Category: Spine

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Postoperative Magnetic Resonance Imaging Can Predict Neurological Recovery After Surgery for Cervical Spondylotic Myelopathy: A Prospective Study With Blinded Assessments

Neurosurgery 69:362–368, 2011 DOI: 10.1227/NEU.0b013e31821a418

Factors that can predict the recovery of cervical spondylotic myelopathy (CSM) patients postoperatively are of significant interest to physicians and patients and their families. Magnetic resonance imaging (MRI) scans are a common method of examination after surgery, and thus of interest as a predictor of outcome.

OBJECTIVE: To investigate whether findings on MRI at 6 months postoperatively could predict recovery at 1 year in CSM patients.

METHODS: In 52 consecutive prospective patients, MRI was performed preoperatively and 6 months postoperatively. T1 and T2 signal change (area, height, and segmentation) and spinal cord re-expansion were measured. Outcome measures evaluated at 1 year postoperatively were compared with preoperative values. Univariate and stepwise multiple regressions were undertaken.

RESULTS: Using univariate analysis, patients whose cord failed to re-expand had poorer outcome according to the modified Japanese Orthopedic Association score and Nurick score (P = .014) and grip test (P = .006) postoperatively. Stepwise multivariate regression showed lack of cord re-expansion to be predictive of prognosis postoperatively in the modified Japanese Orthopedic Association score (P = .013) and Berg Balance Scale (P = .014), and walking test (P = .011). Postoperative hyperintense T2 signal change was predictive of worse outcome on the Berg Balance Scale (P = .014) and walking test (P = .020), Nurick score (P = .001), and Short Form-36 scores (P = .020). In cases in which the T2 signal intensified, there was a poorer outcome on Nurick scores (P = .013), grip test (P = .017), and Short Form-36 scores (P = .030).

CONCLUSION: Findings on postoperative MRI at 6 months is of predictive value in determining outcomes in CSM patients. The persistence and type of T2 signal change and lack of re-expansion of the cord correlate with poorer recovery and likely reflect irreversible structural changes in the spinal cord.

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Occult Spinous Process Fractures Associated With Interspinous Process Spacers

Spine 2011;36:E1080–E1085. DOI: 10.1097/BRS.0b013e318204066a

Biomechanical cadaveric studies have suggested adequate spinous process strength to support placement of interspinous process spacers (IPS). Postoperative spinous process fractures have been reported in one%—to 5.8% of patients in previous series based on routine biplanar radiographic evaluation. However, most fractures occur between the base and midportion of the spinous process in an area that is typically diffi cult to visualize on plain radiographs due to device design.

Methods. All patients underwent preoperative biplanar plain radiographs and computed tomography (CT) of the lumbar spine to confirm anatomy favorable for IPS placement and rule out fracture or spondylolysis. Postoperatively, all patients underwent repeat CT imaging within six months of surgery, biplanar radiographs at two weeks, six weeks, three months, six months, and one year. All studies were reviewed independently by a neuroradiologist and two orthopedic spine surgeons.

Results. Fifty implants (38 L4–5, 12 L3–4) were placed in 38 patients who completed follow-up and were included in final analysis. Three IPS designs were included (34 Medtronic X-STOP titanium, 8 X-STOP PEEK, 8 Lanx Aspen). Postoperative CT revealed 11 nondisplaced spinous process fractures in 11 patients (28.9% of patients, 22% of levels). Five fractures were associated with mild to moderate lumbar back pain and six fractures were asymptomatic. No patient reported a traumatic incident. No fracture was identifiable on plain radiographs. One fracture displaced during follow-up evaluation. Three patients underwent IPS removal and laminectomy. Three fractures healed by CT in one year. Overall, patients with fractures tended toward poorer outcomes by Zurich Claudication Questionnaire (ZCQ) (28.5% vs. 34.8% improvement in symptom severity, P=  0.496; 21.4% vs. 30.7% improvement in physical function, P = 0.199) and tended toward lower satisfaction rates (50% vs. 73.7%, P = 0.24) at one year compared to patients without fracture.

Conclusion. Interspinous process spacer surgery appears associated with a higher rate of early postoperative spinous process fracture than previously reported. In all cases, in this series, plain radiographs were inadequate to identify fractures because all fractures were initially minimal or nondisplaced, many patients were osteopenic, and the metallic wings of the devices often obscured fractures. Moreover, in most patients, fractures were associated with mild or no acute localized pain. This study suggests that unrecognized spinous process fracture may be responsible for a signifi cant number of patients who experience unsatisfactory outcome after IPS surgery. CT imaging is required to identify the vast majority of such fractures.

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How I do it: cervical lateral mass screw fixation

Acta Neurochir. DOI 10.1007/s00701-011-1068-4

Cervical lateral mass screw fixation is indicated for the treatment of cervical subaxial C3-C7 lesions associated with instability.

Method The authors first describe the surgical anatomy of the subaxial cervical posterior approach. Then the Magerl technique is detailed. In particular, tricks to avoid complications are presented. The ideal screw entry point, direction, size and exit point are mentioned. A surgical video, artist’s drawings and a radiological case report are included.

Conclusion The Magerl technique is a safe and effective lateral mass fixation technique. Respecting anatomical landmarks is crucial to avoid nerve root, vertebral artery and facet joint injury.

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Cost effectiveness of disc prosthesis versus lumbar fusion in patients with chronic low back pain: randomized controlled trial with 2-year follow-up

Eur Spine J (2011) 20:1001–1011. DOI 10.1007/s00586-010-1607-3

This  randomized  controlled  health  economic study assesses the cost-effectiveness of the concept of total disc replacement (TDR) (Charité/Prodisc/Maverick) when compared with the concept of instrumented lumbar fusion (FUS) [posterior lumbar fusion (PLF) /posterior lumbar interbody fusion (PLIF)]. Social and healthcare perspectives after 2 years are reported.

In all, 152 patients were randomized  to  either  TDR  (n = 80)  or  lumbar  FUS (n = 72). Cost to society (total mean cost/patient, Swedish kronor = SEK,  standard  deviation)  for  TDR  was  SEK 599,560  (400,272),  and  for  lumbar  FUS  SEK  685,919 (422,903) (ns). The difference was not significant: SEK 86,359 (-45,605  to 214,332). TDR was significantly less costly from a healthcare perspective, SEK 22,996 (1,202 to 43,055). Number of days on sick leave among those who returned to work was 185 (146) in the TDR group, and 252 (189) in the FUS group (ns). Using EQ-5D, the total gain in quality adjusted life years (QALYs) over 2 years was 0.41 units for TDR and 0.40 units for FUS (ns). Based on EQ- 5D,  the  incremental  cost-effectiveness  ratio  (ICER)  of using TDR instead of FUS was difficult to analyze due to the ‘‘non-difference’’ in treatment outcome, which is why cost/QALY  was  not  meaningful  to  define. Using  cost- effectiveness probabilistic analysis, the net benefit (with CI) was found to be SEK 91,359 (-73,643  to 249,114) (ns). We used the currency of 2006 where 1 EURO = 9.26 SEK and 1 USD = 7.38 SEK.

It was not possible to state whether TDR or FUS is more cost-effective after 2 years. Since  disc replacement and lumbar fusion are based on different conceptual approaches, it is important to follow these results over time.

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Tubular Diskectomy vs Conventional Microdiskectomy for the Treatment of Lumbar Disk Herniation: 2-Year Results of a Double-Blind Randomized Controlled Trial

Neurosurgery 69:135–144, 2011 DOI: 10.1227/NEU.0b013e318214a98c

Transmuscular tubular diskectomy has been introduced to increase the rate of recovery, although evidence is lacking.

OBJECTIVE: To evaluate the 2-year results of tubular diskectomy compared with conventional microdiskectomy.

METHODS: Three hundred twenty-eight patients with persistent leg pain caused by lumbar disk herniation were randomly assigned to undergo tubular diskectomy (167 patients) or conventional microdiskectomy (161 patients). Main outcome measures were scores from Roland-Morris Disability Questionnaire for Sciatica, Visual Analog Scale for leg pain and low-back pain, and Likert self-rating scale of global perceived recovery.

RESULTS: On the basis of intention-to-treat analysis, there was no significant difference between tubular diskectomy and conventional microdiskectomy in Roland-Morris Disability Questionnaire for Sciatica scores during 2 years after surgery (between-group mean difference [∆] = 0.6; 95% confidence interval [CI], 20.3-1.6). Patients treated with tubular diskectomy reported more leg pain (∆ = 3.3 mm; 95% CI, 0.2-6.2) and more lowback pain (∆ = 3.0 mm; 95% CI, 20.2-6.3) than those patients treated with conventional microdiskectomy. At 2 years, 71% of patients assigned to tubular diskectomy documented a good recovery vs 77% of patients assigned to conventional microdiskectomy (odds ratio, 0.76; 95% CI, 0.45-1.28; P = .35). Repeated surgery rates within 2 years after tubular diskectomy and conventional microdiskectomy were 15% and 10%, respectively (P = .22).

CONCLUSION: Tubular diskectomy and conventional microdiskectomy resulted in similar functional and clinical outcomes. Patients treated with tubular diskectomy reported more leg pain and low-back pain, although the differences were small and not clinically relevant.

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SPORT: Does Incidental Durotomy Affect Longterm Outcomes in Cases of Spinal Stenosis?

Neurosurgery 69:38–44, 2011 DOI: 10.1227/NEU.0b013e3182134171

Incidental durotomy is a familiar encounter during surgery for lumbar spinal stenosis. The impact of durotomy on long-term outcomes remains a matter of debate.

OBJECTIVE: To determine the impact of durotomy on the long-term outcomes of patients in the Spine Patient Outcomes Research Trial (SPORT).

METHODS: The SPORT cohort participants with a confirmed diagnosis of spinal stenosis, without associated spondylolisthesis, undergoing standard, first-time, open decompressive laminectomy, with or without fusion, were followed up from baseline at 6 weeks, and 3, 6, and 12 months and yearly thereafter at 13 spine clinics in 11 US states. Patient data from this prospectively gathered database were reviewed. As of May 2009, the mean follow-up among all analyzed patients was 43.8 months.

RESULTS: Four hundred nine patients underwent first-time open laminectomy with or without fusion. Thirty-seven of these patients (9%) had an incidental durotomy. No significant differences were observed with or without durotomy in age; sex; race; body mass index; the prevalence of smoking, diabetes mellitus, and hypertension; decompression level; number of levels decompressed; or whether an additional fusion was performed. The durotomy group had significantly increased operative duration, operative blood loss, and inpatient stay. There were, however, no differences in incidence of nerve root injury, mortality, additional surgeries, or primary outcomes (Short Form-36 Bodily Pain or Physical Function scores or Oswestry Disability Index) at yearly follow-ups to 4 years.

CONCLUSIONS: Incidental durotomy during first-time lumbar laminectomy for spinal stenosis did not impact long-term outcomes in affected patients.

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Assessment of adjacent-segment mobility after cervical disc replacement versus fusion: RCT with 1 year’s results

Eur Spine J (2011) 20:934–941. DOI 10.1007/s00586-010-1588-2

Disc prostheses have been designed to restore and maintain cervical segmental motion and reduce the accelerated degeneration of the adjacent level. There is no knowledge about the reaction of the neighboured asymptomatic segments after implantation of prostheses or fusion. The effects of these procedures to segmental movement of the uninvolved vertebrae have not been subjected to studies so far.

The objective of this study was to compare the segmental motion following cervical disc replacement versus fusion and the correlation to the clinical outcome. Another aim was to compare the segmental motion of the asymptomatic segments above the treated ones and to compare both with Roentgen stereometric analysis (RSA) including the asymptomatic segments.

20 patients with one-level cervical radiculopathy scheduled for surgery were randomized to arthroplasty (10 patients, study group) or anterior cervical discectomy and fusion (10 patients, control group). Clinical results were evaluated using Visual Analogue Scale and Neck Disability Index. RSA was performed immediately postoperative, after 6 and 12 months.

The adjacent segment showed a significantly higher segmental motion in all three-dimensional axes in comparison to the segment treated with prostheses (P< 0.05). In the fusion group the segmental motion of the adjacent segment was significantly higher in all three dimensional axes (P< 0.05) at each examination time. When the adjacent level of both groups is compared, the fusion group could show a higher segmental motion in all three-dimensional axes, but without significant difference (P> 0.05) 1 year after surgery. Regarding the clinical results, there was no significant difference in pain relief between both groups (P> 0.05).

In conclusion, the adjacent segment could show a higher segmental motion, when compared with the segment either treated with prostheses or fusion. There was no significant difference in segmental motion adjacent to prosthesis or fusion. Clinical results did also show no significant difference in pain relief between both groups.

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Facetal distraction as treatment for single- and multilevel cervical spondylotic radiculopathy and myelopathy

J Neurosurg Spine 14:689–696, 2011. DOI: 10.3171/2011.2.SPINE10601
The authors discuss their successful preliminary experience with 36 cases of cervical spondylotic disease by performing facetal distraction using specially designed Goel cervical facet spacers. The clinical and radiological results of treatment are analyzed. The mechanism of action of the proposed spacers and the rationale for their use are evaluated. Between 2006 and February 2010, 36 patients were treated using the proposed technique. Of these patients, 18 had multilevel and 18 had single-level cervical spondylotic radiculopathy and/or myelopathy. The average follow-up period was 17 months with a minimum of 6 months. The Japanese Orthopaedic Association classification system, visual analog scale (neck pain and radiculopathy), and Odom criteria were used to monitor the clinical status of the patient. The patients were prospectively analyzed. The technique of surgery involved wide opening of the facet joints, denuding of articular cartilage, distraction of facets, and forced impaction of Goel cervical facet spacers into the articular cavity. Additionally, the interspinous process ligaments were resected, and corticocancellous bone graft from the iliac crest was placed and was stabilized over the adjoining laminae and facets after adequately preparing the host bone. Eighteen patients underwent single-level, 6 patients underwent 2-level, and 12 patients underwent 3-level treatment. The alterations in the physical architecture of spine and canal dimensions were evaluated before and after the placement of intrafacet joint spacers and after at least 6 months of follow-up. All patients had varying degrees of relief from symptoms of pain, radiculopathy, and myelopathy. Analysis of radiological features suggested that the distraction of facets with the spacers resulted in an increase in the intervertebral foraminal dimension (mean 2.2 mm), an increase in the height of the intervertebral disc space (range 0.4–1.2 mm), and an increase in the interspinous distance (mean 2.2 mm). The circumferential distraction resulted in reduction in the buckling of the posterior longitudinal ligament and ligamentum flavum. The procedure ultimately resulted in segmental bone fusion. No patient worsened after treatment. There was no noticeable implant malfunction. During the follow-up period, all patients had evidence of segmental bone fusion. No patient underwent reexploration or further surgery of the neck. Distraction of the facets of the cervical vertebra can lead to remarkable and immediate stabilization-fixation of the spinal segment and increase in space for the spinal cord and roots. The procedure results in reversal of several pathological events related to spondylotic disease. The safe, firm, and secure stabilization at the fulcrum of cervical spinal movements provided a ground for segmental spinal arthrodesis. The immediate postoperative improvement and lasting recovery from symptoms suggest the validity of the procedure.

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O-Arm–Guided Balloon Kyphoplasty: Prospective Single-Center Case Series of 54 Consecutive Patients

Neurosurgery 68[ONS Suppl 2]:ons250–ons256, 2011 DOI: 10.1227/NEU.0b013e31821421b9

Balloon kyphoplasty is widely used to treat vertebral compression fractures. Procedure outcome and safety are directly linked to precise radiological imaging requiring 1 or 2 C arms to allow correct visualization throughout the procedure. This minimally invasive spinal surgery is associated with radiation exposure for both patient and surgeon. In our center, we switched from using a C-arm to an O-arm image guidance system to perform balloon kyphoplasty. Our preliminary experience is reported in Acta Neurochirurgica, and the encouraging results led us to study this subject more extensively. This article presents our complete results. To the best of our knowledge, there is no comparable clinical series describing O-arm use in kyphoplasty procedures published in the literature. OBJECTIVE: To report our complete results of using the O-arm guidance system to perform balloon kyphoplasty.

METHODS: We prospectively evaluated O-arm–guided kyphoplasty procedure in 54 consecutive patients and measured x-ray exposure and fluoroscopy time.

RESULTS: The mean surgical time for the procedure was 38 minutes with a mean fluoroscopy procedure time of 3.1 minutes. The mean fluoroscopy time by level was 2.5 minutes. Mean irradiation dose by procedure was 220 mGy and by level was 166 mGy. There was a significant reduction in fluoroscopy time and x-ray exposure from 5.1 minutes with classic C-arm use to 3.1 minutes when with O-arm use without additional time required for positioning the system.

CONCLUSION: With this new intraoperative system, the overall surgical and fluoroscopy times can be further reduced in the near future.

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Long-term Outcome After Microendoscopic Diskectomy for Lumbar Disk Herniation: A Prospective Clinical Study With a 5-Year Follow-up

Neurosurgery 68:1568–1575, 2011 DOI: 10.1227/NEU.0b013e31820cd16a

Several authors have reported results obtained with the microendoscopic diskectomy (MED) technique, but the long-term outcome has not been described. This report summarizes our clinical experience with the lumbar MED technique with a long-term follow-up period.

OBJECTIVE: To evaluate the efficacy of the MED for lumbar disk herniation and to report long-term outcome and complications (5-year follow-up).

METHODS: One hundred twenty consecutive patients with lumbar disk herniation were treated with the METRx system.We included all types of lumbar herniated disks: contained, not contained, foraminal, and migrated disk herniations. The results were evaluated with the Visual Analog Scale (VAS) pain score, Oswestry Disability Index score, patient satisfaction questionnaire, and modified Macnab criteria.

RESULTS: The average age of patients was 41 years; 65 were men and 55 were women. The most commonly affected level was L5-S1 (54.2%). The follow-up time after surgery was 5 years in all cases. We obtained good or excellent results in 75% of patients and regular results in 18%. Good subjective satisfaction was observed with surgery in 92% of patients. The mean decrease in the Oswestry Disability Index score was 52.8 ± 21.6; the mean decrease in leg VAS score was 6.1 ± 2.3; and the mean decrease in lumbar VAS score was 1.9 ± 3.3. Adjusted mean differences were statistically significant in all cases (P < .05).

CONCLUSION: MED not only reduces the incision, tissue damage, and postoperative period of incapacity but also offers long-term results comparable to those of conventional techniques.

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Cauda equina syndrome: a review of the current clinical and medico-legal position

Eur Spine J (2011) 20:690–697. DOI 10.1007/s00586-010-1668-3

Cauda equina syndrome (CES) is a rare condition with a disproportionately high medico-legal profile. It occurs most frequently following a large central lumbar disc herniation, prolapse or sequestration.

Review of the literature indicates that around 50–70% of patients have urinary retention (CES-R) on presentation with 30–50% having an incomplete syndrome (CES-I). The latter group, especially if the history is less than a few days, usually requires emergency MRI to confirm the diagnosis followed by prompt decompression by a suitably experienced surgeon. Every effort should be made to avoid CES-I with its more favourable prognosis becoming CES-R while under medical supervision either before or after admission to hospital. The degree of urgency of early surgery in CES-R is still not in clear focus but it cannot be doubted that earliest decompression removes the mechanical and perhaps chemical factors which are the causes of progressive neurological damage.

A full explanation and consent procedure prior to surgery is essential in order to reduce the likelihood of misunderstanding and litigation in the event of a persistent neurological deficit.

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Robotic Digital Subtraction Angiography Systems Within the Hybrid Operating Room

Neurosurgery 68:1427–1433, 2011 DOI: 10.1227/NEU.0b013e31820b4f1c

Fully equipped high-end digital subtraction angiography (DSA) within the operating room (OR) environment has emerged as a new trend in the fields of neurosurgery and vascular surgery.

OBJECTIVE: To describe initial clinical experience with a robotic DSA system in the hybrid OR.

METHODS: A newly designed robotic DSA system (Artis zeego; Siemens AG, Forchheim, Germany) was installed in the hybrid OR. The system consists of a multiaxis robotic C arm and surgical OR table. In addition to conventional neuroendovascular procedures, the system was used as an intraoperative imaging tool for various neurosurgical procedures such as aneurysm clipping and spine instrumentation.

RESULTS: Five hundred one neurosurgical procedures were successfully conducted in the hybrid OR with the robotic DSA. During surgical procedures such as aneurysm clipping and arteriovenous fistula treatment, intraoperative 2-/3-dimensional angiography and C-arm-based computed tomographic images (DynaCT) were easily performed without moving the OR table. Newly developed virtual navigation software (syngo iGuide; Siemens AG) can be used in frameless navigation and in access to deep-seated intracranial lesions or needle placement.

CONCLUSION: This newly developed robotic DSA system provides safe and precise treatment in the fields of endovascular treatment and neurosurgery.

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Prospective, Randomized, Double-Blind Clinical Study Evaluating the Correlation of Clinical Outcomes and Cervical Sagittal Alignment

Neurosurgery 68:1309–1316, 2011. DOI:10.1227/NEU.0b013e31820b51f3

Sagittal alignment of the cervical spine has received increased attention in the literature as an important determinant of clinical outcomes after anterior cervical diskectomy and fusion. Surgeons use parallel or lordotically fashioned grafts depending on preference or simple availability.

OBJECTIVE: To quantitatively assess and compare cervical sagittal alignment and clinical outcome when lordotic or parallel allografts were used for fusion.

METHODS: A prospective, randomized, double-blind clinical study that enrolled 122 patients was performed. The mean follow-up was 37.5 months (range, 12-54 months).

RESULTS: The mean postoperative cervical sagittal alignment was 19 (range, 27-36) and 18 (range, 27-37) in the lordotic and parallel graft patient groups, respectively. The mean segmental sagittal alignment was 6 (range, 24-19) and 7 (range, 23-19) in the lordotic and parallel graft patient groups, respectively. There were no statistically significant differences in clinical outcome scores between the lordotic and parallel graft patient groups. However, patients who had maintained or improved segmental sagittal alignment, regardless of graft type, achieved a higher degree of improvement in Short Form-36 Physical Component Summary and Neck Disability Index scores. This was statistically significant (P , .038).

CONCLUSION: The use of lordotically shaped allografts does not increase cervical/ segmental sagittal alignment or improve clinical outcomes. Maintaining a consistent segmental sagittal alignment or increasing segmental lordosis was related to a higher degree of improvement in clinical outcomes.

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Surgical management and outcome of schwannomas in the craniocervical region

J Neurosurg 114:1257–1267, 2011. DOI: 10.3171/2010.5.JNS0966

Schwannomas occupying the craniocervical junction (CCJ) are rare and usually originate from the jugular foramen, hypoglossal nerves, and C-1 and C-2 nerves. Although they may have different origins, they may share the same symptoms, surgical approaches, and complications. An extension of these lesions along the posterior fossa cisterns, foramina, and spinal canal—usually involving various cranial nerves (CNs) and the vertebral and cerebellar arteries—poses a surgical challenge. The primary goals of both surgical and radiosurgical management of schwannomas in the CCJ are the preservation and restoration of function of the lower CNs, and of hearing and facial nerve function. The origins of schwannomas in the CCJ and their clinical presentation, surgical management, adjuvant stereotactic radiosurgery, and outcomes in 36 patients treated at Barrow Neurological Institute (BNI) are presented.

Methods. Between 1989 and 2009, 36 patients (mean age 43.6 years, range 17–68 years) with craniocervical schwannomas underwent surgical resection at BNI. The records were reviewed retrospectively regarding clinical presentation, radiographic assessment, surgical approaches, adjuvant therapies, and follow-up outcomes.

Results. Headache or neck pain was present in 72.2% of patients. Cranial nerve impairments, mainly involving the vagus nerve, were present in 14 patients (38.9%). Motor deficits were found in 27.8% of the patients. Sixteen tumors were intra- and extradural, 15 were intradural, and 5 were extradural. Gross-total resection was achieved in 25 patients (69.4%). Adjunctive radiosurgery was used in the management of residual tumor in 8 patients; tumor control was ultimately obtained in all cases.

Conclusions. Surgical removal, which is the treatment of choice, is curative when schwannomas in the CCJ are excised completely. The far-lateral approach and its variations are our preferred approaches for managing these lesions. Most common complications involve deficits of the lower CNs, and their early recognition and rehabilitation are needed. Stereotactic radiosurgery, an important tool for the management of these tumors as adjuvant therapy, can help decrease morbidity rates.

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Randomized controlled trial of percutaneous vertebroplasty versus optimal medical management for the relief of pain and disability in acute osteoporotic vertebral compression fractures

J Neurosurg Spine 14:561–569, 2011. DOI: 10.3171/2010.12.SPINE10286

Osteoporotic vertebral compression fractures (VCFs) are a major cause of increased morbidity in older patients. This randomized controlled trial compared the efficacy of percutaneous vertebroplasty (PV) versus optimal medical therapy (OMT) in controlling pain and improving the quality of life (QOL) in patients with VCFs. Efficacy was measured as the incidence of new vertebral fractures after PV, restoration of vertebral body height (VBH), and correction of deformity.

Methods. Of 105 patients with acute osteoporotic VCFs, 82 were eligible for participation: 40 patients underwent PV and 42 received OMT. Primary outcomes were control of pain and improvement in QOL before treatment, and these were measured at 1 week and at 2, 6, 12, 24, and 36 months after the beginning of the treatment. Radiological evaluation to measure VBH and sagittal index was performed before and after treatment in both groups and after 36 months of follow-up.

Results. The authors found a statistically significant improvement in pain in the PV group compared with the OMT group at 1 week (difference -3.1, 95% CI -3.72 to -2.28; p < 0.001). The QOL improved significantly in the PV group (difference -14, 95% CI -15 to -12.82; p < 0.028). One week after PV, the average VBH restoration was 8 mm and the correction of deformity was 8°. The incidence of new fractures in the OMT group (13.3%) was higher than in the PV group (2.2%; p < 0.01).

Conclusions. The PV group had statistically significant improvements in visual analog scale and QOL scores maintained over 24 months, improved VBH maintained over 36 months, and fewer adjacent-level fractures compared with the OMT group.

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Posterior ring apophysis separation combined with lumbar disc herniation in adults: a 10-year experience in the surgical management of 87 cases

J Neurosurg Spine 14:475–483, 2011 475. DOI: 10.3171/2010.11.SPINE10392

The association of posterior ring apophysis separation (PRAS) with lumbar disc herniation (LDH) is uncommon and represents a true subgroup of disc herniation mainly seen in the adolescent population. The objective of this study was to describe a decade of experience in the care of adult patients with PRAS with LDH, giving particular attention to its diagnosis, surgical treatment, and outcome.

Methods. This retrospective study focuses on a case series of adult patients with PRAS associated with LDH who underwent surgery for lumbar disc disease in the author’s neurosurgical department between 1999 and 2008. Posterior ring apophysis separation was diagnosed in 87 (5.35%) of 1625 patients surgically treated for LDH; these patients made up the PRAS group. During a 6-month period in 2005, LDH without PRAS was diagnosed in 89 consecutive patients at the same facility; these patients constituted the control group. Presenting symptoms, physical examination findings, and preoperative imaging results were obtained from medical records. Immediate operative results were assessed, as were complications, long-term outcome, and the need for repeat surgery.

Results. This study is the first to document the distinguishing features between adult patients with and those without PRAS. The difference in average age was statistically significant (p < 0.001) between the study group (36.22 years) and the control group (44.30 years), as was the incidence of male patients (86.20% vs 71.91%, p = 0.020), incidence of military patients (74.71% vs 57.30%, p = 0.015), average duration of symptoms (16.13 vs 8.4 months, p = 0.016), and incidence of reactive scoliosis (19.54% vs 4.49%, p = 0.002). The most common anatomical location of disc herniation in the PRAS group was L5–S1 (51.72%) versus L4–L5 (53.93%) in the control group (p = 0.017). In terms of previous injury, motor deficits, back and/or leg pain, lateral or central location of LDH, mean anteroposterior diameter of disc herniation, hard or soft discs, and surgical complications, there was no statistical difference between the 2 patient groups. Similarly, there was no difference in recurrence rates and clinical outcomes between the patients with or without PRAS.

Conclusions. Posterior ring apophysis separation with LDH is probably more common in adults than is generally recognized. It must be suspected when young male patients with persistent sciatic scoliosis and no history of injury show signs of calcified LDH. Computed tomography scanning with sagittal reconstructions is the procedure of choice for diagnosing. The L5–S1 intervertebral disc level is most commonly affected, especially the superior endplate of S-1. This condition needs more extensive surgical exposure and resection to relieve the nerve impingement. The occurrence of an apophyseal lesion was not associated with recurrent disc herniation or a fair outcome.

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The role of DTI in early detection of cervical spondylotic myelopathy: a preliminary study with 3-T MRI

Neuroradiology. DOI 10.1007/s00234-011-0844-4

The radiological diagnosis of cervical spondylotic myelopathy (CSM) has to be made as soon as possible, since surgery performed in earlier stages during the course of CSM was reported to be more successful when compared with later stages. We hypothesized that diffusion tensor imaging (DTI) may detect CSM in earlier stages, before the appearance of signal increase in T2- weighted sequences.

Methods A total of 16 patients with neurological signs and symptoms of CSM but without hyperintensity in spinal cord on T2-weighted sequences enrolled in the study. The magnetic resonance (MR) examinations were performed on a 3-T MR imaging system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were generated on axial plane. The ADC and FA measurements in each individual were made at the level of most severe cervical canal stenosis and at a nonstenotic level. Student’s t test was used to compare FA and ADC values of the spinal cord in stenotic and nonstenotic segments. We also investigated if there was a correlation between DTI parametrics and duration of clinical symptoms by using Pearson correlation analysis.

Results All patients showed changes in DTI parametrics at stenotic segments. While FA values of the spinal cord at the stenotic level showed a statistically significant reduction, there was a statistically significant increase in the measured ADC values (p<0.001). There was no statistical correlation between the duration of symptoms and DTI parametrics.

Conclusion Our preliminary findings indicate that DTI may show abnormalities in the spinal cord before the development of T2 hyperintensity on conventional sequences in patients with CSM.

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Minimally Invasive Lumbar Interbody Fusion in Patients Older Than 70 Years of Age: Analysis of Peri- and Postoperative Complications

Neurosurgery 68:897–902, 2011 DOI: 10.1227/NEU.0b013e3182098bfa

The number of spine operations performed in the elderly population is rising.

OBJECTIVE: To identify and describe perioperative and postoperative complications in patients 70 years and older who have undergone minimally invasive lumbar interbody spine fusion.

METHODS: A retrospective analysis was performed on 66 consecutive patients aged 70 years or older who underwent a minimally invasive interbody lumbar fusion. Electronic medical records were analyzed for patient demographics, procedures, and perioperative and postoperative complications.

RESULTS: Between 2000 and 2009, 66 patients with an average age of 74.9 years (range, 70-86 years) underwent 68 lumbar interbody fusions procedures. The mean follow-up was 14.7 months (range, 1.5-50 months). The minimally invasive approaches included 41 cases of extreme lateral interbody fusion and 27 minimally invasive transforaminal lumbar interbody fusions. We observed 5 major (7.4%) and 17 minor (25%) complications. The 5 major complications consisted of 4 cases of interbody graft subsidence and 1 adjacent level disease. There were no intraoperative medical complications. There were no myocardial infarctions, pulmonary embolisms, hardware complications requiring removal, wound infections, major visceral, vascular, neural injuries, or death in the study period.

CONCLUSION: Minimally invasive interbody fusions can be performed in the elderly (ages 70 years and older) with an overall low rate of major complications. Graft subsidence in this population when not supplemented with posterior instrumentation is a concern. Age should not be a deterrent to performing complex minimally invasive interbody fusions in the elderly.

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Minimally invasive percutaneous transpedicular screw fixation: increased accuracy and reduced radiation exposure by means of a novel electromagnetic navigation system

Acta Neurochir (2011) 153:589–596. DOI 10.1007/s00701-010-0882-4

Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement.

Methods Minimally invasive pedicle screw placement in T8 to S1 pedicles of eight fresh-frozen human cadaveric torsos was guided with EMF or standard fluoroscopy. Setup, insertion, and fluoroscopic times and radiation exposure and accuracy (measured with post-procedural computed tomography) were analyzed in each group.

Results Sixty-two pedicle screws were placed under fluoroscopic guidance and 60 under EMF guidance. Ideal trajectories were achieved more frequently with EMF over all segments (62.7% vs. 40%; p=0.01). Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p=0.03, and 16.2% vs. 42.5%, p=0.01, respectively). Fluoroscopy time was reduced 77% with the use of EMF (22 s vs. 5 s per level; p<0.0001) over all spinal segments. Radiation exposure at the hand and body was reduced 60% (p=0.058) and 32% (p=0.073), respectively. Time for insertion did not vary between the two techniques.

Conclusions Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.

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Diffusion tensor imaging in the cervical spinal cord

Eur Spine J (2011) 20:422–428. DOI 10.1007/s00586-010-1587-3

There are discrepancy between MR findings and clinical presentations. The compressed cervical cord in patients of the spondylotic myelopathy may be normal on conventional MRI when it is at the earlier stage or even if patients had severe symptoms. Therefore, it is necessary to take a developed MR technique—diffusion tensor imaging (DTI)—to detect the intramedullary lesions.

Prospective MR and DTI were performed in 53 patients with cervical compressive myelopathy and twenty healthy volunteers. DTI was performed along six non-collinear directions with single-shot spin echo echo-planar imaging (EPI) sequence. Intramedullary apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in four segments (C2/3, C3/4, C4/5, C5/6) for volunteers, in lesions (or the compressed cord) and normal cord for patients. DTI original images were processed to produce color DTI maps.

In the volunteers’ group, cervical cord exhibited blue on the color DTI map. FA values between four segments had a significant difference (P<0.01), with the highest FA value (0.85 ±  0.03) at C2/3 level. However, ADC value between them had no significant difference (P> 0.05). For patients, only 24 cases showed hyperintense on T2-weighted image, while 39 cases shown patchy green signal on color DTI maps. ADC and FA values between lesions or the compressed cord and normal spinal cord of patients had a significant difference (both P< 0.01). FA value at C2/3 cord is the highest of other segments and it gradually decreases towards the caudal direction. Using single-shot spin echo EPI sequence and six non-collinear diffusion directions with b  value of 400 s mm-2 ,

DTI can clearly show the intramedullary microstructure and more lesions than conventional MRI.

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