect human beings in terms of hormonal malfunction and other symptoms. This procedure provides extra minimal invasive access in severe cases. The objective of this paper is to design and develop a prototype of EET robot with navigation guidance system based on the study of EET workspace and pathway to determine a safe space for surgical tool insertion. METHODS: The EET workspace and its pathway were studied via data collected from EET experiments on 70 cadavers. An optical tracking system was used to detect and record the movement of the surgical tools during the experiments. Delaunay triangulation and Voronoi diagram were utilized to determine the cloud position of the gathered data for EET workspace. Moreover, in order to determine the EET pathway voxelization methods were incorporated. RESULTS: The average diameter of the workspace calculated was 19.08 with 3.32 S. D, the average length and volume of the workspace were 53.9 mm and 15.9cm3, respectively. The S.D values determined for length and volume were 7.2 and 6.02, respectively. For the pathway, a high density area was determined via data obtained through cloud position. CONCLUSION: Dimension of the EET workspace and characters of EET pathway determine robot's requirements to design and develop EET robotic system. This article demonstrates the conceptual design of an EET robot and successfully accomplishes the goal of guidance and aids in assisting the EET procedures.

Determination of Spinopelvic Parameters in Degenerative Lumbar Spondylolisthesis Patients Undergoing Lumbosacral Spine Fusion Surgery: The Lesson Learnt.

AIM: To investigate the relationship between the deformity correction and subsequent alterations in spinopelvic parameters after surgical correction in degenerative lumbar spondylolisthesis patients. MATERIAL AND METHODS: About 100 adult patients were recruited in the study. The eligible cases received surgical treatment from 2003 to 2013 at Ramathibodi Hospital. RESULTS: No significant change was observed in any of the spinopelvic parameters after correction of slip degree following surgery in the transforaminal lumbar interbody fusion group. CONCLUSION: Lumbar spinal fusion procedures cause significant changes in spinopelvic parameters and are efficient in correcting the height of disc in the transforaminal lumbar interbody fusion group.

Electrical stimulation-based nerve location prediction for cranial nerve VII localization in acoustic neuroma surgery.

INTRODUCTION: Cranial nerve (CN) VII localization is a critical step during acoustic neuroma surgery because the nerve is generally hidden due to the tumor mass. The patient can suffer from Bell's palsy if the nerve is accidentally damaged during tumor removal. Surgeons localize CN VII by exploring the target area with a stimulus probe. Compound muscle action potentials (CMAPs) are elicited when the probe locates the nerve. However, false positives and false negatives are possible due to unpredictable tissue impedance in the operative area. Moreover, a single CMAP amplitude is not correlated with probe-to-nerve distance. OBJECTIVES: This paper presents a new modality for nerve localization. The probe-to-nerve distance is predicted by the proposed nerve location prediction model. METHODS: Input features are extracted from CMAP responses, tissue impedance, and stimulus current. The tissue impedance is calculated from the estimated resistance and capacitance of the tissue equivalent circuit. In this study, experiments were conducted in animals. A frog's sciatic nerve and gastrocnemius were used to represent CN VII and facial muscle in humans, respectively. Gelatin (2.8%) was used as a mock material to mimic an acoustic neuroma. The %NaCl applied to the mock material was used to emulate uncontrollable impedance of tissue in the operative area. RESULTS: The 10-fold cross-validation results revealed an average prediction accuracy of 86.71% and an average predicted error of 0.76 mm compared with the measurement data. CONCLUSION: The proposed nerve location prediction model could predict the probe-to-nerve distance across various impedances of the mock material.

Visualization of Needle-Tip Localization by Ultrasound Guidance with Contrast Bubble in Lumbar Selective Nerve Root Block: Clinical Pilot Study.

BACKGROUND: Epidural steroid injection for low back and leg pain has been shown to result in a positive clinical outcome. Lumbosacral selective nerve root block (SNRB) via a transforaminal approach is commonly performed under fluoroscopic guidance. However, ultrasound guidance is an alternative to overcome the radiologic disadvantages. This study examined the accuracy of needle-tip localization under ultrasound guidance with a contrast bubble, compared with fluoroscopic guidance. OBJECTIVE: The primary objectives were to envisage the needle-tip localization with an air bubble by ultrasound and also to determine the accuracy of needle-tip location in transforaminal lumbar SNRB for low back and leg pain patients who were not surgical candidates. METHODS: A prospective study of 30 SNRBs was conducted. An air bubble was produced and was used to envisage the needle-tip location under ultrasound guidance. Finally, the needle tip was confirmed by fluoroscopy. The accuracy of needle-tip location was statistically analyzed. RESULTS: Twenty-four SNRBs were performed at L4-5 and 6 SNRBs at L3-4. The accuracy of needle-tip localization was 80%. CONCLUSION: In order to avoid radiation exposure during the SNRB procedure, ultrasound guidance might be an alternative. Despite being accepted practice, there is a steep learning curve involved in the use of ultrasound guidance for lumbar SNRB, and proper training is crucial. A contrast bubble is a prospective enhancement for better visualization of ultrasound guidance.

Peripheral nerve function estimation by linear model of multi-CMAP responses for surgical intervention in acoustic neuroma surgery.

Nerve function assessments are crucial for surgical intervention during acoustic neuroma surgery. Cranial nerves such as acoustic and facial nerves, can be possibly damaged during tumor dissection. Proper surgical intervention should prevent neurological deficit and achieve total tumor removal. Conventionally, nerve function is qualitatively evaluated by surgeon and neurologist. Facial nerves can be preserved by monitoring the compound muscle action potential (CMAP) response. The differences in the amplitude and latency of CMAP are used as indicators during surgical interventions. However, baseline CMAPs cannot be recorded in the presence of large acoustic tumors. This paper presents a new way of estimating nerve function. Instead of a single CMAP examination, multi-CMAP responses are obtained from a train of varied stimulus intensities and these are applied a mathematical model. Shifts in the mathematical model parameters reflect changes in facial nerve function. In this study, experiments conducted in frog revealed that shifts in the linear model parameters were related to the level of induced nerve injury. Significant differences in the slope parameter of the linear model were found between each nerve condition. The identification of healthy and severed nerves via a support vector machine (SVM) corresponded to 94% accuracy. This classification criterion could be used with surgical intervention to prevent severed facial nerve palsy in acoustic neuroma surgery. The proposed method could be used to estimate nerve outcomes without prior information of a CMAP baseline.

Encapsulation of Nicardipine Hydrochloride and Release from Biodegradable Poly(D,L-lactic-co-glycolic acid) Microparticles by Double Emulsion Process: Effect of Emulsion Stability and Different Parameters on Drug Entrapment.

Poly(D,L-lactic-co-glycolic acid) (PLGA) is an important material used in drug delivery when controlled release is required. The purpose of this research is to design and characterize PLGA microparticles (PLGA MPs) implants for the controlled release of nicardipine hydrochloride (NCH) in vitro. This study used the water-in-oil-in-water (w1/o/w2) double emulsion and solvent diffusion/evaporation approach to prepare PLGA MPs. Optimal processing conditions were found, such as polymer content, surfactant type, stabilizer concentration, inner and outer aqueous phase volumes, and stirring speed. The PLGA MPs for use as nicardipine hydrochloride (NCH) loading and release had spherical morphology, and the average diameter was smaller than 5.20 ± 0.25 µm. The release kinetics were modeled to elucidate the possible mechanism of drug release. In vitro release studies indicated that the NCH release rate is slow and continuous. PLGA MPs are an interesting alternative drug delivery system, especially for use with NCH for biomedical applications.

Assessment and Predicting Factors of Repeated Brain Computed Tomography in Traumatic Brain Injury Patients for Risk-Stratified Care Management: A 5-Year Retrospective Study.

Background and Objective. To determine the value of repeated brain CT in TBI cases for risk-stratified care management (RSCM) and to identify predicting factors which will change the neurosurgical management after repeated brain CTs. Methods. A 5-year retrospective study from January 2009 to August 2013 was conducted. The primary outcome was the value of repeated brain CT in TBI cases. The secondary outcome is to identify predicting factors which will change the neurosurgical management after repeated brain CTs. Results. There were 145 consecutive patients with TBI and repeated brain CT after initial abnormal brain CT. Forty-two percent of all cases (N = 61) revealed the progression of intracranial hemorrhage after repeated brain CT. In all 145 consecutive patients, 67.6% of cases (N = 98) were categorized as mild TBI. For mild head injury, 8.2% of cases (N = 8) had undergone neurosurgical management after repeated brain CT. Only 1 from 74 mild TBI patients with repeated brain CT had neurosurgical intervention. Clopidogrel and midline shift more than 2 mm on initial brain CT were significant predicting factors to indicate the neurosurgical management in mild TBI cases. Conclusion. Routine repeated brain CT for RSCM had no clinical benefit in mild TBI cases.

Bilayer oxidized regenerated cellulose/poly ε-caprolactone knitted fabric-reinforced composite for use as an artificial dural substitute.

A novel bilayer knitted fabric-reinforced composite for potentially being used as a dural substitute was developed by solution infiltration of oxidized regenerated cellulose knitted fabric (ORC) with poly ε-caprolactone (PCL) solution at various concentrations ranging 10-40 g/100 mL. It was found that the density of all formulations did not differ significantly and was lower than that of the human dura. Microstructure of the samples typically comprised a bilayer structure having a nonporous PCL layer on one side and the ORC/PCL composite layer on another side. Tensile modulus and strength of the samples initially decreased with increasing PCL solution concentration for up to 20 g/100 mL and re-increased again with further increasing PCL solution concentration. Strain at break of all formulations were not significantly different. Watertight test revealed that all composites could prevent leakage at the pressure within the normal range of intracranial pressure. In vitro degradation study revealed that the weight loss percentage and change in tensile properties of all samples displayed biphasic profile comprising an initially rapid decrease and followed by a gradual decrease with incubation times afterward. Micro and macro porous channels were observed to be in situ generated in the composite layer by ORC dissolution and PCL resorption during degradation while nonporous layer remained relatively unchanged. The degradation rate was found to decrease with increasing PCL solution concentration. In vitro biocompatibility using alamar blue assay on selected samples showed that fibroblasts could attach and proliferate well at all incubation periods.

Retrospective long term outcome following microvascular decompression surgery in Thai patients with trigeminal neuralgia.

OBJECTIVE: To retrospectively evaluate 5-year pain-free symptoms and clinical outcome for trigeminal neuralgia (TN) patient population after microvascular decompression. MATERIAL AND METHOD: The authors reviewed the medical records of all Thai TN cases admitted at Ramathibodi Hospital, Mahidol University, and Ramkhamhaeng Hospital between 2001 and 2006. The 5-year pain-free symptoms and clinical outcome was determined using marginal homogeneity test (Stuart-Maxwell). RESULTS: There were 99 cases with TN. Women (75.6%) were affected more than men (24.4%). More often, the facial pain occurred on the right side of the face (72.8%) than on the left (27.2%). In 78.8% of cases, the facial pain was located along the mandibular division of the trigeminal nerve. In 19.2% of cases, the facial pain was located along the maxilla division ofthe trigeminal nerve and 30% of cases reported the pain along the combination ofthe maxilla and the mandibular division of the trigeminal nerve. Two percent of cases located pain along all three divisions. In 65.7% of cases, they reported their triggerpoints. Sixty-one cases (61.6%) were operated at Ramkhamhaeng Hospital and 38 cases (38.4%) [corrected] were diagnosed and treated at Ramathibodi Hospital, Mahidol University. Microvascular decompression surgery was the treatment of choice in all cases. As a final point, 97.9% of all cases who were pain free at the 5-year follow-up were significantly different between before and after treatment (p< 0.001). CONCLUSION: In Thai TN patients, the mandibular division of the trigeminal nerve was most commonly involved, in concordance with other population group studies. In the present study, microvascular decompression surgery is the treatment of choice in TN patient. In the 97.9% of all cases that were pain free at the 5-year follow-up, they were significantly different between before and after treatment (p< 0. 001).

Linear model of peripheral nerve after surgical manipulation: preliminary report in animal study and model shift.

Generally, the neurophysiologic intra-operative monitoring (NIOM) is acknowledged to correlate with reducing the risk of perioperative neurological deficits. This electrophysiological method is commonly used and neurosurgeons could aware where the nervous system is at risk of being permanently injured while doing the operation under NIOM. However, this monitoring is quite a qualitative evaluation. Neurosurgeons have to use their own experiences to consider and made the estimation. Traditionally, the peripheral nerve function can be preserved by continuous electromyography (EMG) and compound muscle action potential response (CMAP) monitoring. The spike and burst EMG occur when the nerve trunk is irritated or damaged. Decreased amplitude of CMAP response is also considered as nerve damage even it might cause from a severe irritation. By using this information, the peripheral nerve function is qualitatively evaluated by the surgeons. This present study proposed a new predictive nerve model for peripheral nerve function prediction. This input and output data were used for nerve modeling in each condition. The results showed that parameters of the linear nerve model had significantly differences and tendency changes in each nerve condition. Therefore, the proposed method for predicting the nerve function by the shifted linearly nerve model might be a promising approach for peripheral nerve function estimation in the human nerve model.

Accuracy of needle-tip localization by ultrasound guidance lumbar selective nerve root block: a prospective clinical study of 78 lumbar nerve roots block.

OBJECTIVE: Selective nerve root block (SNRB) is the accepted procedure for diagnostic and therapy in lumbar radicular back pain management. The present study was to determine the accuracy of needle-tip under ultrasound guidance subsequently confirmed with fluoroscopy in patients who underwent SNRB. To date, no study comparing these two techniques has been performed. MATERIAL AND METHOD: After the IRB approval, a prospective trial was conducted to determine the accuracy of ultrasound guidance SNRB in 40 consecutive patients with lumbar radicular pain undergoing fluoroscopic guidance SNRB between January 2010 and January 2011. Firstly, needle-tip was located at the desired optimal landmark under ultrasound guidance and then subsequently fluoroscopic confirmation of needle-tip position was done. Finally, the injection was performed as usual. The primary outcome was the accuracy of needle-tip placement comparing between under ultrasound and subsequently fluoroscopic confirmation. The secondary outcome was the associated factors of the accuracy of needle-tip under ultrasound guidance. RESULTS: Seventy-eight lumbar nerve roots were injected in the patients that underwent SNRB under fluoroscopic guidance. The accuracy of needle-tip on each lumbar nerve root under ultrasound guidance with fluoroscopic confirmation ranged from 7.14% to 80.95%. Mean of the accuracy of needle-tip under ultrasound guidance comparing with subsequently fluoroscopic confirmation was 62.82% while 95% CI ranged from 51.13 to 73.50%. The age older than 65 years old was significantly associated with the poor accuracy under ultrasound guidance (p-value = 0.0095). CONCLUSIONS: To position the needle-tip under ultrasound guidance is feasible and has good safety profile. The accuracy could be achieved individually. However, because the accuracy of ultrasound guidance technique depends on the operator a steep learning curve and larger prospective clinical study is needed.