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Biomedical subjects

M R Mayberg

Publications and source records attributed to M R Mayberg.

85 records · Page 5Linked to original sources
PubMed1989

Angioplasty for the treatment of symptomatic vasospasm following subarachnoid hemorrhage.

Angioplasty of narrowed cerebral arteries was performed in 10 patients who became symptomatic from vasospasm following subarachnoid hemorrhage. This procedure was accomplished with a microballoon catheter via percutaneous transfemoral insertion. Patients were selected for treatment if they had delayed neurological deficits due to vasospasm which were not responsive to hypervolemic hypertensive therapy. Eight patients (80%) showed sustained improvement in neurological function following the procedure. In two patients transcranial Doppler ultrasound recordings were obtained which revealed decreased mean blood flow velocities following angioplasty. Two patients died, one from an aneurysmal rebleed, and one secondary to diffuse vasospasm. There was one case of delayed stroke 6 weeks following the procedure. The overall results of this series indicate that in selected cases percutaneous balloon angioplasty can offer marked improvement to patients with ischemic deficits due to vasospasm following subarachnoid hemorrhage.

Adult↗
PubMed1988

Stereotactic neutron radiosurgery for arteriovenous malformations of the brain.

A technique employing single fraction neutron radiosurgery for treatment of intracranial vascular malformations has been developed at the University of Washington and is described in this report. The natural history of arteriovenous malformations of the brain is briefly reviewed, along with currently available therapeutic methods for treatment of these lesions. The characteristics of the neutron beam used for radiosurgery are described, along with methods for patient immobilization, radiation treatment planning, dosimetry, and delivery of treatment using this technique.

Fast Neutrons↗
PubMed1988

Local anticoagulation without systemic effect using a polymer heparin delivery system.

Polymeric drug delivery systems that allow the application of substances to a localized region for specified periods of time have been developed. A model for intravascular thrombosis in the rat common carotid artery was established using a combination of balloon catheter endothelial injury with 1-hour occlusion of the vessel. After endothelial injury in 11 Sprague-Dawley rats, the adventitial surface of the carotid artery was exposed to the polymer polyvinyl alcohol (PVA) containing heparin and was compared with exposure to PVA alone in the contralateral (control) vessel. Subsequent determinations of the coagulation parameters systemic prothrombin and partial thromboplastin times showed no systemic effect of heparin. All 11 control vessels demonstrated complete or partial thrombosis, whereas only one of 11 heparin/PVA-treated vessels showed a small thrombus. Morphometric analysis of the cross-sectional thrombus: lumen ratio in 10 rats showed a significant reduction (p less than 0.005) in thrombus size for treated vessels (4.1 +/- 9.6%) compared with control vessels (60.2 +/- 25.8%). Scanning electron microscopy verified the absence of thrombus in the treated vessels despite complete endothelial desquamation. In a second group of eight rats, endothelial injury without occlusion did not cause thrombosis in treated or control arteries. The coagulation parameters for this group of eight unoccluded rats were similarly unaffected by heparin/PVA treatment. Our observations suggest that a localized antithrombotic effect of heparin can be achieved without systemic anticoagulation using a polymeric drug delivery system. This technique may be applied to a variety of surgical and nonsurgical clinical conditions.

Animals↗
PubMed1988

Vein of Galen aneurysm associated with dural AVM and straight sinus thrombosis. Case report.

A 64-year-old man presented with symptoms of obstructive hydrocephalus secondary to a vein of Galen aneurysm associated with a dural arteriovenous malformation and straight sinus thrombosis. The interrelationship of these lesions and their clinical and radiological features are discussed. It is proposed that in this case sinus thrombosis was the primary event in the subsequent development of the other lesions.

Arteriovenous Malformations↗
PubMed1986

Meningiomas of the clivus and apical petrous bone. Report of 35 cases.

Between March, 1966, and June, 1985, 23 women and 12 men underwent partial or total resection of apical petrous or clivus meningiomas at The National Hospital for Nervous Diseases. Presenting symptoms were typically of long duration (mean 29 months) and consisted primarily of gait disturbance, headache, hearing loss, and facial pain. Cranial nerve deficits, especially affecting the fifth, seventh, and eighth nerves. were observed in nearly every patient. Tumor size, but not location, was generally associated with degree of preoperative disability. Plain skull films were usually unremarkable, but computerized tomography (CT) proved highly accurate in determining tumor location and size. A characteristic pattern of vascular displacement was seen on vertebral angiograms, although blood supply to the tumors was derived primarily from branches of the internal and external carotid arteries. Subtotal or total resection was undertaken in all cases; nine patients required adjunctive cerebrospinal fluid shunting procedures. Although surgical techniques evolved during the course of the 20-year study, a combined supra- and infratentorial approach proved a relatively safe and effective means of surgical treatment. New or worsened postoperative deficits, especially cranial nerve palsies, and complications in the immediate postoperative period frequently resulted in temporary deterioration of the clinical status during this period; the total operative mortality rate was 9%. Follow-up periods ranged up to 9 years; 70% of patients resumed an independent existence, and none is known to have required subsequent tumor surgery. The size of the lesion was the only significant factor in determining outcome. These data suggest that meningiomas of the clivus and apical petrous bone can be accurately diagnosed by CT and three-vessel angiography, and effectively treated by microsurgical resection.

Adult↗
PubMed1985

Cervical diastematomyelia presenting in adulthood. Case report.

A case of cervical diastematomyelia in an adult is reported. The patient first noted sensory and motor symptoms at 34 years of age after two episodes of cervical trauma. Metrizamide computerized tomography myelography of the cervical spine and cord showed the region of diastematomyelia and revealed a spur containing both bone and fat tissue projecting into the spinal canal and cord. The spur arose from the laminae and spinous processes of C-2 and C-3, and was successfully excised. Postoperatively, the patient's deficits gradually improved. The literature concerning adult cervical diastematomyelia is reviewed.

Adult↗
PubMed1984

Trigeminal projections to supratentorial pial and dural blood vessels in cats demonstrated by horseradish peroxidase histochemistry.

Anatomical and clinical observations suggest that supratentorial vascular structures contain afferent projections from the trigeminal ganglia. To characterize this innervation, horseradish peroxidase (HRP) and HRP conjugated to wheat germ agglutinin were applied to the pial and dural arteries and sinuses of 33 cats. HRP was restricted to the site of interest by applying it dissolved in a viscous polymer, polyvinyl alcohol (PVA), to achieve slow release and minimize diffusion. The ganglia of cranial nerves V, VII, IX, and X and the superior cervical ganglia (SCGs) were examined bilaterally for the presence of retrogradely transported protein. Horseradish peroxidase applied to the proximal middle cerebral artery was located in cell bodies occupying the portion of the ipsilateral trigeminal ganglion corresponding to the ophthalmic division and throughout both SCGs. When the tracer was applied to the right anterior or posterior superior sagittal sinus, HRP-positive cells were present as above, predominantly in the ipsilateral trigeminal ganglia corresponding to the ophthalmic division and throughout both SCG. When applied to the right middle meningeal artery, HRP was observed within neurons of ipsilateral SCG and in the ophthalmic division of trigeminal ganglia; a few enzyme-containing cells were present in ipsilateral regions corresponding to the second and third divisions. These observations support the concept that supratentorial vascular structures receive afferent nervous projections from trigeminal neurons.

Afferent Pathways↗
PubMed1982

Cerebrospinal fluid may nourish cerebral vessels through pathways in the adventitia that may be analogous to systemic vasa vasorum.

Cerebral blood vessels are devoid of vasa vasorum. Therefore, the authors have studied the microarchitecture of the adventitia of large feline cerebral vessels of the same size, in an effort of determine how the vessels are nourished. The cerebral vessels contain a rete vasorum in the adventitia that is permeable to large proteins and is in continuity with the subarachnoid space. This substructure may be analogous to the systemic vasa vasorum and may contribute to the nutrition of the cerebral arteries.

Animals↗
PubMed1978

Ultrastructural changes in feline arterial endothelium following subarachnoid hemorrhage.

Scanning electron microscopy of feline basilar arterial endothelium 4 hours, and 1, 3,5, and 7 days after subarachnoid hemorrhage (SAH) showed longitudinal furrows that correlated with angiographically demonstrated vasospasm. These ridges persisted after fixation at physiological pressure, and probably reflected medial contraction with undulation of the underlying elastic lamina. No change in endothelial cell morphology or thrombogenesis was observed as long as 7 days after SAH. There is no evidence from this study to suggest that ischemia from vasospasm is a product of thromboembolism from damaged endothelial surfaces.

Animals↗
PubMedDate not supplied

Kinetics of bromodeoxyuridine uptake by smooth muscle cells after arterial injury.

The time course of 5-bromo-2'-deoxyuridine (BrdU) uptake by medial and neointimal smooth muscle cells was examined in rat carotid arteries at periods of 1-20 days after balloon catheter injury. DNA-incorporated BrdU was determined by the indirect immunoperoxidase technique in both plastic- and paraffin-embedded specimens. The BrdU labeling index (LI) peaked at 48 h in the media (19.9% paraffin, 9.4% plastic) and at 5 days in the neointima (55.4% paraffin, 60.2% plastic). Immunohistochemistry for the endogenous marker proliferating cell nuclear antigen was variable and generally less reliable than BrdU. Using total viable medial smooth muscle cell number as an index of medial injury, the LI for BrdU was directly proportional to the extent of injury at 48 h, and correlated with loss of actin immunoreactivity. BrdU immunohistochemistry is a reliable alternative to [3H]-thymidine autoradiography for short-term labeling in this model. Proliferation of smooth muscle cells in this model is likely related to the degree of injury to the media.

Actins↗