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Michael S. Edwards and Edward S. Connolly

✓ The authors present two cases of cavernous sinus syndrome with spontaneous onset secondary to arteriovenous malformations and review the cases reported previously. These malformations enlarge slowly and produce symptoms only in adult life. Diagnosis may be difficult when there is no associated bruit. Adequate evaluation necessitates selective angiography of both the internal and external carotid artery circulation and the vertebral circulation. Conservative treatment is recommended unless symptoms worsen or there is progressive loss of vision.

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Stanley Hoang, Omar Choudhri, Michael Edwards and Raphael Guzman

A vein of Galen malformation is a rare intracranial vascular lesion affecting the pediatric population. Its poor prognosis has been significantly improved with the development of endovascular embolization. In this paper the authors review the developmental mechanisms, clinical pathophysiology, and the available data on the management and outcome of the disease.

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Stanley L. Barnwell and Michael S. B. Edwards

✓ The case of an 11-year-old boy is reported in whom two intramedullary lesions developed at the thoracic-cervical and thoracic-lumbar junctions 2½ years after resection and irradiation of a medulloblastoma in the posterior fossa. There was no evidence of subarachnoid spread of the tumor. Magnetic resonance imaging was used to localize these lesions, and provided much better diagnostic information than either computerized tomography scans or myelograms.

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Stephen K. Powers, Catherine A. Bolger and Michael S. B. Edwards

✓ Using a CO2 laser, discrete thoracic spinal cord lesions were made in cats anesthetized with ketamine and xylazine (Rompun). Differences in cortical somatosensory evoked potentials (SEP's) produced with high-intensity stimulation (20 times the motor threshold) of each posterior tibial nerve were determined for nine different combinations of unilateral spinal cord lesions.

The results of these studies show that nerve fibers in the ipsilateral dorsal column, the ipsilateral dorsal spinocerebellar tract, and the contralateral ventrolateral tracts with respect to the side of leg stimulation, contribute to cortical SEP's. A lesion of the dorsal spinocerebellar tract affected only the early waves (< 30 msec) of the SEP from leg stimulation ipsilateral to the side of the lesion, whereas a solitary lesion of the ventrolateral tract caused changes primarily in the amplitude of later waves (> 30 msec) of the SEP produced by contralateral leg stimulation. Lesions involving one-half of the dorsal column caused changes in the amplitude of both the early and late waves produced by stimulation ipsilateral to the side of the lesion. The effects of various combinations of lesions on the cortical SEP's were not additive, which indicates significant interaction between afferent pathways.

These findings suggest that high-intensity peripheral nerve stimulation, which activates both C and A fibers, could be used intraoperatively to assess spinal cord function with more accuracy than the current practice of using a stimulus strength of twice the motor threshold. The importance of using anesthetic agents that do not depress cortical activity (which may affect the later components of the SEP) is also emphasized.

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James E. Boggan, Catherine Bolger and Michael S. B. Edwards

✓ Intracerebral tumors were produced in 99 rats by stereotaxic implantation of 9L gliosarcoma brain-tumor cells. Hematoporphyrin derivative (HPD), 10 or 20 mg/kg, was administered as an intravenous bolus 24 or 48 hours before irradiation of the tumor region with light from an argon pumped-dye laser (632 nm). Laser light, at a dose of 30, 60, or 200 joules/sq cm, was delivered through a craniectomy 10 or 13 days after tumor implantation. Survival times were significantly prolonged in rats exposed to laser light at a dose of 200 joules/sq cm 24 hours after administration of HPD, 20 mg/kg.

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Stephen K. Powers, David Norman and Michael S. B. Edwards

✓ Nine patients with a peripheral nerve lesion (six intrinsic and three extrinsic) were evaluated with computerized tomography (CT). In all but one instance, the CT scans gave useful information regarding the anatomical location, size, and relationship of the lesion to surrounding structures. These cases illustrate the usefulness of CT as a diagnostic tool in the evaluation of peripheral nerve lesions.

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Brian T. Andrews, Michael S. B. Edwards and Peter Gannon

✓ Spontaneous thrombosis of aneurysms occurs rarely in children, and, to our knowledge, there are no reports of aneurysms presenting as an embolic event in a child. We describe the case of a 3-year-old boy whose symptoms initially suggested an ischemic event to the dominant hemisphere. Initial computerized tomography scans indicated an intracranial hemorrhage. Subsequent radiographic study revealed evidence of emboli and, at exploration, a large acutely thrombosed aneurysm of the left middle cerebral artery associated with arterial occlusion was found. Entrapment of the aneurysm and thrombectomy provided excellent operative results.