Bernard H. Guiot

A Minimally Invasive Technique for Decompression of the Lumbar Spine

Study Design. The technical feasibility of percutaneous microendoscopic bilateral decompression of lumbar stenosis via a unilateral approach was evaluated in a human cadaver model. Objectives. The purpose of this study was to determine the feasibility of using a microendoscopic laminotomy technique to treat spinal stenosis. Summary and Background Data. Minimally invasive surgery is an important means of reducing tissue trauma and patient morbidity. This may prove to be essential in improving pain and in reducing postoperative stress responses and delayed sequelae that can lead to unfortunate complications after otherwise uneventful procedures. To date, minimally invasive lumbar endoscopic techniques have not been used to decompress the lumbar spinal canal. Methods. In each of four cadavers, the laminae of L1 through L4 were subjected to one of four procedures consisting of unilateral microendoscopic laminotomy, bilateral microendoscopic laminotomy, unilateral open laminotomy, and bilateral open laminotomy. Every procedure was performed once at all levels. Computed tomography was performed before and after laminotomy to establish the extent of decompression of the spinal canal, and measurements of the midsagittal, interpedicular, and decompression diameters were taken. Results. The four procedures were successfully performed at every level. Satisfactory decompression of the spinal canal was achieved regardless of the approach used. The exiting nerve roots were well visualized when any one of these techniques was used. Complications, including dural tears and facet complex instability, were independent of the procedure performed. Conclusion. Microendoscopic laminotomy can be used to decompress the spinal canal as effectively as an open laminotomy and may prove to be beneficial in decreasing the complications and morbidity of standard treatments for lumbar stenosis.

Ossification of the posterior longitudinal ligament: an update on its biology, epidemiology, and natural history.

SIGNIFICANT PROGRESS HAS been achieved in basic research during the past decade on the pathogenesis of ossification of the posterior longitudinal ligament (OPLL), a multifactorial disease in which complex genetic and environmental factors interact. A review of the literature was conducted to update recent findings on the biology, epidemiology, natural history, and related diseases of OPLL. Gene analysis studies found specific polymorphisms that may be associated with OPLL in several collagen genes, which encode for extracellular matrix proteins. Polymorphisms in the nucleotide pyrophosphate gene, which is involved in regulation of calcification in chondrocytes, may also be associated with OPLL. However, the results of the gene analysis studies have not always been consistent. Involvement of many growth factors and cytokines, including bone morphogenic proteins and transforming growth factor-β, has been demonstrated in various histochemical and cytochemical analyses. Several transcription factors involved in cellular differentiation may also have a role. Recent epidemiological studies reaffirmed an earlier finding that diabetes mellitus is a distinct risk factor for OPLL. The long-term follow-up studies of OPLL patients are disclosing the natural history, as well as the frequency and rate of progression, of OPLL after surgical intervention. Further knowledge on the factors responsible for progression of OPLL may predict its behavior in each patient, and treatment may be tailored accordingly. The coexistence of OPLL with other diseases of ectopic ossification of the spine, such as ossification of the ligamentum flavum and diffuse idiopathic skeletal hyperostosis, is not uncommon. Scientific breakthrough in those diseases may, in turn, give insights into the pathogenesis of OPLL.

Molecular biology of degenerative disc disease

THE INTERVERTEBRAL DISC is a complex anatomic and biochemical structure. It is composed primarily of fibrocytes and chondrocytes that are anatomically segregated in an elaborate avascular macromolecular matrix of collagen and proteoglycans. Degenerative processes associated with aging and trauma result in morphological and molecular changes to the disc. Morphological changes are observed as dehydration, fissuring, and tearing of the nucleus, annulus, and endplates. On the molecular level, degenerative changes include decreased diffusion, decreased cell viability, decreased proteoglycan synthesis, and alteration in collagen distribution. The role of inflammatory mediators in these processes, and the potential use of growth factors to delay or reverse the degenerative cascade, is poorly understood. However, these areas are under active investigation, the results of which may soon contribute significantly to our understanding of degenerative disc disease.

Vertebroplasty for osteoporotic compression fractures: current practice and evolving techniques.

PERCUTANEOUS VERTEBROPLASTY WAS developed in France by Deramond et al., who provided initial reports of the procedure in 1987. This minimally invasive procedure uses a large-bore bone-cutting needle to percutaneously access a vertebral body, inject bone cement, and thereby stabilize and reinforce the remaining bone structure. The procedure was used initially to treat aggressive hemangiomas, but it then was extended to the treatment of osteolytic metastases and myeloma and currently osteoporotic compression fractures refractory to medical therapy. In this article, we review the current technique and its indications along with emerging devices and areas of current research.

Iatrogenic carotid artery injury in neurosurgery

Iatrogenic carotid artery injury (CAI) results from various neurosurgical procedures. A review of the literature was conducted to provide an update on the management of this potentially devastating complication. Iatrogenic CAIs are categorized according to each diagnostic or therapeutic procedure responsible for the injury, i.e., anterior cervical spine surgery, central venous catheterization, chemical substances, chiropractic manipulation, diagnostic cerebral angiography, middle-ear surgery, percutaneous procedures for trigeminal neuralgia, radiation therapy, skull-base surgery, tracheostomy, and transsphenoidal surgery. The incidence, mechanisms of injury, diagnostic imaging modalities, and reparative procedures are discussed for each procedure. Iatrogenic CAI may be more prevalent than had previously been thought, mostly because of a heightened awareness on the part of physicians and the earlier detection of asymptomatic patients owing to sophisticated and less-invasive imaging modalities. Prevention is the best treatment for every iatrogenic injury, and it is expected that further accumulation of experience with and knowledge of iatrogenic CAI will result in further reduction of this complication. Although some CAIs, such as radiation-induced carotid artery stenosis, may not be preventable, earlier intervention before the patient becomes symptomatic may favorably alter the prognosis. Following the rapid development of endovascular techniques in recent years, surgically inaccessible lesions can be treated in a more reliable and safe manner than before.

Respiratory complications in patients with traumatic cervical spine injuries: case report and review of the literature.

Spinal cord injuries continue to be a devastating medical problem. By impairing voluntary and involuntary nervous system function, virtually every body system function is affected. However, pulmonary function alteration and respiratory complications continue to be the major causes of morbidity and mortality in patients with spinal cord injuries. The current understanding of respiratory problems faced by patients with loss of innervation from cervical spinal cord injuries are reviewed.

Validation of a translated version of the modified Japanese orthopaedic association score to assess outcomes in cervical spondylotic myelopathy: an approach to globalize outcomes assessment tools.

BACKGROUNDAlthough the Japanese Orthopaedic Association (JOA) originally developed in Japan, the modified English version (mJOA) has become widely used and is arguably now the accepted standard. OBJECTIVEIn order to apply the mJOA successfully at an international level, we have translated it with a validated approach into Dutch to pave the way for other translated versions. METHODSAfter a thorough forward and backward translation procedure, a final Dutch version of the mJOA was developed. This translated version was used to assess the interobserver reliability among 2 independent examiners by using a cohort of patients with neurological impairment due to spinal pathology. RESULTSThe mJOA grading scale was used by 2 independent examiners in 25 patients with a variety of spinal diseases. Initially, the interobserver reliability expressed as kappa was 0.56 ± 0.11. Then, instructions were given to the instructors to refrain from providing patients with an interpretation of the symptoms. Patients were asked to restrict themselves to the questionnaire and select the most appropriate score without bias from the examiner. Kappa increased to 0.78 ± 0.05. This difference reached statistical significance (P < .001). CONCLUSIONWe present a streamlined approach to translate the mJOA into a language other than English. The approach resulted in a Dutch version of the mJOA that had a high degree of interobserver reliability.

Modifications of the transoral approach to the craniovertebral junction: anatomic study and clinical correlations.

OBJECTIVE This study was designed to more precisely characterize the changes in exposure achieved by modifying the standard transoral approach by sequential mandibulotomy and mandibuloglossotomy with or without palatotomy. METHODS A series of cadaveric dissections was performed and the operative distance and angle of exposure in both axial and sagittal planes was evaluated for each approach, with and without palatotomy. Intraoperative measurements were made in patients undergoing transoral approaches to assess the validity of the anatomic model. The use of this model was then assessed by a retrospective analysis of a group of 19 patients operated on through transoral approaches between 1991 and 2006. RESULTS The simple transoral approach exposed the region from the lower third of the clivus to the middle of the C2 vertebral body at an operative distance of 12.9 ± 1.0 cm from the dura. The axial and sagittal angles of exposure were 39.4 ± 3.5 degrees and 36.8 ± 3.5 degrees, respectively. Mandibulotomy significantly increased the sagittal exposure to 59.0 ± 1.0 degrees (P < 0.001), exposing the area from the midclivus to the C2–C3 interspace while simultaneously increasing the axial angle of exposure to 51.9 ± 7.4 degrees (P < 0.01) and decreasing the operative distance to the dura to 10.7 ± 1.7 cm (P < 0.05). Mandibuloglossotomy augmented sagittal exposure to 85.3 ± 0.3 degrees (P < 0.001), revealing the region between the upper one-third of the clivus and the C4–C5 interspace (P < 0.001) while decreasing the operative distance to the dura to 8.7 ± 0.3 cm (P < 0.05). Palatotomy significantly increased the rostral exposure achieved by each approach by 8.5 to 12.3 degrees (P < 0.01) without altering caudal or axial exposure or the operative distance. CONCLUSION The cadaveric data correlated well with intraoperative measurements and the need for modifications of the transoral approach in 15 of the 16 adult patients (93.8%). Pediatric patients, patients with limited mouth opening, elevated craniovertebral junctions, and particularly deep lesions required more extensive exposure. This analysis may be useful for determining the optimal approach for patients undergoing transoral surgery.

Thoracolumbar junction injuries after motor vehicle collision: are there differences in restrained and nonrestrained front seat occupants?

OBJECTnMotor vehicle collision (MVC) is one of the most common causes of thoracolumbar junction (TLJ) injury. Although there is little doubt that the use of seat belts reduces the incidence and severity of TLJ injury after MVC, the mechanism by which this is protective against TLJ injury for drivers and passengers is relatively unknown.nnnMETHODSnThirty-nine patients with TLJ (T11-L2) injury who were front seat occupants of a four-wheeled vehicle at the time of MVC (frontal crash) were admitted between 2000 and 2004. The 39 patients were divided into two groups: 18 who had been restrained and 21 who had not been restrained at the time of the MVC. Patient demographics, including the mean Injury Severity Scale score, incidence of neurological deficit, level of TLJ injury, and type of TLJ injury according to the Denis classification were compared.nnnRESULTSnThe incidence of neurological deficit in the restrained group was significantly lower compared with the nonrestrained group (5.6% compared with 33.3%, p < 0.05). The incidence of flexion-distraction/fracture-dislocation injuries in the restrained group was also significantly lower (0.0% compared with 33.3% in the nonrestrained group, p < 0.01). The restrained group was significantly older (37.4 +/- 3.6 years compared with 28.0 +/- 2.5 years in the nonrestrained group, p < 0.05), but otherwise there were no significant differences between the two groups regarding the patients demographic data.nnnCONCLUSIONSnIt is likely that the high incidence of neurological deficit in the nonrestrained front seat motor vehicle occupants who had a TLJ injury was mostly due to the high incidence of flexion-distraction/fracture-dislocation injuries. This retrospective study indirectly shows the efficacy of three-point seat belt systems in reducing the severity of a TLJ injury after an MVC. Compression/burst fractures still occur in restrained front seat occupants, however, and elucidation of the injury mechanism of such axial loading fractures may be important to improve safety further for automobile occupants.

Transoral vertebroplasty for renal cell metastasis involving the axis: case report.

Study Design. Case report. Objective. This is one of the first reported cases of transoral vertebroplasty for a solid metastatic tumor at C2 body. Summary of Background Data. Percutaneous vertebroplasty has gained popularity as a treatment option for painful neoplastic lesions of the spine. The technique has been useful in reducing pain and stabilizing the spinal segment that is vulnerable to fracture. However, there is very little experience with vertebroplasty in the cervical spine and, more specifically, at C2. Methods. We present a case of metastatic renal cell carcinoma of the C2 body. The patient, a 61-year-old woman, presented with an excruciating neck pain. Diagnostic workup revealed the presence of tumor in the right kidney. Multiple spinal levels were involved in addition to C2, and the C2 lesion was treated for palliative purpose. Under biplanar fluoroscopy, a vertebroplasty trocar was placed transorally into the central portion of the C2 body, and polymethyl methacrylate was injected. Results. The transoral vertebroplasty achieved complete pain relief and enhanced stability of an extensive osteolytic lesion involving the C2 body. Conclusions. This minimal access procedure was effective in completely relieving pain from a metastatic deposit at C2, while adequately stabilizing the vulnerable segment by the injection of polymethyl methacrylate. The transoral route requires meticulous fluoroscopic control to prevent the leakage of polymethyl methacrylate but provides the most direct access to the C2 body.