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

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.

We undertook a retrospective analysis of 306 procedures on 233 patients, with a mean age of 12 years (1 to 21), in order to evaluate the use of somatosensory evoked potential (SSEP) monitoring for the early detection of nerve compromise during external fixation procedures for limb lengthening and correction of deformity. Significant SSEP changes were identified during 58 procedures (19%). In 32 instances (10.5%) the changes were transient, and resolved once the surgical cause had been removed. The remaining 26 (8.5%) were analysed in two groups, depending on whether or not corrective action had been performed in response to critical changes in the SSEP recordings. In 16 cases in which no corrective action was taken, 13 (81.2%, 4.2% overall) developed a post-operative neurological deficit, six of which were permanent and seven temporary, persisting for five to 18 months. In the ten procedures in which corrective action was taken, four patients (40%, 1.3% overall) had a temporary (one to eight months) post-operative neuropathy and six had no deficit.

After appropriate intervention in response to SSEP changes, the incidence and severity of neurological deficits were significantly reduced, with no cases of permanent neuropathy. SSEP monitoring showed 100% sensitivity and 91% specificity for the detection of nerve injury during external fixation. It is an excellent diagnostic technique for identifying nerve lesions when they are still highly reversible.

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. The British Scoliosis Society published a document in 2008 which set out the minimum standards for paediatric spinal deformity services to achieve over a period of time. But how do the UK paediatric spinal deformity centres measure up to these benchmarks?. Methods. We performed a telephonic survey, contacting every UK spinal deformity centre. The questionnaire probed how each unit compared to the recommended standards. Results. Twenty three centres were interviewed, covering 81 surgeons in total (range 1-8 surgeons per centre). Four centres (17%) did not have 24-hour access to a MRI scanner and all but 2 centres had on-site facilities for long-cassette films/scoliograms. Five centres (22%) always had 2 consultant surgeons per case, 9 centres (39%) routinely have only 1 consultant surgeon per case, and the rest had 1 or 2 consultant surgeons depending on seniority. Six centres (26%) did not routinely have shared care of their patients with the paediatric team. All centres used intra-operative SSEP monitoring, a minority used MEP monitoring (34%), and all but 2 centres had either direct or indirect supervision by a consultant neurophysiologist. All centres have cell saver units available with over half using them routinely (14/23). None of the centres used routine chemoprophylaxis. All units used thromboembolic stockings, with five centres (22%) routinely using foot pumps. Nineteen centres (83%) routinely sent their spinal deformity patients to ITU/PICU postoperatively. Our survey also asked each center what supporting facilities were available, whether they ran adolescent clinics, and whether they participate in multi-disciplinary meetings and audit. In addition, we questioned what typed of drains each center used and the length of time that patients were followed-up. Conclusion. This survey shows how the UK spinal deformity units stand up against the BSS standards, provides an insight in to current UK practice and highlights areas for improvement

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

Objective To assess the validity of Somatosensory Evoked Potential (SSEP) monitoring in identifying potential spinal cord vascular damage resulting from segmental artery ligation in anterior spinal deformity correction. Design SSEP monitoring was undertaken in patients deemed at risk of spinal cord vascular injury during corrective surgery. The segmental vessels of the vertebral bodies to be instrumented were identified. Baseline SSEPs were obtained prior to application of non-crushing microvascular clamps. After ten minutes of occlusion, further SSEP recordings were made. Surgery proceeded with either, vessel ligation and division allowing anterior instrumentation, or vessel sparing anterior release. Subjects 22 patients were included; 7 had Scheuermann’s hyperkyphosis and 15 had scoliosis (11 idiopathic, 3 syndromic, 1 neuromuscular). Perceived risk was defined by the presence of hyperkyphosis, abnormal neurological examination or radiologically identified spinal cord anomaly. Outcome Measures A drop of 30% from baseline reading was taken as significant. Post-operative neurological outcome was correlated with intra-operative signal change and alteration in planned surgery. Results There was no significant drop in post-clamping SSEPs in the hyperkyphotic patients. In 3 scoliosis patients anterior instrumentation was abandoned and a release was performed. Staged posterior instrumentation followed. In a further 2, anterior instrumentation proceeded but in a modified fashion. The remaining 10 patients had no significant drop and underwent the surgery as planned. No patient sustained a neurological injury. Conclusions SSEP monitoring is safe in assessing the apparent contribution of segmental vessel blood supply to the spinal cord in spinal deformity surgery. It has allowed timely alteration of planned surgical procedures that potentially may have caused vascular spinal cord injury

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

We reviewed retrospectively the role of monitoring of somatosensory spinal evoked potentials (SSEP) in 99 patients with neuromuscular scoliosis who had had operative correction with Luque-Galveston rods and sublaminar wiring. Our findings showed that SSEP monitoring was useful and that a 50% decrease in the amplitude of the trace optimised both sensitivity and specificity. The detection of true-positive results was higher than in cases of idiopathic scoliosis, but the method was less sensitive and specific and there were more false-negative results. In contrast with the findings in idiopathic scoliosis, recovery of the trace was associated with a 50% to 60% risk of neurological impairment. Only one permanent injury occurred during the use of this technique, and any temporary impairment resolved within two months