Intracranial abnormalities in infants treated with extracorporeal membrane oxygenation: imaging with US and CT

Findings at neuroimaging in 100 consecutive infants treated with extracorporeal membrane oxygenation (ECMO) are presented. Imaging in these infants consisted of pretreatment cranial ultrasonography (US), daily US studies while on ECMO, and follow-up cranial computed tomography (CT) after treatment. There were findings of abnormalities in 43 patients. Thirty had intracranial bleeding, often of unusual extent and distribution. Thirteen additional infants had nonhemorrhagic abnormalities alone. Bleeding considered to be major was seen in 12% of infants. Large parenchymal hemorrhages and infarcts, cerebellar hemorrhages, and diffuse edema were the most significant abnormalities, with a 50% mortality (eight of 16 patients). No lateralization was noted with respect to distribution of bleeding sites or areas of nonhemorrhagic abnormalities. US was a sensitive but imperfect screening tool for intracranial abnormalities. Abnormalities missed with US included peripheral and small parenchymal lesions, subarachnoid hemorrhage, cerebral atrophy, and sagittal sinus thrombosis.     

Frequency, severity, and physiologic importance of carotid siphon lesions

Atherosclerotic stenosis of the intracranial portion of the internal carotid artery (SIPHON) may be the cause of neurologic symptoms. The frequency and severity of these lesions were studied in 226 vessels subjected to conventional two-plane carotid angiography, and the impact of sequential or tandem lesions on cerebral flow was assessed in the 167 arteries from this group that also underwent Gee oculoplethysmography (OPG-Gee), a commonly accepted indicator of the physiologic importance of internal carotid stenosis. Atherosclerotic involvement of the SIPHON was present in 46% (103/226) of the vessels studied, including six total occlusions, 11 severe stenoses (severe, 80% to 99% area reduction [AR]), 27 moderate stenoses (moderate, 50% to 79% AR), 40 mild stenoses (mild, 10% to 49% AR), and 19 instances of mural disease (MUR). This was compared with a 73% rate (166 of 226) of proximal internal carotid artery (PICA) stenosis in the neck, including six to 43 severe, 29 moderate, 50 mild, and 38 MUR. There was little correlation (r = 0.33) between the degree of angiographic stenosis in the PICA and the SIPHON. All of the totally occluded arteries had a positive OPG-Gee, whereas a positive study was noted in only 6% (7 of 109) of the arteries with less than moderate stenosis in the PICA. Twenty-one vessels had moderate stenosis of the PICA. Eight of these arteries had an associated moderate or severe lesion in the SIPHON, and seven of eight (88%) had a positive OPG-Gee. The remaining 13 of this subset had had a normal or mildly diseased SIPHON, and 12 of 13 (92%) had a normal OPG-Gee.(ABSTRACT TRUNCATED AT 250 WORDS)     

Objective measurement of limb perfusion by dermal fluorometry. A criterion for healing of below-knee amputation

Quantitative fluorometry has been recommended as an accurate adjunct to clinical judgment in the preoperative assessment of lower-extremity amputation level. In this prospective study of 56 patients who had below-knee amputation, clinical judgment was used as the sole criterion for site selection. Quantitative fluorometry was compared with clinical judgment in a prospective, blinded study. All patients were studied before amputation with administration of intravenous fluorescein. Fifteen minutes after injection, objective measurement of dye fluorescence was performed at multiple sites with a quantitative fluorometer, and a dye fluorescence index was derived. All limbs undergoing amputation were ischemic, manifested by rest pain, nonhealing ulcers, or gangrene. Five patients (8.7%) failed to heal at the below-knee level. The mean dye fluorescence index for the group that healed was 81 +/- 51 (range, 13 to 259) and for the group that failed to heal, 110 +/- 49 (range, 70 to 195). Objective measurement of fluorescein perfusion did not correlate with amputation healing at the below-knee level in our patient population.     

Chondromalacia patellae: assessment with MR imaging

Magnetic resonance (MR) images of the posterior patellar hyaline articular cartilage were obtained in 23 subjects to determine if MR imaging could accurately demonstrate the patellar cartilage. Arthroscopy was used as the standard of reference. Three subjects were asymptomatic volunteers. In the remaining 20 who had patellofemoral pain, arthroscopy was performed before MR imaging in seven and afterward in 12; one did not undergo arthroscopy. MR imaging showed focal areas of swelling of the patellar cartilage, focal hypointensity, surface irregularity, areas of thinning, and areas of cartilage loss with exposure of subchondral bone. The surgical findings agreed with those from MR images in all seven patients who underwent arthroscopy before MR imaging and in ten of the 12 who underwent surgery afterward. MR imaging is an accurate means of examining the posterior patellar cartilage and should be considered as an alternative to diagnostic arthroscopy when chondromalacia patellae is suspected.     

Mediastinal tumors: biopsy under US guidance

Percutaneous biopsies of mediastinal tumors were successfully performed under sonographic guidance in 14 of 21 patients. In 10 of 11 malignant lesions, malignancy was determined by means of cytologic and histologic examination of the specimens obtained. A histologic diagnosis was reached in seven patients with malignant mediastinal tumors, including all four cases of Hodgkin lymphoma. Mediastinal biopsy under sonographic guidance is a technically simple, rapid, and accurate procedure, but its application is limited to tumors of the anterior mediastinum.     

The effects of calcium hydroxide on dentin permeability

Calcium hydroxide paste was applied to human dentin in vitro to determine its effects on dentin permeability. Discs of dentin were acid-etched on both sides to permit determination of their maximum permeability. Smear layers were then applied to the enamel sides of the discs, thereby reducing dentin permeability 99%. Topical application of Ca(OH)2 paste to the smear layer reduced dentin permeability further, to levels 48% below that of untreated smear layers. When the Ca(OH)2-treated smear layers were exposed to 6% citric acid for two min, dentin permeability returned to the initial acid-etched value, demonstrating that Ca(OH)2 offers little protection to acid challenge. Treatment of acid-etched dentin with Ca(OH)2 produced a similar reduction in dentin permeability, which was restored to normal following acid challenge. Thus, Ca(OH)2 is effective at reducing the permeability of both the smear layer and of acid-etched dentin, in vitro.