Surface Of Cord Research Articles

Endoscopic-guided percutaneous radiofrequency cordotomy

The authors present the first clinical implementation of an endoscopic-assisted percutaneous anterolateral radiofrequency cordotomy. The aim of this article is to demonstrate the intradural endoscopic visualization of the cervical spinal cord via a percutaneous approach to refine the spinal target for anterolateral cordotomy, avoiding undesired trauma to the spinal tissue or injury to blood vessels. Initially, a lateral puncture of the spinal canal in the C1-2 interspace is performed, guided by fluoroscopy. As soon as CSF is reached by the guide cannula (17-gauge needle), the endoscope can be inserted for visualization of the spinal cord and its surrounding structures. The endoscopic visualization provided clear identification of the pial surface of the spinal cord, arachnoid membrane, dentate ligament, dorsal and ventral root entry zone, and blood vessels. The target for electrode insertion into the spinal cord was determined to be the midpoint from the dentate ligament and the ventral root entry zone. The endoscopic guidance shortened the fluoroscopy usage time and no intrathecal contrast administration was needed. Cordotomy was performed by a standard radiofrequency method after refining of the neurophysiological target. Satisfactory analgesia was provided by the procedure with no additional complications or CSF leak. The initial use of this technique suggests that a percutaneous endoscopic procedure may be useful for particular manipulation of the spinal cord, possibly adding a degree of safety to the procedure and improving its effectiveness.

Utility of neurophysiological monitoring using dorsal column mapping in intramedullary spinal cord surgery

Intramedullary spinal cord tumors can displace the surrounding neural tissue, causing enlargement and distortion of the normal cord anatomy. Resection requires a midline myelotomy to avoid injury to the posterior columns. Locating the midline for myelotomy is often difficult because of the distorted anatomy. Standard anatomical landmarks may be misleading in patients with intramedullary spinal cord tumors due to cord rotation, edema, neovascularization, or local scar formation. Misplacement of the myelotomy places the posterior columns at risk of significant postoperative disability. The authors describe a technique for mapping the dorsal column to accurately locate the midline. A group of 10 patients with cervical and thoracic intramedullary spinal cord lesions underwent dorsal column mapping in which a strip electrode was used to define the midline. After the laminectomy and durotomy, a custom-designed multielectrode grid was placed on the exposed dorsal surface of the spinal cord. The electrode is made up of 8 parallel Teflon-coated stainless-steel wires (76-microm diameter, spaced 1 mm apart) embedded in silastic with each of the wires stripped of its insulating coating along a length of 2 mm. This strip electrode maps the amplitude gradient of conducted spinal somatosensory evoked potentials elicited by bilateral tibial nerve stimulation. Using these recordings, the dorsal columns are topographically mapped as lying between two adjacent numbers. The authors conducted a retrospective analysis of the preoperative, immediate, and short-term postoperative neurological status, focusing especially on posterior column function. There were 8 women and 2 men whose mean age was 52 years. There were 4 ependymomas, 1 subependymoma, 1 gangliocytoma, 1 anaplastic astrocytoma, 1 cavernous malformation, and 2 symptomatic syringes requiring shunting. In all patients the authors attempted to identify the midline by using anatomical landmarks, and then proceeded with dorsal column mapping to identify the midline electrophysiologically. In the 2 patients with syringomyelia and in 5 of the patients with tumors, the authors were unable to identify the midline anatomically with any certainty. In 2 patients with intramedullary tumors, they were able to identify the midline anatomically with certainty. Dorsal column mapping allowed identification of the midline and to confirm the authors' anatomical localization. In 2 patients with intramedullary tumors, posterior column function was preserved only on 1 side. All other patients had intact posterior column function preoperatively. Dorsal column mapping is a useful technique for guiding the surgeon in locating the midline for myelotomy in intramedullary spinal cord surgery. In conjunction with somatosensory evoked potential, motor evoked potential, and D-wave recordings, we have been able to reduce the surgical morbidity related to dorsal column dysfunction in this small group of patients.

Localization of cervical and cervicomedullary stimulation leads for pain treatment using median nerve somatosensory evoked potential collision testing

Spinal cord stimulation (SCS) is being currently used to treat medically refractory pain syndromes involving the face, trunk, and extremities. Unlike thoracic SCS surgery, during which patients can be awakened from conscious sedation to confirm good lead placement, safe placement of paddle leads in the cervical spine has required general anesthesia. Using intraoperative neurophysiological monitoring, which is routinely performed during these cases at the authors' institution, the authors developed an electrophysiological technique to intraoperatively lateralize lead placement in the cervical epidural space. Data from 44 patients undergoing median and tibial nerve somatosensory evoked potential (SSEP) monitoring during cervical laminectomy or hemilaminectomy for placement or replacement of dorsal column stimulators were retrospectively reviewed. Paddle leads were positioned laterally or just off midline and parallel to the axis of the cervical spinal cord to effectively treat what was most commonly a predominant unilateral pain syndrome. During SSEP recording, the spinal cord stimulator was activated at 1.0 V and increased in increments of 1.0 V to a maximum of 6.0 V. A unilateral reduction or abolishment of SSEP amplitude was regarded as an indicator of lateralized placement of the stimulator. A bilateral diminutive effect on SSEPs was interpreted as a midline or near midline lead placement. Epidural stimulation abolished or significantly reduced SSEP amplitudes in all patients undergoing placement for a unilateral pain syndrome. In 15 patients, electrodes were repositioned intraoperatively to achieve the most robust SSEP amplitude reduction or abolishment using the lowest epidural stimulation intensity. In all cases in which a significant unilateral reduction in SSEP was observed, the patient reported postoperative sensory alterations in target locations predicted by intraoperative SSEP changes. Placement of cervical spinal cord stimulators for bilateral pain syndromes often resulted in bilateral but asymmetrical SSEP changes. In no cases were significant SSEP changes, other than those induced using the device to directly stimulate the dorsal surface of the spinal cord, observed. No case of new postoperative neurological deficit was observed. Somatosensory evoked potentials can be used safely and successfully for predicting the lateralization of cervical spinal cord stimulator placement. Moreover, they can also intraoperatively alert the surgical team to inadvertent displacement of a lead during anchoring. Further studies are needed to determine whether apart from assisting with proper lateralization, SSEP collision testing may help to optimize electrode positioning and improve pain control outcomes.

Effects of Disturbing Parameters on the Stability of Latex and Resorcinol Formaldehyde Latex Based Adhesives

Synthetic cords may be coated with resorcinol formaldehyde latex (RFL)-based adhesives to adhere the cord to the rubber in industrial goods such as tires and conveyor belts. The stability of the adhesive and the stability of its component latex are crucial, both for ideal adhesion and for the homogeneity of the cord surface. Latex is a colloidal polymeric dispersion, which may lose its stability upon mechanical stress or upon interaction with some chemicals that lead to the formation of coagulated polymeric particles. This article reports on the influences of both external mechanical stresses and chemical interactions on RFL adhesives and latex stability, adhesion, and viscosity. High speed mixing, treatment with excess RF, and temperature variations were applied as disrupting parameters.

Pattern of Inspiratory Intercostal Muscle Activation during High Frequency Spinal Cord Stimulation (HF‐SCS)

ObjectiveHF‐SCS is a novel technique of inspiratory muscle activation involving spinal cord pathways. The purpose of the present study was to compare the distribution of motor drive to the intercostal muscles during spontaneous breathing with that occurring during HF‐SCS.MethodsIn 4 anesthetized dogs, electrical stimulation was applied via a stimulating electrode on the ventral surface of the upper thoracic spinal cord at the T2 level. Fine wire recording electrodes were used to assess single motor unit (SMU) pattern of activation of the parasternal (PA, 2nd interspace) and external [dorsal portions of the 3rd (EI‐3D) and 5th (EI‐5D) and ventral portion of the 3rd (EI‐3V) interspaces] intercostal muscles.ResultsMean maximum discharge frequency of PA was 10.6±0.3 Hz. Mean maximum discharge frequency of EI‐3D (13.7±0.5Hz) was significantly greater than that of the EI‐3V (8.8±0.3Hz) and the EI‐5D (9.9±0.3Hz) (p<0.05). Importantly, these values were not significantly different than those occurring in the same animals during spontaneous breathing.ConclusionThis study demonstrates that HF‐SCS results in the same differential pattern of activation of the various intercostal muscles as that which occurs during spontaneous breathing. Moreover, the neural circuitry resulting in physiologic activation of the rib cage muscles exists within the spinal cord.Support: NIH‐NINDS (R01NS064157)

A Transmedullary Approach to Occlusion of a Ventral Perimedullary Arteriovenous Fistula of the Thoracic Spinal Cord

A spinal perimedullary arteriovenous fistula (PMAVF) is a direct fistula of one or more spinal arteries into the perimedullary venous network with reversed venous flow and subsequent venous congestion of the spinal cord. The therapeutic goal of surgery is to normalize the venous drainage by obliterating the fistula. Strictly ventral lesions typically require an anterior approach to ensure adequate exposure of the fistula as well and the preservation of the physiological blood supply to the spinal cord. We present a case of a ventral PMAVF at the level of T10 with feeders from the anterior spinal artery, caudally draining veins on the ventral spinal cord, and a dilated transmedullary vein filling cranially draining veins on the dorsal aspect of the spinal cord. The dilated transmedullary vein was approached by a laminectomy. The vein was coagulated, and the gliotic channel was used to approach the ventral fistula site from the dorsal surface of the spinal cord. Complete obliteration of the fistula was achieved, and the preoperative neurological deficit improved. We conclude that transmedullarly draining veins offers a possible dorsal approach for the occlusion of some ventral PMAVFs, thus avoiding more complex anterior approaches to the ventral spinal cord.

Rapid semi-automatic segmentation of the spinal cord from magnetic resonance images: Application in multiple sclerosis

A new semi-automatic method for segmenting the spinal cord from MR images is presented. The method is based on an active surface (AS) model of the cord surface, with intrinsic smoothness constraints. The model is initialized by the user marking the approximate cord center-line on a few representative slices, and the compact surface parametrization results in a rapid segmentation, taking on the order of 1 min. Using 3-D acquired T1-weighted images of the cervical spine from human controls and patients with multiple sclerosis, the intra- and inter-observer reproducibilities were evaluated, and compared favorably with an existing cord segmentation method. While the AS method overestimated the cord area by approximately 14% compared to manual outlining, correlations between cord cross-sectional area and clinical disability scores confirmed the relevance of the new method in measuring cord atrophy in multiple sclerosis. Segmentation of the cord from 2-D multi-slice T2-weighted images is also demonstrated over the cervical and thoracic region. Since the cord center-line is an intrinsic parameter extracted as part of the segmentation process, the image can be resampled such that the center-line forms one coordinate axis of a new image, allowing simple visualization of the cord structure and pathology; this could find wider application in standard radiological practice.

Cervical (Non-terminal) Myelocystocele Associated With Rapidly Progressive Hydrocephalus and Chiari Type II Malformation -Case Report-

An infant presented with a rare cervical (non-terminal) myelocystocele as a congenital skin-covered mass located in the midline of the posterior aspect of her neck. Magnetic resonance (MR) imaging and computed tomography showed a cystic mass filled with cerebrospinal fluid in the midline of the posterior aspect of the neck, with a fibrous streak extending from the bottom of the sac to the dorsal surface of the cervical cord. Brain MR imaging also showed a dilated ventricular system and Chiari type II malformation. The patient underwent plastic repair of the lesion, which was diagnosed as myelocystocele. After the surgery, the patient experienced respiratory distress. Ultrasound tomography from the anterior fontanel revealed deterioration of hydrocephalus, so a ventriculoperitoneal shunt was inserted, and the respiratory distress improved. The present case illustrates the possibility of rapidly worsening of hydrocephalus and Chari type II malformation after surgical repair of cervical (non-terminal) myelocystocele.

Padronização da lesão de medula espinal em ratos Wistar

OBJETIVO: Padronizar um modelo experimental de lesão de medula espinal em ratos Wistar, utilizaram-se um equipamento computadorizado para impacto por queda de peso e os parâmetros determinados pelo Multicenter Animal Spinal Cord Injury Study - MASCIS. MÉTODOS: Avaliaram-se 30 ratos, com idade variando entre 20 e 25 semanas de vida. O peso variou de 200 a 300 g, para as fêmeas, e de 232 a 430 g para os machos. Realizaram-se impactos com pesos de 10 g de 12,5; 25 e 50 mm de altura, controlando-se a velocidade de impacto e o coeficiente de compressão. O impacto ocorreu sobre a superfície da medula espinal na altura da décima vértebra torácica, após laminectomia. Monitoraram-se os sinais vitais e realizaram-se gasometrias previamente e posteriormente à lesão da medula. O volume de lesão foi avaliado pela análise quantitativa dos íons de sódio e potássio. RESULTADOS: Verificaram-se correlações estatisticamente significantes entre o volume de lesão e os parâmetros mecânicos. O volume de lesão provocado por queda de 50 mm de altura foi superior aos de 12,5 e 25 mm, que não diferiram entre si. CONCLUSÃO: O modelo demonstrou-se eficaz e capaz de gerar lesões medulares padronizadas em ratos Wistar.

Impact of acute inflammation on spinal motoneuron synaptic plasticity following ventral root avulsion.

BackgroundVentral root avulsion is a proximal nerve root lesion in which ventral motor nerve rootlets are torn from surface of the spinal cord, resulting in extensive death of motoneurons. It has been previously shown that if such lesioning is performed in an animal with experimental autoimmune encephalomyelitis (EAE), a significant number of motoneurons can be rescued despite an intense inflammatory reaction. This rescue effect has been attributed to production of a number of neurotrophic factors by invading T cells. Synaptological changes may be involved in neuronal degeneration, and a better understanding of the role of these changes may be of importance for developing new strategies to promote neuronal survival. The objective of the present work was to evaluate neuronal survival, astroglial reaction and synaptic input changes in spinal cord anterior horn motor nuclei after ventral root avulsion in animals with EAE, both during peak disease and after remission.MethodsLewis rats were subjected to unilateral avulsion of lumbar ventral roots (VRA) and divided into three groups: VRA control, VRA at peak of EAE, and VRA during EAE remission. The animals were sacrificed and their lumbar spinal cords processed for immunohistochemistry, transmission electron microscopy, and motoneuron counting.ResultsThe results indicate a reduction in astroglial reaction, a maintenance of microglial reactivity, and increases in synaptic covering of, and survival of, motoneurons in the VRA+EAE group as compared to VRA alone.ConclusionThe present findings indicate that CNS inflammation may directly influence synaptic plasticity as well as the stability of neuronal networks, positively influencing the survival of lesioned neurons.

回転性めまいを主訴とした脳表ヘモジデリン沈着症例

Superficial central nervous system siderosis is a very rare disease related to hemosiderin deposits in the brain, brain stem, cerebellum, and spinal cord due to chronic subarachnoid hemorrhage. Clinical findings are progressive bilateral sensorineural hearing loss, cerebellar ataxia, and pyramidal tract signs. A 62-year-old woman exhibited vertigo, worsening tinnitus, unstable gait, and spontaneous Bruns-like horizontal nystagmus. A central nervous system disorder was suspected due to the vertical vector that emerged when the woman looked upward. Magnetic resonance imaging (MRI) showed a low-intensity rim in T2-weighted imaging enveloping the brain and spinal cord surface.

Distribution of oxytocin-immunoreactive neuronal elements in the rat spinal cord

We investigated the distribution of oxytocin in rat spinal cord using immunocytochemistry and radioimmunoassay (RIA). Each segment of the spinal cord from cervical to coccygeal contained oxytocin-immunoreactive fibers. The Rexed laminae I and II of the dorsal horn showed moderate to intense immunoreactivity. A dense network was found around the central canal where some fibers apposed the ependyma. The autonomic centers of the spinal cord at the thoracolumbar and sacral segments were heavily innervated. Few fibers were found around the motoneurons. In the white matter, the immunoreactivity was localized mainly in the dorsal part of the lateral funiculus, in the pars funicularis of the nucleus intermediolateralis and in a longitudinal network of the lateral funiculus below the spinal cord surface. Some fibers from this network entered the pia mater. RIA measurements revealed that the cervical spinal cord had lower oxytocin content than that found in either the thoracic, lumbar, sacral or coccygeal region. Our results show that the distribution of oxytocin-immunoreactive fibers in the spinal cord correlates with anatomic locations related to nociceptive, autonomic and motor functions. We assume that oxytocin-containing axons play a role in secreting oxytocin directly into the liquor space of the spinal cord.

Long-term voice outcome following partial cricotracheal resection in children for severe subglottic stenosis

Objective To correlate the postoperative voice outcome to preoperative glottic involvement, following partial cricotracheal resection (PCTR) in children. The glottic involvement was analysed based on the extent of subglottic stenosis (SGS) in the endoscopic image and functional dynamic assessment using flexible endoscopy. Methods We conducted an interobserver study in which two ENT surgeons, blinded to one another's interpretation, independently rated the extent of SGS based on the endoscopic image along with the dynamic functional airway assessment, of 108 children who underwent PCTR for grade III or IV stenosis. Based on the observation, the glottic involvement was rated into 4 categories: A. SGS clear from vocal cords (3–4 mm below vocal cords). B. SGS reaching the free border of vocal cord and/or the posterior commissure with slightly limited abduction with no true posterior glottic stenosis (PGS). C. SGS with associated PGS or vocal cord fusion without cricoarytenoid ankylosis (CAA). D. Transglottic stenosis with/or without bilateral CAA. Evaluation of the voice was based on a parent/patient proxy questionnaire sent in 2008 to assess the current functional status of the patient's voice. Results Among the 77 patients available for long-term outcome with a minimum 1-year follow-up, 31 patients had isolated SGS free from vocal cords (group A) and 30 had SGS reaching the under surface of vocal cords with partial or no impairment of abduction of vocal cords (group B). Twelve patients belonged to group C with posterior glottic stenosis and/or vocal cord fusion (without cricoarytenoid ankylosis) and 4 patients had transglottic stenosis and or/bilateral cricoarytenoid ankylosis (group D). The long-term voice outcome following PCTR as perceived by the parent or patient was normal in 18% (14 of 77 patients) and the remaining 63 patients demonstrated mild to severe dysphonia. Patients belonging to group A and B exhibited either normal voice or mild dysphonia. Patients in group C demonstrated dysphonia, which was moderate in severity in the majority (83%). All patients in group D with transglottic stenosis and/or CAA showed severe dysphonia. Conclusion Children with associated glottic involvement are at high risk for poor voice outcome following PCTR. The severity of dysphonia was found to be proportional to the preoperative glottic involvement. Preoperative rating of the extent of glottic involvement based on endoscopic image and dynamic assessment was found to be useful in prognosticating the voice outcome.

Antiapoptotic and neuroprotective effects of mycophenolate mofetil after acute spinal cord injury in young rats

The aim of this study was to investigate the possible beneficial effects of mycophenolate mofetil in comparison with methylprednisolone in an experimental model of spinal cord injury in young rats. Young female Wistar albino rats weighing 100-120 g were used in this study. The animals were anesthetized, the paravertebral muscles were dissected to expose thoracic spinal nerve 7 (T7)-T11 vertebrae, and the spinal cord was exposed at T8-T10 levels by laminectomy with the assistance of a surgical microscope. Weight-drop trauma model was used to perform spinal cord trauma. The animals were subjected to an impact of 50 g/cm to the dorsal surface of the spinal cord. The animals were divided into six groups, and all the groups include 12 animals. Group 1 laminectomy, group 2 laminectomy+ trauma, group 3 was treated with mycophenolate mofetil, group 4 was treated with methylprednisolone, group 5 was treated with mycophenolate mofetil+methylprednisolone, and group 6 served as a vehicle. Immediately after the trauma, 25 mg/kg mycophenolate mofetil (to group 3 and 5) and 30 mg/kg methylprednisolone (to group 4 and 5) were given in a single dose. Biochemical, behavioral, pathological, and immunohistochemical analysis were done. Significant decrease in the number of apoptotic cells were detected in the lesion zone 24 h after the spinal cord injury with the mycophenolate mofetil treatment group. Histologic and functional recovery was also significant. Our results showed that the administration of mycophenolate mofetil on traumatic spinal cord injury decreases apoptosis and improves neurologic recovery.

High-frequency spinal cord stimulation of inspiratory muscles in dogs: a new method of inspiratory muscle pacing

Despite clinically available methods of diaphragm pacing, most patients with ventilator-dependent tetraplegia are still dependent on mechanical ventilation. Given the significant disadvantages of these devices, additional pacing options are needed. The objective of this study was to evaluate a novel and potentially more physiological method of inspiratory muscle activation, which involves the application of high-frequency (>200 Hz) stimulation to the ventral surface of the spinal cord in the high thoracic region. Studies were performed in 13 anesthetized dogs. High-frequency spinal cord stimulation (HF-SCS) results in the activation of both the diaphragm and inspiratory intercostal muscles, in concert, at physiological firing frequencies and the generation of large inspired volumes. Mean maximum firing frequencies of motor units in the parasternal (2nd interspace), the external intercostal (3rd interspace), and the diaphragm muscles were 10.6 +/- 0.4, 11.7 +/- 0.4, and 10.4 +/- 0.3 Hz, respectively. These values were not significantly different from those occurring during spontaneous breathing at comparable inspired volumes. Maximum inspired volume was 0.93 +/- 0.01 liter, which approximates the inspiratory capacity of these animals. Moreover, ventilation can be maintained on a chronic basis by this method (6 h) without evidence of system fatigue. Our results suggest that HF-SCS results in activation of spinal cord tracts that synapse with the inspiratory motoneuron pools, allowing processing of the stimulus and consequent physiological activation of the inspiratory muscles. HF-SCS has the potential to provide an effective method of inspiratory muscle pacing.

Effect of spinal cord stimulation in a rodent model of post‐operative ileus

Post-operative ileus (POI) is a transient impairment of gastrointestinal (GI) transit that develops after abdominal surgery. The goal of this study was to investigate the effect of spinal cord stimulation (SCS) on gastric emptying and upper GI transit in a rat model of POI. All rats had an electrode placed on the dorsal surface of the spinal cord between the T(5) and T(8) segments. After recovery, gastric emptying and upper GI transit (geometric centre and head of meal) were assessed using a radiolabelled meal fed to each rat via oral gavage. In unanaesthetized rats, SCS (15, 25, 50, 100, 200 Hz, 0.2 ms at 90% motor threshold for 15 min) was performed immediately after the meal. The sham control group had no current applied. The naïve group was without POI or SCS. Gastric emptying was significantly delayed in sham-stimulated rats with POI compared with naïve controls (39.8 +/- 6.2%vs 76.5 +/- 4.9%, P < 0.001). In rats with POI that underwent SCS, there was a significant acceleration of gastric emptying to levels that resembled those of naïve controls (65.1 +/- 7.4%, P < 0.05). However, while SCS did not normalize the geometric centre and head of the meal when compared with the naïve group, it did significantly improve both parameters compared with the sham stimulation group. In summary, SCS normalizes gastric emptying and improves upper GI transit in a rodent model of POI. Further experiments are required to address the mechanism(s) by which SCS exhibits prokinetic activity.

Superficial Siderosis Revealed by Isolated Cognitive Impairment

Superficial siderosis (SS) is a rare disorder due to chronic bleeding into the subarachnoid or intraventricular space. The most common clinical presentation is progressive ataxia and hearing loss. The authors report two patients who presented with dementia as the primary manifestation of SS. The cognitive impairment marked by cortical frontotemporoparietal dysfunction was consistent with the pattern of signal abnormalities seen on brain magnetic resonance imaging (MRI). Diagnosis of SS must be considered when T2*-weighted MRI shows typical signal hypointensity outlining the brain and spinal cord surfaces. Performing such MRI sequences appears to be of particular interest in the context of dementia etiological diagnosis.

Cord Dose Specification and Validation for Stereotactic Body Radiosurgery of Spine

Effective dose to a portion of the spinal cord in treatment segment, rather than the maximum point dose in the cord surface, was set as the dose limit in stereotactic-body radiosurgery (SBRS) of spine. Such a cord dose specification is sensitive to the volume size and position errors. Thus, we used stereotactic image guidance to minimize phantom positioning errors and compared the results of a 0.6-cm 3 Farmer ionization chamber and a 0.01-cm 3 compact ionization chamber to determine the detector size effect on 9 SBRS cases. The experimental errors ranging from 2% to 7% were estimated by the deviation of the mean dose in plans to the chamber with spatial displacements of 0.5 mm. The mean and measured doses for the large chamber to individual cases were significantly (∼17%) higher than the doses with the compact chamber placed at the same point. Our experimental results shown that the mean doses to the volume of interest could represent the measured cord doses. For the 9 patients, the mean doses to 10% of the cord were about 10 Gy, while the maximum cord doses varied from 11.6 to 17.6 Gy. The mean dose, possibly correlated with the cord complication, provided us an alternative and reliable cord dose specification in SBRS of spine.

Investigation into the Effects of Accelerated Aging Conditions on Adhesion of Resorcinol–Formaldehyde–Latex Treated Synthetic Cords

The adhesion between the interface of synthetic fiber and rubber is achieved by coating the surface of synthetic cord with Resorcinol–Formaldehyde–Latex (RFL) adhesive solution. The strength of adhesion between fiber–RFL–rubber, depends on several factors. These include an optimum coating and curing conditions involving the control of timing, tension and temperature. Even if good adhesion is obtained by controlling the optimum conditions, the adhesion could be lost to some extend, if the RFL coated cords are exposed to indifferent and harsh ambient conditions. In this article, the adhesion behaviour of RFL dipped cord, after prolonged exposure to temperature, humidity and daylight was investigated. The adhesion was monitored by the pull out method. The analysis of the un-aged and aged cords were carried out by contact angle measurement, ATR spectroscopy and cord cross-section microscopic analysis.

Peripheral nerve grafts in a spinal cord prosthesis result in regeneration and motor evoked potentials following spinal cord resection

To evaluate whether a standardized nerve graft bridging of a spinal cord injury gap in a device with white to grey matter projections allows regeneration and electrophysiological contact from supraspinal centers to the leg, since previous studies using nerve grafts in combination with acidic fibroblast growth factor have been difficult to microsurgically reproduce. A moulded prosthesis containing twelve peripheral nerve grafts with estimated pre-set projections guiding white tracts to grey matter replaced a spinal cord resection gap at level T11 in adult rats. The animals were evaluated with electrophysiology, morphology, immunohistochemistry and functional scoring. At six months postoperatively the grafts were found to be positioned at the desired locations, motor evoked potentials were detected in 80% of the animals subjected to nerve graft bridging. Morphology and immunohistochemical analysis revealed numerous de novo axons in the grafts, which possibly reached into the spinal cord on the other side. Replacing the resected spinal cord with oblique peripheral nerve grafts results in spinal cord regeneration and positive motor evoked potential. Transplantation of nerve grafts organized in a prosthesis is re-producible, sustains desired projections and ensures transverse ends towards the spinal cord surface and may be useful in the future.