Biomedical subjects

L A Mack

Publications and source records attributed to L A Mack.

At least 73 records · Page 4Linked to original sources

PubMed1988

Exencephaly--clinical and ultrasonic correlation to anencephaly.

The antenatal sonographic diagnosis of exencephaly in four gestations is reported. Exencephaly is an uncommon malformation of the cranium that characteristically involves a large, disorganized mass of cerebral tissue. The flat bones of the calvaria are absent, leaving the brain mass uncovered. Secondarily, anencephaly may develop as a result of prolonged exposure of the developing encephalon to amniotic fluid and trauma in utero. As in anencephaly, facial structures and the bony base of the calvarium are often preserved in exencephaly. Sonographically, the outstanding feature of exencephaly is the cerebral mass, with convolutions or "pseudo" sulcal patterns present. These findings correlate well with the pathologic examination and define a clinical entity that is incompatible with human life.

Anencephaly↗

PubMed1988

Fetal rhombencephalon: normal US findings.

Using ultrasound (US), the authors examined 25 embryos that were 8-10 menstrual weeks old for gestational age and the presence of a small cystic structure (3-4 mm) in the posterior aspect of the cranium. This structure was seen in all embryos. The US images of an in vitro embryo at 8 weeks menstrual age were also evaluated for anatomic correlation. Analysis of these US images determined that the cystic structure was the open rhombencephalon or hindbrain. Follow-up US studies or postpartum clinical examinations of the 25 in utero embryos demonstrated no abnormal posterior cranial cystic structures or neurologic deficits. This first-trimester structure should be considered a normal finding, since it develops into the normally proportioned fourth ventricle after the 11th menstrual week.

Female↗

PubMed1988

Abnormalities of fetal cranial contour in sonographic detection of spina bifida: evaluation of the "lemon" sign.

Previous reports have shown that visualization of the "lemon" sign on fetal cranial sonograms may indicate the presence of spina bifida before 24 weeks. To further characterize this sign and determine whether other factors might be associated with it, the authors retrospectively (n = 31) and prospectively (n = 19) evaluated 50 fetuses with spina bifida. The lemon sign was noted in 32 (64%), including 24 of 27 (89%) fetuses evaluated before 24 weeks. The presence of both ventricular dilatation, found in 41 (82%) of the fetuses, and a lemon sign correctly predicted spina bifida in all but one case. The location of the spinal defect and other anomalies were not associated with the lemon sign. The lemon sign is an important indicator of spina bifida, particularly in high-risk pregnancies, and should improve sonographic detection of spina bifida before 24 weeks.

Female↗

PubMed1988

Early pregnancy complications: endovaginal sonographic findings correlated with human chorionic gonadotropin levels.

Endovaginal sonography results were compared with quantitatively determined human chorionic gonadotropin (hCG) levels in 84 women referred for early pregnancy complications. Of the 27 with normal intrauterine pregnancies, an intrauterine gestational sac was prospectively identified in one of five cases (20%) in which hCG levels were below 500 IU/L (Second International Standard), four of five (80%) with hCG levels of 500-1,000 IU/L, and all 17 with hCG levels above 1,000 IU/L. In comparison, 17 of the 26 women with ectopic pregnancies (65%) had hCG levels greater than 1,000 IU/L, and none of the 26 had an intrauterine gestational sac. Endovaginal sonography demonstrated an adnexal mass and/or a gestational sac-like structure in 16 of the 17 cases (94%) in which hCG levels were above 1,000 IU/L, compared with only three of the nine (33%) with lower hCG levels (P less than .01). These findings indicate that an intrauterine gestational sac should be normally visualized with endovaginal sonography when the hCG level exceeds 1,000 IU/L, and that visualization of an extrauterine gestational sac and/or adnexal mass is significantly more likely in ectopic pregnancies when the hCG level exceeds 1,000 IU/L.

Abortion, Incomplete↗

PubMed1988

Suspected leaking abdominal aortic aneurysm: use of sonography in the emergency room.

To determine the value of sonography in the emergent evaluation of suspected leaking abdominal aortic aneurysms, the authors examined 60 patients in the emergency department using sonography and a protocol involving advance radio notification from the ambulance; arrival of sonographic personnel and equipment in the triage room before patient arrival; and, during other triage activities, rapid sonographic evaluation of the aorta for aneurysm and of the paraaortic region for extraluminal blood. Sonographic findings were correlated with surgical results and clinical outcome. When performed under these circumstances, sonography was accurate in demonstrating presence or absence of aneurysm (98%), but its sensitivity for extraluminal blood was poor (4%). A combination of sonographic confirmation of aneurysm, abdominal pain, and unstable hemodynamic condition resulted in the correct decision to perform emergent surgery in 21 of 22 patients (95%). An abbreviated sonographic examination done in the emergency room can provide accurate, useful information about the presence of aneurysm; this procedure does not significantly delay triage of these patients.

Aorta, Abdominal↗

PubMed1988

Mild idiopathic lateral cerebral ventricular dilatation in utero: sonographic evaluation.

The authors prospectively studied 20 fetuses with mild dilatation of the lateral cerebral ventricles but no other detectable central nervous system abnormality. One case (5%) occurred in a diabetic pregnancy, and three (15%) involved twin pregnancies. Fifteen (75%) fetuses were male, and one (5%) had trisomy 21. Postnatal follow-up at 15-31 months showed a normal outcome in eight cases (40%), an uncertain prognosis in four cases (20%), and death in eight cases (40%). Serial antenatal sonograms were obtained in 17 cases. Among the eight cases with a normal outcome, seven demonstrated no additional sonographic abnormalities and six showed resolution of the ventricular dilatation antenatally. Conversely, all 12 fetuses with demise or an uncertain prognosis demonstrated additional sonographic abnormalities, and six showed stable or progressive ventricular dilatation on follow-up sonograms. Since mild idiopathic lateral ventricular dilatation has a widely variable prognosis, antenatal detection of this finding warrants search for additional findings and follow-up sonography.

Adult↗

PubMed1988

Sonography of the postoperative shoulder.

Fifty-three patients with 60 symptomatic shoulders underwent shoulder sonography for recurrent postoperative symptoms after either acromioplasty (10 shoulders) or repair of a full-thickness rotator cuff tear in addition to acromioplasty (50 shoulders). Because surgery distorts landmarks, an understanding of the surgical procedures and their characteristic sonographic appearances is essential. After acromioplasty, the characteristic sharp margination or the acromion was replaced by a less distinct, irregular surface. After repair of a cuff tear, characteristic sonographic appearances included visualization of a reimplantation trough and loss of the echogenic subdeltoid bursa. When the cuff was intact after surgery, echogenicity was abnormal in all cases (17 shoulders). Sonography accurately diagnosed recurrent cuff tears in all 26 shoulders in which surgical proof was available and confirmed an intact cuff in 10 of 11 cases. In one shoulder, a cuff hematoma was incorrectly interpreted as a full-thickness tear. These findings suggest that sonography is an effective procedure for evaluating a postoperative patient with recurrent shoulder symptoms.

Acromion↗

PubMed1988

The Dandy-Walker malformation prenatal sonographic diagnosis and its clinical significance.

To determine the usual sonographic findings and clinical significance of the Dandy-Walker malformation (DWM) identified in utero, we reviewed seven proven cases diagnosed by prenatal ultrasound during a 6-year period. All patients demonstrated complete or partial absence of the cerebellar vermis and a posterior fossa cyst. Other central nervous system (CNS) findings included hydrocephalus (five cases) and agenesis of the corpus callosum (one case). Extra-CNS abnormalities were prospectively identified in 3 of 4 fetuses with multiple anomalies. Chromosomal analysis was performed on all four fetuses with multiple extra-CNS anomalies, yielding 2 abnormal karyotypes (trisomy 18 and mosaic trisomy 13). Fetal mortality was directly dependent on the presence of extra-CNS anomalies. Five fetuses ultimately died, including all four with multiple extra-CNS anomalies. The remaining two patients are alive at 1.5 and 6 years of age. We conclude that DWM has a distinctive sonographic appearance that can be identified by prenatal ultrasound and that identification of DWM should initiate a careful search for concurrent anomalies as well as consideration of chromosomal analysis.

Abnormalities, Multiple↗

PubMed1988

Value of the yolk sac in evaluating early pregnancies.

To determine the potential value in identifying a yolk sac in women with suspected ectopic pregnancies, 211 consecutive women who were referred to pelvic sonography with this clinical indication were prospectively studied. Of the 211 patients examined, 104 proved to have a normal intrauterine pregnancy (IUP), 59 had an abnormal (nonviable) IUP, and 48 had a surgically-proven ectopic pregnancy. Considering only intrauterine "sacs" that lacked a visible embryo, a yolk sack was identified in 16 of 26 (62%) normal IUPs, and 3 of 19 (16%) abnormal IUPs, but was not seen in any of six pseudo-gestational sacs in women with ectopic pregnancies. In comparison, a double decidual sac (DDS) finding was thought to be present in 24 of 26 (92%) normal gestational sacs, 12 of 19 (63%) abnormal gestational sacs, and 2 of 6 (33%) pseudogestational sacs. We conclude that in women in whom a living embryo is not identified, demonstration of a yolk sac is reliable evidence for early IUP, and virtually excludes the possibility of an ectopic gestation. Although a yolk sac is less frequently observed than a DDS finding, it is also more specific evidence for an IUP. Careful attention to the yolk sac should permit earlier, more reliable diagnoses of IUP than previously possible.

Female↗

PubMed1988

Prenatal diagnosis of agenesis of the corpus callosum.

The prenatal sonographic findings in seven cases of agenesis of the corpus callosum (AGCC) are reported. Findings that suggest AGCC on standard transverse views of the fetal cranium are emphasized. All seven cases demonstrated ventricular abnormalities including four fetuses (57%) who demonstrated laterally displaced lateral ventricles and/or disproportionate enlargement of the occipital horns. Two additional fetuses demonstrated a large midline fluid collection, representing a dilated third ventricle. The remaining case demonstrated atypical findings of a septated periventricular cystic mass. Following birth, additional malformations were found in 5 of the 7 fetuses (71%), including one fetus with trisomy 8. We conclude that AGCC can be suggested on the basis of prenatal sonographic findings and that awareness of typical findings should permit more frequent detection of this anomaly in utero. Due to the frequency of concurrent anomalies, identification of AGCC should initiate a careful search for additional malformations.

Agenesis of Corpus Callosum↗

PubMed1988

Significance of a single umbilical artery in fetuses with central nervous system malformations.

To determine whether the presence of a single umbilical artery (SUA) is useful information for evaluating fetuses with known central nervous system (CNS) malformations, the present study reviewed 107 consecutive cases of fetal CNS malformations (hydrocephalus, meningomyelocele, Dandy-Walker malformation, and holoprosencephaly) identified by prenatal sonography. Of the 107 fetuses studied, 20 (18%) had a SUA noted at the time of delivery or autopsy and 87 (81.3%) had two umbilical arteries. Of the 20 fetuses with a SUA, six were prospectively recognized on sonography, six were identified retrospectively, and eight could not be evaluated due to oligohydramnios or technical factors. All 20 fetuses with a SUA had extra-CNS anomalies and 8 of 15 (53%) fetuses tested had chromosomal abnormalities. These rates were significantly higher (P less than .05) than observed in 87 fetuses with two umbilical arteries who had extra-CNS anomalies in 35 cases (39%) and chromosomal abnormalities in 11 of 45 (24%) cases tested. We conclude that identification of a SUA in combination with a CNS anomaly should suggest the presence of additional extra-CNS anomalies and is an indication for chromosomal analysis.

Abnormalities, Multiple↗

PubMed1988

Sonographic evaluation of the rotator cuff. Accuracy in patients without prior surgery.

Since 1982 a sonographic technique has been devised to evaluate the integrity of the rotator cuff. In a series of 139 shoulders in 134 consecutive patients without prior surgery, sonographic results were correlated with surgical findings and/or arthrography. When sonography was compared with surgical findings (n = 90 shoulders), the overall accuracy was 95%. The sonographic diagnosis was the same as the arthrographic diagnosis in 91% of the cases (n = 50). Cuff lesions were also created in two cadavers, and images were made to confirm sonographic appearances. Because in the authors' experience sonography is accurate, safe, painless, rapid, and inexpensive, it has now been adopted as the primary study for the examination of the rotator cuff at the authors' institution. Arthrography is recommended in cases in which sonography is negative but there is significant clinical evidence of rotator cuff tear.

Arthrography↗

PubMed1988

Sonographic evaluation of the rotator cuff.

This article emphasizes the utility of ultrasound examination in the diagnosis of rotator cuff disease. A complete description is given of the way in which ultrasound examination of the shoulder is performed, the illustrations demonstrating normal anatomy as well as staging of the disease. The use of ultrasound in this setting can help to prevent a great deal of the pain associated with shoulder injury by establishing the nature and stage of injury before rotator cuff tear occurs.

Humans↗

PubMed1988

Ultrasonography of the knee.

Sonography is a useful modality in the diagnosis of a wide variety of knee disorders, including lesions of the articular cartilage, tendons and ligaments, menisci, synovial space, and adjacent vessels and muscles. Sonography is noninvasive, rapidly performed, widely available, readily accepted by patients, uses no ionizing radiation, and is relatively inexpensive compared to other conventional imaging studies of the menisci, making it a potentially attractive screening examination for knee injuries. Although it is difficult to state the exact place of sonography in the diagnostic workup of knee disorders, we feel that sonography is vastly underutilized. With additional refinements in ultrasound technology and scanning techniques, we expect further expansion of its role in the evaluation of the knee.

Humans↗

PubMed1988

Histologic evolution of the reactions to hemorrhage in the premature human infant's brain. A combined ultrasound and autopsy study and a comparison with the reaction in adults.

With the development and routine use of real-time ultrasound scanning, it has been possible to collect 20 autopsy cases of infants in whom the ultrasound scan was first normal and then showed evidence of subependymal/intraventricular hemorrhage (SEH/IVH). Analysis of these cases with known postnatal origin of the hemorrhage permitted the development for the first time of a time scale to characterize the temporal evolution of the histopathologic reactions to hemorrhage in the premature human brain. This time scale was then used to define the histologic stage of the lesions in 27 other cases of infants who had a scan demonstrating SEH/IVH prior to death but who had not a previously normal scan. Only 2 cases were found to lie off the original scale, indicating a prenatal onset of the hemorrhage in about 5% of the total cases. Thus, postnatal events immediately preceding the onset of the hemorrhage are more likely to be implicated in the pathogenesis of SEH/IVH than prenatal or obstetric events. Comparison with similar reactions in the adult indicate that the early reactions by macrophages occur at about the same rate but the routine transfer of iron from macrophages to astrocytes and the much slower rate of absorption to form a cyst in the adult combine to form a complicated pattern that requires a different set of criteria for the intermediate and late stages in the adult.

Adult↗

PubMed1987

Does "physiologic" mitral valve prolapse occur with acute blood loss?

Intravascular volume changes are reported to affect the clinical and echocardiographic spectrum of patients with known mitral valve prolapse syndrome (MVPS). We tested whether acute blood loss can produce MVP in normal adults. Twenty-one subjects were studied with Doppler echocardiography before and after donating 550 ml whole blood. Two subjects demonstrated minimal (1+) prolapse postphlebotomy, but in only one echocardiographic view, and without mitral regurgitation by Doppler. Three subjects demonstrated slight, early (not late or pansystolic) mitral regurgitation after phlebotomy, but without prolapse. Left atrial dimensions decreased significantly after the blood donation but the left ventricular size was not significantly smaller. The 1+ MVP is within the range of superior systolic motion found in 35% of a normal population, free of heart disease, and without intervention. We find no evidence in our study or in the literature that pathologic degrees of MVP can be produced in normal subjects by physiologic alteration in blood volume.

Blood Volume↗

PubMed1987

Efficacy of thromboresistant umbilical artery catheters in reducing aortic thrombosis and related complications.

Previous in vitro and in vivo reports suggest that catheters constructed of polyurethane with heparin bonded to the surface (HB-PU) are less thrombogenic than catheters made of polyvinyl chloride (PVC). A randomized trial sufficiently large (power 80%) to detect a reduction in the incidence of umbilical artery (UA) catheter complications, including aortic thrombus formation, from 45% to 20% was conducted in 125 infants. The infants were monitored for complications possibly related to the use of a UA catheter, such as systemic hypertension and abnormalities of lower extremity perfusion. The presence of aortic thrombi was assessed by ultrasound study 3.5 +/- 1.2 (SD) days and 11.1 +/- 2.3 days after insertion of the catheter. The use of HB-PU umbilical catheters did not lead to a significant reduction in the incidence of complications and aortic thrombi compared with the use of PVC catheters. The lack of reduction may have been related to the prolonged duration of catheter use in both groups. A much larger study would have been required to detect a smaller, but perhaps clinically significant, reduction in catheter-associated complications.

Aorta↗

PubMed1987

Cross-sectional imaging method. A system to compare ultrasound, computed tomography, and magnetic resonance with histologic findings.

Studies comparing imaging modalities require a precise knowledge of the type and location of tissue structures. When comparing cross-sectional techniques such as ultrasound, computed tomography, and magnetic resonance imaging, the images must be obtained through the same tissue section that is examined histologically. An experimental system that permits comparison of these modalities with histologic sections of precisely corresponding tissue is described. Application in 30 gastrointestinal tissue specimens shows a high degree of correspondence between cross-sectional images and histologic sections. This method should be useful in tissue imaging research for anatomic correlation and for comparisons between imaging modalities.

Digestive System↗