✓ Neurosurgical instrumentation over the last two decades has improved with the increasing use of the operating microscope and has provided much better visualization and lighting of the surgical field. During this time, dissecting instruments have become smaller, but they sacrifice some of the microscopic gains because they are made of opaque metal. This has the disadvantage of hiding from the surgeon the area of the surgical field being worked on. This paper reports the development of transparent instruments that are strong enough to be used in dissection and yet do not sacrifice part of the improved visualization and lighting gained with the operating microscope. Made of a high-strength plastic, these instruments can be used for dissection in surgical procedures and allow the surgeon to look through them and observe the tissues underneath. He can watch the condition of blood vessels and nervous tissues with an improved visibility that can help to avoid damage to delicate structures. Furthermore, as hidden structures such as small vessels come into view they are identified earlier. These instruments can also incorporate jeweled cutting edges and use their optical properties to improve further visualization of the surgical field.
Walter J. Levy
Walter J. Levy
✓ There is a need to monitor the motor system, but it has a different blood supply and a different location in the spinal cord from those measured by traditional somatosensory evoked potential monitoring. This paper reports a motor evoked potential monitoring system that uses direct spinal cord stimulation overlying the areas of the motor tract in the cord. In nine cats, evoked potentials were recorded from the dura, which gave a much faster main signal component than the traditional dorsal column evoked potentials, which were also recorded. This 100-m/sec signal was not affected by sectioning of the dorsal columns, which was verified histologically. This mode of monitoring the motor system can be used during surgery. It may also provide a better evaluation of patients after spinal cord trauma.
John J. Oro, Linda E. Ansbacher, and Walter J. Levy
✓ The authors describe the case of a septate ependymal cyst involving both frontal lobes. The clinicopathological features, treatment, and results of previously reported cases are reviewed, and the etiology and pathogenesis of these cysts discussed.
Walter J. Levy Jr., Janet Bay, and Donald Dohn
✓ The authors present a retrospective analysis of 97 cases of spinal meningioma. Age, sex, tumor location, and clinical presentation are similar to that reported by others. Importantly, even among paraplegic patients, one-third eventually walked. Other findings of note were poor results among those with calcified or recurrent tumors, and a high incidence of invasiveness among the rare epidural lesions. Males do not show the preference for a thoracic location that is found among females, and cervical tumors are almost all anterior to the cord. This last point suggests a different surgical approach in some cases. A large percentage of cases carried other diagnoses before tumor was recognized.
Report of three cases
Walter J. Levy, Alan Nutkiewicz, Q. Michael Ditmore, and Clark Watts
✓ Dorsal root entry zone lesions have been documented as effective for control of intractable pain in patients with brachial plexus avulsion or severe spinal cord injury. These lesions are usually made with the radiofrequency technique. The authors report three cases in which the CO2 laser was used as an alternative means of making the lesions. This latter technique provided effective pain relief in two of the patients and was efficient to use. It was noted that the presence of overlying scar tissue can be deceptive in judging the depth of the lesion made with the laser. The CO2 laser provided a means of producing controlled spinal cord lesions which may be more precise than the radiofrequency method.
A preliminary report
Walter J. Levy, Janet W. Bay, Bhupinder Sawhny, and Thomas Tank
✓ Cerebral vasospasm following subarachnoid hemorrhage continues to elude effective treatment. Volume expansion is very helpful at times, but cannot be relied on. The authors have combined elements of two vasospasm regimens that could have additive effects. After a trial of volume expansion, aminophylline, dopamine, and nitroprusside were used in combination in each of five patients. All had documented vasospasm and all improved markedly.
Ron Levy, Robin G. Cox, Walter J. Hader, Terry Myles, Garnette R. Sutherland, and Mark G. Hamilton
Over the past decade, the use of intraoperative MR (iMR) imaging in the pediatric neurosurgical population has become increasingly accepted as an innovative and important neurosurgical tool. The authors summarize their experience using a mobile 1.5-T iMR imaging unit with integrated neuronavigation with the goal of identifying procedures and/or pathologies in which the application of this technology changed the course of surgery or modified the operative strategy.
A database has been prospectively maintained for this patient population. The authors reviewed the hospital charts and imaging results for all patients in the database. This review revealed 105 neurosurgical procedures performed in 98 children (49 male and 49 female) between March 1998 and April 2008. Intradissection (ID) and/or quality assurance images were obtained at the discretion of the surgeon.
The median age at surgery was 12 years (4 months–18 years). One hundred intracranial and 5 spinal procedures were performed; 22 of these procedures were performed for recurrent pathology. Surgical planning scans were obtained for 102 procedures, and neuronavigation was used in 93 patients. The greatest impact of iMR imaging was apparent in the 55 procedures to resect neoplastic lesions; ID scans were obtained in 49 of these procedures. Further surgery was performed in 49% of the procedures during which ID scans had been obtained. A smaller proportion of ID scans in the different cranial pathology groups (5 of 21 epilepsy cases, 4 of 9 vascular cases) resulted in further resections to meet the surgical goal of the surgeon. Two ID scans obtained during 5 procedures for the treatment of spinal disease did not lead to any change in surgery. Postoperative scans did not reveal any acute adverse events. There was 1 intraoperative adverse event in which a Greenberg retractor was inadvertently left on during ID scanning but was removed after the scout scans.
The application of iMR imaging in the pediatric neurosurgical population allows, at minimum, the opportunity to perform less invasive surgical exposures. Its potential is greatest when its high-quality imaging ability is coupled with its superior neuronavigation capabilities, which permits tracking of the extent of resection of intracranial tumors and, to a lesser extent, other lesions during the surgical procedure.