Visual loss from arterial steal in patients with maxillofacial arteriovenous malformation.

OBJECTIVE: To determine whether an arterial "steal" from the ophthalmic artery accounts for the ocular manifestations associated with maxillofacial arteriovenous malformation (AVM) outside the orbit. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Seven patients with maxillofacial AVM who had been previously treated, unsuccessfully, with proximal ligation of the supplying external carotid artery branches were evaluated clinically and by superselective cerebral angiography. No cases had intraorbital arteriovenous shunting or abnormal venous drainage to the orbit. INTERVENTION: Endovascular embolization. MAIN OUTCOME MEASURES: Signs and symptoms of ocular ischemia were correlated with findings on cerebral/orbital angiography. RESULTS: Four of seven patients had signs of ocular ischemia. By selective angiography, these four patients were found to have a significant ophthalmic artery supply to the AVM. In contrast, the three patients without signs of ocular ischemia had minimal or no ophthalmic artery supply to the AVM. CONCLUSIONS: When the ophthalmic arterial blood supply is recruited, ophthalmic artery "steal" phenomenon occurs in patients with maxillofacial AVMs that do not directly involve the orbit. This mechanism appears to be the cause of ocular ischemia. It is possible that this "steal" is precipitated or worsened by previous surgical proximal ligation of external carotid arterial branches that are potential collaterals with the ophthalmic artery but fail to occlude the arteriovenous (AV) shunts.

Orbital avitene granuloma formation after enucleation for intraocular retinoblastoma.

PURPOSE: To report a case of orbital foreign body granuloma formation, mimicking tumor recurrence, secondary to the use of Avitene after enucleation for intraocular retinoblastoma. METHODS: Eight months after undergoing enucleation for retinoblastoma, a 21-month-old boy underwent a biopsy of an orbital mass. RESULTS: Histopathologic examination of the orbital biopsy specimen disclosed a proliferative granulomatous foreign body reaction surrounding multiple foci of a coarse fibrillar intercellular substance consistent with Avitene. No retinoblastoma cells were present. CONCLUSION: A foreign body reaction should be included in the differential diagnosis of orbital mass lesions after surgery in which Avitene is used.

Localization of alkaline phosphatase on basolateral plasma membrane of normal and regenerating retinal pigment epithelium. A cytochemical study in rabbits.

Ultrastructural cytochemistry was used to analyze the polarized distribution of alkaline phosphatase (AP) on the plasma membranes of normal and regenerating retinal pigment epithelium (RPE) and the ciliary body epithelium in rabbits. The AP activity was concentrated on the basolateral plasma membrane in normal RPE. In regenerating RPE (after intravenous administration of sodium iodate to damage the RPE), there was a differential expression of AP activity according to the site on the regenerating epithelial sheet. At the edge of the sheet, where cells were undifferentiated and immature (ie, without the polarized distribution of basolateral and apical plasma membrane specializations seen in normal RPE), no plasma membrane AP activity was observed. The AP activity was reexpressed more proximal in the regenerating sheet. It was first evident where contiguous cells formed junctional complexes and cytologic polarization again became apparent. New AP activity was restricted to the basolateral plasma membrane. Eventually, the polarized distribution of AP activity seen in normal RPE was reestablished. In the ciliary body, AP activity was localized to the basolateral plasma membranes of the outer, nonpigmented epithelial cells. It was concluded (1) that cytochemical activity for nonspecific AP is concentrated on the basolateral plasma membrane domain of normal RPE and the normal pattern of AP activity is lost initially and then reexpressed.

Expression of plasma membrane alkaline phosphatase in normal and regenerating choriocapillaris in the rabbit.

Ultrastructural histochemistry for plasma membrane nonspecific alkaline phosphatase was performed on the normal and regenerating choriocapillaris (CC) of rabbits. In normal animals the CC endothelium expressed little or no staining, whereas in regenerating CC the endothelium exhibited staining. The staining was most intense at the unfenestrated plasma membrane. As the capillaries matured and the fenestrated plasma membrane became more extensive, the staining was reduced and eventually eliminated. Pericytes did not stain in normal or regenerating CC.