Lumbar sagittal contour after posterior interbody fusion: threaded devices alone versus vertical cages plus posterior instrumentation.

STUDY DESIGN: An observational radiographic study examining lumbar sagittal contour of patients undergoing posterior interbody arthrodesis. OBJECTIVES: To compare operative alterations of lumbar sagittal contour after posterior interbody fusion using threaded interbody devices alone versus vertical cages combined with posterior compression instrumentation. SUMMARY OF BACKGROUND DATA: Technique-related alterations of lumbar sagittal contour during interbody arthrodesis have received little attention in the spinal literature. METHODS: Standing lumbar radiographs were measured for preoperative and postoperative segmental lordosis at levels undergoing posterior interbody arthrodesis using either stand-alone side-by-side threaded devices or vertical cages combined with posterior transpedicular compression instrumentation. Sagittal plane segmental correction (or loss of correction) was calculated and statistically compared. RESULTS: The radiographs of 30 patients (34 spinal segments) undergoing lumbar or lumbosacral arthrodesis were compared. Seventeen patients (18 segments) had undergone interbody fusion using threaded cages,whereas 13 patients (16 segments) underwent fusion using vertically oriented mesh cages combined with posterior compression instrumentation. Preoperative segmental lordosis averaged 8 degrees for both groups. For patients undergoing fusion with threaded cages, there was a mean lordotic loss of 3 degrees/segment. For patients undergoing fusion with vertically oriented mesh cages combined with posterior compression instrumentation,there was a mean lordotic gain of 5 degrees/segment. This difference in segmental sagittal plane contour was highly significant (P = 0.00). CONCLUSION: Threaded fusion devices placed under interbody distraction with the endplates parallel fail to preserve or reestablish segmental lordosis. Vertical cages, however, when combined with posterior compression instrumentation, not only maintain segmental lordosis, but also can correct sagittal plane deformity.

Measurement of thoracic and lumbar fracture kyphosis: evaluation of intraobserver, interobserver, and technique variability.

STUDY DESIGN: Statistical analysis of various measurement techniques for thoracolumbar burst fracture kyphosis on lateral radiograph. OBJECTIVE: To determine the most reliable measurement technique. SUMMARY OF BACKGROUND DATA: The treatment of thoracic and lumbar burst fractures involves many factors, including the degree of resultant kyphosis. Although various methods have been described, no study has directly compared these methods for reliability and reproducibility. METHODS: Fifty lateral radiographs of thoracic and lumbar burst fractures were randomly selected and measured on two separate occasions by three spine surgeons using five different measurement techniques. Radiograph quality, fracture type, and the center beam location were determined. Statistical analysis included analysis of variance for repeated measures and analysis of variance using a generalized linear model. RESULTS: Intraclass correlation coefficients were most consistent for Method 1 (rho = 0.83-0.94) followed by Method 4 (rho = 0.65-0.89) and Method 5 (rho = 0.73-0. 85). Intraobserver agreement (% of repeated measures within 5 degrees of the original measurement) ranged between 72% and 98% for all techniques for all three observers, with Method 1 showing the best agreement (84%-98%). Paired comparisons between observers varied considerably with interobserver reliability correlation coefficients ranging from 0.52 to 0.93. Method 1 showed the highest interobserver reliability coefficient (0.81, range 0.71-0.93) followed by Method 5 (0.71, range 0.68-0.75). Method 1 also had the highest percentage of agreement within categories (90% within 5 degrees ). CONCLUSIONS: Method 1 (measuring from the superior endplate of the vertebral body one level above the injured vertebral body to the inferior endplate of the vertebral body one level below) showed the best intraobserver and interobserver reliability overall.

Segmental stability and compressive strength of posterior lumbar interbody fusion implants.

STUDY DESIGN: Human cadaveric study on initial segmental stability and compressive strength of posterior lumbar interbody fusion implants. OBJECTIVES: To compare the initial segmental stability and compressive strength of a posterior lumbar interbody fusion construct using a new cortical bone spacer machined from allograft to that of titanium threaded and nonthreaded posterior lumbar interbody fusion cages, tested as stand-alone and with supplemental pedicle screw fixation. SUMMARY OF BACKGROUND DATA: Cages were introduced to overcome the limitations of conventional allografts. Radiodense cage materials impede radiographic assessment of the fusion, however, and may cause stress shielding of the graft. METHODS: Multisegmental specimens were tested intact, with posterior lumbar interbody fusion implants inserted into the L4/L5 interbody space and with supplemental pedicle screw fixation. Three posterior lumbar interbody fusion implant constructs (Ray Threaded Fusion Cage, Contact Fusion Cage, and PLIF Allograft Spacer) were tested nondestructively in axial rotation, flexion-extension, and lateral bending. The implant-specimen constructs then were isolated and compressed to failure. Changes in the neutral zone, range of motion, yield strength, and ultimate compressive strength were analyzed. RESULTS: None of the stand-alone implant constructs reduced the neutral zone. Supplemental pedicle screw fixation decreased the neutral zone in flexion-extension and lateral bending. Stand-alone implant constructs decreased the range of motion in flexion and lateral bending. Differences in the range of motion between stand-alone cage constructs were found in flexion and extension (marginally significant). Supplemental posterior fixation further decreased the range of motion in all loading directions with no differences between implant constructs. The Contact Fusion Cage and PLIF Allograft Spacer constructs had a higher ultimate compressive strength than the Ray Threaded Fusion Cage. CONCLUSIONS: The biomechanical data did not suggest any implant construct to behave superiorly either as a stand-alone or with supplemental posterior fixation. The PLIF Allograph Spacer is biomechanically equivalent to titanium cages but is devoid of the deficiencies associated with other cage technologies. Therefore, the PLIF Allograft Spacer is a valid alternative to conventional cages.

A critical appraisal of the reporting of the National Acute Spinal Cord Injury Studies (II and III) of methylprednisolone in acute spinal cord injury.

From the beginning, the reporting of the results of National Acute Spinal Cord Injury Studies (NASCIS) II and III has been incomplete, leaving clinicians in the spinal cord injury (SCI) community to use or avoid using methylprednisolone in acute SCI on the basis of faith rather than a publicly developed scientific consensus. NASCIS II was initially reported by National Institutes of Health announcements, National Institutes of Health facsimiles to emergency room physicians, and the news media. The subsequent report in the New England Journal of Medicine implied that there was a positive result in the primary efficacy analysis for the entire 487 patient sample. However, this analysis was in fact negative, and the positive result was found only in a secondary analysis of the subgroup of patients who received treatment within 8 hours. In addition, that subgroup apparently had only 62 patients taking methylprednisolone and 67 receiving placebo. The NASCIS II and III reports embody specific choices of statistical methods that have strongly shaped the reporting of results but have not been adequately challenged or or even explained. These studies show statistical artifacts that call their results into question. In NASCIS II, the placebo group treated before 8 hours did poorly, not only when compared with the methylprednisolone group treated before 8 hours but even when compared with the placebo group treated after 8 hours. Thus, the positive result may have been caused by a weakness in the control group rather than any strength of methylprednisolone. In NASCIS III, a randomization imbalance occurred that allocated a disproportionate number of patients with no motor deficit (and therefore no chance for recovery) to the lower dose control group. When this imbalance is controlled for, much of the superiority of the higher dose group seems to disappear. The NASCIS group's decision to admit persons with minor SCIs with minimal or no motor deficit not only enables statistical artifacts it complicates the interpretation of results from the population actually sampled. Perhaps one half of the NASCIS III sample may have had at most a minor deficit. Thus, we do not know whether the results of these studies reflect the severely injured population to which they have been applied. The numbers, tables, and figures in the published reports are scant and are inconsistently defined, making it impossible even for professional statisticians to duplicate the analyses, to guess the effect of changes in assumptions, or to supply the missing parts of the picture. Nonetheless, even 9 years after NASCIS II, the primary data have not been made public. The reporting of the NASCIS studies has fallen far short of the guidelines of the ICH/FDA and of the Evidence-based Medicine Group. Despite the lucrative "off label" markets for methylprednisolone in SCI, no Food and Drug Association indication has been obtained. There has been no public process of validation. These shortcomings have denied physicians the chance to use confidently a drug that many were enthusiastic about and has left them in an intolerably ambiguous position in their therapeutic choices, in their legal exposure, and in their ability to perform further research to help their patients.

Spinal epidural abscess: contemporary trends in etiology, evaluation, and management.

BACKGROUND: Despite advances in neuroimaging and neurosurgical treatment, spinal epidural abscess remains a challenging problem; early diagnosis is often difficult and treatment is delayed. Optimal management is unclear, and morbidity and mortality are significant. To define contemporary trends in etiology and management, and establish diagnostic and therapeutic guidelines, we reviewed our 10-year experience with spinal epidural abscess. METHODS: We examined medical records, laboratory data, radiological (CT and MRI) studies, and operative reports from 75 cases of spinal epidural abscess between 1983 and 1992. Demographic characteristics, frequency, clinical features, pathogens, risk factors, surgical and medical treatment, and outcome were analyzed. RESULTS: We found a significant increase in the frequency of spinal epidural abscess over the 10-year period (p-value = 0.0195). Intravenous drug abuse was present in 28 patients (33%), diabetes mellitus in 22 patients (27%), and prior spinal surgery in 11 patients (17%). Back pain, progressive neurologic deficit, and low grade fever remained the distinguishing diagnostic features. Erythrocyte sedimentation rate was elevated in 48 of 50 patients (95%); peripheral leukocyte count was elevated in 45 patients (60%). MRI was the most effective technique for diagnosing spinal epidural abscess, revealing or suggesting the diagnosis in all 59 patients (100%) studied. Sites of spinal epidural abscess were equally distributed along the spinal axis. Staphylococcus aureus was the predominant organism (67% of patients, with 15% having a methicillin-resistant strain); 8% of patients had Streptococcal species. Most patients had open surgical drainage followed by prolonged antibiotic treatment; 22 patients were managed with antibiotics alone; 50 patients (66%) had a good clinical outcome after treatment. Multiple medical problems, prior spinal surgery, and methicillin-resistant Staphylococci were correlated with a significantly worse outcome. CONCLUSIONS: The frequency of diagnosis of spinal epidural abscess is increasing. To prevent serious morbidity and mortality, early diagnosis is essential. Patients with localized back pain who are at risk for developing such abscesses or who have an increased erythrocyte sedimentation rate and/or neurologic deficit should have an immediate MRI scan with contrast enhancement. Surgical drainage and prolonged antibiotic use are the cornerstones of treatment, although selected patients may be treated conservatively.

The "dural tail sign": not always a meningioma.

Periorbital masses are often referred to oculoplastic surgeons. We report a 20-year-old patient presenting with a tender supertemporal mass that on gadolinium-enhanced magnetic resonance imaging (MRI) demonstrated a prominent dural enhancement adjacent to the mass, the so-called "dural tail sign." This sign has been reported to be highly specific for a meningioma; however recent literature challenges this view. In this case as well, the "dural tail sign" was not produced by a meningioma.

Intracranial metastatic adenocarcinoma of the prostate presenting as visual disturbance.

We report two cases of intracranial metastatic adenocarcinoma of the prostate that presented with visual disturbance. The two patients had no prior history of prostate cancer and both underwent invasive neurosurgical procedures. Progressive neurological decline mandated craniotomy in one patient and the other patient underwent transphenoidal surgery for biopsy. Androgen deprivation therapy was instituted postoperatively for both patients when prostate cancer was determined to be the source of the metastatic lesions.

Trends and complications in cervical spine surgery: 1989-1993.

In an effort to determine trends in surgery of cervical spine disorders and the incidence of complications resulting from this treatment, a mechanism was established for the collection and analysis of multicenter data on an every-5-year basis. This data collection technique allowed the tracking of trends in the treatment for specific diagnoses and determination of complication rates for individual procedures. We present the results occurring in 4,589 patients operated on by 35 surgeons per year between 1989 and 1993. Principal diagnoses included spondylosis, herniated nucleus pulposus, trauma, rheumatoid arthritis, ankylosing spondylitis, ossification of the posterior longitudinal ligament, and tumor. Surgical procedures included anterior cervical discectomy, anterior cervical discectomy and fusion, corpectomy, laminectomies, posterior arthrodesis, laminoplasty, and cervical plating. Complications reported include: bone graft failure, cerebrospinal fluid leak, recurrent laryngeal nerve injury, root injury, quadriplegia, and death. The yearly percentages of each diagnosis have been roughly stable for each year of the study. However, the operative procedures revealed some interesting trends. There was no overall trend with regard to complications over time, and the overall complication risk was approximately 5%. The present data confirm that cervical spine disease is primarily degenerative or discogenic. However, trauma still remains a major part of the practice, accounting for upwards of 17% of reported cases. Anterior procedures were twice as common as posterior ones. The risk of operative complications remains small yet significant.

Pneumosinus dilatans: a sign of intracranial meningioma.

BACKGROUND: Pneumosinus dilatans affecting the sphenoid and posterior ethmoid sinuses has been reported in association with spheno-orbital meningiomas and is believed by some authors be a sign of an adjacent meningioma. METHODS: We report the case of a 57-year-old man who developed progressive neurologic signs and symptoms consistent with a frontal lobe lesion. Neuroimaging studies revealed a large partially cystic mass at the base of the anterior cranial fossa that appeared to be invading the left frontal lobe and that was associated with pneumosinus dilatans of the adjacent left frontal sinus. RESULTS: Although the appearance of the mass by neuroimaging was thought to be most consistent with a malignant glioma, the lesion was found at craniotomy to be a benign meningothelial meningioma. CONCLUSIONS: Many previous cases of progressive optic neuropathy associated with pneumosinus dilatans affecting the sphenoid and posterior ethmoid sinuses have been found to be caused by adjacent optic nerve sheath meningiomas. This case provides further evidence that pneumosinus dilatans is a sign of intracranial meningioma.

Clinical applications of pharmacologic therapies for spinal cord injury.

We review the evidence supporting the role of glucocorticosteroids, trilazad, and GM1 ganglioside in spinal cord injury and provide our critique of the published studies, along with our recommendations for pharmacologic therapy for this complex and difficult problem.

One-stage anterior cervical decompression and posterior stabilization. A study of one hundred patients with a minimum of two years of follow-up.

One hundred patients were managed with one-stage anterior decompression and posterior stabilization of the cervical spine. The underlying indication for the operation was cervical trauma in thirty-one patients; a neoplasm with a pathological fracture or an incomplete neurological deficit in fifty-five; and a miscellaneous condition, such as infection, rheumatoid arthritis, or cervical spondylotic myelopathy, in fourteen. The duration of follow-up ranged from twenty-four to 108 months (mean, thirty-two months) for the living patients. Sixteen patients had the procedure after the failure of an operation that had been performed elsewhere. The development of more biomechanically rigid cervical instrumentation did not obviate the need for a combined anterior and posterior approach. Twenty-six patients (26 per cent) had supplemental cervical instrumentation as part of the circumferential arthrodesis: seventeen had insertion of an anterior cervical plate and nine had insertion of a posterior facet plate. There were no iatrogenic neurological deficits. Of the seventy-five patients who had had a neurological deficit preoperatively, fifty-one improved one grade and six improved two grades according to the system of Frankel et al. Of the thirty-five patients who had not been able to walk preoperatively, twenty-one regained enough motor strength to walk postoperatively. Because the anterior and posterior procedures were performed during one session of general anesthesia, the prevalence of perioperative complications related to the airway was lower than that previously reported in the literature. No patient had an obstruction of the airway.

Complications of cervical discography: analysis of 4400 diagnostic disc injections.

Despite extensive experience with diagnostic cervical disc injection, the role of this procedure in the evaluation of patients with degenerative disc disease and severe neck pain remains controversial. Beyond the debate regarding its efficacy in identifying the site of cervical symptomatology and directing appropriate intervention are the potential morbidity and mortality associated with this diagnostic procedure. Discitis, subdural empyema, spinal cord injury, vascular injury, and prevertebral abscess have all been reported as complications of diagnostic cervical disc injection. Any meaningful assessment of the role of cervical discography in the evaluation of degenerative disc disease must include a determination of the risks inherent in the procedure. We retrospectively analyzed 4400 cervical disc injections in 1357 patients performed by an experienced radiologist between 1988 and 1993 to define the morbidity and mortality associated with discography. In addition, we reviewed the extant medical literature on the complications of this controversial procedure. This study demonstrates significant complications from diagnostic discography procedures occurring in less than 0.6% of the patients and 0.16% of the cervical disc injections.

Reversibility of white matter changes and dementia after treatment of dural fistulas.

We describe two patients with dural fistulas who presented with dementia and diffuse white matter signal changes on MR that significantly improved after surgery. One patient had preoperative embolization.

Differentiating lymphocytic adenohypophysitis from pituitary adenoma in the peripartum patient.

Lymphocytic adenohypophysitis (LAH) is an autoimmune disorder of the pituitary gland with a predilection for the peripartum period and often mimics a pituitary adenoma. We sought to define the clinical, endocrinologic and radiographic characteristics differentiating peripartum LAH from pituitary adenoma to enable the use of noninvasive diagnosis and appropriate therapy. From published reports and our own case, the clinical histories and laboratory and radiographic studies of 45 patients fulfilling the diagnosis of peripartum LAH were reviewed. History of infertility or menstrual irregularity, symptomatology, endocrinologic evaluation, diagnostic imaging and associated medical conditions were analyzed. For comparison, 806 patients with pituitary adenoma and pregnancy from published series were evaluated. The spontaneous pregnancy rate in pituitary adenoma patients was 2.4% vs. 100% in LAH patients. Visual disturbances and headaches were significantly more frequent in patients with LAH. Prolactin levels were significantly lower in patients with LAH than in those with pituitary adenomas (34.6 +/- 46.3 [SD] vs. 393.0 +/- 300.4, P < .0001). Abnormalities in thyroid and/or adrenal function were also more common in patients with LAH (57.5% vs. 2.5%, P < .001). There were no distinguishing characteristics on radiographic studies. History and endocrinologic evaluation can differentiate between LAH and pituitary adenoma in the peripartum patient.

Primary care for women. Comprehensive assessment of the neurologic system.

This article reviews the essential neuroanatomy and neurophysiology, and summarizes the components of the health history, physical exam, and laboratory tests required for an assessment of the neurologic system within the primary care setting. Brief case studies illustrate the wide range of symptoms associated with neurologic disorders in women and the manner in which the pattern of symptoms can be used to locate the site of pathology and indicate the need for referral and follow-up.

Intraventricular rupture of a purulent brain abscess: case report.

The mortality of patients with brain abscesses has decreased significantly from 38% in the 1950s to 25% in the 1980s (P = 0.003, Fisher's exact test by decade of report; asymptotic P values based on chi 2 distribution with 3 degrees of freedom, 28 series, 2825 total patients). This decrease in mortality has been attributed to improved diagnostic imaging, the evolution of neurosurgical techniques and understanding of intracranial pressure pathophysiology, greater critical care understanding, and newer antibiotics. However, the mortality associated with the intraventricular rupture of brain abscesses (IVROBA) remained consistently high (at or above 80% once IVROBA was identified) throughout these decades. Although 129 cases (84.5% mortality, 20 survivors) of IVROBA were located in these series and an additional six case reports of survival after IVROBA were found in the literature, treatment advice and detailed clinical description of these surviving cases are sparse or absent. A case of IVROBA with good quality of survival is presented along with the aggressive five-component therapeutic plan used. The five components are: 1) open craniotomy with debridement of abscess cavity, 2) lavage of the ventricular system, 3) 6 weeks of intravenous antibiotics, 4) intraventricular gentamicin twice daily for 6 weeks, and 5) intraventricular drainage for 6 weeks.

Rheumatoid arthritis. Neuroanatomy, compression, and grading of deficits.

STUDY DESIGN: The authors summarize published data regarding cervical spine involvement in rheumatoid arthritis, define the neurologic manifestations, and provide recommendations for management of these complex and difficult problems. OBJECTIVES: The authors attempted to accurately define the neurologic lesions resulting from rheumatoid involvement of the cervical spine despite the complexity of the neuroanatomy of the cervicomedullary region and the diversity of pathology. SUMMARY OF BACKGROUND DATA: Despite the long-standing recognition of cervical spine involvement in rheumatoid arthritis, appreciation of the different neurologic manifestations of this disease has been lacking or misunderstood. METHODS: The authors reviewed the relevant neuroanatomy, neurovascular anatomy, and neuropathologic lesions that interact to create these complex and often confusing clinical situations. RESULTS: Rheumatoid arthritis produces encroachment on the brainstem and cervical spinal cord. The minimum space available at the craniocervical junction for the neural structures is 13 to 14 mm, which is fairly constant. Below C2, the available space is only 12 mm. When the amount of space reduced below this amount, there is, by definition, neural compression. The site of compression and/or repeated microcontusions will determine subsequent neurologic deficits. At the craniovertebral junction, neural compression and traumatic injury typically occur anteriorly at the pyramidal decussation producing cruciate paralysis with considerable weakness in both arms and minimal leg involvement. Cranial settling can result in lower medulla and cranial nerve dysfunction. Subaxial stenosis typically results in a more typical myelopathy. CONCLUSIONS: Accurate diagnostic studies are mandated to determine the location of compression and to fully appreciate the resultant neurologic deficits. To improve more complete comprehension of the neurologic manifestations of rheumatoid arthritis, the relevant neuroanatomy, neurovascular anatomy, and neuropathologic lesions must be understood.

Spinal cord injury. Role of steroid therapy.

STUDY DESIGN: The authors review the evidence supporting the role of glucocorticosteroids in spinal cord injury, critique published studies, and provide recommendations for steroid use in this complex and difficult problem. OBJECTIVES: The authors detail the evolution of the use of glucocorticosteroids for acute spinal cord injury and objectively assess the results of NASCIS I and II. SUMMARY OF BACKGROUND DATA: Glucocorticosteroids were first used in patients with acute spinal cord injury in the 1960s. An initial randomized clinical trial (NASCIS I) did not demonstrate a difference in outcome between the low- and high-dose steroid therapy. A subsequent study (NASCIS II) demonstrated that a treatment could enhance neurologic recovery. METHODS: The authors critically review the preclinical studies of glucocorticosteroids, NASCIS I and NASCIS II: The majority of the critique focuses on NASCIS II and independent analysis of the data generated by that trial. RESULTS: NASCIS II suggests clinical benefit from high-dose intravenous methylprednisolone therapy. The true benefit of steroid therapy is unclear because of the difference in outcome of the two placebo groups who entered the protocol before and after 8 hours. The initial promising results may be negated by the better recovery of the delayed treatment and/or untreated group of patients in the greater than 8-hour placebo group. However, until the raw patient data from NASCIS II is made available for independent review, the actual benefit of intensive steroid therapy will remain elusive. CONCLUSIONS: Even with the controversies and unresolved issues, we advocate initiation of intensive glucocorticosteroid therapy as soon as possible after acute spinal cord injury, and not beyond the first 8 hours. There is too much data available to arrive at any other conclusion.

Posterior cervical laminoforaminotomy for radiculopathy: review of 172 cases.

Laminoforaminotomy performed with the patient in the sitting position with our improved techniques represents an effective treatment for cervical radiculopathy. We present the results of laminoforaminotomies performed in 172 patients with cervical radiculopathy during a 7-year period. The posterior approach in the surgical management of cervical radiculopathy is not only acceptable, but in certain cases is preferable to the anterior approach. When the abnormality is central, broad based and anterior, posterior procedures are unlikely to achieve decompression. However, with lateral or foraminal nerve root compression, the simpler posterior keyhole laminoforaminotomy works well. In our opinion, physicians advocating either procedure exclusively are not providing the patient with the optimal level of care. Our purpose is to present in detail our surgical technique in conjunction with an analysis of our long-term results in clinical situations in which our technique is clearly indicated.