Category: Spine

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Surgical treatment of thoracic disc disease via minimally invasive lateral transthoracic trans/retropleural approach

Surgical treatment of thoracic disc disease via minimally

Neurosurg Rev (2013) 36:455–465

Thoracic disc herniations are associated with serious neurological consequences if not treated appropriately. Although a number of techniques have been described, there is no consensus about the best surgical approach. In this study, the authors report their experience in the operative management of patients with thoracic disc herniations using minimally invasive lateral transthoracic trans/retropleural approach.

A series of 33 consecutive patients with thoracic disc herniations who underwent anterior spinal cord decompression followed by instrumented fusion through lateral approach is being reported. Demographic and radiographic data, perioperative complications, and clinical outcomes were reviewed.

Forty disc levels in 33 patients (18F/15M; mean age, 52.9) were treated. Twenty-three patients presented with myelopathy (69 %), 31 had radiculopathy (94 %), and 31 had axial pain (94 %). Among patients with myelopathy, 14 (42.4 %) had bladder and/or bowel dysfunction. In the last eight cases (24 %), the approach was retropleural instead of transpleural. Patients were followed up for 18.2 months on average. The mean length of hospital stay was 5 days. None of the patients developed neurological deterioration postoperatively. Among 23 patients who had myelopathy signs, 21 (91 %) had improved postoperatively. The mean preoperative visual analog scale pain score, Oswestry Disability Index score, SF-36 PCS, and mental component summary scores were 7.5, 42.4, 29.6, and 37.5 which improved to 3.5, 33.2, 35.5, and 52.6, respectively. Perioperative complications occurred in six patients (18.1 %), all of which resolved uneventfully.

Minimally invasive lateral transthoracic trans/retropleural approach is a safe and efficacious technique for achieving adequate decompression in thoracic disc herniations in a less invasive manner than conventional approaches.

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Effect of Load Carriage on Lumbar Spine Kinematics

Lumbar Spine Kinematics

Spine 2013 ;38:E783–E791

Feasibility study on the acquisition of lumbar spine kinematic data from upright magnetic resonance images obtained under heavy load carrying conditions.

Objective. To characterize the effect of the load on spinal kinematics of active Marines under typical load carrying conditions from a macroscopic and lumbar-level approach in active-duty US Marines.

Summary of Background Data. Military personnel carry heavy loads of up to 68 kg depending on duty position and nature of the mission or training; these loads are in excess of the recommended assault loads. Performance and injury associated with load carriage have been studied; however, knowledge of lumbar spine kinematic changes is still not incorporated into training. These data would provide guidance for setting load and duration limits and a tool to investigate the potential contribution of heavy load carrying on lumbar spine pathologies.

Methods. Sagittal T2 magnetic resonance images of the lumbar spine were acquired on a 0.6-T upright magnetic resonance imaging scanner for 10 active-duty Marines. Each Marine was scanned without load (UN1), immediately after donning load (LO2), after 45 minutes of standing (LO3) and walking (LO4) with load, and after 45 minutes of side-lying recovery (UN5). Custom-made software was used to measure whole spine angles, intervertebral angles, and regional disc heights (L1–S1). Repeated measurements analysis of variance and post hoc Sidak tests were used to identify significant differences between tasks ( α = 0.05).

Results. The position of the spine was significantly ( P < 0.0001) more horizontal relative to the external reference frame and lordosis was reduced during all tasks with load. Superior levels became more lordotic, whereas inferior levels became more kyphotic. Heavy load induced lumbar spine flexion and only anterior disc and posterior intervertebral disc height changes were observed. All kinematic variables returned to baseline levels after 45 minutes of side-lying recovery.

Conclusion. Superior and inferior lumbar levels showed different kinematic behaviors under heavy load carrying conditions. These fi ndings suggest a postural, lumbar fl exion strategy aimed at centralizing a heavy posterior load over the base of support.

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Management of Operative Complications Related to Occipitocervical Instrumentation

Management_of_Operative_Complications_Related_to

Neurosurgery 72[ONS Suppl 2]:ons214–ons228, 2013

The continued evolution of instrumentation techniques for fusions at the craniovertebral junction has enabled surgical treatment of a wide range of developmental, neoplastic, traumatic, and degenerative conditions. There has been an increased recognition of the morbidity associated with the complications secondary to occipitocervical instrumentation.

OBJECTIVE: To present representative complications secondary to occipitocervical instrumentation in patients who presented to our institution and to emphasize underlying principles in diagnosis and management of craniovertebral disease conditions through illustrative examples of their presentation, management, and follow-up.

METHODS: Clinical records for patients referred to the senior author (A.H.M.) between 2005 and 2010 for evaluation and management of their symptoms arising as a consequence of surgical intervention by a different primary neurosurgeon were reviewed.

RESULTS: Eight patients were identified with representative complications secondary to occipitocervical instrumentation. These complications included incorrect surgical technique, persistent instability, hardware misplacement with potential for vascular injury, associated neural injury, and secondary complications of wound healing resulting from methyl methacrylate use. Surgical revision was required in 2 patients. The remaining patients improved with removal of the offending hardware and acrylic cement. All patients reported symptom resolution, and dynamic imaging studies on follow-up indicated stable alignment and bony fusion.

CONCLUSION: These cases serve as illustrative examples of the spectrum of neural, vascular, biomechanical, and instrument-related complications associated with occipitocervical arthrodesis. Basic principles of occipitocervical instrumentation that enable safe and successful treatment of craniovertebral junction disease conditions have been highlighted. Potential complications and management strategies are discussed.

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Degree of kyphosis correction and neurological outcome

Cervical lordosis

J Neurosurg Spine 18:537–544, 2013

Reversal of the normal cervical spine curvature, as seen in cervical kyphosis, can lead to mechanical pain, neurological dysfunction, and functional disabilities. Surgical intervention is warranted in patients with sufficiently symptomatic deformities in an attempt to correct the deformed cervical spine. In theory, improved outcomes should accompany a greater degree of correction toward lordosis, although there are few data available to test this relationship. The purpose of this study is to determine if the degree of deformity correction correlates with improvement in neurological symptoms following surgery for cervical kyphotic deformity.

Methods. A retrospective review of 36 patients with myelopathic symptoms who underwent cervical deformity correction surgery between 2001 and 2009 was performed. Preoperative and postoperative radiographic findings related to the degree of kyphosis were collected and compared with functional outcome measures. The minimum follow-up time was 2 years.

Results. A significant relationship was observed between a greater degree of focal kyphosis correction and improved neurological outcomes according to the modified Japanese Orthopaedic Association (mJOA) score (r = -0.46, p = 0.032). For patients with severe neurological symptoms (mJOA score < 12) a trend toward improved outcomes with greater global kyphosis correction was observed (r = -0.56, p = 0.057). Patients with an mJOA score less than 16 who attained lordosis postoperatively had a significantly greater improvement in total mJOA score than patients who maintained a kyphotic position (achieved lordosis: 2.7 ± 2.0 vs maintained kyphosis: 1.1 ± 2.1, p = 0.044).

Conclusions. The authors’ results suggest that the degree of correction of focal kyphosis deformity correlates with improved neurological outcomes. The authors also saw a positive relationship between attainment of global lordosis and improved mJOA scores. With consideration for the risks involved in correction surgery, this information can be used to help guide surgical strategy decision making.

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The high-risk discectomy patient: prevention of reherniation in patients with large anular defects using an anular closure device

Barricaid

Eur Spine J (2013) 22:1030–1036

With lumbar discectomy for disc herniation, surgeons must choose between limited nucleus removal associated with higher reherniation risk or more aggressive nucleus removal associated with increased back pain and disc degeneration. This trade-off is particularly challenging in patients with large anular defects, which carry the highest risk of reherniation. We examined the effect of an anular closure device on reherniation and clinical outcomes.

Methods Seventy-five primary discectomy patients had a limited discectomy followed by implantation of an anular closure device and were followed-up to 2 years. Anular defect size and volume of removed nucleus was recorded at surgery. Reherniations were reported, pain and function were monitored throughout, and imaging was performed at annual visits.

Results The overall symptomatic reherniation rate was 1.4 %, and the asymptomatic reherniation rate was 1.5 % at 12 months and 5.1 % at 24 months. Both rates compare favorably with literature reports which include symptomatic rates ranging between 2 and 18 % (up to 27 % for patients with large anular defects) and an asymptomatic rate of 13 %.

Conclusions The low reherniation rate in patients at highrisk of reherniation based on anular defect size, despite discectomy being only limited, suggests that an anular closure device may reduce reherniation risk. Clinical outcomes for pain and function at 1 and 2 years post-operatively compared favorably with literature reports. Further study in a randomized controlled trial is required to confirm these results.

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Endoscopic transnasal odontoidectomy to treat basilar invagination with congenital osseous malformations

Basilar invagination

Eur Spine J (2013) 22:1127–1136

Transoral resection of the odontoid has been accepted as a standard procedure to decompress the cervicomedullary junction during the past several decades. The endoscopic transnasal odontoidectomy is emerging as a feasible surgical alternative to conventional microscopic transoral approach. In this article, we describe several operative nuances and pearls from our experience about this approach, which provided successful decompression.

Methods From September 2009 to April 2010, three consecutive patients with basilar invagination, of which the etiology was congenital osseous malformations, underwent endoscopic transnasal odontoidectomy. All patients presented with myelopathy. The last two cases also received occipitocervical fixation and bone fusion during the same surgical episode to ensure stability.

Results All the patients were extubated after recovery from anesthesia and allowed oral food intake the next day. Cerebrospinal fluid rhinorrhea was found in the second case and cured by continuous lumber drainage of cerebrospinal fluid. No infection was noted. The average follow- up time was more than 24 months. Remarkable neurological recovery was observed postoperative in all patients.

Conclusion The endoscopic transnasal odontoidectomy is a feasible approach for anterior decompression of pathology at the cervicomedullary junction. The advantages over the standard transoral odontoidectomy include elimination of risk of tongue swelling and teeth damaging, improvement of visualization, alleviation of prolonged intubation, reduction of need for enteral tube feeding and less risk of affecting phonation. The minimally invasive access and faster recovery associated with this technique make it a valid alternative for decompression of the ventral side of the cervicomedullary junction

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Use of microscope-integrated near-infrared indocyanine green videoangiography in the surgical treatment of intramedullary cavernous malformations

ICG video intram. cavernomas

J Neurosurg Spine 18:443–449, 2013

The characteristics and efficacy of indocyanine green (ICG) videoangiography in cavernous malformation (CM) have not been fully elucidated. The purpose of this paper is to examine the potential utility of ICG videoangiography in the surgical treatment of intramedullary CMs.

METHODS
The authors conducted a retrospective review of 8 cases involving 5 men and 3 women who had undergone surgery for intramedullary CM between January 2008 and July 2011. All patients were evaluated by means of MRI. The MRI findings and clinical history in all cases suggested intramedullary CM as a preoperative diagnosis. In 2 of 8 cases, dilated venous structures associated with CMs were demonstrated. In one of these cases, there were coexisting extramedullary CMs. Intraoperatively, ICG fluorescence was observed for 5 minutes using microscope-integrated videoangiography.

RESULTS
In all 8 cases, intra- and extramedullary CMs were seen as avascular areas on ICG videoangiography. Indocyanine green videoangiography helped surgeons to localize and predict margins of the lesions before performing myelotomy. Importantly, in the cases with associated venous anomalies, ICG videoangiography was useful in delineating and preserving the venous structures. In extramedullary CMs located dorsal to the spinal cord, gradual ICG infiltration was seen, starting at 110 seconds and maximal at 210 seconds after injection. Postoperative MRI confirmed total removal of the lesions in all cases, and subsequent recovery of all patients was uneventful.

CONCLUSIONS
Indocyanine green videoangiography provided useful information with regard to the detection of lesion margins by demonstrating intramedullary CMs as avascular areas. In cases associated with venous anomalies, ICG contributed to safe and complete removal of the CMs by visualizing the venous structure. In extramedullary CMs, ICG videoangiography demonstrated the characteristic of slow blood flow within CMs.

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Indocyanine green videoangiography ‘‘in negative’’: definition and usefulness in spinal dural arteriovenous fistulae

SDAVF

Eur Spine J (2013) 22 (Suppl 3):S471–S477

Indocyanine green videoangiography (IGV) has proven its effectiveness in the field of exovascular neurosurgery, both in the intracranial and spinal compartment, but is necessary to define a systematic process for the performance of the IGV to facilitate its interpretation during the procedure. We have defined and applied the concept of videoangiography ‘‘in negative’’ (INIGV) to spinal dural arteriovenous fistulae (dAVF) for the detection and treatment of arteriovenous shunts, so called because the first phase is performed with the vessel suggestive of being pathological occluded.

Methods A Pentero-operating microscope with nearinfrared IGV-integrated system (Carl Zeiss Co., Germany) was used. At our institution, 24 patients were treated for a spinal dAVF between 1995 and 2011, only in the last 4 cases, INIGV was performed.

Results We describe the IGV in negative procedure and show the most illustrative cases. In all cases, the fistula occlusion was confirmed by postoperative selective digital subtraction angiography (DSA). INIGV demonstrate its capacity in detecting vessels not actually arterialized that should be respected and avoid some of the main limitations of the conventional IGV. This is a technical description about an Indocyanine green (ICG) videoangiographic procedure modification that is superior to merely performing ICG before and after clipping of a dAVF.

Conclusion The INIGV results are rapid and easy to interpret procedure and provide great advantages to the dAVF treatment. Nevertheless, further studies are needed with a larger sample size to determine if INIGV may reduce the need to perform immediate postoperative DSA.

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C2 root nerve sheath tumors management

C2 tumor

Acta Neurochir (2013) 155:779–784

Upper cervical nerve sheath tumors (NST) arising mainly from C2 root and to lesser extent from C1 root are not uncommon, they constitute approximately 5-12% of spinal nerve sheath tumors and 18-30% of all cervical nerve sheath tumors, unique in presentation and their relationship to neighbouring structures owing to the discrete anatomy at the upper cervical-craniovertebral region, and have a tendency for growth reaching large-sized tumors before manifesting clinically due to the capacious spinal canal at this region; accordingly the surgical approaches to such tumors are modified.

The aim of this paper is to discuss the surgical strategies for upper cervical nerve sheath tumors.

Methods Eleven patients (8 male and 3 females), age range 28 – 63 years, with C2 root nerve sheath tumors were operated upon based on their anatomical relations to the spinal cord. The magnetic resonance imaging findings were utilized to determine the surgical approach. The tumors had extra and intradural components in 10 patients, while in one the tumor was purely intradural. The operative approaches included varied from extreme lateral transcondylar approach( n =1) to laminectomy, whether complete( n =3) or hemilaminectomy( n =7), with partial facetectomy( n =7), and with suboccipital craniectomy( n =2).

Results The clinical picture ranged from spasticity ( n =8, 72,72 %), tingling and numbness below neck ( n =6, 54,54 %), weakness ( n =6, 54,54 %), posterior column involvement ( n =4, 26,36 %), and neck pain ( n =4, 36,36 %). The duration of symptoms ranged from 1 to 54 months, total excision was performed in 7 patients; while in 3 patients an extraspinal component, and in 1 patient a small intradural component, were left in situ. Eight patients showed improvement of myelopathy; 2 patients maintained their grades. One poor-grade patient was deteriorated.

Conclusion The surgical approaches for the C2 root nerve sheath tumors should be tailored according to the relationship to the spinal cord, determined by magnetic resonance imaging.

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Reoperation Rate After Surgery for Lumbar Herniated Intervertebral Disc Disease

herniated_disc

Spine 2013 ; 38 : 581 – 590

Retrospective cohort study using national health insurance data.

Objective. To provide a longitudinal reoperation rate after surgery for lumbar herniated intervertebral disc (HIVD) disease, and to compare the reoperation rates of surgical methods.

Summary of Background Data. Herniated intervertebral disc disease is the most common cause of lumbar spinal surgery. Despite improved surgical techniques and instrumentation, reoperation cannot be avoided. The reoperation rates were in the range of 6% to 24% in previous studies. A population-based study is less subject to bias; hence, a nationwide longitudinal analysis was warranted.

Methods. A national health insurance database was used to identify a cohort of patients who underwent fi rst surgery for herniated intervertebral disc disease in 2003 and 18,590 patients were selected. Individual patients were followed for at least 5 years through their encrypted unique resident registration number. The primary endpoint was any type of second lumbar surgery. After adjusting for confounding factors, 5 surgical methods (fusion, laminectomy, open discectomy, endoscopic discectomy, and nucleolysis [including mechanical nucleus decompression]) were compared. Open discectomy was used as the reference method.

Results. Open discectomy was the most common procedure (68.9%) followed by endoscopic discectomy (16.1%), laminectomy (7.9%), fusion (3.9%), and nucleolysis (3.2%). The cumulative reoperation rate was 5.4% at 3 months, 7.4% at 1 year, 9% at 2 years, 10.5% at 3 years, 12.1% at 4 years, and 13.4% at 5 years. The reoperation rates were 18.6%, 14.7%, 13.8%, 12.4%, and 11.8% after laminectomy, nucleolysis, open discectomy, endoscopic discectomy, and fusion, respectively. Compared with open discectomy, the reoperation rate was higher after laminectomy at 3 months, whereas the other surgical methods had similar rates.

Conclusion. The cumulative reoperation rate after 5 years was 13.4% and half of the reoperations occurred during the fi rst postoperative year. With the exception of laminectomy, the reoperation rates of the other procedures were not different from that of open discectomy.

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Rigid occipitocervical fixation: indications, outcomes, and complications in the modern era

Rigid occipitocervical fixation- indications, outcomes, and complications in the modern era

J Neurosurg Spine 18:333–339, 2013

Over the past 40 years, various methods and instrumentation types have been developed for occipitocervical fixation (OCF) in the management of occipitocervical instability. This study reports indications, outcomes, and complications with rigid OCF using screw-rod and screw-plate instrumentation, which has comparatively less long-term data.

Methods. A prospectively maintained database identified 100 consecutive patients who underwent rigid OCF in a single unit over a period of 13 years. Patient demographics, clinical indications, pre- and postoperative radiographic findings, neck disability indices (NDIs), myelopathy disability indices (MDIs), visual analog scale (VAS) scores, and Ranawat scores were recorded. Complications including instrumentation failure were also documented.

Results. Underlying etiologies included rheumatoid arthritis (RA; 41%), tumor (16%), trauma (15%), congenital etiologies (14%), metabolic (6%) and inflammatory (6%) conditions, and infection (2%). The pre- and postoperative MDI and VAS scores for neck pain showed significant improvements in the RA group (MDI 64.5% vs 42.5%, p = 0.02; mean VAS 7.5 of 10 vs 3.7 of 10, p < 0.001). Improvements in MDI and NDI outcome measures were also seen in the trauma and tumor categories. Overall, there were 4 cases of instrumentation failure; all included broken rods in the stress riser region of occipitocervical rod curvature, and 1 patient also had occipital plate screw pullout. Other complications included 5 wound infections requiring wound washout, 1 vertebral artery injury (no clinical sequelae), and 1 perioperative death due to myocardial infarction.

Conclusions. Rigid OCF is a safe and effective method of managing occipitocervical instability due to a variety of causes. Outcome measures are favorable, and patients with chronically debilitating diseases such as RA may benefit in terms of improvements in neurological deficit and neck pain. The complication profile is comparable to that reported in other series of OCF in the literature, as well as to the previously used semirigid type of rod/sublaminar wire fixation.

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Accuracy and complications associated with the freehand C-1 lateral mass screw fixation technique

Accuracy and complications associated with the freehand C-1 lateral mass screw fixation technique

J Neurosurg Spine 18:372–377, 2013

The aims of this study were to evaluate a large series of posterior C-1 lateral mass screws (LMSs) to determine accuracy based on CT scanning findings and to assess the perioperative complication rate related to errant screw placement.

Methods. Accuracy of screw placement was evaluated using postoperative CT scans obtained in 196 patients with atlantoaxial instability. Radiographic analysis included measurement of preoperative and postoperative CT scans to evaluate relevant anatomy and classify accuracy of instrumentation placement. Screws were graded using the following definitions: Type I, screw threads completely within the bone (ideal); Type II, less than half the diameter of the screw violates the surrounding cortex (safe); and Type III, clear violation of transverse foramen or spinal canal (unacceptable).

Results. A total of 390 C-1 LMSs were placed, but 32 screws (8.2%) were excluded from accuracy measurements because of a lack of postoperative CT scans; patients in these cases were still included in the assessment of potential clinical complications based on clinical records. Of the 358 evaluable screws with postoperative CT scanning, 85.5% of screws (Type I) were rated as being in the ideal position, 11.7% of screws (Type II) were rated as occupying a safe position, and 10 screws (2.8%) were unacceptable (Type III). Overall, 97.2% of screws were rated Type I or II. Of the 10 screws that were unacceptable on postoperative CT scans, there were no known associated neurological or vertebral artery (VA) injuries. Seven unacceptable screws erred medially into the spinal canal, and 2 patients underwent revision surgery for medial screws. In 2 patients, unilateral C-1 LMSs penetrated the C-1 anterior cortex by approximately 4 mm. Neither patient with anterior C-1 penetration had evidence of internal carotid artery or hypoglossal nerve injury. Computed tomography scanning showed partial entry of C-1 LMSs into the VA foramen of C-1 in 10 cases; no occlusion, associated aneurysm, or fistula of the VA was found. Two patients complained of postoperative occipital neuralgia. This was transient in one patient and resolved by 2 months after surgery. The second patient developed persistent neuralgia, which remained 2 years after surgery, necessitating referral to the pain service.

Conclusions. The technique for freehand C-1 LMS fixation appears to be safe and effective without intraoperative fluoroscopy guidance. Preoperative planning and determination of the ideal screw insertion point, the ideal trajectory, and screw length are the most important considerations. In addition, fewer malpositioned screws were inserted as the study progressed, suggesting a learning curve to the technique.

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Three-dimensional angioarchitecture of spinal dural arteriovenous fistulas, with special reference to the intradural retrograde venous drainage system

Three-dimensional angioarchitecture of spinal dural arteriovenous fistulas, with special reference to the intradural retrograde venous drainage system

J Neurosurg Spine 18:398–408, 2013

There have been significant advances in understanding the angioarchitecture of spinal dural arteriovenous fistulas (AVFs). However, the major intradural retrograde venous drainage system has not been investigated in detail, including the most proximal sites of intradural radiculomedullary veins as they connect to the dura mater, which are the final targets of interruption in both microsurgical and endovascular treatments.

Methods. Between April 1984 and March 2011, 27 patients with 28 AVFs were treated for spinal dural AVFs at the authors’ university hospital. The authors assessed vertebral levels of feeding arteries and dural AVFs by using conventional digital subtraction angiography. They also assessed 3D locations of the most proximal sites of intradural radiculomedullary veins and the 3D positional relationship between the major intradural retrograde venous drainage system and intradural neural structures, including the spinal cord, spinal nerves, and the artery of Adamkiewicz, by using operative video recordings plus 3D rotational angiography and/or 3D computer graphics. In addition, they statistically assessed the clinical results of 27 cases. Of these lesions, 23 were treated with open microsurgery and the rest were treated with endovascular methods.

Results. Feeding arteries consisted of T2–10 intercostal arteries with 19 lesions, T-12 subcostal arteries with 3 lesions, and L1–3 lumbar arteries with 6 lesions. The 3D locations of the targets of interruption (the most proximal sites of intradural radiculomedullary veins as they connect to the dura mater) were identified at the dorsolateral portion of the dura mater adjacent to dorsal roots in all 19 thoracic lesions, whereas they were identified at the ventrolateral portion of the dura mater adjacent to ventral roots in 7 (78%) of 9 cases of conus medullaris/lumbar lesions (p < 0.001). The major intradural retrograde venous drainage system was located dorsal to the spinal cord in all 19 thoracic lesions, whereas it was located ventral to the spinal cord in 4 (44%) of 9 cases of conus/lumbar lesions (p = 0.006). In 3 (11%) of 27 cases, AVFs had a common origin of the artery of Adamkiewicz. In 2 lumbar lesions, the artery of Adamkiewicz ascended very close to the vein because of its ventral location. Although all lesions were successfully obliterated without major complications and both gait and micturition status significantly improved (p = 0.005 and p = 0.015, respectively), conus/lumbar lesions needed careful differential diagnosis from ventral intradural perimedullary AVFs, because the ventral location of these lesions contradicted the Spetzler classification system.

Conclusions. The angioarchitecture of spinal dural AVFs in the thoracic region is strikingly different from that in conus/lumbar regions with regard to the intradural retrograde venous drainage system. One should keep in mind that spinal dural AVFs are not always dorsal types, especially in conus/lumbar regions.

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Diastematomyelia: A 35-Year Experience

Dyastematomyelia

SPINE Volume 38, Number 6, pp E344–E349

Diastematomyelia is a rare entity, which presents distinct clinical characteristics and requires different managements compared with other more common occult spinal dysraphism.

Methods. A total of 156 patients with diastematomyelia were reviewed. All the patients underwent neurological and radiological examinations. Surgical excision of the lesion was performed for most patients and intradural exploration of the lumbar region was done to release tethering of conus in some patients. One patient died and autopsy was performed. Follow-up was carried out for all the patients, including surgical and nonsurgical approaches.

Results. There were 123 cases of type I diastematomyelia and 33 cases of type II diastematomyelia. The lumbar and thoracolumbar region was the most common site for diastematomyelia, and most spinal cords were split among 6 segments. The postoperative course was complicated by cerebrospinal fl uid leakage in 2 patients, temporary neurological deterioration in 4 patients, and epidural hematoma in 1 patient. All cases did not have aggravation of symptoms during the follow-up of 2 to 20 years (mean of 4.5 yr). For the 123 patients with type I diastematomyelia, clinical symptoms were improved in 96 after surgical intervention and no worsening or occurrence of new clinical signs were observed during the follow-up. Those who did not receive surgery showed stabilization of neurological manifestation. Of the 33 type II cases, 9 surgical patients remained neurologically stable during the postoperative years without signifi cant improvement in function, and 24 nonsurgical patients neither improved nor worsened in their neural defi cit.

Conclusion. Surgical treatment is the necessary management for type I diastematomyelia causing progressive neurological deterioration or with tethered fi lum, whereas conservative treatment is recommended to asymptomatic type I diastematomyelia and all type II diastematomyelia.

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Predictors of Surgical Outcome in Cervical Spondylotic Myelopathy

Predictors of Surgical Outcome in Cervical Spondylotic Myelopathy

Spine 2013 ; 38 : 392 – 400

Study Design. Prospective study.

Objective. To determine whether magnetic resonance imaging and clinical and demographic fi ndings in patients with cervical spondylotic myelopathy (CSM) were independently associated with baseline functional scores and whether these were also predictive of postoperative functional outcomes.

Summary of Background Data. There are considerable limitations in current literature that prevent making formal recommendations regarding the use of clinical and radiological prognostic factors in patients with CSM.

Methods. This prospective study included 65 consecutive patients with CSM treated in a tertiary referral center. The modifi ed Japanese Orthopaedic Association (mJOA) scale was used to quantify disability at admission and at 12-month follow-up. Age, sex, duration of symptoms, severity of myelopathy, spinal column alignment, surgical technique, levels of compression, anteroposterior diameter and transverse area at the site of maximal cord compression, and magnetic resonance imaging signal intensity changes were assessed. Data were analyzed using Spearman rank correlation test, analysis of variance, Mann–Whitney U test, and stepwise multivariate regression.

Results. Higher baseline mJOA scores were associated with younger age ( P = 0.0002), shorter duration of symptoms ( P = 0.03), and greater transverse area ( P = 0.02). Better recovery ratio was associated with younger age ( P = 0.005) and higher baseline mJOA score ( P = 0.003). Greater changes in mJOA score were associated with higher baseline mJOA score (P < 0.0001). Using multivariate analysis, the functional outcomes after surgery were best predicted by baseline mJOA score and age of patient.

Conclusion. Age and baseline mJOA scores were highly predictive of outcome for patients undergoing surgical treatment of CSM. The degree of spinal cord compression and patterns of signal intensity changes on T1/T2 weighted images were not independently predictive of outcome, but it was found to correlate with the functional status at the time of presentation and age of the patient. The duration of symptoms correlated well with preoperative functional status but did not seem to affect the postoperative outcome.

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Long-term Follow-up of Minimal-Access and Open Posterior Lumbar Interbody Fusion for Spondylolisthesis

plif2

Neurosurgery 72:443–451, 2013

Although posterior lumbar interbody fusion (PLIF) is regarded as an effective treatment for spondylolisthesis, few studies have reported comprehensive, longterm outcome data, and none has investigated the incidence of deterioration of outcomes.

OBJECTIVE: To determine and compare the success rates and long-term stability of outcomes of open PLIF and minimal-access PLIF in the treatment of radicular pain and back pain in patients with spondylolisthesis.

METHODS: Forty-three patients were followed for a minimum of 3 years. They completed a Short-Form Health Survey and visual analog scores for back pain and leg pain and underwent lumbar spine radiography. Outcomes were compared with baseline data and 12-month data.

RESULTS: Surgery succeeded in reducing listhesis and increasing disc height, but had little effect on lumbar lordosis or the angulation of the segment treated. At 12 months after surgery, listhesis was reduced, disc height was increased, leg pain was reduced or eliminated, and physical functioning restored. Back pain was less often relieved. These outcomes were largely maintained over the ensuing 2 years. Only 5% to 10% of patients reported deterioration in their relief of pain. Depending on the definition adopted for success, the long-term success rate of PLIF may be as high as 70%.

CONCLUSION: For the relief of leg pain, the success rates of open PLIF (70%) and minimalaccess PLIF (67%) for spondylolisthesis are high and durable in the long-term. PLIF is less often successful in relieving back pain, but the outcomes are maintained. The outcomes of open PLIF and minimal-access PLIF were statistically indistinguishable.

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Motion characteristics of the vertebral segments with lumbar degenerative spondylolisthesis in elderly patients

Motion characteristics of the vertebral segments with lumbar degenerative spondylolisthesis in elderly patients

Eur Spine J (2013) 22:425–431

Although some studies have reported on the kinematics of the lumbar segments with degenerative spondylolisthesis (DS), few data have been reported on the in vivo 6 degree-of-freedom kinematics of different anatomical structures of the diseased levels under physiological loading conditions. This research is to study the in vivo motion characteristics of the lumbar vertebral segments with L4 DS during weight-bearing activities.

Methods Nine asymptomatic volunteers (mean age 54.4) and 9 patients with L4 DS (mean age 73.4) were included. Vertebral kinematics was obtained using a combined MRI/ CT and dual fluoroscopic imaging technique. During functional postures (supine, standing upright, flexion, and extension), disc heights, vertebral motion patterns and instability were compared between the two groups.

Results Although anterior disc heights were smaller in the DS group than in the normal group, the differences were only significant at standing upright. Posterior disc heights were significantly smaller in DS group than in the normal group under all postures. Different vertebral motion patterns were observed in the DS group, especially in the left–right and cranial–caudal directions during flexion and extension of the body. However, the range of motions of the both groups were much less than the reported criteria of lumbar spinal instability.

Conclusion The study showed that lumbar vertebra with DS has disordered motion patterns. DS did not necessary result in vertebral instability. A restabilization process may have occurred and surgical treatment should be planned accordingly.

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Diagnosis and surgical strategy for sacral meningeal cysts with check-valve mechanism

sacral cysts

Acta Neurochir (2013) 155:309–313

There is agreement that symptomatic sacral meningeal cysts with a check-valve mechanism and/or large cysts representing space-occupying lesions should be treated surgically. This study investigated factors indicating a need for surgical intervention and surgical techniques for sacral meningeal cysts with a check-valve mechanism.

Methods In ten patients presenting with sciatica and neurological deficits, myelography, computed tomography (CT) myelography, and magnetic resonance imaging (MR imaging) detected sacral meningeal cysts with a check-valve mechanism. One patient had two primary cysts. Ten cysts were type 2 and one cyst was type 1. Nine of the ten patients had not undergone previous surgery, while the remaining case involved recurrent cyst. For the seven patients with normal (i.e., not huge or recurrent) type 2 cysts and no previous surgery (eight cysts), suture after collapse of the cyst wall was performed. For the recurrent type 2 cyst, duraplasty and suture with collapse of the cyst wall were performed to eliminate the check-valve mechanism. For the remaining type 2 cyst, a primary root was sacrificed because of the huge size of the cyst. For the type 1 cyst, the neck of the cyst was ligated.

Results In all cases, chief complaints disappeared immediately postoperatively and no deterioration of clinical symptoms has been seen after a mean follow-up of 27 months.

Conclusions The presence or absence of a check-valve mechanism is very important in determining the need for surgical intervention for sacral meningeal cysts.

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Axial Spondylectomy and Circumferential Reconstruction via a Posterior Approach

Axial spondylectomy

Neurosurgery 72:300–309, 2013

Spinal metastases of the second cervical vertebra are a subset of tumors that are particularly difficult to address surgically. Previously described techniques require highly morbid circumferential dissection posterior to the pharynx for resection and reconstruction.

OBJECTIVE: To perform a biomechanical analysis of instrumented reconstruction configurations used after axial spondylectomy and to demonstrate safe use of a novel construct in a patient case report.

METHODS: Several different published and novel reconstruction configurations were inserted into 7 occipitocervical spines that underwent axial spondylectomy. A biomechanical analysis of the stiffness of the constructs in flexion and extension, lateral bending, and rotation was performed. A patient then underwent a posterior-only approach for axial spondylectomy and circumferential reconstruction.

RESULTS: Biomechanical analysis of different constructs demonstrated that anterior column reconstruction with bilateral cages spanning the C1 lateral mass to the C3 facet in combination with occipitocervical instrumentation was superior in flexion-extension and equivalent in lateral bending and rotation to currently used constructs. The patient in whom this construct was placed via a posterior-only approach for axial spondylectomy and instrumentation remained at neurological baseline and demonstrated no recurrence of local disease or failure of instrumentation to date.

CONCLUSION: When C1 lateral mass to C3 facet bilateral cage plus occipitocervical instrumentation is compared with existing anterior and posterior constructs, this novel reconstruction is biomechanically equivalent if not superior in performance. In a patient, the posterior-only approach for C2 spondylectomy with the novel reconstruction was safe and durable and avoided the morbidity of the anterior approach.

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C1–2 transarticular screws combined with C1 laminar hooks fixation

C1–2 transarticular screws combined with C1 laminar hooks fixation

Eur Spine J (2013) 22:260–267

Purpose To retrospectively evaluate the outcome of C1–2 transarticular screws combined with C1 laminar hooks fixation.

Methods All patients underwent atlantoaxial fixation during a 5-year period. The surgical technique and treatment procedures were intensively reviewed and clinical symptoms, neurological function and imaging appearance were retrospectively evaluated.

Results The clinical and radiology follow-up indicated a stable arthrodesis and clinical relief from symptoms for all patients. All patients with neurological defects improved an average of 1.33 grade at their most recent clinical assessment, P≤0.05; their average admission ASIA motor score, pin prick score and light touch score improved to an average follow-up ASIA score of 99.80 (99.83 ± 0.38), 111.83 (111.83 ± 0.45), and 111.89 (111.89 ± 0.32), respectively. No neurovascular impairment and case of implant failure were observed.

Conclusions The C1–2 transarticular screws combined with C1 laminar hooks fixation is a reliable technique for atlantoaxial instability.

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