Introduction. Somatosensory evoked potential (SSEP) monitoring allows for assessment of the spinal cord and susceptible structures during complex spinal surgery. It is well validated for the detection of potential neurological injury but little is known of surgeon's responses to an abnormal trace and its effect on neurological outcome. We aimed to investigate this in spinal deformity patients who are particularly vulnerable during their corrective surgery. Methods. Our institutional neurophysiology database was analysed between 1. st. October 2005 and 31. st. March 2010. Monitoring was performed by a team of trained neurophysiology technicians who were separate from the surgical team. A significant trace was defined as a 50% reduction in trace amplitude or a 10% increase in signal latency. Patients suffering a significant trace event were examined post-operatively by a Consultant Neurologist who was separate from the surgical team. Results. 2386 consecutive operations (F:1719, M:667 median age 16 yrs) were performed in the time period and 72 operations reported a significant trace event (‘red alert’). From these cases 47 (65%) had a clearly documented intervention by the surgeon and 7 patients overall suffered a lasting neurological deficit (0.3%). The most common timing events were during instrumentation (50%) and during correction/distraction (16%). Most common responses were optimisation of patient/monitoring set-up (23%) and adjustment of metalwork (22%). There were 18 wake-up tests performed. We found SSEP monitoring to have a sensitivity of 100%, specificity 97.4%, positive predictive value 14% and negative predictive value 100%. A Chi-square test (p=0.016) was significant suggesting intervention had a beneficial effect on neurological outcome. Conclusion. We would advocate the use of SSEP monitoring in all patients undergoing spinal deformity surgery. These patients tend to be young, neurologically intact pre-operatively and are particularly vulnerable to the large corrective forces their surgery requires

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

Introduction: Somatosensory evoked potentials are monitored during the surgical treatment of spinal disorders to reduce the risk of cord injury. Whilst studies have examined its role in patients undergoing correction of idiopathic and neuromuscular scoliotic curves, its effectiveness in patients undergoing operative treatment for spinal injury is less certain. Methods and Results: We reviewed the medical records of patients who underwent surgery for spinal trauma. between 1995 and 2000. There were 82 patients with adequate data for analysis who underwent 83 spinal reconstructive procedures. We recorded the age at injury, diagnosis, time of operation, levels instrumented, systolic and diastolic blood pressures and surgical approach. The intraoperative somatosensory evoked potential (SSEP) traces were examined. The SSEP at insertion of electrode was taken as the control level. The highest and lowest intraoperative somatosensory evoked potentials and SSEP at closure were noted and expressed as a percentage of the control value. Forty patients (48%) had a pre-operative neurological deficit. Neurological deterioration occurred postoperatively in three patients. Eighty-three traces from 82 patients were available for analysis. Fifty-seven patients had a fall in trace amplitude by more than 25% of the control, 25 by more than 50% and eight by more than 75%. With an SSEP amplitude loss of 60%, both sensitivity and specificity for the prediction of post-operative neurological injury were optimised at 67 and 81% respectively, with one false negative result. SSEP rise at completion of spinal reconstruction and highest intraoperative SSEP rise was compared with neurological outcome in the 40 patients with abnormal pre-operative neurology. Neurology improved in all patients in this group who had a trace amplitude more than 60% above the control value at end of operation. None had neurological deterioration. There was no correlation between intraoperative SSEP rise and neurological outcome. Conclusion: Loss of trace amplitude more than 50% is common during spinal reconstructive surgery after trauma, however a 60% threshold for SSEP fall improves specificity by reducing the rate of false positive results. A trace amplitude 60% above the control value at completion of operation is specific but not sensitive for postoperative neurological improvement

Purpose. To compare the incidence and nature of ‘neurophysiological events’ identified, post hoc, by a consultant neurophysiologist with those identified intra-operatively by clinical physiologists, before and after intervention(s). Methods. The IOM wave-recordings, event-logs and reports of all spinal deformity cases conducted by a team of clinical physiologists from April to June 2009 (Group 1) were reviewed retrospectively by the same, experienced clinical neurophysiologist, (MG). Interventions were then agreed. The first was to alter the IOM report document to drop down menus. The second was to arrange a series of teaching sessions for the clinical physiologists on a variety of aspects of IOM. Finally during these teaching sessions recent cases were brought to review in an informal setting to discuss. Following implementation of the interventions a further review from April to June 2010 (Group 2) was carried out in the same manner. The clinical physiologists did not know the time periods over which the review would be taking place. Results. From April to June 2009 (Group 1) thirty two patients were studied and from April to June 2010 (Group 2) thirty four patients were studies. Group 1. Twenty seven of these had been monitored using ‘multimodal’ IOM consisting of cortical (CSEP) and spinal (SSEP) somatosensory evoked potentials and motor (MEP/CMAP) evoked potentials. Two patients were inappropriate for MEP recording and two were monitored using epidural SSEP recording. During 10 operations (31%) the surgeons were notified of an ‘intra-operative neurological event’ judged by the clinical neurophysiologist as potentially requiring a surgical response. When the results were audited, only 2 (6%) of these ‘events’ were considered by the consultant clinical neurophysiologist to represent ‘true positive’ intra-operative neurophysiological findings. Group 2. Twenty six of these had been monitored using ‘multimodal’ IOM consisting of cortical (CSEP) and spinal (SSEP) somatosensory evoked potentials and motor (MEP/CMAP) evoked potentials. Four patients were inappropriate for MEP recording and had a combination of SSEP and CSEP. The remainder had IOM with unimodal. No epidural IOM was used during this period. During 4 operations (12%) the surgeons were notified of an ‘intra-operative neurological event’ judged by the clinical neurophysiologist as potentially requiring a surgical response. Post-operative examination of all the patients in both groups revealed that no ‘false negative’ conclusions had been reached. Conclusion. In this series clinical physiologists were found to alert the surgeons 5 times more frequently than was likely to have been the case with an experienced consultant clinical neurophysiologist (31% and 6% respectively). However the increased reporting of intra-operative events did not result in any alteration of the ultimate surgical strategy in any operation although tactical changes were sometimes necessary during the operation in order to test the reversibility of the flagged event. The implementation of two simple interventions resulted in the clinical physiologists alerting the surgeons only 1/3 of that previously (12%) of cases. The log indicated that on all occasions appropriate surgical action had been taken with no residual neurological deficit. This study, owing to its size, cannot answer the key question of safety. Further work to estimate the statistical power required of such a study is being sought. In the interim proving a track record of successful cases provides evidence of efficacy. Ethics Approval: None. Interest Statement: None

Radiological diagnosis is not the only tool in detection, monitoring of progress and making easy to undertake a decision about the surgical scoliosis correction. The below presented algorithm of scoliosis monitoring with complex and repetitive (comparative) neurophysiological examinations facilitates the doctor’s decision about method of the conservative treatment or just the moment of surgical intervention [3, 14]. Neurogenic changes in muscles can be found in early stages of the spine deformation – usually when the Cobb’s angle is over 100 [1]. Vertebral rotation and curvature progression follow simultaneously leading to deformation of the spinal cord together with the local ventral roots compression and sometimes inflammation of them. The structure of the grey matter especially in the ventral horn changes its form more on the convex side of scoliosis. Cell bodies together with the axonal hillocks in the motoneuronal pools show deformations comparing to the analogical area of the concave side. This produce discrete unilateral axonopathy in both efferent fibers of peroneal and tibial nerves in scoliotic patients at the age of about 10. This can be found in electroneurographical (ENG) recordings of M and F potentials even at the angle of scoliosis of 100 [10, 14]. Both parameters of the amplitudes and conduction velocities in M-wave studies are decreased and the frequency of F wave recording is diminished what suggests pathological asymmetrical changes just at the level of the ventral root. That is why electromyographical (EMG) recordings show asymmetrical, according to the ventral root somatotopical innervation, selective (found only in some muscles) deficits in frequency and amplitude of motor units action potentials, predominantly in girls. These girls have scoliosis accelerating the most with angle changes of 50 per year [2] that rapidly deepens the neurogenic changes. Other significant evaluation of the scoliosis acceleration is using the somatosensory evoked potentials (SEPs) for recording progression of pathology in the afferent transmission within the long ascending spinal cord pathways running in dorsal, dorsolateral and lateral funiculi [4, 5]. Changes in parameters more amplitude than conduction velocity from SEPs studies recorded at the cervical level are more visible on the concave than convex side of scoliosis. These changes are correlated with increasing the Cobb’s angle at the apical thoracic vertebrae (Th7–8) while peripheral sensory transmission remains only slightly disturbed [6, 7]. These changes were found to be twice greater when recording of SEPs was performed over cranially on the contralateral side of the scalp to the stimulation site at the ankle (tibial nerve than peroneal nerve fibers excitation) both in mothers and their daughters [4]. This points at the strong inhibition of the afferent transmission at the level of the brain stem (probably thalamus or medial lemniscus). During the comparative SEPs recordings at the cervical level, when parameters of waves change dramatically (or even they disappear), this may suggest that the lateral angle of scoliosis exceeded 450 with great acceleration of the torsion [9]. Somatosensory evoked potential recordings during the surgical correction of scoliosis showed only rarely the immediate improvement of the afferent transmission [7, 8, 11]. However, they make sure a surgeon about lack of blockade within the spinal pathways which comes from derotation and distraction procedures performed on the spine during implantation of the corrective instrumentation. First visible results of improvement in the SEPs parameters recorded postoperatively are usually seen a week after the surgery [14]. The above analogical phenomena but referring to the efferent transmission were shown in motor evoked potentials studies which were induced with the magnetic field (MEP) in areas of motor cortex and recorded from centres of cervical and lumbosacral spinal cord as well as from nerves and muscles of upper and lower extremities [12,13, 15]. Usually when AIS reaches the Cobb’s angle of 200 at the age of 25 and does not progress more it can be assumed, that its development is finished. In these patients the signs of neurogenic changes found in EMG examinations performed in lower extremities, paravertebral and gluteal muscles do not progress, too [14]

To examine the effect of lateral spine curvature on somatosensory evoked potentials (SSEP) in patients with adolescent idiopathic scoliosis (AIS) compared to normal controls. We hypothesise that patients with AIS will show increased latency in their SSEPs when bending into their curve suggesting that their spinal cord is more sensitive to this increased lateral curvature. Patients were recruited from the paediatric scoliosis clinic in a single centre. Inclusion criteria were: diagnosis of AIS, age 10–18 years, major thoracic curve measuring greater than 10 degrees on Cobb measurement, and undergoing nonoperative management. Exclusion criteria were: any detectable neurologic deficit, and previous surgery on the brain or spine. SSEP recordings were obtained via stimulation of the posterior tibial nerve with surface electrode and measurement of the cortical response over the scalp. All recordings were performed three times: with the patient in neutral standing and maximum right and left side bending. SSEP recordings show that when AIS subjects bend into their curve, latency slows by an average of 0.5ms. However there was a bimodal distribution with most subjects showing minimal change (3ms). This subset was statistically different from both a control group, and the larger AIS group. There appears to be a subset of patients with AIS who have subclinical spinal cord dysfunction demonstrated by abnormal SSEPs. This may place these patients at slightly higher risk of neurologic injury at the time of surgery

Introduction. The rate of total hip arthroplasty (THA) surgery continues to dramatically rise in the United States, with over 300,000 procedures performed in 2010. Although a relatively safe procedure, THA is not without complications. These complications include acetabular fracture, heterotopic ossification, implant failure, and nerve palsy to name a few. The rates of neurologic injury for a primary THA are reported as 0.7–3.5%. These rates increase to 7.6% for revision THA. The direct anterior total hip arthroplasty (DATHA) is gaining popularity amongst orthopedic surgeons. Many of these surgeons elect to use the Hana® table during this procedure for optimal positioning capability. Although intraoperative mobility and positioning of the hip joint during DATHA improves operative access, select positions of the limb put certain neurologic structures at risk. The most commonly reported neurologic injuries in this regard are to the sciatic and femoral nerves. To our knowledge, the use of neuromonitoring during DATHA, especially those using the Hana® table, has not been described in the literature. Methods. The patient was a 60-year-old male with long standing osteoarthritis of the right hip and prior left THA. Somatosensory evoked potential (SSEP) leads were placed bilaterally into the hand (ulnar nerve) as well as the popliteal fossae (posterior tibial nerve). Unilateral electromyography leads were placed into the vastus medialis obliquus, biceps femoris, gastrocnemius, tibialis anterior, and abductor hallucis of the operative limb (Fig. 1). Once the patient was sterilely draped, a direct anterior Smith-Peterson approach to the hip was used. Results. After the patient completed standard pre-operative protocol, neuromonitoring leads were placed as described above. There were no complications, neuromonitoring remained stable from baseline, and the patient tolerated the procedure well. Moreover, the senior author routinely uses a prophylactic cable around the calcar, particularly in patients with osteoporotic bone, as was the case with this patient. The patient's post-operative course has been without complications as well. Conclusion. There are a few studies that have examined the pressure changes around the femoral nerve during a DATHA and found that the nerve was at most danger with misplacement of a retractor near the anterior lip of the acetabulum. Furthermore, the popularity of DATHA and the Hana® table make neuromonitoring more amenable for use since the whole limb does not need to be sterilely prepped as with other approaches to the hip. The reported rates of neurologic injury during any THA along with those developed from passage of prophylactic cerclage cables and the goals of reducing surgical complications make this novel technique intriguing. It allows the surgeon yet another safe and effective tool to decrease the likelihood of neurologic injury during DATHA. For any figures or tables, please contact the authors directly

Aim: Of Calveston (USA) and Crete (HELLAS). We studied immediate and long-term outcome of 50 patients who underwent subaxial lateral mass fixation of the cervical spine between January 1997 and March 2001. Patients and Methods: Intraopeartive fluoroscopy and somatosensory evoked potential monitoring were employed in all patients. Immediate postoperative CT scans were performed to determine screw trajectory and placement. Follow up ranged from 1 to 5 years. Results: Postoperative CT scans showed that 113 of 210 screws (54%) had unicorticate and 46% had bicorticate purchase. Forty-five screws (31 %) had suboptimal trajectory, but only 7 of these screws minimally penetrated the foramen transversarium without resultant vascular or neurological sequelae. The overall fusion success rate in our series was 90%, while pseudoarthrosis occurred in 5 patients (10%), with screw breakage in 1 patient (2%). Two of these patients had bone graft supplementation and in other 2 patients was done anterior fusion. Conclusions: Results of this study show that the recommended drilling technique and trajectory (15–25 degrees postal to the sagital plane, 20–30 degrees lateral I the axial plane), supplemented bone grafting and intraoperative SEP monitoring are all associated to good screw placement, fusion and neurological outcome and are recommended for all lateral mass fusion procedures

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

Purpose: Despite advances in surgical technique, neurological injury remains a potentially devastating complication of spinal deformity correction surgery. The purpose of the study is to describe surgical and patient factors associated with “electrophysiologic (EP) events” and neurogenic deficits. Method: A retrospective chart review, looking at “EP events” during surgery, was conducted on 162 patients who received surgical treatment of their pediatric spine deformity from 1999 to 2004. Results: Ninety three percent of cases (n=151) were successfully monitored by either somatosensory evoked potential (SEP) or motor evoked potential (MEP) monitoring. All three neurologic deficits that occurred in this study cases were successfully detected by EP monitoring (0.02%, p=.002). In those 151 cases that were successfully monitored, “EP events” were occured in twenty (13.2%) cases. The most common cause was systemic change (45%) and curve correction (40%). In those 20 cases, when corrective actions were made (n=15) “EP events” reversed to baseline values in all cases. When no corrective actions were taken (N=5) there was no reversals of “EP events” to baseline. Patients with kyphosis had a trend toward significantly higher rates of “EP events” (p=.174) and patients who had cardiopulmonary comorbidities had significantly higher rates of “EP events” (p=.007). Conclusion: Consistent with existing literature, the EP monitoring was successful in the vast majority of deformity surgeries. “EP events” were able to be reversed with corrective action and to predict neurologic deficits. Our study found that patients with kyphosis and/or cardiopulmonary comorbidities have higher risk of significant “EP events” during the surgeries

Aims:This study: a)revisits the effectiveness of preoperative embolization alone for hypervascular lesions of the thoracolumbar spine and b) compares its action with intraoperative cryotherapy alone or in conjunction with embolization. Methods:14 patients underwent 15 surgeries for hypervascular spinal tumors. Ten of the surgeries were augmented by preoperative embolization alone. Four surgeries involved intraoperative cryocoagulation, and one surgery used a combination of preoperative embolization and intraoperative cryocoagulation for tumor resection. When cryocoagulation was used, its extend was controlled by intraoperative ultrasound or by establishing physical separation of the spinal cord from the tumor. Results:Among cases treated with embolization alone, 50% still had intraoperative blood-loss in excess of 3 liters. Mean blood-loss was of 2.8 liters/patient. One patient bled excessively (over 8000ml) terminating the surgery prematurely and resulted in suboptimal tumor resection. All procedures using cryo-coagulation achieved adequate hemostasis with average blood-loss of only 500 ml/patient by far better than embolization (P< 000.1). Conclusions:Preoperative embolization alone may not always be satisfactory for surgery of hypervascular tumors of the thoracolumbar spine. Although experience with cryocoagulation is limited, its use, with or without embolization, suggests its effectiveness in limiting blood-loss. Cryocoagulation may also assist resection by preventing tumor spillage, facilitating more radical excision of the tumor and enabling spinal reconstruction that eventually may contribute to improve survival. The extent of cryocoagulation could be controlled adequately with ultrasound. Somatosensory evoked potentials may provide early warning of cord cooling. No new neurological deþcits were attributable to the use of cryocoagulation

Objective: To demonstrate possible advantages of combined (motor and sensory) versus single modality (either motor or sensory) intraoperative spinal cord monitoring. Design: Retrospective and prospective clinical study. Materials and Methods: One hundred and twenty-six consecutive operations in 97 patients had peroperative monitoring the lower limb motor evoked potentials (MEPs) to multi- pulse transcranial electrical stimulation (TES), and tibial nerve somatosensory evoked potentials (SEPs). Seventy-nine patients had spinal deformity surgery, and eighteen had surgery for trauma, tumor or disc herniation. Results: Combined motor and sensory monitoring was successfully achieved in 104 of 126 (82%) operations. Monitoring was limited to MEPs alone in two, and SEPs alone in eighteen cases. Neither MEPs nor SEPs were obtainable in two cases with Friedreich’s ataxia. Significant evoked potentials (EP) changes occurred in one or both modalities in 16 patients, in association with instrumentation (10) or systemic changes (6). After appropriate remedial measures, SEPs recovered either fully or partially in all cases (8/8) and MEPs in 10/15. New neurodeficits developed post-operatively in six of the sixteen patients with abnormal EPs, including two in whom SEPs had either not changed or recovered fully after remedial measures. One patient developed S3–5 sensory loss despite full recovery of both SEPs and MEPs. Two patients without neurological consequences had persistent MEP changes. Normal MEPs (but not SEPs) at the end of the operation correctly predicted the absence of new motor deficits. There were no false negative MEP changes. Conclusion: MEPs are more sensitive than SEPs, but may rarely raise false positive alarm. SEPs are unaffected by anaesthetics and can be monitored more frequently. Combined monitoring is safe, complimentary to each other, and increases sensitivity and predictivity of adverse neorological consequences. True incidence of false positive MEP or SEP changes are difficult to define. Remedial measures after monitoring changes may help cord ischaemia to recover and absence of neurological deficit, therefore, may not indicate a false positive monitoring change

AIS has different image than paralytic scoliosis or scoliosis accompanying some diseases of the spinal cord in electromyographical and electroneurographical examinations (EMG and ENG). These differences are concerned to different progression, characteristic properties in skeletal system pathology or curves angles at the thoracic and lumbosacral spine. There are always two sites in patients with AIS where changes in transmission from the motor cortex to the motoneuronal centres in lumbosacral region appear. These phenomena were shown in motor evoked potentials studies which were induced with the magnetic field (MEP) in areas of motor cortex and recorded from centres of cervical and lumbosacral spinal cord as well as from muscles of upper and lower extremities. Changes in efferent transmission are greater twice in recordings from muscles of lower extremities and in oververtebral recordings at L5-S1 regions what suggests, that secondary slowing down takes place at the level of the apical thoracic vertebrae of primary curve (mostly at Th7–8), predominantly on the concave than convex side of scoliosis. MEP study confirmed a previous finding with somatosensory evoked potentials (SEPs) similarly about two focuses of disturbances in of afferent transmission on the spinal centres-supraspinal centres pathway. MEP showed changes in the efferent transmission on the supraspinal centres-spinal motor generator pathway. Such changes are not observed in scolioses other than idiopathic. Results of the complex neurophysiological studies suggest that the primary origin of AIS is the brain stem area at the level of thalamus where changes of afferent and efferent transmission are detected. There is a close relationship of this structure with the pineal gland and secretion of neurotransmitters at this level in correlation to disturbances in melatonin secretion and other neurohormones. Disorders in melatonin secretion and other neurohormones may induce a scoliosis what was shown in previous genetic and experimental neurophysiological studies on animals, together with cutting of the pineal stalk. Some aspects of this problem were also mentioned in our previous clinical neurophysiological studies [1–3]. Results of studies suggest that in patients with AIS, there are structural and functional changes in the area of thalamus, which cause disturbances in afferent and efferent transmission at this level. Pathology in the pineal secretion of neurohormones can be one of the factors influencing the formation and progression of AIS, as a disease of probably secondary origin to the functional changes in brain. Results of MEP studies discussed in this report confirm that the primary origin of AIS takes place at the level of the brain stem but not in the spinal cord

Objective: Recent reports have suggested a low incidence of neurological complications following anterior deformity surgery; however in patients with co-existing intra-spinal anomalies no quantification of this risk has been made. Also, whether SSEP monitoring and soft clamping of segmental vessels prior to their division is necessary for these anterior procedures is controversial. The aims of this study were to determine the incidence of significant SSEP changes in patients undergoing anterior spinal deformity surgery; to ascertain whether the ‘at risk’ cord was more likely to demonstrate significant intraoperative SSEP changes and what proportion of these changes yielded post operative neurological deficit. Design: Retrospective analysis of operative notes and somatosensory evoked potential (SSEP) traces of patients who underwent anterior spinal deformity surgery between 1990–2001. Subjects: All patients who underwent anterior spinal deformity surgery between 1990–2001, who had complete data sets (preoperative MRI scan, patient and procedural documentation and intraoperative SSEP traces) were included in the study. Outcome measures: All post operative neurological deficits and significant SSEP changes were noted, whether or not patients had a ‘cord at risk’. Results: In total, 871 patients had elective anterior spinal deformity surgery. Preoperative MRI revealed 95 patients (11%) demonstrated intraspinal anomalies on MRI but of these only 27 showed abnormal pre-operative SSEP i.e. cord at risk (CAR). Seventeen (2% of total) of this group developed abnormal intraoperative SSEP responses and ten (1.3%) occurred in the normal group. The incidence of post-operative paraparesis for the whole series was 0.6% (n=5): four in the CAR group, one in the normal cord group. Sensitivity of SSEPs in detecting potential neurological deficit was 100%; specificity 98.6%, positive predictive value 29.4% and negative predictive value 100%. Significant intraoperative SSEP changes occurred more frequently in the CAR group and were more likely to have post operative paraparesis. Conclusions: SSEP monitoring is a sensitive and specific test, which in experienced hands yields no false positive results. Spinal cord monitoring and soft clamping of segmental vessels should be performed in patients with CAR undergoing anterior spinal deformity surgery to minimise the risk of post operative paraparesis

Background: Campbell et al from Texas have pioneered the use of Vertical Expandable Prosthetic Titanium Rib (VEPTR) in congenital scoliosis. Our centre is the first in the UK to use it and we report our experience of 5 cases done in the past 2 years. VEPTR works on the principle of expansion thoracoplasty and thoracic spinal growth of upto 0.8 cms/year has been reported by the developers of this device. Methods: This case series includes one child who had the index surgery in America and is undergoing sequential expansion in Cardiff. All surgeries were done using a standard technique with monitoring of somatosensory evoked potentials. After appropriate soft tissue and bony releases, VEPTR was inserted and expanded by 0.5 cms to maintain tissue tension. Subsequent expansions were done as day case surgeries at 4–6 month intervals through a small incision over the VEPTR. We assessed clinical and radiographic assessment, which included – hemithorax height ratio, Cobb angle, interpedicular line ratio, space available for the lung. Results: There were 3 males and 2 females with mean age of 6.3 years (range 0.9 to 9 years) at the time of index operation. Average follow up is 2 years (0.4 to 5 years). Average hospital stay for the index surgery was 5 days (4–7 days). All patients had mean of 3 expansions (range: 0–6). Mean improvement in the Cobb angle was seen from 48° to 36° at last followup. Space available for lung improved from a mean of 72 % to 86 %. Mean improvement in hemithorax height ratio was from 72.5% to 86%. One child had mild pain due to prominent metalwork; 2 children had transient brachial plexus neurapraxia, one of whom had progression of a secondary cervical curve and is awaiting further surgery for the same. Conclusion: Our early results show good improvement of clinical and radiographic parameters. Transient nerve palsies have been well reported on the concave side and occur due to traction on the nerves as a result of increased height of the thoracic cage. This occurred in one initial case and has not been seen later. These results are encouraging but do indicate a learning curve

Introduction: Observation of sub-clinical neurological abnormalities has led to the proposal of a neuro-developmental etiologic model for adolescent idiopathic scoliosis (AIS). We have previously demonstrated prolonged latency in somatosensory evoked potentials (SSEP) and impaired balance control in subjects with AIS. Furthermore we have compared regional brain volumes in right thoracic AIS subjects and normal controls. Significant neuro-anatomic regional differences were observed in the corpus callosum, premotor cortex, proprioceptive and visual centers of the AIS subjects compared to control subjects. Most of these regional differences involved the brain unilaterally, indicating there may be abnormal asymmetrical development in the brain of subjects with right thoracic AIS. Methods: Following ethical committee approval a total of 29 subjects with AIS were recruited. Patients with congenital, neuromuscular or syndromic scoliosis were excluded from the study. Twenty-eight age- and sex-matched controls were recruited from local schools. All recruits underwent three-dimensional isotropic magnetization prepared rapid acquisition gradient echo (3D_MPRAGE) magnetic resonance (MR) imaging of the brain. Modern morphometric analyses of the MR images were carried out including classification of tissue into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF). Tissue densities were compared between AIS subjects and controls. Comparisons were made between those subjects with left thoracic AIS (n=9) and age and sex-matched controls (n=11) and those subjects with right thoracic AIS (n=20) and age and sex-matched controls (n=17). Results: For subjects with left thoracic curves the mean Cobb angle was 19 degrees. For subjects with right thoracic curves the mean Cobb angle was 33.8 degrees There was no significant differences observed between AIS subjects and normal controls when comparing both absolute and relative (i.e. adjusted for brain size) volumes of GM and WM. However voxel-based morphometric analysis identified significant differences in the density of WM in the genu of the corpus callosum, the left internal capsule and WM underlying the left orbitofrontal cortex when comparing those subjects with left thoracic scoliosis to controls. The above differences were not not observed when those subjects with right thoracic scoliosis were compared to controls. Discussion: This controlled study of regional brain tissue density has demonstrated important differences in the corpus callosum, the left internal capsule and the left orbitofrontal cortex when the brain of those subjects with left thoracic scoliosis is compared to age and sex matched controls. In this study significant regional brain differences have not been identified in those subjects with right thoracic scoliosis. Further studies are warranted to ascertain whether these morphologial differences in the brain are linked with the etiopathogenisis of left sided thoracic scoliosis. A larger sample and a longitudinal study are required to establish whether brain abnormalities are predictive of curve progression

The December 2012 Children’s orthopaedics Roundup³⁶⁰ looks at: whether arthrodistraction is the answer to Perthes’ disease; deformity correction in tarsal coalitions; ultrasound used to predict pain in Osgood-Schlatter’s disease; acetabular tilt; hip replacement for juvenile arthritis sufferers; whether post-operative radiographs are needed for supracondylar fractures; intra-articular local anaesthetic following supracondylar fracture fixation; and limb deformity.