Do socio-demographic characteristics and/or health status explain the magnitude of differences between patient and general public utility values? A chronic low back pain patients case study.

BACKGROUND: Utility values can be obtained from different respondent groups, including patients and members of the general public. Evidence suggests that patient values are typically higher than general public values. This study explores whether the magnitude of disagreement between both values can be explained by socio-demographic characteristics and/or health status. METHODS: Data of 5037 chronic low back pain patients were used. Self-reported EQ-VAS was employed as a proxy of patients' preference for their own health state. General public values for the patients' EQ-5D-3L health states were obtained using the Dutch VAS-based tariff. The difference between patient and general public values was assessed using a paired t-test. Subsequently, this difference was used as a dependent variable and regressed upon dummy variables of socio-demographic and health status characteristics. Coefficients represented age, gender, education level, social support, back pain intensity, leg pain intensity, functional status, comorbidities, catastrophizing, and treatment expectations. RESULTS: Patient values were higher than general public values (0.069; 95%CI:0.063-0.076). The magnitude of disagreement between both values was associated with age, gender, education level, social support, functional status, and comorbidities, but not with back pain intensity, leg pain intensity, catastrophizing, and treatment expectations. CONCLUSIONS: Patients were found to value their own health status higher than members of the general public. The magnitude of disagreement between both values was found to differ by various socio-demographic and/or health status characteristics. This suggest that patient characteristics account for a relevant fraction of the identified disagreements between patient and general public values, and that mechanisms thought to be responsible for these disagreements, such as adaptation and response shift, have a differential impact across patient sub-groups.

Pulmonary function in patients with adolescent idiopathic scoliosis: an explorative study of a wearable smart shirt as a measurement instrument.

PURPOSE: Adolescent idiopathic scoliosis (AIS) presents various challenges, including respiratory symptoms that impact pulmonary function. This study aims to explore the feasibility of using a smart shirt for continuous monitoring of lung volumes and heart rate during routine activities in AIS patients. METHODS: A single-center exploratory feasibility study was conducted with AIS patients aged 16-22 years with a thoracic curvature of ≥ 30 degrees and absence of respiratory comorbidities. A smart shirt was utilized to continuously monitor cardiopulmonary parameters during mild exercise, which included a standardized walking route with the ascent of multiple stairs. RESULTS: Five participants completed the study. Baseline spirometry measurements showed a range of values for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC ratio. During mild exercise, participants exhibited variability in tidal volume, heart rate, breathing rate, and minute ventilation, with increases observed during stair climbing. Breathlessness levels also varied throughout the activity but did not correlate with the measured lung volumes. Overall, the use of the smart shirt for assessing pulmonary function in AIS patients was deemed feasible and well tolerated by participants during the test activities. CONCLUSION: The study confirms the feasibility of using a smart shirt for continuous measurement of cardiopulmonary parameters in AIS patients during daily activities. Incongruities between spirometry results and perceived dyspnea exists, which questions the nature of the perceived dyspnea. Further research is needed to validate these findings and explore the impact of AIS characteristics on measurement accuracy.

The risk of delayed spinal cord injury in pediatric spinal deformity surgery.

Delayed spinal cord injury (SCI) hours or days after surgery, with uneventful monitoring and initial normal postoperative neurological examination, is a rare complication. Based on anecdotal evidence, the risk of delayed spinal cord injury might be higher than previously assumed. Therefore the aim of this study was to determine the risk of delayed SCI after pediatric spinal deformity surgery between 2013-2019 in the Netherlands. The total number of pediatric spinal deformity surgeries performed for scoliosis or kyphosis between 2013-2019 was obtained from the Dutch National Registration of Hospital Care. All eleven Dutch hospitals that perform pediatric spinal deformity surgery were contacted for occurrence of delayed SCI. From the identified patients with delayed SCI, the following data were collected: patient characteristics, details about the SCI, the surgical procedure, management and degree of improvement.2884 pediatric deformity surgeries were identified between 2013-2019. Seven patients (0.24%) with delayed SCI were reported: 3 idiopathic, 2 neuromuscular (including 1 kypho-scoliosis) and 2 syndromic scoliosis. The risk of delayed SCI after pediatric deformity surgery was 1:595 in idiopathic scoliosis, 1:214 in syndromic scoliosis, 1:201 in neuromuscular scoliosis. All seven patients had a documented normal neurological examination in the first postoperative period; neurological deficits were first diagnosed at a median 16h (range 2.5-40) after surgery. The risk of delayed SCI after pediatric deformity surgery is higher than previously reported, especially in patients with non-idiopathic scoliosis. Regular postoperative testing for late neurologic deficit should be performed for timely diagnosis and management of this devastating complication.

Risk factors for deep surgical site infections after spinal fusion.

Surgical site infections (SSI) are undesired and troublesome complications after spinal surgery. The reported infection rates range from 0.7 to 11.9%, depending on the diagnosis and the complexity of the procedure. Besides operative factors, patient characteristics could also account for increased infection rates. Because the medical, economic and social costs of SSI are enormous, any significant reduction in risks will pay dividends. The purpose of this study is to compare patients who developed deep SSI following lumbar or thoracolumbar spinal fusion with a randomly selected group of patients who did not develop this complication in order to identify changeable risk factors. With a case-control analysis nested in a historical cohort of patients who had had a spinal fusion between January 1999 and December 2008, we identified 36 cases with deep SSI (CDC criteria). Information regarding patient-level and surgical-level risk factors was derived from standardized but routinely recorded data and compared with those acquired in a random selection of 135 uninfected patients. Univariate analyses and a multivariate logistic regression were performed. The overall rate of infection in 1,615 procedures (1,568 patients) was 2.2%. A positive history of spinal surgery was associated with an almost four times higher infection rate (OR = 3.7, 95% BI = 1.6-8.6). The risk of SSI increased with the number of levels fused, patients with diabetes had an almost six times higher risk and smokers had more than a two times higher risk for deep SSI. The most common organism cultured was Staphylococcus aureus. All infected patients underwent at least one reoperation, including an open débridement and received appropriate antibiotics to treat the organism. Patients who had had a previous spinal surgery are a high-risk group for infection compared with those that never had surgery. Total costs associated with preventive measures are substantial and should be compensated by health care insurance companies by means of separate clinical pathways. High-risk patients should be informed about the increased risk of complications.

Biomechanical properties in motion of lumbar spines with degenerative scoliosis.

Degenerative lumbar scoliosis presumably alters spinal biomechanics, but a lack of quantitative reference measurements of these spines exists. We aimed to assess the biomechanical properties of spines with degenerative scoliosis, and to relate these to intervertebral disc degeneration (DD) and Cobb angle. Secondly, we compared these results to previous measurements of non-scoliotic spines. Ten cadaveric spines (Th12-L5, mean age 82 ±â€¯11 years) with Cobb angle ≥10° and apex at L3 were acquired. Three loading cycles (-4 to 4 Nm) were applied in flexion/extension (FE), lateral bending (LB), and axial rotation (AR). The range of motion (ROM), neutral zone (NZ) stiffness, NZ ROM, elastic zone (EZ) stiffness and hysteresis were calculated for each motion segment in the loading direction. ROM was calculated in coupled directions, expressed as a percentage of rotation in the loaded direction. For Th12-L5, there was a ROM (degrees ±â€¯SD) of 14.9 ±â€¯6.5 in FE, 14.9 ±â€¯7.8 in LB, and 10.2 ±â€¯5.5 in AR. The median (Nm/degree (Q1;Q3)) NZs was 0.24 (0.19;0.35) in FE, 0.25 (0.22;0.42) in LB, and 0.49 (0.33;0.99) in AR. Greater coupled motions related to higher Cobb angle, especially during AR on segments around the apex (FE: ρ = 0.539, p = 0.021 and LB: ρ = 0.821, p = 0.000). DD correlated to lower ROM and increased NZs on L2-L3 in FE (ρ = -0.721, p = 0.028 and ρ = 0.694, p = 0.038, respectively). Compared to non-scoliotic spines, smaller ROM in FE (p = 0.030) was found. This study describes the biomechanical properties of lumbar spines with degenerative scoliosis. Compared to non-scoliotic spines, they tended to be stiffer and exhibited smaller ROM in FE. DD only affected the ROM and NZs of the segments around the apex.

No effect of traction in patients with low back pain: a single centre, single blind, randomized controlled trial of Intervertebral Differential Dynamics Therapy.

Low back pain (LBP) poses a significant problem to society. Although initial conservative therapy may be beneficial, persisting chronic LBP still frequently leads to expensive invasive intervention. A novel non-invasive therapy that focuses on discogenic LBP is Intervertebral Differential Dynamics Therapy (IDD Therapy, North American Medical Corp. Reg U.S.). IDD Therapy consists of intermittent traction sessions in the Accu-SPINA device (Steadfast Corporation Ltd, Essex, UK), an FDA approved, class II medical device. The intervertebral disc and facet joints are unloaded through axial distraction, positioning and relaxation cycles. The purpose of this study is to investigate the effect of IDD Therapy when added to a standard graded activity program for chronic LBP patients. In a single blind, single centre, randomized controlled trial; 60 consecutive patients were assigned to either the SHAM or the IDD Therapy. All subjects received the standard conservative therapeutic care (graded activity) and 20 sessions in the Accu-SPINA device. The traction weight in the IDD Therapy was systematically increased until 50% of a person's body weight plus 4.45 kg (10 lb) was reached. The SHAM group received a non-therapeutic traction weight of 4.45 kg in all sessions. The main outcome was assessed using a 100-mm visual analogue scale (VAS) for LBP. Secondary outcomes were VAS scores for leg pain, Oswestry Disability Index (ODI), Short-Form 36 (SF-36). All parameters were measured before and 2, 6 and 14 weeks after start of the treatment. Fear of (re)injury due to movement or activities (Tampa Scale for Kinesiophobia), coping strategies (Utrecht Coping List) and use of pain medication were recorded before and at 14 weeks. A repeated measures analysis was performed. The two groups were comparable at baseline in terms of demographic, clinical and psychological characteristics, indicating that the random allocation had succeeded. VAS low back pain improved significantly from 61 (+/-25) to 32 (+/-27) with the IDD protocol and 53 (+/-26) to 36 (+/-27) in the SHAM protocol. Moreover, leg pain, ODI and SF-36 scores improved significantly but in both groups. The use of pain medication decreased significantly, whereas scores for kinesiophobia and coping remained at the same non-pathological level. None of the parameters showed a difference between both protocols. Both treatment regimes had a significant beneficial effect on LBP, leg pain, functional status and quality of life after 14 weeks. The added axial, intermittent, mechanical traction of IDD Therapy to a standard graded activity program has been shown not to be effective.

A prospective analysis of motion and deformity at the shoulder level in surgically treated adolescent idiopathic scoliosis.

BACKGROUND: Although posterior spinal correction and fusion surgery (PSF) of adolescent idiopathic scoliosis (AIS) limits counter rotation between thorax and pelvis, the physical function, and more specifically gait of these patients is only slightly affected after PSF. Possibly, shoulders-thorax counter-rotation increases to compensate for the loss in thorax-pelvis motion. This would subsequently result in a higher phase-difference and range of motion (ROM) between the shoulders and thorax. RESEARCH QUESTIONS: What is the effect of PSF on the phase difference and ROM between the shoulders and thorax? What is the effect of PSF on upper body deformity? METHODS: 18 AIS patients underwent gait analysis at increasing walking speeds (0.45 to 2.22 m/s) before, and 3 and 12 months after PSF. The phase difference, ROM, and deformity between the shoulders, thorax, and pelvis were calculated. RESULTS: The shoulders- thorax phase difference was unaffected by surgery. At 3 months postoperatively the shoulders-thorax ROM was decreased (3.5° ± 0.2° versus 2.7° ± 0.2°, p=0.001). This recovered to preoperative values 12 months postoperatively (3.2° ± 0.2°, p=0.213). The shoulder-pelvis phase difference was decreased 3 months postoperatively (-98.9° ± 6.8° vs. -77.2° ± 7.2°, p=0.010), and recovered to pre-op values at the 12 months postoperative measurement (-89.6° ± 6.9°, p=0.290). Walking speed did not influence the effect of surgery on phase difference or ROM. The pre-operative shoulders-thorax asymmetry decreased from 3.4° ± 2.4° to 0.6° ± 3.1° (p<0.001). Shoulders-pelvis and thorax-pelvis asymmetry decreased from 10.0° ± 3.7° to 2.8° ± 4.3° (p<0.001) and from 6.5° ± 3.4° to 1.8° ± 3.2° (p=0.006) respectively. SIGNIFICANCE: No compensatory mechanisms could be identified in the relative motion between the shoulders and the thorax. Possibly, compensatory mechanisms are not required for normal gait after surgery. The asymmetry of the shoulders in the transversal plane improved without specific surgical strategies.

Conditioning stimulation techniques for enhancement of transcranially elicited evoked motor responses.

INTRODUCTION: In spite of the use of multipulse, transcranial electrical stimulation (TES) is still insufficient in a subgroup of patients to elicit motor-evoked potentials during intraoperative neurophysiological monitoring (IONM). Classic facilitation methods used in awake patients are precluded under general anaesthesia. Conditioning techniques can be used in this situation. OBJECTIVE: To present clinical experimental data and models of motor-neuron (MN) excitability for homonymous and heteronymous conditioning and discuss their applications in IONM. MATERIAL AND METHODS: Data were obtained in a prospective study on multipulse TES-conditioning of the monosynaptic H-reflex and double multipulse TES. DISCUSSION: The principle of facilitation by conditioning stimulation is to apply a test stimulus when motor neurons (MNs) have been made maximally excitable by a conditioning stimulus. Both conditioning and test stimuli recruit separate populations of MNs. The overlapping fraction of MNs controls the efficacy of facilitation. Heteronymous conditioning stimulation, which is performed at a different site from the test stimulus, is illustrated by the TES-conditioned H-reflex (HR). Autonomous conditioning stimulation, which is performed at the same stimulation site, is illustrated by double-train TES (dt-TES). The facilitating curves obtained by conditioning stimulation are often 3-modal and show peaks of facilitation at short intertrain intervals (S-ITIs) of 10ms and between 15 and 20ms and at longer intertrain intervals (L-ITI) of over 100ms. The facilitation curves from HR and dt-TES are not always identical since different alphaMN pools are involved. Dt-TES is often successful in neurologically impaired patients whereas facilitation of the HR can be used when conditioned by TES at subthreshold levels allowing continuous IONM without movement in the surgical field. Alternatively, facilitation by conditioning from peripheral-nerve stimulation can be used for selective transmission of subthreshold TES motor responses to peripheral muscles, permitting motor-monitoring by a so-called selective motor-gating technique. CONCLUSIONS: Facilitation techniques offer many possibilities in IONM by enhancing low-amplitude TES-MEP responses. They can also selectively enhance responses in a few muscle groups for the reduction of movement.

Criteria for transcranial electrical motor evoked potential monitoring during spinal deformity surgery A review and discussion of the literature.

Transcranial electrical stimulated motor evoked potential monitoring (TES-MEP) has proven to be a successful and reliable neuromonitoring technique during spinal correction surgery. However, three criteria for TES-MEP monitoring have been described in the literature. This study aims at discussing and comparing the following criteria: (1) the "threshold level criterion" introduced by Calancie et al. (J Neurosurg 88 (1998) 457-70): a more than 100V over more than 1h increase of threshold level to get useful TES-MEP responses indicated neurological impairment; (2) the "amplitude criterion": for TES-MEP monitoring in corrective surgery of the spine, a more than 80% decrease of one or more response amplitudes was considered a valuable criterion for impending neurological deficits by Langeloo et al. (Spine 28 (2003) 1043-50); (3) "the morphology criterion": introduced in 2005 by Quinones et al. (Neurosurgery 56 (2005) 982-93), it is based on the morphology of the MEP-compound muscle action potentials (CMAP). The criterion was applied during TES-MEP monitoring during intramedullary spinal cord tumour resection. Neurological events are defined by a sharp decrease of response duration and/or waveform complexity and an increase in voltage threshold of 100V or greater. Although all methods have been reported to be successful during spinal surgery, the threshold criterion and the morphology change criterion carry several drawbacks. We consider the amplitude reduction method to be most useful during corrective spinal surgery. The sequences of observations and decisions during a TES-MEP monitoring that is based on this criterion are schematized in a flowchart.

Spinal fusion limits upper body range of motion during gait without inducing compensatory mechanisms in adolescent idiopathic scoliosis patients.

INTRODUCTION: Previous studies show a limited alteration of gait at normal walking speed after spinal fusion surgery for adolescent idiopathic scoliosis (AIS), despite the presumed essential role of spinal mobility during gait. This study analyses how spinal fusion affects gait at more challenging walking speeds. More specifically, we investigated whether thoracic-pelvic rotations are reduced to a larger extent at higher gait speeds and whether compensatory mechanisms above and below the stiffened spine are present. METHODS: 18 AIS patients underwent gait analysis at increasing walking speeds (0.45 to 2.22m/s) before and after spinal fusion. The range of motion (ROM) of the upper (thorax, thoracic-pelvic and pelvis) and lower body (hip, knee and ankle) was determined in all three planes. Spatiotemporal parameters of interest were stride length and cadence. RESULTS: Spinal fusion diminished transverse plane thoracic-pelvic ROM and this difference was more explicit at higher walking speeds. Transversal pelvis ROM was also decreased but this effect was not affected by speed. Lower body ROM, step length and cadence remained unaffected. DISCUSSION: Despite the reduction of upper body ROM after spine surgery during high speed gait, no altered spatiotemporal parameters or increased compensatory ROM above or below the fusion (i.e. in the shoulder girdle or lower extremities) was identified. Thus, it remains unclear how patients can cope so well with such major surgery. Future studies should focus on analyzing the kinematics of individual spinal levels above and below the fusion during gait to investigate possible compensatory mechanisms within the spine.

Triple osteotomy of the pelvis for acetabular dysplasia: results at a mean follow-up of 15 years.

We report the long-term results of 51 pelvic osteotomies in 43 patients with a mean follow-up of 15 years (13 to 20). The mean age of the patients was 28 years (14 to 46). At review three patients were lost to follow-up, and six had received a total hip arthroplasty. Of 48 hips, 42 (88%) were preserved, with good to excellent clinical results in 27 (64%). Pre-operatively, 41 (80%) of the treated hips had shown no sign of osteoarthritis. Thirty-one (65%) hips showed no progression of osteoarthritis after follow-up for 15 years. Significant negative factors for good long-term results were the presence of osteoarthritic changes and a fair or poor clinical score pre-operatively. Pelvic reorientation osteotomy for symptomatic hip dysplasia can give satisfactory and reproducible long-term clinical results.

A cluster of tularaemia after contact with a dead hare in the Netherlands.

Tularemia is thought to be rare in the Netherlands. Here we describe a cluster of two patients who contracted tularaemia after field dressing of a hare found dead. Additionally, infection from the same source is suggested in three animals.

Triple osteotomy of the pelvis for acetabular dysplasia: results at 8 to 15 years.

Reorientation of the acetabulum may be required in adolescents and young adults with developmental dysplasia of the hip. We have carried out a retrospective review of 51 hips after triple osteotomy with an average follow-up of ten years (8 to 15). Forty-eight hips (94%) were available for review and of these 39 (81%) were improved compared with before operation, 29 (60%) scoring good or excellent. Radiographic assessment showed improvement of the average centre-edge angle by 19 degrees, the acetabular index by 12 degrees and the anterior centre-edge angle by 26 degrees. The degree of osteoarthritis progressed by one grade in ten hips (21%) over a period of ten years. The satisfactory long-term clinical and radiographic results have encouraged us to continue this treatment for symptomatic acetabular dysplasia in these patients.

Influence of electrode impedance on threshold voltage for transcranial electrical stimulation in motor evoked potential monitoring.

Motor potentials evoked by transcranial electrical stimulation (TES) are used for monitoring the motor pathways, with emphasis on the spinal cord and brainstem. The stimulus voltage threshold is the voltage below which no motor response can be elicited. It has frequently been used as a monitoring parameter. However, its value can be limited, because it is affected by the impedance of the stimulus electrode. For example, the voltage threshold can change owing to formation of oedema of the scalp. The relationship between the TES voltage threshold and the electrode impedance of different electrode types was studied and discussed in the context of neuromonitoring: 323 impedance and voltage threshold pairs were studied, and TES was performed with disc cup EEG electrodes (six), corkscrew electrodes (type I: seven, type II: eight), multiple EEG needle electrodes (16) and a large needle electrode Cz' (anode) together with a ground strip over the forehead (cathode) (286). The study found the voltage threshold to be strongly dependent on electrode impedance when the impedance was higher than 460 omega (correlation: R2=0.87; p < 0.001). Below 460 omega, which included 91% of the category with the largest electrode surfaces, 25% of the multiple EEG electrodes and 75% of type II corkscrew electrodes, no significant correlation (R2=0.0064; p=0.15) was found. It was concluded that the correlation between the TES voltage threshold and electrode impedance can be markedly reduced by using TES electrodes with large contact surfaces, resulting in limit values for these parameters. This also may improve the reliability of TES motor evoked potential monitoring.

Improved neuromonitoring during spinal surgery using double-train transcranial electrical stimulation.

Motor evoked potentials (MEPs) evoked by transcranial electrical stimulation (TES) have become an important technique for monitoring spinal cord function intra-operatively, but can fail in some patients. A new technique of double-train stimulation is described. A multipulse transcranial electrical stimulus is preceded by a preconditioning pulse train that leads to larger MEP responses. An MEP monitoring system was adapted for double-train transcranial stimulation (DTS). MEP responses from 160 anterior tibial muscles obtained by double-train stimulation were analysed. All patients received propofol/remifentanil/O2/N2O anaesthesia. Fifty-two (83%) out of 63 single-train tibial MEPs with response amplitudes below 100 microV were magnified to over 100 microV, with an inter-train (inter-stimulus) interval ITI = 10-35 ms. These 63 amplitudes were magnified by an overall logarithmic mean factor of 15.5. For 97 MEPs with amplitudes above 100 microV, the logarithmic mean facilitation factor was 2.4. It was concluded that double-train TES stimulation can markedly facilitate responses to a single stimulus train (STS). The facilitation appears to be most effective when the responses to STS would otherwise be small or absent. This preconditioning stimulation technique is therefore useful when an STS leads to responses that are too small for effective monitoring.

Aneurysmal bone cyst of the spine: 31 cases and the importance of the surgical approach.

Thirty-one cases of aneurysmal bone cyst of the spine with a minimum follow-up of 1 year as registered by the Netherlands Committee for Bone Tumors are reported. Aneurysmal bone cyst is a benign, sometimes expansive and destructive, lesion frequently occurring between the ages of 10 and 20 years. Located in the vertebral column, it undermines the structural integrity of the spine, and neurologic complications can occur. In all cases the posterior elements were involved, with extension into the vertebral body occurring in 22 cases. Extension to adjacent vertebra occurred 5 times, but the intervertebral disc appeared to be left intact. Twenty-nine of 31 cases were treated surgically. Posterior approaches provided insufficient access to lesions also located to the vertebral body and were associated with a higher recurrence rate (5 of 18 cases) than anterior approaches (1 of 11 cases). Of 10 cases in which the surgical removal was incomplete, 4 healed and 6 had a local recurrence. Selective embolization was used twice, and its application is discussed. On the basis of this material and a review of the literature, treatment by intralesional curettage combined by adjuvant therapy such as preoperative embolization is advised.

[The disc prosthesis: myths and facts]. / De discusprothese: mythen en feiten.

The results of surgical treatment of degenerative low-back conditions by means of a fusion (spondylodesis) are in general less predictable than operative treatments for arthrosis of the (large) peripheral joints. Recently, new techniques of disc replacement have been developed as an alternative to traditional fusion operations. The most important theoretical advantage is the prevention of adjacent segment degeneration in the longer term. Because the disc prosthesis replaces the presumably painful intervertebral disc--just as an intercorporal fusion--the short-term results are expected to be comparable to ventral fusion. The results with a short follow-up period described in the literature are comparable to those published for spondylodesis. However, disc prosthesis requires a more extensive approach and therefore more serious complications are to be expected. In the longer term, prosthesis-related complications can be expected because these prostheses are used in young and active patients. Despite 15 years of small-scale experience in some European countries, there is a lack of reliable information about the middle and long-term performance of these prostheses in the peer-reviewed literature. Therefore, these implantations should be regarded as experimental procedures and should be confined to clinical trials in centres with sufficient experience in the operative treatment of degenerative low-back conditions as well as the necessary infrastructure to follow up these usually young patients in a scientifically responsible manner over a period of decades. These centres should also have the expertise necessary to adequately deal with the possible complications.

Late Proximal Pedicle Hook Migration Into Spinal Canal After Posterior Correction Surgery of Scoliosis Causing Neurologic Deficit: "Proximal Junctional Scoliosis"? Case Series and a Review of the Literature.

STUDY DESIGN: Case series. OBJECTIVES: We describe 4 patients with proximal pedicle hook migration as a late complication (greater than 12 months postoperatively) of posterior correction surgery in adolescent idiopathic scoliosis. We studied failure mechanisms and propose strategies for revision surgery. SUMMARY OF BACKGROUND DATA: Few published cases of hook migration into the spinal canal concern mainly intra-operative or early postoperative dislodgement. Re-operation rates for adolescent idiopathic scoliosis are 2% to 10%. METHODS: We retrospectively reviewed medical records and radiographic images in 4 patients with symptomatic pedicle hook migration into the spinal canal. We studied our scoliosis revision surgery rates over the past 10 years and reviewed the literature for instrumentation failure after scoliosis surgery. RESULTS: Our total re-operation rate between January 2002 and April 2012 was 7.0% (56 of 800 procedures), with a mean follow-up of 61 months (range, 6-129 months). Proximal hook migration presented in 1.0% (8 of 800 procedures), including 4 into the spinal canal. These 4 patients presented with pain symptoms 19-78 months after uneventful index posterior correction surgery. In all 4 patients, radiographic imaging showed proximal pedicle hook migration into the spinal canal without proximal sagittal alignment problems. In all patients, spinal fusion was observed on computed tomographic imaging and at revision surgery. Revision surgery consisted of at least hook removal. In all 4 patients, symptoms completely resolved over time. CONCLUSIONS: Hooks can migrate and potentially cause neurologic impairment and pain long after index surgery, despite the presence of solid spinal fusion. We believe this is partly the result of the surgical technique we used and have since abandoned, and partly the proximal spine settling and fusion mass deformation over time, which we call "proximal junctional scoliosis." We recommend computed tomographic imaging in case of postoperative symptoms and removal of hooks in case of hook migration into the spinal canal.

Spinal reconstruction with free vascularised bone grafts; approaches and selection of acceptor vessels.

The use of free vascularised bone grafts is an infrequently performed surgical technique for the reconstruction of spinal defects. This field of surgery brings many challenges concerning the choice of free vascularised bone graft, planning of the operative procedure and selection of recipient vessels. This study aims to report our experience with free vascularised bone grafts, with special emphasis on the surgical approach and the selection of recipient vessels. Over a period of 17 years (1994-2011), we used these grafts for anterior spinal reconstruction in 30 patients. In 28 patients, a free vascularised fibular graft was used, and in two cases a free vascularised iliac crest graft was used. The spinal segments reconstructed involved the cervical or cervicothoracic spine (6 cases), the thoracic spine (11 cases) and the thoracolumbar and lumbosacral spine (13 cases). Revascularisation of the free vascularised bone graft proved to be technically feasible in 30 patients, but failed in one fibular graft due to difficulties with recipient vessels in the lumbar region. Technical challenges were met with respect to the choice of the recipient vessel at various anatomical sites. Availability of acceptor vessels was highly de-pendant of the type of surgery (resection or stabilisation) and the selected surgical approach. Based on these findings, a preferred approach is given for each region. The use of free vascularised bone grafts is a valuable technique for the reconstruction of complex spinal disorders. Successful execution requires microvascular expertise with respect to graft harvesting and appropriate choice of recipient vessels. Adequate preoperative planning in a multidisciplinary setting and adherence to the basic principles for spinal reconstruction are required.

Optimum interpulse interval for transcranial electrical train stimulation to elicit motor evoked potentials of maximal amplitude in both upper and lower extremity target muscles.

OBJECTIVE: The aim of this study was to determine the optimum interpulse interval (OIPI) for transcranial electrical train stimulation to elicit muscle motor evoked potentials (TES-MEP) with maximal amplitude in upper and lower extremities during intra-operative spinal cord monitoring. METHODS: Intraoperative spinal cord monitoring with TES-MEP was performed in 26 patients who had (corrective) spine surgery. Optimum interpulse interval (OIPI) were determined for the abductor pollicis brevis muscle (APB) representing the upper extremity and the anterior tibialis muscle (TA) representing the lower extremity. The IPI was varied between 0.5 and 4.0ms, where the OIPI was defined as the IPI with the highest muscle MEP amplitude for each muscle group. Differences between upper and lower extremity OIPIs were analyzed. Furthermore, the MEP amplitudes difference between the upper and lower extremity OIPIs and between the OIPI and IPI 2 ms was determined. RESULTS: The mean OIPI(APB) representing the upper extremity was 1.78 ± 1.09 ms on the left side and 1.82 ± 0.93 ms on the right side. The lower extremity showed a mean OIPI(TA) of 2.26 ± 1.16 ms on the left and 2.73 ± 0.88 ms on the right side. The mean differences between the OIPI(APB) and OIPI(TA) were significant for p=0.019 (Student's T-test). No within patient differences in OIPIs between the left and the right side were found. The mean MEP amplitude reduction, the APB amplitude at OIPI(TA) compared to the APB at OIPI(APB), was 32.5 ± 27.9%. For the TA a mean amplitude reduction of 33.4 ± 27.4% was found. The mean amplitude reduction for the OIPI amplitudes compared to the amplitudes at IPI 2 ms was 53.6 ± 25.5% for the APB and 45.8 ± 28.3% for the TA. CONCLUSION: Large intra- and interindividual differences were found between the mean OIPIs of the TA and APB muscles (range 1.78-2.73 ms) representing the upper and lower extremity. SIGNIFICANCE: Based on the results of this study, it is advisable to perform a set-up procedure for each individual patient undergoing TES-MEP to determine the optimal parameter settings when using supramaximal intensity of TES.