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Cary D. Alberstone, Stephen L. Skirboll, Edward C. Benzel, John A. Sanders, Blaine L. Hart, Nevan G. Baldwin, Charles L. Tessman, John T. Davis and Roland R. Lee

Object. The availability of large-array biomagnetometers has led to advances in magnetoencephalography that permit scientists and clinicians to map selected brain functions onto magnetic resonance images. This merging of technologies is termed magnetic source (MS) imaging. The present study was undertaken to assess the role of MS imaging for the guidance of presurgical planning and intraoperative neurosurgical technique used in patients with intracranial mass lesions.

Methods. Twenty-six patients with intracranial mass lesions underwent a medical evaluation consisting of MS imaging, a clinical history, a neurological examination, and assessment with the Karnofsky Performance Scale. Magnetic source imaging was used to locate the somatosensory cortex in 25 patients, the visual cortex in six, and the auditory cortex in four. The distance between the lesion and the functional cortex was determined for each patient.

Twenty-one patients underwent a neurosurgical procedure. As a surgical adjunct, a frameless stereotactic navigational system was used in 17 cases and a standard stereotactic apparatus in four cases. Because of the results of their MS imaging examination, two patients were not offered surgery, four underwent a stereotactic biopsy procedure, 10 were treated with a subtotal surgical resection, and seven were treated with complete surgical resection. One patient deteriorated before a procedure could be scheduled and, therefore, was not offered surgery, and two patients were offered surgery but declined. Three patients experienced surgery-related complications.

Conclusions. Magnetic source imaging is an important noninvasive neurodiagnostic tool that provides critical information regarding the spatial relationship of a brain lesion to functional cortex. By providing this information, MS imaging facilitates a minimum-risk management strategy and helps guide operative neurosurgical technique in patients with intracranial mass lesions.

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Mark D. D'Alise, Edward C. Benzel and Blaine L. Hart

Object. Confirmation of cervical spine stability is difficult to obtain in the comatose or obtunded trauma patient. Concurrent therapies such as endotracheal intubation and the application of rigid cervical collars diminish the utility of plain radiographs. Bony as well as supportive soft-tissue structures must be evaluated before the cervical spine can be determined to be uninjured. Although major injuries to extradural soft-tissue structures in the awake trauma patient are frequently excluded by physical examination, when the patient is obtunded the physical examination may be unreliable. Therefore, an enhanced diagnostic method for the evaluation of soft-tissue injury is desirable. The authors conducted a study in which magnetic resonance (MR) imaging was used as such a method to assess posttraumatic spinal stability in the comatose or obtunded patient.

Methods. Early, limited (sagittal T1- and T2-weighted) MR imaging was performed posttruama in 121 patients to assess soft-tissue injury. In all patients the mechanism of injury potentially could be associated with cervical spine instability, and each patient was endotracheally intubated because of head injury or severe multisystem injuries. All patients underwent imaging studies within 48 hours of injury and were either treated or cleared and spinal precautions were discontinued. Patients were excluded from this study if they had an obvious cervical spine injury identified on the initial radiographic studies or if they were determined to be too medically unstable to undergo MR imaging within the acute period (<48 hours postinjury).

Thirty-one (25.6%) of the 121 patients were found to have sustained significant injury to the paravertebral ligamentous structures, the disc interspace, or the bony cervical spine. These injuries were undetected by plain radiography. The other 90 patients (74.4%) were determined within 48 hours not to have sustained a soft-tissue injury. Eight patients (6.6%) ultimately underwent surgery to treat the cervical spine injury, and MR imaging was the first test that identified the injury in each of these patients. There were no complications related to imaging procedures.

Conclusions. Sagittal T1- and T2-weighted MR imaging appears to be a safe, reliable method for evaluating the cervical spine for nonapparent injury in comatose or obtunded trauma patients. In the early postinjury period, nursing and medical care are thereby facilitated for patients in whom occult injury to the spine is ruled out and for whom those attendant precautions are unnecessary.

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Cary D. Alberstone, Edward C. Benzel and Deborah Garcia

Although trends in the marketplace demand for neurosurgeons should be of interest to neurosurgeons and prospective neurosurgeons, little data are available that accurately document these trends. A recent report published in the general medical journal Journal of the American Medical Association (JAMA) used the Conference Board help-wanted index to evaluate trends in physician marketplace demand. The authors of the JAMA study concluded that over the past 5 years there has been a significant fall in demand for specialist physicians. Because the discipline of neurosurgery was not included in the JAMA study, the authors of the present report attempt to evaluate the trend in the marketplace demand for neurosurgeons, using the same methodology of the JAMA study. The authors' data suggest that the conclusion of the JAMA study of steep declines in the demand for specialist physicians does not accurately reflect the job market for neurosurgeons, which in fact appears to be relatively stable. The present study attempts to document the stability of the neurosurgery market and outline the steps necessary to protect this market from existing threats.

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Edward C. Benzel

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Sait Naderi, Edward C. Benzel and Nevan G. Baldwin

Cervical spondylotic myelopathy can produce a variety of clinical signs and symptoms secondary to neural compromise and biomechanical involvement of the spine. The surgical treatment of cervical spondylotic myelopathy remains a controversial issue after many years of study, evolution, and refinement. Several ventral, dorsal, or combined approaches have been defined. The complications associated with ventral approaches and the concerns about kyphosis following dorsal approaches led to the development of a variety of laminoplasty procedures. This paper reviews the biomechanical basis of cervical spondylotic myelopathy and its effect on choosing the appropriate surgical approach.

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Sait Naderi, Cary D. Alberstone, Frederick W. Rupp, Edward C. Benzel and Nevan G. Baldwin

Forty-four patients with cervical spondylotic myelopathy who underwent a ventral surgical approach were evaluated with respect to the results of surgery. The neurological status of the patients was categorized according to the modified Japanese Orthopedic Association scale (0-18). Three patients had a functional score of 8, one patient 9, five patients 10, five patients 11, seven patients 12, seven patients 13, seven patients 14, and nine patients had a functional score of 15, preoperatively. Twenty-three patients underwent a one-level corpectomy, 15 patients a two-level corpectomy, and six patients underwent a three-level corpectomy. Forty-one (93.1%) of the 44 patients underwent ventral cervical plate fixation. Complications among the 44 patients included graft-and instrumentation-related complications in seven cases, iliac crest donor-site infection in three cases, and respiratory complications in three cases. The follow-up periods ranged between 7 and 60 months (mean 42.3 months). Overall, the fusion rate was 97.72%. Three patients showed no functional change (6.8%), two patients were worse (4.5%), and 39 patients (88.6%) showed functional improvement in their score between +1 and +6 points (mean 2.16 points). There was no statistically significant difference in the functional improvement score in patients younger or older than 60 years old. The mean improvement in the functional score was found to be +2.857 ± 1.352, +2.400 ± 1.454, and +0.5000 ± 1.871 following one-level corpectomy, two-level, and three-level corpectomies, respectively. There were statistically significant differences in the neurological improvement observed between patients with one-level corpectomy and three-level corpectomy (p < 0.01), as well as between those with two-level and three-level corpectomy (p < 0.05). There was no statistically significant difference in the neurological outcome between patients with one-level and two-level corpectomy (p > 0.05). The results of this study demonstrate a high rate of solid bone fusion and a high rate of functional (neurological) improvement. Five patients underwent reoperation, predominantly for instrumentation failure. The use of instrumentation dictates careful consideration of the risk/benefit ratio associated with its use in each case.

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Edward C. Benzel, Blaine L. Hart, Perry A. Ball, Nevan G. Baldwin, William W. Orrison and Mary C. Espinosa

✓ Because it is often difficult to diagnose accurately the structurally intact cervical spine after acute trauma, a series of patients was evaluated with magnetic resonance (MR) imaging to assess its efficacy for the evaluation and clearance of the cervical spine in a trauma victim in the early posttrauma period. Ultralow-field MR imaging was used to evaluate 174 posttraumatic patients in whom physical findings indicated the potential for spine injury or minor radiographic findings indicated injury. This series includes only those patients who did not appear to harbor disruption of spinal integrity on the basis of a routine x-ray film. None had clinically obvious injury.

Of the 174 patients, 62 (36%) had soft-tissue abnormalities identified by MR imaging, including disc interspace disruption in 27 patients (four with ventral and dorsal ligamentous injury, three with ventral ligamentous injury alone, 18 with dorsal ligamentous injury alone, and two without ventral or dorsal ligamentous injury). Isolated ligamentous injury was observed in 35 patients (eight with ventral and dorsal ligamentous injury, five with ventral ligamentous injury alone, and 22 with dorsal ligamentous injury alone). One patient underwent a surgical fusion procedure, 35 patients (including the one treated surgically) were placed in a cervical collar for at least 1 month, and 27 patients were placed in a thermoplastic Minerva jacket for at least 2 months. All had a satisfactory outcome without evidence of instability.

The T2-weighted sagittal images were most useful in defining acute soft-tissue injury; axial images were of minimal assistance. Posttraumatic soft-tissue cervical spine injuries and disc herniations (most likely preexisting the trauma) are more common than expected. A negative MR image should be considered as confirmation of a negative or “cleared” subaxial cervical spine. Diagnostic and patient management algorithms may be appropriately tailored by this information. Thus, MR imaging is useful for early acute posttrauma assessment in a very select group of patients.

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