Introduction Spinal cord monitoring in posterior scoliosis surgery has become a standard of care. It has been our practice since 1999, to monitor the somato-sensory potential (SEP) and motor evoked potential (MEP) in all posterior cases. We report on and discuss the meaning of alteration in the spinal cord monitor signal that occurred in 15 cases from a total of 165 procedures. Methods This is a retrospective review of patients from a hospital database. Over a six year period, 167 posterior scoliosis instrumented fusion procedures were performed by paired combinations of the four authors. In 13 cases we have been alerted to a change in one or both signals during the procedure. Associated with these, were two cases of intra-operative cardiac arrest, and six cases of post-operative neurological deficit. All patients remain under continued regular review. Results In the two cases of intra-operative cardiac arrest, the SEP and MEP signals were lost approximately three minutes prior to the arrest. Both patients had neurological deficits post-operatively, one has totally recovered, and one has a residual complex regional pain syndrome of the right leg. This last patient is the only one of six who has not had complete resolution of the post-operative neurological deficit. In five of the six cases who sustained post-operative neurological deficits, the SEP and usually the MEP was lost and did not return. In the sixth case, the SEP did return. In the remaining seven cases, there were changes of decreased amplitude or increased latency in the SEP or MEP that did not appear to result in a postoperative clinical consequence, however; in two patients, signal changes were directly related to changes in blood pressure, and in two other patients, signal changes were directly related to concave hook placement. Discussion On review of the management and outcome of these cases, we conclude that profound hypotension will alter the SEP and may herald a catastrophic cardiovascular or neurological event. Furthermore, the modality of continuous spinal cord monitoring can provide specificity in the diagnosis of an actual or impending neurological insult and allow for appropriate and timely intervention. We believe spinal cord monitoring in the posterior approach for spinal deformity is an invaluable tool, and is in fact, mandatory for all idiopathic and ambulant non-idiopathic spinal deformities

Introduction Transcranial motor evoked potentials are routinely used at The Children’s Hospital at Westmead to monitor the spinal cord in spinal surgery. This study is a prospective review of all spinal cord monitoring procedures from 1999 to 2004 in patients undergoing elective spinal deformity correction surgery at The Children’s Hospital at Westmead and Westmead Hospital. Spinal cord monitoring with Somatosensory Evoked Potentials (SSEP) and MEP has been widely used in combination during spinal surgery with good sensitivity and specificity. The use of CMAP as the only modality has not been widely used and its efficacy has not been fully elucidated. Using MEP and CMAP only may increase the sensitivity of spinal cord monitoring compared with combined SSEP and MEP monitoring. Methods The intra-operative monitoring outcomes were compared with patient’s post-operative clinical outcomes. The sensitivity and specificity were calculated and determined for our monitoring protocol. Results Transcranial MEPs were measured in 146 patients in 175 procedures. In 2 patients (2 procedures) we were unable to record any CMAPS. There were 15 intra-operative monitoring changes (8.7%). There were no new post-operative neurological deficits. Our results compare favourably to the literature with respect to the false-negative rate or new neurological events. Discussion Using our anaesthetic protocol and spinal monitoring criteria, we were able to successfully monitor patients undergoing elective spinal deformity correction surgery for a variety of diagnoses. The monitoring criteria are sufficiently strict to achieve a sensitivity of 1.0 (95%CI = 0.66–1.00) and a specificity of 0.97 (95%CI = 0.83–0.99). Monitoring of CMAPs alone has been adequate to avoid clinical neurological deficits

The April 2012 Children’s orthopaedics Roundup. 360 . looks at osteonecrosis of the femoral head and surgery for dysplasia, femoral head blood flow during surgery, femoroacetabular impingement and sport in adolescence, the Drehmann sign, a predictive algorithm for septic arthritis, ACL reconstruction and arthrofibrosis in children, spinal cord monitoring for those less than four years old, arthroereisis for the flexible flat foot, fixing the displaced lateral humeral fracture, and mobile phones and inclinometer applications

Introduction. Evidence suggests that intra-operative spinal cord monitoring is sensitive and specific for detecting potential neurological injury. However, little is known about surgeons' responses to trace changes and the resultant neurological outcome. Objective. To examine the role of intra-operative somatosensory evoked potential (SSEP) monitoring in the prevention of neurological injury, specifically sensitivity and specificity, and whether the abnormalities were reversible. Methods. 2953 consecutive complex spine operations (male 36% female 64%, median age 25yrs) prospectively performed using spinal cord monitoring at a single institution (2005–2009). All traces and neurophysiological events were prospectively recorded by the neurophysiology technician. All patients with a significant neurophysiology event were examined clinically by a neurologist, separate from the spinal surgery team. Significant trace abnormality was defined as a decrease in signal amplitude of 50% or a 10% increase in latency. Timing of trace abnormality, surgeon's response and prospective neurological outcome were recorded. Sensitivity, specificity, positive/negative predictive value were calculated. A Chi-squared test was performed to assess the impact of intervention on neurological outcome (p < 0.05). Results. 2953 operations involving SSEP monitoring were performed and 106 recorded a significant trace abnormality. This most often occurred during instrumentation and the most common reaction was adjustment of metalwork. SSEP monitoring had a sensitivity of 100%, specificity 97.3%, PPV 24%, NPV 100%. There were 79 false positives and no false negatives in this series. Chi-squared test was not significant (p=0.18) suggesting that intervention might not affect neurological outcome in this cohort. Conclusions. Triggering events are uncommon and the development of a persistent neurological deficit is rare with an incidence of 0.85% in this series of 2953 operations. In the majority of cases detection of a monitoring abnormality prompts a corrective reaction by the surgeon. Of those with an abnormal trace 76% were neurologically normal at follow up

Abstract. Objective. Spinal cord surgery is a technically challenging endeavour with potentially devastating complications for patients and surgeons. Intra-operative neurophysiological monitoring(IONM), or spinal cord monitoring (SCM), is one method of preventing and identifying damage to the spinal cord. At present, indications for its use are based more on individual surgeon preference and for medico legal purposes. Our study aimed to determine IONM's utility as a clinical tool. Methods. This is a retrospective case series of 169 patients who underwent spinal surgery with IONM at two institutions between 2013 and 2018. Signal changes detected were recorded as well as the surgeon's response to these changes. Patients were followed up to one-year post-surgery using our institution's EVOLVE system. The main outcome measure in this study was new post-operative neurological signs and/or symptoms and what effect, if any, IONM and subsequent surgeon intervention had on these complications. Result. Indications for IONM included cervical stenosis, cervical disc prolapse, unstable fractures and bony metastases. Signal changes were observed in 33% (n=55) of cases. 24 of these patients responded to re-positioning. There were 7 total complications with full resolution by 12 months. False negative rate was 2.4% (n=4). There was one true positive. The largest cohort of patients included those who experienced no signal changes and subsequently no post-operative deficits (n=124). Conclusion. IONM is a non-invasive clinical tool that may be utilised for medicolegal reasons. Its use as a clinical tool is questionable given its relatively high false negative rate and low false positive rate. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Percutaneous vertebroplasty (PVP), where vertebral bodies are injected with polymethylmethacrylate (PMMA) cement, is used to treat various spinal lesions. Although the complication rate for PVP is low, thermal damage caused by the exothermic curing of PMMA has been implicated. This study was to measure the temperatures reached during PVP as PMMA cures as well as assessing the cement volume effect and inter cement differences. Validating spinal cord monitoring during PVP was also undertaken. In the in vivo experiment each of the lumbar vertebral bodies of 10 sheep were injected with one of two cements and one of two volumes. Thermocouple monitoring was undertaken at the bone cement interface. While undertaking the in vivo experimental studies 6 sheep underwent epidural monitoring using Motor Evoked Potentials (MEPs). The mean peak temperature at the bone-cement interface was 49.5 C (3.0ml Simplex); 61.47 C (6.0ml Simplex); 42.1 C (DePuy 3ml) and 47.2 (DePuy 6ml). Spinal cord monitoring showed that when cement was injected into the correct location within the trabeculae of the vertebral body no change in amplitude monitoring was noted. When leakage occurred, deliberate or unintended, amplitude changes were noted. Using cement volumes similar to those used in human clinical practice in a sheep model we were able to monitor temperature changes. The temperature of the bone cement interface reached temperatures that are known to cause tissue necrosis. Using epidural monitoring we were able to detect leakage of cement during injection

Introduction Vertebroplasty (VP), where vertebral bodies are injected with polymethylmethacrylate (PMMA) cement, is used to treat various spinal lesions. More recently VP has been used for augmenting osteoporotic vertebral bodies that have fractured or are at risk of fracture. Although the complication rate for VP is low, thermal damage caused by the exothermic curing of PMMA has been implicated. The aim of this series of experiments was to measure the temperatures reached during VP using a sheep model. The cement volume effect and inter cement differences were assessed. Spinal cord monitoring was undertaken to monitor spinal cord function during this procedure to validate this for clinical use. Methods In the in vivo experiment each of the lumbar vertebral bodies of 10 sheep were injected with one of two cements (Simplex & Vertebroplastic) and one of two volumes (3.0ml or 6.0ml). This was undertaken through an open approach in the lumbar vertebrae. While performing the in vivo experimental studies 6 of the sheep were concurrently monitored using epidural Motor Evoked Potentials (MEP’s). Results There was a significant increase in the temperature at the bone cement interface. The mean peak temperature at the bone-cement interface was 49.5 C (3.0ml Simplex); 61.47 C (6.0ml Simplex); 42.1 C (DePuy 3ml) and 47.2 (DePuy 6ml). Spinal cord monitoring showed that when PMMA was injected into the correct location within the vertebral body there was no change in amplitude of the evoked potentials. When significant leakage of PMMA occurred, there was a decrease in amplitude of MEP’s. Discussion In this sheep model, using cement volumes similar to those used in human clinical practice, we were able to monitor temperature changes within the vertebral body at the bone cement interface. The temperature of the bone cement interface reached temperatures that are known to cause tissue necrosis. Using epidural monitoring we were able to show that when PMMA is injected into the correct location within the vertebral body there is no change in amplitude of MEP’s

Background: To review the results of spinal cord monitoring over a five year period and determine whether the generally accepted criterion used for warning the surgeon is appropriate and whether this criterion could be modified without compromising patient safety. Methods: This was a retrospective study of patients monitored at the John Radcliffe hospital between October 1999 and June 2004. Monitoring is carried out by stimulating the peroneal nerve behind the knee and monitoring using an epidural electrode above the surgical site. Results are recorded throughout the surgery using a Synergy mobile system. Exponential averaging is used and the surgeon is warned of possible damage if the amplitude of the signal drops by more than 50% from the reference value which is set as soon as the surgical site has been exposed. 1. Two hundred and twenty two patients were studied all of whom had spinal surgery with instrumentation. The age range was from 4 to 80 years old. Patient notes were assessed to determine whether there was any neurological damage and if so what the nature and duration of this was. These results were compared with the results of monitoring, both the absolute value of amplitude change and also the time course of any variations in amplitude. Results: Of the 223 cases studied 78 exhibited a 50% drop of amplitude of the signal on one or both sides at some stage during the surgery. In 30 of these the deficit remained on at least one side at the end of surgery, 6 having a deficit on both sides. There were no cases of neurological damage in the patients where the signal amplitude was greater then 50% at the end of surgery. In the 30 cases where the signal amplitude was less than 50% at the end of surgery only one had any lasting neurological damage and one showed a transient neurological deficit. The time course of the change of amplitude appeared to be different in the cases of neurological damage than in those without damage. Conclusion: In this study all patients suffering neurological damage were identified by the spinal cord monitoring. However, there was a significant number of “false positives” which could possibly be reduced by developing new criteria for warning the surgeon. It is also possible that the exact methodology used in monitoring may affect the number of false positives. Both the stimulus method and recording method may contribute to this. 2. Development of evidence based criteria for warning the surgeon and optimizing methods of monitoring would need co-operation between many centres. We would propose that a multicentre study should be set up with this objective

Purpose of the study. Two patients with very severe thoracolumbar Scheuermann's kyphosis who developed spontaneous bony fusion across the apex of the deformity are presented and their treatment, as well as surgical outcome is discussed. Summary of Background Data. Considerable debate exists regarding the pathogenesis, natural history and treatment of Scheuermann's kyphosis. Surgical correction is indicated in the presence of severe kyphosis which carries the risk of neurological complications, persistent back pain and significant cosmetic deformity. Methods. We reviewed the medical notes and radiographs of 2 adolescent patients with severe thoracolumbar Scheuermann's kyphosis who developed spontaneous posterior and anteroposterior fusion across the apex of the deformity. Results. Patient 1. A male patient aged 17 years and 11 months underwent kyphosis correction when the deformity measured 115o and only corrected to 100o on supine hyperextension radiograph against the bolster; he had a small associated scoliosis. The surgery involved a combined single-stage anterior and posterior spinal arthrodesis T4-L3 with the use of posterior pedicle hook/screw/rod instrumentation and autologous rib graft. The anterior longitudinal ligament was ossified from T10 to L1 with bridging osteophytes extending circumferentially from T11 to T12 at the apex of kyphosis and displacing the major vessels anteriorly. The intervertebral discs from T9 to T12 were very stenotic and immobile. The osteophytes were excised both on the convexity and concavity of the associated thoracolumbar scoliosis. The anterior longitudinal ligament was released and complete discectomies back to the posterior longitudinal ligament were performed from T7 to L1. During the posterior exposure, the spine was found to be spontaneously fused across the apex of the kyphosis from T9 to L1. There were no congenital vertebral anomalies. Extensive posterior apical closing wedge osteotomies were performed from T7 to T12. The fused facets and ossified ligamentum flavum were excised and the spine was mobilised at completion of the anterior and posterior osteotomies. The kyphosis was corrected using a cantilever maneuver from proximal to distal under spinal cord monitoring. Excellent correction to 58o was achieved and maintained at follow-up. Autologous rib graft was used to enhance a solid bony fusion. Patient 2. A female patient aged 18 years and one month underwent kyphosis correction when the deformity measured 115o and only corrected to 86o on supine hyperextension radiograph against the bolster; she had a small thoracolumbar scoliosis. The surgery involved a single-stage posterior spinal arthrodesis T2-L4 with the use of posterior pedicle hook/screw/rod instrumentation and autologous iliac crest bone. The spine was spontaneously fused across the apex of kyphosis from T9 to L1. There were no congenital vertebral anomalies. Extensive posterior apical closing wedge osteotomies were performed from T6 to T12. The fused facets and ossified ligamentum flavum were excised and the spine was mobilised at completion of the osteotomies. The kyphosis was corrected using a cantilever maneuver from proximal to distal under spinal cord monitoring. Excellent correction to 60o was achieved and maintained at follow-up. Autologous iliac crest graft was used to achieve a solid bony fusion. In both patients the preoperative MRI assessed the intraspinal structures but failed to diagnose the solid fusion across the posterior bony elements at the apex of kyphosis. A CT scan with 3D reconstruction would have illustrated the bony anatomy across the kyphosis giving valuable information to assist surgical planning. This is recommended in the presence of rigid thoracolumbar Scheuermann's kyphosis which does not correct in hyperextension, especially if the plain radiograph shows anterior bridging osteophytes. Conclusion. Spontaneous posterior or anteroposterior fusion can occur across the apex of severe thoracolumbar Scheuermann's kyphosis; this should be taken into account when surgical correction is anticipated. The bony ankylosis may represent the natural history of an extreme deformity as an attempt of the spine to auto-stabilise. A combination of factors including a rigid deformity, which limits significantly active movement of the spine, as well as anterior vertebral body wedging with severe adjacent disc stenosis which induces bridging osteophyte formation may result in the development of spontaneous fusion across the apex of the kyphosis either posteriorly or anteroposteriorly. In the presence of an isolated posterior fusion, segmental posterior closing wedge osteotomies with complete excision of the ossified ligamentum flavum and fused facets should mobilise the thoracolumbar spine and allow for kyphosis correction. An additional anterior spinal release including complete discectomies, resection of the anterior longitudinal ligament and osteophytes is required if the bony fusion extends anteroposteriorly. Patients with Scheuermann's kyphosis should be ideally treated at an earlier stage and with a lesser degree of deformity so that this ossification process is prevented

To determine whether neurophysiological electrical pedicle testing (EPT) is a useful aid in the detection of malpostioned pedicle screw tracts. EPT data from 246 screws in 32 spinal operations on 32 patients over a 5 year period (2009–2014) were recorded and analysed. In addition to physical palpation, a ball-tipped electrode delivered stimuli and the output was recorded by evoked electromyogram (EMG). When breach threshold values were recorded, the surgeon rechecked the tract for breaches and responded appropriately. In addition, standard motor evoked potential (MEP) and sensory evoked potential(SEP) spinal cord monitoring was performed. There were 24(9.8%) pedicle breaches by tract testing and 8(3.3%) by screw testing. In 11 instances in 7 patients where the tract testing showed a breach, the tract was redirected and subsequent screw testing showed adequate integrity of the pedicle. The total time for tract and screw testing was 25 seconds. There were no associated changes in MEP or SEP monitoring with any of the recorded pedicle breaches and none of the patients had any post-operative neurological deficit. EPT for the pedicle screw and tract is a safe, simple, practical and reliable technique which improves the accuracy of screw placement. Further studies would be required to confirm (and possibly revise) the threshold levels and to demonstrate whether EPT reduces the risk of misplaced screws or post-operative neurological deficit

Comparison of efficacy of multi-modality spinal cord monitoring [SCM] (SSEP & MEP) in surgery of paediatric deformity using two classification systems I (traditional) vs. II (modified). SSEP SCM has low sensitivity in a normal spinal cord; this is only marginally improved with additional MEP monitoring. Traditional definitions of a ‘false’ positive' test ignores anaesthetic & surgical interventions following notification of altered SCM signals. Retrospective, paediatric cohort. 232 patients; mean age 14 years (26% males). 68% idiopathic scoliosis; 62% posterior surgery. Primary: Post-operative neurologic deficit. Secondary: significant (>50%↓ amplitude) SSEP or any MEP loss. PPV- Positive predictive value, NPV- Negative predictive value; LR+ve- Positive likelihood ratio, LR-ve Negative likelihood ratio; N/C – Not calculable. Efficacy of SCM is determined by definitions of ‘false positive’. System II classification was more efficacious and reflects current surgical practice

Introduction:. Scheuermann's kyphosis is a fixed round back deformity characterised by wedged vertebrae seen on radiograph. It is known patients presented with a negative sagittal balance before operation. Few studies investigated the outcome after operation, especially the change in the lumbar hyperlordosis. Aim:. To investigate the change in sagittal profile after correction surgery. Method:. This is a retrospective review of cases from 2001 to 2012. Our centre uses a posterior, four rod cantilever reduction technique for all Scheuermann's Kyphosis correction. 36 cases are identified. They include 24 males and 12 females with an average age of 20 and follow up of 27 months. First 8 cases used the stainless steel hybrid implants. The remaining 28 had titanium all pedicle screw system. All had intra-operative spinal cord monitoring. Results:. The target of thoracic kyphosis correction is around the accepted upper end of normal limit (40°). The average thoracic kyphosis Cobb angle was 78.5°. The immediate post-op angle was 43.2° and at final follow up, 43.6°. The average lumbar lordosis changed from 65.7° pre-op to 48.8° post-op, which is now bigger than the thoracic kyphosis. The result is the transfer of average sagittal balance (C7 plumb line) from −2.2 cm to −3.5 cm, which remains posterior to the posterior corner of S1 after the surgery. Discussion:. Surgery can improve the roundback deformity but not the overall sagittal profile. We have no explanation to this phenomenon. This could imply the pathology of Scheuermann's Kyphosis involves the whole spine, not just the wedging thoracic segment. Conflict Of Interest Statement: No conflict of interest

To establish the current practice of spinal cord monitoring in units carrying out scoliosis surgery in the UK. To illustrate the benefit of routinely monitoring motor evoked potentials (MEPs). Questionaire: Nationwide survey of spinal monitoring modalities used by spinal units carrying out deformity surgery. 10 out of 27 units routinely measure motor evoked potentials (MEPs), the remainder use only sensory potentials (SEPs). There is significant variability in use of monitoring around the UK and we have compared this to the practice elsewhere in the world. We report the case of a thirteen year old girl who underwent posterior instrumentation for correction of an idiopathic scoliosis. Intra-operatively there was a significant reduction in the amplitude of the MEPs without any corresponding change in the SEPs. These changes reversed when the correction was released. The surgery was abandoned and was carried out as a staged procedure, initially anteriorly then posteriorly. There was no loss of motor potentials during either operation and no post operative neurological abnormalities. We propose that the changes noted initially were due to transient ischaemia of the cord which would not have been detected without MEPs and may have led to long term sequelae. This highlights the safety benefit of routinely using MEPs in scoliosis surgery. Nationally there is wide variation in the monitoring of spinal cord function during scoliosis surgery. We feel that monitoring of motor potentials is a vital component in ensuring scoliosis surgery is as safe as possible

Aim:. Recent guidelines have been published by the Association of Neurophysiological Scientists / British Society for Clinical Neurophysiology (ANS/BSCN) regarding the use of intra-operative neurophysiological monitoring (IOM) during spinal deformity procedures. We present our unit's experience with IOM and the compliance with national guidelines. Method:. All patients undergoing intra-operative spinal cord monitoring during adult and paediatric spinal deformity surgery between Jan 2009 and Dec 2012 were prospectively followed. The use of somatosensory-evoked potentials (SSEPs) and motor-evoked potentials (MEPs) was recorded and monitoring outcomes were compared to post-operative clinical neurological outcomes. Compliance with the national ANS/BSCN guidelines was assessed. Results:. 333 patients were included in this study. IOM was successful in 312 patients (94%), with both MEPs and SSEPs obtained in 282 patients (85%). SEPs were achieved in 91% and MEPs in 87%. Aetiology was idiopathic in 199 cases, 53 neuromuscular, 28 degenerative, 16 congenital, 16 other. Nine patients had changes in IOM related to surgical activity; six had MEP changes only, three had MEPs and SSEPs changes. All but one of these changes returned to baseline following surgical action; the one remaining patient had a temporary postoperative neurological deficit. One patient had a post-operative single radiculopathy requiring surgical exploration, without change in initial IOM. Final IOM findings demonstrated a positive predictive value (PPV) of 1 and a negative predictive value (NPV) of 0.996. Discussion:. IOM is essential during spinal deformity surgery and, using MEPs, has a high PPV and NPV. Our unit meets guidelines for MEP use and frequently meets guidelines for SSEP use. Conflict Of Interest Statement: No conflict of interest

Background:. Spinal deformity surgery carries the risk of loss of neurological function which may be permanent. Although the overall the incidence is low it is much higher in complex congenital deformities or those with pre-existing myelopathy. Intra-operative spinal cord monitoring allows this risk to be reduced by providing feedback to the surgeon while the corrective manoeuvres are performed. Although ideally a trained technician with multimodal monitoring is recommended, it is often not an option in a resource limited environment and surgeon operated technology is used. Aim:. to evaluate the use of surgeon operated trans-cranial motor evoked potentials (tcMEP) in spinal deformity surgery. Methods:. A retrospective review was conducted on a single surgeon series of 108 consecutive cases utilising the NIM system (Medtronic). Percutaneous needles were employed in the scalp, both hands and feet to allow the upper limbs to act as controls. Forty-nine patients were 13 years old or less, 47 were 14–18, and 12 adults. The cohort consisted of 54 AIS, 27 neuromuscular scoliosis, 14 congenital, 2 old TB and 11 miscellaneous. The vast majority were posterior based procedures. Results:. In 4 cases initial traces could not be obtained. One was a severe myelopathy and further efforts to monitor were abandoned. In one case the anaesthetist had broken protocol and once converted to TIVA the traces improved. Two others were poor initially but improved as the case progressed. In 8 cases intra-operative traces were lost. One was thought to be due to hypothermia and the patient woke intact. Two were unrelated to surgical intervention and recovered spontaneously with patients waking intact. Four cases deteriorated during the corrective manoeuvre (one delayed) and recovered with reduction of correction. One case required removal of instrumentation after repeated loss each time rods were inserted and awoke with a weak leg but recovered and was re-operated two weeks later. Conclusion:. Surgeon operated tcMEP's allows feedback in terms of safety of deformity correction with a 100% negative predictive value and an 8% incidence of signal loss during correction allowing immediate remedial action

Objective. Posterior vertebral column resection (PVCR) is indicated in the management of severe rigid spine deformities. It is a complex surgical procedure and is only performed in a few spine centres due to the technical expertise required and associated risk. The purpose of this study is to review the indications, surgical challenges and outcomes of patients undergoing PVCR. Methods. 12 patients with severe spinal deformities who underwent PVCR were retrospectively reviewed after a follow-up of 2 years. Surgery was performed with the aid of motor evoked spinal cord monitoring and cellsaver when available. The average surgical duration was 310 minutes (100–490). The average blood loss was 1491 ml (0–3500). The indication for PVCR was gross deformity and myelopathy which was due to congenital spinal deformities and one case of old tuberculosis. Clinical records and the radiographic parameters were reviewed. Results. Kyphosis of an average of 72 degrees was corrected to 28 degrees. The associated scoliosis was corrected from an average of 49.2 to 21.2 degrees. Ten patients improved neurologically to ASIA D and E. One patient deteriorated markedly, required revision with no initial improvement but reached ASIA E at 6 months after surgery. Four patients had associated syringomyelia. All were re-scanned at 1 year. The three with small syrinx's demonstrated no progression on MRI and the large syrinx resolved completely. In addition to the neurological deterioration, complications included 1 right lower lobe pneumonia. Conclusion. PVCR is an effective option to correct complex rigid kyphoscoliosis. In addition it allows excellent circumferential decompression of the cord and neurological recovery. When the congenital scoliosis is associated with syringomyelia with no other cause evident, it may allow resolution of the syrinx. Key words: Posterior vertebral column resection, severe spinal deformities, myelopathy, syringomyelia. NO DISCLOSURES

Purpose: to analyse the outcomes of scoliosis surgery in osteogenisis imperfecta (OI) in this single–surgeon series. Methods: Case notes of OI patients having scoliosis surgery from September 2003 were analysed. Results: 15 patients (three male) were identified. Mean age was 15.6 years (range 10–23). There were 11 cases of OI III and 4 cases of OI IV. The mean duration of bisphosphonate treatment was 6.1 years (range 2–10). The mean BMD was 0.840 g/cm2. There was a double-curve in 10 cases, single-curve in 5. The mean Cobb-angle was 72°. The standard construct was a double rod with pedicle/pelvic screws at the base, double claw at the proximal end and sublaminar wires at intervening levels. The most proximal level was T1–T4 in 13 cases. Instrumentation was carried to the pelvis in 7 cases. Intra-operative fractures occurred in 5 cases. The mean blood loss was 999 mls (range 295–5500). Spinal cord monitoring was abnormal in 3 cases. 1 case resulted in postoperative lower limb paralysis, which recovered. The mean hospital stay was 7.5 days. Serious postoperative complications included one case of bilateral anterior compartment syndrome and one tibial fracture. The mean curve correction was 31%. Two cases required revision surgery: extension of fusion to the pelvis. The mean follow-up was 22.7 months (range 4–40). There was no measurable change in position over time. Conclusion: Scoliosis surgery in OI is effective, but may have serious complications. Fusion to the pelvis should be considered, especially in OI III. Ethics approval: None – Audit. Interest statement: None

Objective: Determine the incidence of abnormal somatosensory evoked potentials (SSEP) in patients with ‘at risk’ spinal cords undergoing anterior spinal deformity surgery. Design: A retrospective chart and SSEP trace review of cases between 1982–2001. Subjects: Patients undergoing elective anterior spinal deformity surgery were included. Excluded were those with inadequate SSEP monitoring or no pre-operative MRI scan. Outcome measures: Paraparesis due to cord ischaemia based on an abnormal SSEP trace, i. e. > 50% decrease in SSEP baseline amplitude +/− > 10% increase in latency. 1. . Results: Partial data was available for 1982–1990, thus analysis was based on cases between 1990–2001.871 patients underwent elective anterior spinal deformity surgery, 11% were ‘at risk cords’; 2% demonstrated intraoperative SSEP changes. Post operative paraparesis ws found in 0.6%. Intra-operative changes were significantly more common in ‘at risk cords’ (chi-squared test = 30.3, df = 2; p< 0.005). No statistical difference in the incidence of paraparesis in normal cords vs ‘at risk’ cords. Conclusions: Post operative neurological deficit is rare in anterior spinal deformity surgery. Significant SSEP changes do occur with ligation of segmental vessels, implying cord ischaemia. Therefore, for the ‘at risk cord’, these patients should be considered for spinal cord monitoring and temporary clamping of segmental vessels prior to their division

Study Design: Retrospective study. Objective: To describe a modified cervico-thoracic extension osteotomy and evaluate clinical & radiographic outcomes. Subjects: 10 patients with fixed cervico-thoracic kyphosis, average age 56 years, minimum 12 months follow-up. Three patients had psoriatic spondyloarthropathy, Three patients had previous lumbar osteotomies. Technique: General anaesthesia and SSEP spinal cord monitoring was used. Complete laminectomy of C7, hemilaminectomy of C6 and T1, plus pedicle subtraction osteotomy and decancellisation of C7 was performed. Upon completion of the osteotomy, controlled halo manipulation allowed closure of the osteotomy: the pivot point being the anterior longitudinal ligament. Segmental fixation with lateral mass and pedicle screws plus bone graft was then added. All patients were immobilised for three months in halo-jacket. Results: Restoration of normal forward gaze was achieved in all patients. Mean preoperative kyphosis of 17 degrees was corrected to lordosis of 36 degrees (mean total correction 53 degrees). No spinal cord injuries or permanent nerve root palsies occurred. Three patients had mild sensory radiculopathies lasting a few weeks. No loss of correction, no pseudarthrosis, one patient had 50% anterior subluxation that later united. Two deep infections were successfully treated with wound washout and antibiotics. Conclusions: Cervico-thoracic osteotomy in ankylosing spondylitis continues to be challenging and hazardous. C7 decancellisation and extension osteotomy supplemented with segmental internal fixation provides immediate spinal stability, reduces sagittal spinal translation and associated high risk of neurological injury, whilst maintaining correction until bony union

Introduction: We report the result of cervical osteotomy in 11 patients using a controlled reduction technique and assess the safety and efficacy of this operation. Methods: Between 1993 and 2006, 11 patients with ankylosing spondylitis underwent correction of cervical kyphosis utilizing an extension osteotomy at the C7/T1 junction. The procedure was carried out under general anaesthesia with spinal cord monitoring. Lateral mass screws were placed from C3–C6 and thoracic pedicle screws placed from T2 to T5. After completion of the osteotomy, the reduction manoeuvre was carried out by the senior surgeon lifting the halo, while bilateral temporary malleable rods (fixed to cervical lateral mass screws) were allowed to pass through top loading thoracic pedicle screws, before tightening by the assistant when the desired position had been achieved. The temporary malleable rods were then replaced with definitive rods, thereby creating a solid internal fixation. A halo vest was maintained for 12 weeks to support the instrumentation and allow the fusion mass to develop. Results: Surgery was performed on 10 males and one female. The mean age at surgery was 56 years (range 40–74). Duration of symptoms averaged 2.7 years (range 1–5 yrs). The average duration of surgery was 4.7 hours (range 3–6.5) with a mean blood loss of 1938cc (range 1000–3600). The mean follow up was 6.5 years (range 2–13). The mean pre-op chin brow vertical angle was 54º (range 20–70) reducing to 7º (range 2–20) at final follow-up. The mean pre-operative kyphotic angle was 19.2º reducing to minus 34º at final follow up. Restoration of normal forward gaze was achieved in all cases. No patient suffered spinal cord injury or permanent nerve root palsy. Conclusion: Cervico-thoracic osteotomy is a potentially hazardous procedure. The technique described reduces the risk of translation during the reduction manoeuvre thereby reducing the risk of serious neurological injury