Reversibility of nerve root sedimentation sign in lumbar spinal stenosis patients after decompression surgery.

PURPOSE: The nerve root sedimentation sign (SedSign) is a magnetic resonance imaging (MRI) sign for the diagnosis of lumbar spinal stenosis (LSS). It is included in the assessment of LSS to help determine whether decompression surgery is indicated. Assessment of the reversibility of the SedSign after surgery may also have clinical implications for the decision about whether or not a secondary operation or revision is needed. This study investigated if lumbar decompression leads to a reversal of the SedSign in patients with LSS and a positive SedSign pre-operatively; and if a reversal is associated with more favourable clinical outcomes. If reversal of the SedSign is usual after sufficient decompression surgery, a new positive SedSign could be used as an indicator of new stenosis in previously operated patients. METHODS: A prospective cohort study of 30 LSS patients with a positive pre-operative SedSign undergoing decompression surgery with or without instrumented fusion was undertaken to assess the presence of nerve root sedimentation (=negative SedSign) on MRI at 3 months post-operation. Functional limitation (Oswestry Disability Index, ODI), back and leg pain (Visual Analogue Scale, VAS), and treadmill walking distance were also compared pre- and 3 months post-operatively. The short follow-up period was chosen to exclude adjacent segment disease and the potential influence of surgical technique on clinical outcomes at longer follow-up times. RESULTS: 30 patients [median age 73 years (interquartile range (IQR) 65-79), 16 males] showed a median pre-operative ODI of 66 (IQR 52-78), a median VAS of 8 (IQR 7-9), and a median walking distance of 0 m (IQR 0-100). Three months post-operation 27 patients had a negative SedSign. In this group, we found improved clinical outcomes at follow-up: median post-operative ODI of 21 (IQR 12-26), median VAS of 2 (IQR 2-4), and median walking distance of 1000 m (IQR 500-1000). These changes were all statistically significant (p < 0.001). Three patients had a positive SedSign at 3-month follow-up due to epidural fat (n = 2) or a dural cyst following an intra-operative dural tear (n = 1), but also showed improvements in clinical outcomes for ODI, VAS and walking distance. CONCLUSION: The reversibility of a pre-operative positive SedSign was demonstrated after decompression of the affected segmental level and associated with an improved clinical outcome. A persisting positive SedSign could be the result of incomplete decompression or surgical complications. A new positive SedSign after sufficient decompression surgery could be used as an indicator of new stenosis in previously operated patients.

C1-C2 Instrumentation According to Harms/Goel in Case of Vertebral Artery below the Arch of C1: A Case Report.

Study Design Case report. Background and Study Aims For stabilizing surgery of the atlantoaxial region, a precise evaluation of the course of the vertebral artery (VA) is essential to avoid vessel injury and life threatening complications. In patients with aberrant VA course, an appropriate way for fusion needs to be found. This article presents a case of an unusual VA course and illuminates the importance of surgical planning with computed tomography angiography identifying VA variations at the atlantoaxial region. Case Report A 71-year-old woman with atlantoaxial arthrosis had a VA variation (persistent first intersegmental artery). She underwent C1-C2 posterior fixation according to Harms/Goel using the typical entry points, requiring VA dissection in caudal direction. The postoperative clinical as well as radiographic result was excellent. Angiography 6 months postoperatively showed the VAs below the C1 screws with normal blood flow. Conclusions Placement of C1 screws in a patient with a persistent first intersegmental VA is possible. Careful VA dissection is the key step for safe screw placement, screw anchoring, and clinical success.

Resection of a Hemivertebra Within the Craniocervical Junction.

STUDY DESIGN: Case report on resection of a hemivertebra at the craniocervical junction. OBJECTIVE: To describe technique and result of a hemivertebra resection within the craniocervical junction (axis). SUMMARY OF BACKGROUND DATA: To our knowledge, this is the first report on a transoral and posterior hemivertebra resection at C2. METHODS: A 42-year-old patient presented with coronal imbalance due to a hemivertebra at C2. Correction was performed by a combined anterior (transoral) and posterior approach with hemivertebra resection and compression instrumentation. RESULTS: The postoperative course was uneventful. The radiographs showed a complete correction of the deformity with a perfect clinical result. CONCLUSION: Hemivertebra resection at the craniocervical junction can be performed safely with good clinical and radiographical outcome. LEVEL OF EVIDENCE: 4.

Increased intraoperative epidural pressure in lumbar spinal stenosis patients with a positive nerve root sedimentation sign.

PURPOSE: The sedimentation sign (SedSign) has been shown to discriminate well between selected patients with and without lumbar spinal stenosis (LSS). The purpose of this study was to compare the pressure values associated with LSS versus non-LSS and discuss whether a positive SedSign may be related to increased epidural pressure at the level of the stenosis. METHODS: We measured the intraoperative epidural pressure in five patients without LSS and a negative SedSign, and in five patients with LSS and a positive SedSign using a Codman(™) catheter in prone position under radioscopy. RESULTS: Patients with a negative SedSign had a median epidural pressure of 9 mmHg independent of the measurement location. Breath and pulse-synchronous waves accounted for 1-3 mmHg. In patients with monosegmental LSS and a positive SedSign, the epidural pressure above and below the stenosis was similar (median 8-9 mmHg). At the level of the stenosis the median epidural pressure was 22 mmHg. A breath and pulse-synchronous wave was present cranial to the stenosis, but absent below. These findings were independent of the cross-sectional area of the spinal canal at the level of the stenosis. CONCLUSIONS: Patients with LSS have an increased epidural pressure at the level of the stenosis and altered pressure wave characteristics below. We argue that the absence of sedimentation of lumbar nerve roots to the dorsal part of the dural sac in supine position may be due to tethering of affected nerve roots at the level of the stenosis.

Clinical validity of the nerve root sedimentation sign in patients with suspected lumbar spinal stenosis.

BACKGROUND CONTEXT: The nerve root sedimentation sign in transverse magnetic resonance imaging has been shown to discriminate well between selected patients with and without lumbar spinal stenosis (LSS), but the performance of this new test, when used in a broader patient population, is not yet known. PURPOSE: To evaluate the clinical performance of the nerve root sedimentation sign in detecting central LSS above L5 and to determine its potential significance for treatment decisions. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: One hundred eighteen consecutive patients with suspected LSS (52% women, median age 62 years) with a median follow-up of 24 months. OUTCOME MEASURES: Oswestry disability index (ODI) and back and leg pain relief. METHODS: We performed a clinical test validation study to assess the clinical performance of the sign by measuring its association with health outcomes. Subjects were patients referred to our orthopedic spine unit from 2004 to 2007 before the sign had been described. Based on clinical and radiological diagnostics, patients had been treated with decompression surgery or nonsurgical treatment. Changes in the ODI and pain from baseline to 24-month follow-up were compared between sedimentation sign positives and negatives in both treatment groups. RESULTS: Sixty-nine patients underwent surgery. Average baseline ODI in the surgical group was 54.7%, and the sign was positive in 39 patients (mean ODI improvement 29.0 points) and negative in 30 (ODI improvement 28.4), with no statistically significant difference in ODI and pain improvement between groups. In the 49 patients of the nonsurgical group, mean baseline ODI was 42.4%; the sign was positive in 18 (ODI improvement 0.6) and negative in 31 (ODI improvement 17.7). A positive sign was associated with a smaller ODI and back pain improvement than negative signs (both p<.01 on t test). CONCLUSIONS: In patients commonly treated with decompression surgery, the sedimentation sign does not appear to predict surgical outcome. In nonsurgically treated patients, a positive sign is associated with more limited improvement. In these cases, surgery might be effective, but this needs investigation in prospective randomized trials (Australian New Zealand Clinical Trial Registry, number ACTRN12610000567022).

Effect of anterior mobilization and shortening in the correction of rigid idiopathic thoracic scoliosis.

STUDY DESIGN: Retrospective study of patients with anterior release and posterior correction instrumentation in a 2-stage procedure for rigid thoracic scoliosis. OBJECTIVE: To examine the effect of the anterior release and shortening alone as well as its role in the overall correction. SUMMARY OF BACKGROUND DATA: With segmental transpedicular instrumentation the need for an additional anterior mobilization became rare. However, its effect on sagittal profile was not sufficiently acknowledged. METHODS: Twenty-two patients with rigid thoracic scoliosis (Lenke 1A, n = 3; 2A, n = 6; 2B, n = 2; 2C, n = 1; 4B, n = 1; 4C, n = 9 patients) were operated in a 2-stage procedure with anterior release followed by posterior correction. The anterior release included convex resection of the rib heads and shortening of the anterior column by resection of the discs and the convex anterolateral endplates in a mean of 8 (4-11) segments.After 14 days (6-27), the posterior instrumentation and correction was done. RESULTS: The preoperative thoracic scoliosis measured a mean of 80°, upper thoracic 42°, and lumbar 49°. The thoracic curve corrected in bending 20° (25%), upper thoracic 10° (24%), and lumbar 26° (53%). The mean thoracic kyphosis (T5-T12) was 11°, lumbar lordosis was -41°.After the anterior release and shortening, thoracic scoliosis improved to 50°, thoracic kyphosis increased to 32°.After the posterior surgery the following values were noted: thoracic scoliosis 10°, upper thoracic 9°, lumbar 8°, thoracic kyphosis 25°, and lumbar lordosis -41°. The results were maintained at follow-up. CONCLUSION: Anterior shortening results in a spontaneous correction of the thoracic scoliosis and hypokyphosis. In this series, the Cobb angle reduced 38% from a mean of 80° to a mean of 50°. Thoracic kyphosis increased from 11° to 32°. This correction was achieved without any corrective force or instrumentation. The second-stage posterior correction is facilitated and nearly complete correction is achieved with a residual curve on average of 10° with a physiological sagittal profile. LEVEL OF EVIDENCE: 4.

Histomorphometric and radiographical changes after lumbar implantation of the PEEK nonfusion interspinous device in the BB.4S rat model.

STUDY DESIGN: An experimental animal study. OBJECTIVE: To investigate histomorphometric and radiographical changes in the BB.4S rat model after PEEK (polyetheretherketone) nonfusion interspinous device implantation. SUMMARY OF BACKGROUND DATA: Clinical effectiveness of the PEEK nonfusion spine implant Wallis (Abbott, Bordeaux, France; now Zimmer, Warsaw, IN) is well documented. However, there is a lack of evidence on the long-term effects of this implant on bone, in particular its influence on structural changes of bone elements of the lumbar spine. METHODS: Twenty-four male BB.4S rats aged 11 weeks underwent surgery for implantation of a PEEK nonfusion interspinous device or for a sham procedure in 3 groups of 8 animals each: (1) implantation at level L4-L5; (2) implantation at level L5-L6; and (3) sham surgery. Eleven weeks postoperatively osteolyses at the implant-bone interface were measured via radiograph, bone mineral density of vertebral bodies was analyzed using osteodensitometry, and bone mineral content as well as resorption of the spinous processes were examined by histomorphometry. RESULTS.: Resorption of the spinous processes at the site of the interspinous implant was found in all treated segments. There was no significant difference in either bone density of vertebral bodies or histomorphometric structure of the spinous processes between adjacent vertebral bodies, between treated and untreated segments and between groups. CONCLUSION: These findings indicate that resorption of spinous processes because of a result of implant loosening, inhibit the targeted load redistribution through the PEEK nonfusion interspinous device in the lumbar spinal segment of the rat. This leads to reduced long-term stability of the implant in the animal model. These results suggest that PEEK nonfusion interspinous devices like the Wallis implants may have time-limited effects and should only be used for specified indications.

Disc volume reduction with percutaneous nucleoplasty in an animal model.

STUDY DESIGN: We assessed volume following nucleoplasty disc decompression in lower lumbar spines from cadaveric pigs using 7.1Tesla magnetic resonance imaging (MRI). PURPOSE: To investigate coblation-induced volume reductions as a possible mechanism underlying nucleoplasty. METHODS: We assessed volume following nucleoplastic disc decompression in pig spines using 7.1-Tesla MRI. Volumetry was performed in lumbar discs of 21 postmortem pigs. A preoperative image data set was obtained, volume was determined, and either disc decompression or placebo therapy was performed in a randomized manner. Group 1 (nucleoplasty group) was treated according to the usual nucleoplasty protocol with coblation current applied to 6 channels for 10 seconds each in an application field of 360°; in group 2 (placebo group) the same procedure was performed but without coblation current. After the procedure, a second data set was generated and volumes calculated and matched with the preoperative measurements in a blinded manner. To analyze the effectiveness of nucleoplasty, volumes between treatment and placebo groups were compared. RESULTS: The average preoperative nucleus volume was 0.994 ml (SD: 0.298 ml). In the nucleoplasty group (n = 21) volume was reduced by an average of 0.087 ml (SD: 0.110 ml) or 7.14%. In the placebo group (n = 21) volume was increased by an average of 0.075 ml (SD: 0.075 ml) or 8.94%. The average nucleoplasty-induced volume reduction was 0.162 ml (SD: 0.124 ml) or 16.08%. Volume reduction in lumbar discs was significant in favor of the nucleoplasty group (p<0.0001). CONCLUSIONS: Our study demonstrates that nucleoplasty has a volume-reducing effect on the lumbar nucleus pulposus in an animal model. Furthermore, we show the volume reduction to be a coblation effect of nucleoplasty in porcine discs.

Percutaneous disc decompression with nucleoplasty-volumetry of the nucleus pulposus using ultrahigh-field MRI.

PURPOSE: To evaluate changes in nucleus pulposus volume as a potential parameter for the effects of disc decompression. METHODS: Fifty-two discs (T8 to L1) were extracted from 26 pigs and separated into thoracic (T8 to T11) and thoracolumbar discs (T12 to L1). The discs were imaged using 7.1 Tesla ultrahigh-field magnetic resonance imaging (MRI) with acquisition of axial T2-weighted turbo spin-echo sequences for determination of baseline and postinterventional nucleus pulposus volumes. Volumes were calculated using OsiriX® (http://www.osirix-viewer.com). After randomization, one group was treated with nucleoplasty, while the placebo group was treated with an identical procedure but without coblation current. The readers analyzing the MR images were blinded to the kind of procedure performed. Baseline and postinterventional volumes were compared between the nucleoplasty and placebo group. RESULTS: Average preinterventional nucleus volume was 0.799 (SD: 0.212) ml. Postinterventional volume reduction in the nucleoplasty group was significant at 0.052 (SD: 0.035) ml or 6.30% (p<0.0001) (thoracic discs) and 0.082 (SD: 0.042) ml or 7.25% (p = 0.0078) (thoracolumbar discs). Nucleoplasty achieved volume reductions of 0.114 (SD: 0.054) ml or 14.72% (thoracic) and 0.093 (SD: 0.081) ml or 11.61% (thoracolumbar) compared with the placebo group. CONCLUSIONS: Nucleoplasty significantly reduces thoracic and thoracolumbar nucleus pulposus volumes in porcine discs.

Perforation of the sigmoid colon due to intradiscal spacer dislocation.

A case of late dislocation of a disc spacer L5/S1 with perforation of the sigmoid colon and transanal passage 4 years after implantation is reported. The objective is to describe an uncommon complication of anterior endoscopic spondylodesis L5/S1. To our knowledge, this is the first report on this rare complication. A 39-year-old patient suffering from a spondylolisthesis L5/S1 (Meyerding grade 2) with bilateral lysis L5 was operated with posterior instrumentation L5/S1 and anterior endoscopic insertion of two disc spacers. 4 years after surgery the patient noticed one of the spacers in the toilet. Radiographic examination of the colon with contrast dye revealed a perforation at the distal sigmoid colon. At the lumbosacral junction there was a bony defect at the site of the absent spacer and an anterior dislocation of the second spacer. A partial resection of the colon at the perforation site with end-to-end anastomosis was performed. The second spacer was removed, and the defect was packed with autologous cancellous bone and local antibiotics. The further course was uneventful. 2 weeks postoperatively the patient was discharged without signs of infection. The radiographic examination after 6 months showed healing of the bone graft with bony fusion L5/S1. In case of incomplete or absent bony fusion the dislocation of intradiscal spacers may arise even years after the primary surgery. In consequence periodical radiographic examinations of spinal instrumentations are recommended until complete bony fusion occurred. Unclear abdominal symptoms following anterior spine surgery require immediate examination.

Nerve root sedimentation sign: evaluation of a new radiological sign in lumbar spinal stenosis.

STUDY DESIGN: Retrospective case-referent study. OBJECTIVE: To assess whether the new sedimentation sign discriminates between nonspecific low back pain (LBP) and symptomatic lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: In the diagnosis of LSS, radiologic findings do not always correlate with clinical symptoms, and additional diagnostic signs are needed. In patients without LSS, we observe the sedimentation of lumbar nerve roots to the dorsal part of the dural sac on supine magnetic resonance image scans. In patients with symptomatic and morphologic central LSS, this sedimentation is rarely seen. We named this phenomenon "sedimentation sign" and defined the absence of sedimenting nerve roots as positive sedimentation sign for the diagnosis of LSS. METHODS: This study included 200 patients. Patients in the LSS group (n = 100) showed claudication with or without LBP and leg pain, a cross-sectional area <80 mm, and a walking distance <200 m; patients in the LBP group (n = 100) had LBP, no leg pain, no claudication, a cross-sectional area of the dural sac >120 mm, and a walking distance >1000 m. The frequency of a positive sedimentation sign was compared between the 2 groups, and intraobserver and interobserver reliability were assessed in a random subsample (n = 20). RESULTS: A positive sedimentation sign was identified in 94 patients in the LSS group (94%; 95% confidence interval, 90%-99%) but none in the LBP group (0%; 95% confidence interval, 0%-4%). Reliability was kappa = 1.0 (intraobserver) and kappa = 0.93 (interobserver), respectively. There was no difference in the detection of the sign between segmental levels L1-L5 in the LSS group. CONCLUSION: A positive sedimentation sign exclusively and reliably occurs in patients with LSS, suggesting its usefulness in clinical practice. Future accuracy studies will address its sensitivity and specificity. If they confirm the sign's high specificity, a positive sedimentation sign can rule in LSS, and, with a high sensitivity, a negative sedimentation sign can rule out LSS.

Ventral cancellous bone augmentation of the dens and temporary instrumentation C1/C2 as a function-preserving option in the treatment of dens pseudarthrosis.

STUDY DESIGN: An innovative function preserving technique for the treatment of odontoid nonunion via ventral cancellous bone augmentation of the dens is described. A retrospective clinical study of 17 patients, thus treated by this technique is reported. OBJECTIVES: Assessment of a new method, which preserves the rotational mobility of the C1/C2 joint. SUMMARY OF BACKGROUND DATA: Nonunion after odontoid fractures are usually treated by posterior fusion of C1/C2. Although there are reports of good clinical results, restriction of rotational mobility is inevitable. METHODS: Seventeen patients with dens pseudarthrosis or delayed healing were operated on between the year 1991 and 2005. A hole was drilled in the dens and packed with autologous bone graft. Temporary Instrumentation C1/C2 (anteriorly or posteriorly) was performed for 3 to 4 months. Patients were evaluated clinically and radiographically, rotation computed tomography or magnetic resonance imaging studies were conducted. RESULTS: Fifteen patients were available for follow-up. Nine patients demonstrated healing of the pseudarthrosis with preservation of C1/C2 joint mobility (confirmed by rotation-computed tomgraphy or rotation -magnetic resonance imaging in 7 cases, average segmental rotation 37.3 degrees). Four patients showed persistent pseudarthrosis (2 were fused by posterior C1/C2 fixation) and 2 patients demonstrated spontaneous C1-C2 fusion. CONCLUSIONS: Ventral cancellous bone augmentation of the dens and temporary instrumentation C1/C2 is a function-preserving option in the treatment of dens pseudarthrosis.

The diagnostic value of a treadmill test in predicting lumbar spinal stenosis.

Lumbar spinal stenosis is a frequent indication for spinal surgery. The predictive quality of treadmill testing and MRI for diagnostic verification is not yet clearly defined. Aim of the current study was to assess correlations between treadmill testing and MRI findings in the lumbar spine. Twenty-five patients with lumbar spinal stenosis were prospectively examined. Treadmill tests were performed and the area of the dural sac and neuroforamina was examined with MRI for the narrowest spinal segment. VAS and ODI were used for clinical assessment. The median age of the patients was 67 years. In the narrowest spinal segment the median area of the dural sac was 91 mm(2). The median ODI was 66 per cent. The median walking distance in the treadmill test was 70 m. The distance reached in the treadmill test correlated with the area of the dural sac (Spearman's rho = 0.53) and ODI (rho = -0.51), but not with the area of the neuroforamina and VAS. The distance reached in the treadmill test predicts the grade of stenosis in MRI but has a limited diagnostic importance for the level of clinical symptoms in lumbar spinal stenosis.

Treatment of vertebral osteomyelitis by radical debridement and stabilization using titanium mesh cages.

STUDY DESIGN: A retrospective clinical and radiologic evaluation of patients with vertebral osteomyelitis treated via radical debridement and stabilization using titanium mesh cages. OBJECTIVE: To assess the efficacy of titanium mesh cages in the treatment of active vertebral osteomyelitis. SUMMARY OF BACKGROUND DATA: Although titanium mesh cages have proven to be superior in trauma and tumor reconstructions, there are few reports regarding the use of titanium mesh cages in the presence of active pyogenic or tuberculotic vertebral osteomyelitis. METHODS: A total of 88 cases with vertebral osteomyelitis were operated on between January 2000 and December 2002. There were 2 craniocervical, 13 cervical, 19 thoracic, 11 thoracolumbar, and 43 lumbar infections. The titanium mesh cages replaced 1 disc in 34 cases, 1 vertebral body in 28 cases, 2 vertebral bodies in 23 cases, and 3 vertebral bodies in 3 cases. RESULTS: All patients showed a solid bony fusion without any recurrence of infection at latest follow-up. Changes in pain score, Frankel's classification, and blood parameters demonstrated a significant clinical improvement in all patients. The sagittal profile was restored. CONCLUSIONS: The use of titanium mesh cages in the treatment of vertebral osteomyelitis effectively reconstructs the anterior column, while adding stability and restoring the sagittal profile. There is no increase in the rate of recurrence or persistence of infection related to the implantation of titanium mesh cages.

Iatrogenic fractures in ankylosing spondylitis--a report of two cases.

STUDY DESIGN: Two cases of intraoperative, iatrogenic cervical spine fractures in patients with ankylosing spondylitis are reported. OBJECTIVE: To describe the uncommon complication of iatrogenic cervical spine fractures occurring during spine surgery in patients with ankylosing spondylitis. SUMMARY OF BACKGROUND DATA: To our knowledge, this is the first report on this rare complication. METHODS: A 39-year-old patient (1) with ankylosing spondylitis was operated on for cervical stenosis due to C1/2 anterolisthesis. Fifteen hours postoperatively, he developed acute quadriplegia. MRI revealed a fracture/dislocation of C6 on C7 and compression of the spinal cord at this level. Revision was performed with decompression and instrumentation from the occiput to T3. A 55-year-old patient (2) with ankylosing spondylitis and thoracic hyperkyphosis underwent a correction procedure consisting of costotransversectomy, anterior cage implantation at T8/9, and posterior instrumentation from T4 to L1. Halo traction was temporarily applied for correction. At the end of the operation, with the patient still under anesthesia, increased mobility of the cervical spine was noticed. Emergent MRI revealed a fracture of the anterior structures of C6/7. Posterior instrumentation from C5 to T1 was then performed. RESULTS: Quadriplegia persisted in patient 1 until his death secondary to further complications. Patient 2 was mobilized without any neurologic deficits. The fracture healed in good alignment. CONCLUSIONS: Iatrogenic fractures of the cervical spine during surgery in ankylosing spondylitis patients are a rare but potentially severe complication. Early diagnosis and therapy are necessary before dislocation, cord compression, and subsequent neurologic impairment occur.