Seth M. Zeidman

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.

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 associatedwith other cage technologies. Therefore, the PLIF Allograft Spacer is a valid alternative to conventional cages.

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 gluco‐corticosteroid 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.

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 longstanding 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.

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.