Martin Wilby

The Prevalence and Pathogenesis of Synovial Cysts Within the Ligamentum Flavum in Patients With Lumbar Spinal Stenosis and Radiculopathy

Study Design. A clinicopathologic study of synovial cysts in the ligamentum flavum (LF) in patients with spinal stenosis. Objective. To investigate the pathogenesis of lumbar juxtafacet cysts. Summary of Background Data. Contradictions in the terminology applied to lumbar juxtafacet cysts arise from the frequent sparsity of synovial lining cells, which has led to synovial cysts often being called “ganglion cysts” despite lacking confirmatory pathology. Methods. A total of 27 consecutive patients with radiologically confirmed stenosis underwent laminectomy. LF/facet joint (FJ) relationships were retained by en bloc excision of the LF and the medial inferior FJ. Controls were LF/FJ specimens from 47 cadaver lumbar spines. Results. The 27 patients yielded 51 LF/FJ specimens containing 28 synovial cysts, 12 of which were unilateral and 8 were bilateral. Fragments of articular cartilage and bone were embedded in the walls of 89% of cysts and in the walls of a bursa-like channel originating from the medial aspect of the FJ capsule and extending into the LF. Communication with the FJ via this channel was observed in 21 (75%) of the 28 synovial cysts. Extending up to 12 mm in length, the channel was present in nearly all control spines at the L4–L5 level but in only about half at the T12–L1 level. Conclusion. Cysts having an extensive or meagre synovial cell lining are common in the LF of patients with symptomatic lateral or central stenosis. The cysts communicate with the FJ by a bursa-type channel within the LF. Advanced osteoarthritis of the FJ causes the liberation of fragments of cartilage and bone into the synovial fluid of the joint space. This enables some fragments to escape from the joint into the channel and become lodged within its wall where they provoke granulation tissue and scar formation. The tissue response to articular debris may block the synovial-lined channel to cause synovial cyst formation.

Conservative management of type II and III odontoid fractures in the elderly at a regional spine centre: A prospective and retrospective cohort study.

Abstract Background. The optimal management of odontoid fractures in the elderly population is unclear and management of this group of patients is complicated by multiple co-morbidities. This study aimed to determine the outcomes after conservative management strategies were applied in this patient group. Methods. We carried out retrospective and prospective analyses of all patients with axial cervical spine injuries, at a single centre. We included patients aged over 60 years with type II and III odontoid fractures. Information was gathered on demographics, ASA grading-associated injuries and complications. The outcome measures were rates and type of union, pain and neurological functions, specifically ambulation. Results. Fifty-seven adult patients with a median age of 78 years (range 60–92 years) were included. There were 42 type II and 15 type III odontoid fractures. Three patients required surgical fixation due to displaced fractures, which could not be reduced with manual traction. Twenty-four (41%) patients were managed with a rigid pinned halo orthosis to obtain adequate reduction and immobilisation. The remaining 30 (53%) were managed in a hard cervical collar. Patients managed with a halo were significantly younger and had more associated injuries than patients managed in a collar (age: t-test = 4.05, p < 0.01, associated injuries: Chi-square = 4.38, p < 0.05). At a mean follow-up of 25 weeks, 87% of type II and 100% of type III fractures had achieved bony union or stable, fibrous non-union. There were no statistical differences in fracture type, follow-up or neurological outcomes between the halo and collar groups. However, overall more patients managed in a collar developed stable fibrous non-union than bony fusion (Fishers exact test, p < 0.05), although this was not significant when analysed by each fracture type individually. A regression model was constructed and identified fracture type as the only independent predictor of time to union, with type III fractures healing faster than type II. Conclusions. High rates of bony union and stable fibrous non-union with a good functional outcome can be achieved in the elderly population sustaining type II or III odontoid fractures, when managed non-surgically. Halo orthosis may not offer any clear advantage over hard collar in this group. Close follow-up is needed for late complications and there must be a willingness to perform surgery if conservative measures fail.

Management of Typical and Atypical Hangman's Fractures

Study Design Retrospective study of a prospectively maintained database. Objective Our aim was to retrospectively review management and outcomes of patients with low-grade hangmans fractures, specifically looking at differences in outcomes between collars and halo immobilization. We also studied fracture patterns and their treatment outcomes. Methods Forty-one patients with hangmans fractures were identified from 105 patients with axis fractures between 2007 and 2013. Typical hangmans fractures were defined as traumatic spondylolisthesis of the axis causing a bilateral pars interarticularis fracture. Fractures involving the posterior cortex of C2 on one or both sides or an asymmetrical pattern were defined as atypical. Results There were 41 patients with a mean age of 59 years, with 13 (31.7%) typical and 28 (68.2%) atypical fractures. There were 22 (53.6%) type 1 fractures, 7 (41.4%) type 2 fractures, and 2 (4.9%) type 2a fractures in this series. Cervical collars were used to manage 11 patients (27% of all patients with hangmans fractures) and halo orthosis was used in 27 (65.8%). Three (7.3%) patients underwent surgical fixation of the fracture. Bony union was achieved in all patients on radiologic follow-up. Permanent neurologic deficit occurred in one patient due to associated injuries. Neck pain and stiffness were reported more commonly in the atypical group, but this finding was not statistically significant. Conclusions The majority of hangman type fractures can be treated nonoperatively. We found no difference in outcomes between a rigid collar or halo immobilization for treatment of low-grade fractures. Radiologic follow-up is essential to identify cases of nonunion.

Applications of the ultrasonic bone cutter in spinal surgery – our preliminary experience

Abstract Objective. To present our experience with the Misonix Ultrasonic Bone scalpel in spinal surgery, highlighting its potential applications and advantages. Methods. Between March and December 2011, a total of 937 spinal cases were performed at a single centre. The Misonix Bone Scalpel (MBS) was used in 62 of these cases. Data were collected prospectively using the Spine Tango registry. Patient demographics, disease type, surgery performed and complications were all recorded along with pre- and post-operative core measures outcome index (COMI). Results. The majority of cases were for spinal degenerative disorders, in particular, revision cases. The bone cutter was also used to achieve laminotomies for access to intradural tumours, corpectomies and a mixture of other pathologies. Of the 62 patients only 1 (1.6%) experienced a blood loss greater than 500 ml, and there was only 1 dural tear (1.6%) as a direct result of the MBS. Four illustrative cases are discussed. Conclusions. The MBS is a useful adjunct in spinal surgery with particular value in revision cases where scar tissue distorts the normal anatomy. There was a low complication rate with a trend to reduced blood loss. This was most apparent to the senior authors during cervical and thoracic corpectomies.

Does early surgical decompression in cauda equina syndrome improve bladder outcome

Study Design. We analyzed retrospectively whether early surgery for cauda equina syndrome (CES) within 24, 48, or 72 hours of onset of autonomic symptoms made any difference to bladder function at initial outpatient follow-up. Objective. CES potentially causes loss of autonomic control including bladder dysfunction, resulting in significant disability. There is significant debate regarding appropriate timing of surgery. Summary of Background Data and Methods. We conducted a retrospective cohort study of 200 patients between 2000 and 2011 who underwent decompressive surgery for CES at a regional neurosurgical center. Data collected were from clinical admission and at initial follow-up. Presentation was categorized into CES with retention (CESR) and incomplete CES (CESI) and duration of autonomic symptoms before surgical intervention. Results. A total of 200 patients had complete clinical records; 61 cases with CESR and 139 cases with CESI. Average initial follow-up time was 96 days. For the 36 cases with CESI less than 24 hours, normal bladder function was seen at follow-up in all patients except 4 (11.1%), but with 103 cases with CESI more than 24 hours, 48 (46.6%) had bladder dysfunction (Pearson &khgr;2P = 0.000). For the 64 cases with CESI less than 48 hours, normal bladder function was seen at follow-up in all except 10 (15.6%), but with 75 cases with CESI more than 48 hours, 42 (56%) had bladder dysfunction (Pearson &khgr;2P = 0.000). For the 35 patients with CESR, operating within 24, 48, or 72 hours made no obvious difference to bladder outcome. Data were also reanalyzed changing the dataset groups to CESI less than 24 hours, 24 to 48 hours, and more than 48 hours to calculate odds ratios regarding normal bladder outcome. Conclusion. We identified that decompressive surgery within 24 hours of onset of autonomic symptoms in CESI reduces bladder dysfunction at initial follow-up, but no statistically significant difference in outcome was observed in CESR regarding timing of operation. Level of Evidence: 3

Neurogenic claudication secondary to degenerative spondylolisthesis: is fusion always necessary?

Abstract Objective: This study examines the efficacy and long-term safety of a midline sparing decompression for patients with degenerative spondylolisthesis (DS). We specifically looked at the rate of re-operation with a lumbar fusion. Of the patients that did require a secondary fusion procedure, we examined retrospectively any risk factors (both clinical and radiological) that could have been identified pre-operatively to predict the necessity of a primary fusion procedure. Materials and methods: Data was collected prospectively within a single surgeon practice at our institution. All patients had a diagnosis of neurogenic claudication secondary to DS. Radiological and clinical risk factors that could have predicted the requirement of a fusion procedure were retrospectively analysed. Results: This is a study of 70 patients (46F:24M). The median age at surgery was 68 years. All patients had a diagnosis of neurogenic claudication and were treated with a mid-line sparing decompression. Following the primary procedure, patients’ VAS and ODI scores for both leg and back pain improved significantly both at short-term follow-up (mean seven months) and sustained at long-term follow-up (range 16–57 months, mean 33 months; p < 0.0001 Wilcoxon matched pair ranks). Eight (11%) patients had symptom progression and required a further fusion procedure. We found that if on the pre-operative MRI, the patient had a facet joint angle of greater than 60°, and a preserved disc height (greater than 7 mm) this would increase the likelihood of the requirement for fusion. Of the patients that required a secondary fusion procedure, 6/8 patients (75%) had sagittal facets, hyperlordosis and a preserved disc height pre-operatively. Conclusions: A primary decompression using a midline sparing osteotomy is an effective procedure for the treatment of neurogenic claudication caused by DS. The second message is that on inspection of the pre-operative imaging, sagittally placed facet joints, a hyperlordosis and a preserved disc height then a fusion procedure should be considered primarily.

Is the rate of re-operation after primary lumbar microdiscectomy affected by surgeon grade or intra-operative lavage of the disc space?

Abstract Study design. Retrospective audit of consecutive patients. Objective. To investigate the re-operation rate following elective primary lumbar microdiscectomy and to determine whether principal surgeon grade and/or disc space lavage is a factor in recurrence. Summary of background data. Recurrent herniation of disc material following lumbar microdiscecomy surgery is one of the commonest complications of the procedure. Any reduction in the number of revision microdiscectomies performed per year would have a significant impact on patients’ lives and on the health service economy. We undertook this study to ascertain whether principal surgeon grade and/or disc space lavage has an impact in reducing the re-operation rate. Methods. We undertook a retrospective audit of patients who underwent elective primary lumbar microdiscectomy, over a 3-year period (n = 971). Results. The overall re-operation rate for primary elective microdiscectomy was 3.8%, consistent with the published literature. The relative risk of re-operation in patients primarily operated by registrar surgeons was 1.2 fold the risk in patients operated by consultants (95% CI: 0.62, 2.35) although not statistically significant (p = 0.568). The risk of re-operation in the ‘non lavage’ group was 2.15 times the risk in the ‘lavage’ group (95% CI: 0.63, 7.34), but it did not reach significance (p = 0.222). Conclusions. Principal surgeon grade and intervertebral disc lavage have not been found conclusively to be factors in the rate of recurrence. This information is useful to reassure patients that their outcome from such surgery is not dependent on the grade of surgeon performing the operation. There is a possible trend towards intervertebral disc lavage reducing the rate of recurrence.

Spontaneous CSF Collection in the Cervical Spine may Cause Neurological Deficit and Intra-cranial Hypotension

Objective: a case is described of a spontaneously occurring cerebrospinal fluid collection in the ventral cervical spine which caused radiculopathy and spontaneous intracranial hypotension. Case: a sixty eight year old Caucasian man presented with a 2 year history of proximal upper limb weakness with a his-tory of trivial cervical trauma many years previously. Methods: the patient was investigated with blood tests for causes of peripheral neuropathy, nerve conduction and electro-myography studies, lumbar puncture and MRI of the brain and spine with contrast. Results: a cerebrospinal fluid collection was identified in the ventral cervical spinal cord causing mass effect associated with cord atrophy and there were signs of spontaneous intracranial hypotension on the MRI brain including subdural cere-brospinal fluid collections, meningeal enhancement and slumped posterior fossa. Conclusions: this is the first description of a spontaneous spinal fluid collection causing direct compression and cord sig-nal change, manifest as a motor deficit, with intracranial signs of spontaneous hypotension. Spinal imaging is recom-mended in cases of spontaneous intracranial hypotension and cerebrospinal fluid collections in the spine may rarely be a cause of radiculopathy in such cases.

A framework for prospectively defining progression rules for internal pilot studies monitoring recruitment

Just over half of publicly funded trials recruit their target sample size within the planned study duration. When recruitment targets are missed, the funder of a trial is faced with the decision of either committing further resources to the study or risk that a worthwhile treatment effect may be missed by an underpowered final analysis. To avoid this challenging situation, when there is insufficient prior evidence to support predicted recruitment rates, funders now require feasibility assessments to be performed in the early stages of trials. Progression criteria are usually specified and agreed with the funder ahead of time. To date, however, the progression rules used are typically ad hoc. In addition, rules routinely permit adaptations to recruitment strategies but do not stipulate criteria for evaluating their effectiveness. In this paper, we develop a framework for planning and designing internal pilot studies which permit a trial to be stopped early if recruitment is disappointing or to continue to full recruitment if enrolment during the feasibility phase is adequate. This framework enables a progression rule to be pre-specified and agreed upon prior to starting a trial. The novel two-stage designs stipulate that if neither of these situations arises, adaptations to recruitment should be made and subsequently evaluated to establish whether they have been successful. We derive optimal progression rules for internal pilot studies which minimise the expected trial overrun and maintain a high probability of completing the study when the recruitment rate is adequate. The advantages of this procedure are illustrated using a real trial example.

Management of Giant Calcified Thoracic Disks and Description of the Trench Vertebrectomy Technique

Study Design Case series and review of the literature. Objective To review the management of giant calcified disks in our large cohort and compare with the existing literature. We discuss our surgical technique. Methods Twenty-nine cases of herniated thoracic disk between 2000 and 2013 were reviewed. Eighteen patients were identified as having giant calcified thoracic disks, defined as diffusely calcified disks occupying at least 40% of the spinal canal. Demographic data was collected in addition to presentation, imaging findings, operative details, and outcomes using the modified Japanese Orthopaedic Association (mJOA) scale. Results Giant calcified thoracic disks (GCTDs) are unique clinical entities that require special neurosurgical consideration owing to significant (≥40%) involvement of the spinal canal and compression of the spinal cord, often leading to myelopathy. The median age at diagnosis was 51.2 years (range 37 to 70) with the mean duration of presenting symptoms being 9.9 months (range 2 weeks to 3 years). Seventeen (94.4%) patients presented with at least one sign of myelopathy (hyperreflexia, hypertonia, bladder or bowel dysfunction) with the remaining 1 (5.6%) patient presenting with symptoms in keeping with radiculopathy. Thoracotomy was performed on 17 (94.4%) patients, and 1 (5.6%) patient had a costotransverse approach. Mean follow-up was 19.8 months (range 7 months to 2 years). mJOA score improved in 15 (83.3%) patients. mJOA scores in the other patients remained stable. Conclusions GCTDs are difficult neurosurgical challenges owing to their size, degree of spinal cord compression, and consistency. We recommend a trench vertebrectomy via a thoracotomy in their surgical management. This procedure safely allows the identification of normal dura on either side of the compressed segment prior to performing a diskectomy. Excellent fusion rates were achieved with insertion of rib head autograft in the trench.