Intratentorial lipomas with Meckel's cave and cerebellopontine angle extension.

An unusual case of bilateral intratentorial lipomas with extension into Meckel's caves and the cerebellopontine angle is described. Surgical and histopathologic correlation demonstrate that the lipoma encased the trigeminal nerve in Meckel's caves. The origin of the lipoma from the anteromedial margins of the tentorium is discussed and correlated with a recently proposed theory for the development of intracranial lipomas.

Use of internal fiducial markers in frameless stereotactic navigational systems during spinal surgery: technical note.

OBJECTIVE: The use of frameless stereotaxy has expanded the spine surgeon's ability to perform surgical procedures with instrumentation in areas of narrow anatomic tolerance. In many circumstances, however, it is difficult to register the frameless stereotactic probe using known anatomic landmarks. This occurs typically because landmarks are indistinct, and congenital or surgical defects limit the availability of anatomic fiducials. We propose an accurate and efficient method for registering the frameless stereotactic probe for spinal surgery when a staged procedure is planned. METHODS: During the first stage of a planned two-stage procedure, a minimum of four cranial fiducial screws are implanted in the posterior element of each vertebra in which stereotactic registration is desired. Stage 1 is completed, and all suture closure is performed. A computed tomographic scan formatted for the frameless stereotactic unit is obtained postoperatively. In the second stage of surgery, registration is performed using cranial screws as internal fiducial markers. RESULTS: Registration is performed easily and quickly using cranial screws as internal fiducial markers. No more than four registration points are necessary to calibrate the system to accuracy within 1.5 mm. CONCLUSION: Implantation of fiducial markers during Stage 1 of a complex staged spinal surgery renders the frameless stereotactic navigational system registration extremely fast and accurate. We advocate the technique to enhance the use of frameless navigational systems for reliable and quick registration of the spine.

Cryptococcal skull infection: a case report with review of the literature.

A case of cryptococcal osteomyelitis of the skull is presented. The patient was an immunocompetent host with skull and skin involvement without central nervous system or pulmonary extension. The radiographic findings are reviewed to include skull films, bone scan, and computed tomographic and magnetic resonance imaging scans. The patient underwent surgical debridement of the lesion as well as systemic medical therapy with amphotericin B and flucytosine. The medical and surgical therapy for such lesions is reviewed. Surgical intervention is emphasized for the removal of bony sequestrum and nonviable bone while maintaining an intact dura.

Heparin-associated thrombocytopenia in the neurosurgical patient.

Although thrombocytopenia occurs in approximately 10% of medical patients who receive heparin, this complication has not been described in neurosurgical patients. We report the clinical course of two patients who in the immediate postoperative period developed heparin-associated thrombocytopenia that resulted in significant morbidity. In these two cases, the origin of the heparin was in "flush" solutions used to maintain the patency of indwelling vascular catheters and was infused at a dose of 250 to 500 units/day. The minimal daily dose previously reported to result in thrombocytopenia is 9000 units/day administered in divided doses subcutaneously. The case reports indicate that heparin in "flush" solutions should be considered as a cause for unexpected thrombocytopenia and that platelet counts should be monitored in patients receiving heparin in any amount.

Surgical excision of a cavernous hemangioma of the rostral brain stem: case report.

A 23-year-old pregnant woman presented with sudden diplopia, ataxia, hemiparesis, and headache secondary to a brain stem hemorrhage. Magnetic resonance imaging (MRI) revealed a hematoma associated with a probable cavernous hemangioma of the rostral brain stem. In this report, we discuss the MRI findings leading to the preoperative diagnosis, as well as the surgical techniques involved in the successful resection.

Cervical spondylotic myelopathy: treatment with posterior decompression and Luque rectangle bone fusion.

Cervical spondylotic myelopathy appears to result from a combination of factors. The two major components are 1) compressive forces resulting from narrowing of the spinal canal, and 2) dynamic forces owing to mobility of the cervical spine. There is substantial evidence to suggest that the repetitive trauma to the spinal cord that is sustained with movement in a spondylotic canal may be a major cause of progressive myelopathy. Utilization of extensive anterior procedures that remove the diseased ventral features as well as eliminate the dynamic forces owing to the accompanying fusion have grown in popularity. Cervical laminectomy enlarges the spinal canal, but does not reduce the dynamic forces affecting the spinal cord, and may actually increase cervical mobility, leading to a perpetuation of the myelopathy. The authors propose the combination of posterior decompression and Luque rectangle bone fusion to deal with both the compressive and the dynamic factors that lead to cervical spondylotic myelopathy. Ten patients who had advanced myelopathy underwent the combined procedures. Nine of the 10 experienced significant neurological improvement, and the 10th has had no progression. The combination of posterior decompression and Luque rectangle bone fusion may offer a simple, safe, and effective alternative treatment for cervical spondylotic myelopathy.

The natural history of symptomatic arteriovenous malformations of the brain: a 24-year follow-up assessment.

The authors have updated a series of 166 prospectively followed unoperated symptomatic patients with arteriovenous malformations (AVM's) of the brain. Follow-up data were obtained for 160 (96%) of the original population, with a mean follow-up period of 23.7 years. The rate of major rebleeding was 4.0% per year, and the mortality rate was 1.0% per year. At follow-up review, 23% of the series were dead from AVM hemorrhage. The combined rate of major morbidity and mortality was 2.7% per year. These annual rates remained essentially constant over the entire period of the study. There was no difference in the incidence of rebleeding or death regardless of presentation with or without evidence of hemorrhage. The mean interval between initial presentation and subsequent hemorrhage was 7.7 years.

The removal of a transdural pedicle screw placed for thoracolumbar spine fracture.

STUDY DESIGN: This report describes the method of removal of a pedicle screw that had been misplaced through the thecal sac and the cauda equina instead of its proper location within the pedicle. OBJECTIVES: A patient who previously had undergone placement of pedicle screws and Roy-Camille plates for fixation of L1 burst fracture presented to the authors with neurologic deficits and a cerebrospinal fluid leak. Computed tomography myelogram and surgical findings demonstrated misplacement of three of the screws, one of which was placed through the dura with resulting impingement of nerve roots within the thecal sac. SUMMARY OF BACKGROUND DATA: Removal of the screws was required for neural decompression and resolution of the cerebrospinal fluid leak. METHODS: The patient underwent laminectomy to expose the screw and primary durotomy to include the entry point of the screw. This technique allowed safe removal under direct vision, with direct protection of the nerve roots. A subsequent anterior fusion procedure was performed. RESULTS: The patient regained full neurologic function, and his cerebrospinal fluid leak ceased. At 2-year follow-up evaluation, he describes only mild, occasional back pain. CONCLUSIONS: Penetration of the dura and injury to the neural elements can occur when pedicle screw instrumentation is used. Removal of the screw under these circumstances may cause additional neurologic injury. Durotomy and direct visualization of the neural elements in this case was a valuable adjunct to safe removal of the screw.

A method for radiographic evaluation of pedicle screw violation of the vertebral endplate. Technique.

STUDY DESIGN: This study evaluated the utility of intraoperative radiographs for minimizing the risk of pedicle screw tip violation of the superior vertebral endplate. OBJECTIVES: An intraoperative radiographic technique is demonstrated that ensures that a screw has not penetrated the intervertebral disk. SUMMARY OF BACKGROUND DATA: Although methods to avoid penetration of the medial pedicle cortex and the anterior body cortex have been described, no study has discussed screw penetration of the superior endplate and disc. METHODS: Pedicle screws were inserted into 11 cadaveric lumbar spines, randomly, with the tip interior to the endplate, at the endplate, and through the endplate. Radiographs were evaluated to measure the penetration, if any, of the screws. Spine segments were dissected and evaluated anatomically. The anatomic and radiographic results were then compared. RESULTS: The overall error rate for radiographs was 22/312 (7%). Oblique radiographs gave a much higher error rate. CONCLUSIONS: A true lateral or anteroposterior radiographic view of the vertebra provides a high degree of certainty that the screw has not crossed the endplate when a "safe zone" of 3 mm remains superior to the screw tip. Intraoperative radiography can reduce concern about violation of the superior vertebral endplate.

Spinal cord compression in beta-thalassemia: case report and review of the literature.

STUDY DESIGN: A case report of thoracic spinal cord compression in a 34-year-old male with beta-thalassemia is reported. OBJECTIVES: In patients with thalassemia, neurologic complaints should lead to a high index of suspicion for spinal cord compression from marrow expansion, ectopic bone formation and resultant stenosis. Initial presentation, diagnosis, radiographic findings, surgical treatment and follow-up are reviewed. SETTING: This case is reported from Chicago, Illinois. METHOD: A chart review is performed for the purposes of this case report. RESULTS: Patient underwent decompressive laminectomy with good surgical outcome. CONCLUSION: Rapid diagnosis and treatment of such a condition is essential to optimize the chances of recovery.

Nonneoplastic pineal cysts: a clinicopathologic study of twenty-one cases.

Twenty-one cases of nonneoplastic pineal cyst are presented. The patients were 13 women and 8 men, with a median age of 33 years. Sixteen patients were symptomatic. Symptomatic cysts had an average size of 16.5 mm. In most cases, symptoms and signs were related to increased intracranial pressure, cerebrospinal fluid obstruction, neuroophthalmologic dysfunction, brainstem and cerebellar compression, and mental status changes. Uncommon clinical presentations in three cases were related to increased cyst size caused by hemorrhage, sudden death, and postural syncope and loss of consciousness. Imaging studies showed a uniform hypodense or hypointense, nonenhancing pineal mass with occasional peripheral calcification and associated with hydrocephalus, aqueductal compression, tectal deformity, and hemorrhage within the cavity, in decreasing order of frequency. Fourteen patients underwent open cyst resection. Histologically, the intact lesions show a unilocular or multilocular cavity, surrounded by a wall comprised of variable amounts of glial tissue, remnants of pineal gland, and an external fibrous capsule. Follow-up information showed 12 patients alive and well without recurrence between 26 and 144 postoperative months. One patient who underwent stereotactic drainage had a recurrence. One symptomatic patient who did not have surgery died suddenly of causes related to the cyst. The present study supports the role of surgical excision for the treatment of symptomatic pineal cysts to obtain adequate tissue for diagnosis and relief of symptoms. The use of histochemical and immunohistochemical studies may prove useful in the distinction of these lesions with astrocytomas and cystic pineal parenchymal tumors.

Combined transmandibular-zygomatic approach and infratemporal craniotomy for intracranial skull base tumors.

Large intracranial skull base tumors remain surgically treacherous lesions. The preauricular transzygomatic infratemporal approach to this area has rapidly gained popularity. This article presents modifications to this approach which improved visualization and access to the infratemporal fossa. The procedure increases visualization, minimizes brain retraction, and results in improved resection and outcome. Reconstruction is rapid and there are minimal functional and cosmetic deficits.

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.