Posterior Vitreous Detachment and the Posterior Hyaloid Membrane.

PURPOSE: Despite posterior vitreous detachment being a common ocular event affecting most individuals in an aging population, there is little consensus regarding its precise anatomic definition. We investigated the morphologic appearance and molecular composition of the posterior hyaloid membrane to determine whether the structure clinically observed enveloping the posterior vitreous surface after posterior vitreous detachment is a true basement membrane and to postulate its origin. Understanding the relationship between the vitreous (in both its attached and detached state) and the internal limiting membrane of the retina is essential to understanding the cause of rhegmatogenous retinal detachment and vitreoretinal interface disorders, as well as potential future prophylactic and treatment strategies. DESIGN: Clinicohistologic correlation study. PARTICIPANTS: Thirty-six human donor globes. METHODS: Vitreous bodies identified to have posterior vitreous detachment were examined with phase-contrast microscopy and confocal microscopy after immunohistochemically staining for collagen IV basement membrane markers, in addition to extracellular proteins that characterize the vitreoretinal junction (fibronectin, laminin) and vitreous gel (opticin) markers. The posterior retina similarly was stained to evaluate the internal limiting membrane. Findings were correlated to the clinical appearance of the posterior hyaloid membrane observed during slit-lamp biomicroscopy after posterior vitreous detachment and compared with previously published studies. MAIN OUTCOME MEASURES: Morphologic appearance and molecular composition of the posterior hyaloid membrane. RESULTS: Phase-contrast microscopy consistently identified a creased and distinct glassy membranous sheet enveloping the posterior vitreous surface, correlating closely with the posterior hyaloid membrane observed during slit-lamp biomicroscopy in patients with posterior vitreous detachment. Immunofluorescent confocal micrographs demonstrated the enveloping membranous structure identified on phase-contrast microscopy to show positive stain results for type IV collagen. Immunofluorescence of the residual intact internal limiting membrane on the retinal surface also showed positive stain results for type IV collagen. CONCLUSIONS: The results of this study provide immunohistochemical evidence that the posterior hyaloid membrane is a true basement membrane enveloping the posterior hyaloid surface. Because this membranous structure is observed only after posterior vitreous detachment, the results of this study indicate that it forms part of the internal limiting membrane when the vitreous is in its attached state.

Acute necrotizing encephalopathy of childhood: typical findings in an atypical disease.

Acute necrotizing encephalopathy of childhood (ANEC) is a disease entity seen nearly exclusively in East Asian children that is characterized by multifocal, symmetric lesions involving the thalami, brainstem, cerebellum, and white matter. We present a child who developed dramatic neurologic symptoms following a viral prodrome. Serial MRI examinations demonstrated characteristic lesions of ANEC, while laboratory analyses revealed evidence of acute infection with human herpesvirus-6 (HHV-6). We highlight the MRI findings in both the acute and convalescent phases of ANEC, discuss the implications of neuroimaging on the child's clinical course, and emphasize the integral role of the radiologist in correctly diagnosing this rare disease.

Diverticular perforation masquerading as maxillary sinusitis.

Although diverticular perforation and diverticulitis is usually a straightforward diagnosis, an occasional case can be difficult. In this report, we describe a patient who initially presented with symptoms suggestive of maxillary sinusitis and hip fracture. Findings of subcutaneous craniofacial emphysema eventually led to the diagnosis of a perforated sigmoid diverticulum with abscess.

Transcatheter thrombolytic therapy for acute mesenteric and portal vein thrombosis.

PURPOSE: The purpose of this study was to evaluate the utility of transcatheter thrombolytic therapy in 20 patients with acute or subacute (symptoms <40 days) portal and/or mesenteric vein thrombosis with severe symptoms, deteriorating clinical condition, and/or persistent symptoms despite anticoagulation. MATERIALS AND METHODS: This retrospective study examined 12 male patients and eight female patients seen over a period of 11 years. The average age was 37.6 years. Four of the patients had previously undergone liver transplantation. An anatomic classification system was established to describe the extent of thrombus at the time of diagnosis. Patients were treated with thrombolytic therapy via the transhepatic route, common femoral vein route, and/or superior mesenteric artery route. Improvement in symptoms, avoidance of bowel resection, complications, and radiographic evidence of clot resolution were the main clinical outcomes. RESULTS: Fifteen of the 20 patients exhibited some degree of lysis of the thrombus. Three patients had complete resolution, 12 had partial resolution, and five had no resolution. Eighty-five percent of patients (n = 17) had resolution of symptoms. Sixty percent of patients (n = 12) developed a major complication. No patients required bowel resection after thrombolytic therapy. One patient died with gastrointestinal hemorrhage and septic shock 2 weeks after thrombolytic therapy. Other major complications included bleeding and conditions requiring transfusion. No patients developed new portal or mesenteric thromboses. Two of the patients who received transplants eventually required repeat transplantation. CONCLUSIONS: Transcatheter thrombolysis was beneficial in avoiding patient death, resolving thrombus, improving symptoms, and avoiding bowel resection. However, there was a high complication rate, indicating that this therapy should be reserved for patients with severe disease. Further evaluation of these techniques and outcomes should continue to be pursued.