Study of the posterior circulation in moyamoya disease. Part 2: Visual disturbances and surgical treatment

Use of the omentum in chest-wall reconstruction

Increased use of the omentum in chest-wall reconstruction has paralleled the refinement of anatomic knowledge and the development of safe mobilization techniques. Important anatomic points are the omental attachments to surrounding structures, the major blood supply from the left and right gastroepiploic vessels, and the collateral circulation via the gastroepiploic arch and Barkow's marginal artery. Mobilization of the omentum to the thorax involves division of its attachments to the transverse colon and separation from the greater curvature to fabricate a bipedicled flap. Most anterior chest wounds and virtually all mediastinal wounds can be covered with the omentum based on both sets of gastroepiploic vessels. The arc of transposition is increased when the omentum is based on a single pedicle, allowing coverage of virtually all chest-wall defects. The final method of increasing flap length involves division of the gastroepiploic arch and reliance on Barkow's marginal artery as collateral circulation to maintain flap viability. With regard to chest-wall reconstruction, we have included the omentum in the armamentarium of flaps used to cover mediastinal wounds. The omentum is our flap of choice for the reconstruction of most radiation injuries of the chest wall. The omentum may also be used to provide protection to visceral anastomoses, vascular conduits, and damaged structures in the chest, as well as to cover defects secondary to tumor excision or trauma. In brief, the omentum has proved to be a most dependable and versatile flap, particularly applicable to chest-wall reconstruction.

Pitfalls in the surgical treatment of moyamoya disease. Operative techniques for refractory cases

Eleven cases of moyamoya disease refractory to indirect non-anastomotic revascularization, including encephalomyosynangiosis in two, encephaloduroarteriosynangiosis in seven, and encephalomyoarteriosynangiosis in two, are described. The patients suffered from recurrent cerebral ischemic symptoms, and further operative intervention, including superficial temporal artery-middle cerebral artery anastomosis and intracranial omental transplantation, was performed. The choice of operative maneuver depended on the availability of scalp arteries and on the nature of the ischemic symptoms. Although indirect non-anastomotic revascularization procedures have the advantage of technical ease and most patients respond to these procedures alone, there are some patients like the 11 presented here who are not cured by such procedures. In such cases, direct anastomotic revascularization is necessary for the prevention of stroke.

Hemodynamic characteristics of the vertebrobasilar system in moyamoya disease: a histometric study

Two autopsy cases of adult moyamoya disease were investigated by histometric and histopathologic techniques and the findings compared with those in three normotensive and five hypertensive controls in order to clarify the hemodynamic characteristics of the vertebrobasilar system in this disease. A thorough histologic examination of the vertebral and basilar arteries revealed that the fundamental arterial structures were well preserved in the vertebrobasilar system, unlike in the internal carotid system. A histometric study disclosed that the mean thickness of the media was considerably greater than that in comparable arteries of normotensive controls. From these observations, it was suggested that the essential arterial alterations in the vertebrobasilar system in moyamoya disease were hypertensive in nature and that this might be due to the increased pressure load on this system to compensate for the occlusive state of the internal carotid system. The medial hypertrophy in the vertebrobasilar system, even after massive medial atrophy in the carotid system, was impressive and suggestive of the complexity of hemodynamic changes and consequent tissue responses in this moyamoya disease.

Ocular symptoms of moyamoya disease

We examined four patients with moyamoya disease who had ocular symptoms. The diagnosis of the disease was based on an abnormal vascular network in the cerebral basilar region, observed by carotid angiography. One patient had amaurosis fugax. A second patient demonstrated bilaterally decreased visual acuity and visual spatial agnosia. The other two patients had homonymous hemianopsia; one also had transient diplopia and the other had temporal pallor of the optic disks. We found that patients with moyamoya disease exhibited various ocular symptoms but had few abnormal intraocular findings.

Choline acetyltransferase activity in omental tissue

Choline acetyltransferase (ChAT), the enzyme responsible for the formation of ACh from choline and acetyl-coenzyme A, is a marker of cholinergic function and is significantly depressed in the brains of Alzheimer patients. It has been shown that omental tissue contains several neuroactive substances and causes revascularization when placed upon the brain of stroke patients. In this study, it was demonstrated that omental tissue exhibits specific ChAT activity. This activity was choline-dependent, inhibited by N-ethylmaleimide (a known ChAT inhibitor), and was characterized by kinetic parameters consistent with values for the neuronal enzyme. It is suggested that omental placement to the brain together with oral choline administration might prove to be useful for increasing ACh synthesis in Alzheimer's disease.