Dichoptic luminance beat visual evoked potentials in the assessment of binocularity in children.

Direct evidence of a distinct cortical binocular pathway has been provided by the production of nonlinear (difference) beats from dichoptic luminance stimulation in stereonormal adults and the absence or diminution of these beats in stereoblind subjects. We have investigated a clinically useful application of this technique in a pediatric population with potentially abnormal binocular vision. We recorded dichoptic luminance beat visual evoked potentials (VEPs) from 20 children (ages 7 months to 8 years) with abnormal binocular ability secondary to strabismus and/or amblyopia and compared this to a control group of 20 children with normal binocularity. Stereoblind children generated significantly lower dichoptic signal-to-noise ratios than stereonormal children (P < .001). Responses to monoptic multifrequency flicker were not significantly different between the two groups (P = .936). This dichoptic VEP can be performed quickly and easily on young children and gives a quantitative assessment of cortical binocularity that may not be determinable by standard clinical methods. This technique may also prove useful for the preoperative gradation of binocular potential and prediction of postoperative binocular fusion.

One state's response to the malpractice insurance crisis: North Carolina's Rural Obstetrical Care Incentive Program.

In the period 1985-89, there was a severe drop in obstetrical services in rural areas of North Carolina, partly because of rising malpractice insurance rates. The State government responded with the Rural Obstetrical Care Incentive (ROCI) Program that provides a malpractice insurance subsidy of up to $6,500 per participating physician per year. Enacted into law in 1988, the ROCI Program was expanded in 1991, making certified nurse midwives eligible to receive subsidies of up to $3,000 per year. To participate, practitioners must provide obstetrical care to all women, regardless of their ability to pay for services. Total funding for the program has increased from $240,000 to $840,000, in spite of extreme budgetary constraints faced by the State. The program and how its implementation has maintained or increased access to obstetrical care in participating counties are described on the basis of site visits to local health departments in participating counties and data from the North Carolina Division of Maternal and Child Health. The program is of significance to policy makers nationwide as both a response to rising malpractice insurance rates and reduced access to obstetrical care in rural areas, and as an innovative, nontraditional State program in which the locus of decision making is at the county level.

Optic neuropathy and central nervous system disease secondary to Sjögren's syndrome in a child.

The authors describe a 10-year-old girl in whom optic neuropathy and central nervous system (CNS) disease developed in association with primary Sjögren's syndrome. There was angiographic evidence of cerebral vasculitis and multiple infarcts present on neuroimaging. Results of parotid biopsy, cerebrospinal fluid, and serologic analyses showed abnormalities that were consistent with the diagnosis of Sjögren's syndrome. Although the patient had optic disc pallor on initial evaluation, her color vision and acuity improved with immunosuppressive therapy, as did her other neurologic symptoms. The authors believe this represents the first reported case of optic neuropathy and CNS disease associated with primary Sjögren's syndrome in the pediatric population. The possibility of improvement in visual function with early institution of immunosuppressive therapy makes prompt diagnosis essential.

Computed and conventional arthrotomography of the glenohumeral joint: normal anatomy and clinical experience.

The glenohumeral joint was studied in 25 cadavers and 136 patients using computed arthrotomography (CAT) and conventional arthrotomography (AT) to assess shoulder instability. Cadaver shoulders were injected with air or latex, sectioned with a band saw, and normal articular anatomy outlined. CAT was performed in 81 patients and characterized the glenoid labrum as normal, abnormal, or detached in 38 of the 44 patients who had surgery or arthroscopy (sensitivity, 96%; accuracy, 86%). Hill-Sachs defects were seen in 20 out of 29 patients with anterior labral abnormalities, while bicipital tendon abnormalities were evident on CAT in 6. Of 55 patients who had AT, the status of the labrum was clarified in 13 of the 16 patients who had surgery or arthroscopy (sensitivity, 86%; accuracy, 81%). Both methods can characterize the labrum; however, CAT is more comprehensive and appears ideal for both detection of Hill-Sachs defects and imaging the bicipital tendon. CAT requires less technical expertise and radiation than AT and is tolerated better by patients in pain.

Newborn screening for phenylketonuria: predictive validity as a function of age.

Data from questionnaires were assembled for 109 infants with phenylketonuria (PKU) and 114 control infants to assess the predictive validity of newborn screening for PKU as a function of age. Patients with PKU had values of less than 4 mg/dL in cord blood and in samples from days 1, 2, and 4 through 7. The proportion of patients with PKU expected to fall below screening cutoffs of 2, 4, and 6 mg/dL was predicted for each age range. Using a cutoff of 4 mg/dL, approximately one third of patients with PKU would be missed by a sample taken from the neonate in the first 12 hours of life, and nearly 10% would be missed with a sample from the second 12 hours of life. This study shows that not all patients with PKU will be detected by newborn screening, and that the phenomenon of early nursery discharges must be considered in developing appropriate screening strategies.

Arthrography of the shoulder.

Arthrography of the shoulder is a simple, safe, and relatively painless diagnostic procedure that is used to demonstrate the integrity, shape, and capacity of the glenohumeral joint space.

Multiple-lead QRS changes with exercise testing. Diagnostic value and hemodynamic implications.

To evaluate the diagnostic potential and hemodynamic significance of exercise-induced multiple-lead QRS changes, we studied exercise test responses in 230 patients with chest pain syndromes undergoing Bruce protocol exercise tests. When increases in the R waves of multiple ECG leads (epsilon R) plus ST segment change greater than 1 mm were present, 74 of 75 patients (99%) had coronary disease; this was a higher percentage than that achieved with either measurement alone or when ST change was combined with increase in R in a single lead. Sixty-four of the 75 patients (85%) had multivessel disease, the most severe form of coronary artery disease. Left ventricular end-diastolic pressure (both at rest and after left ventriculography), presence and degree of resting ventricular asynergy, and ejection fraction were all significantly more abnormal in patients whose epsilon R increased, regardless of ST-segment change. Further, in patients who stopped exercise because of cardiac symptoms, exercise duration and the product of heart rate times blood pressure were significantly lower when epsilon R increased. Thus, the mechanism for the increase in epsilon R with exercise in patients with coronary artery disease appears to be related to abnormalities in left ventricular function.

Right ventricular diastolic pressure in coronary artery disease.

Right ventricular hemodynamics were evaluated in 179 patients with coronary artery disease to determine the effects of chronic ischemia on right ventricular diastolic pressure. Abnormal right ventricular filling pressures occurred only in patients with an abnormal right ventricular systolic pressure or an abnormal left ventricular end-diastolic pressure. Of the 63 patients whose right ventricle was stressed by an increased systolic load secondary to passive pulmonary hypertension, 44 (72 percent) had an abnormal right ventricular end-diastolic pressure. In this group obstruction of vessels serving the right ventricular free wall or septum, or both, was almost universal (43 of 44, 98 percent) and a significantly increased incidence of inferior infarction (P less than 0.05) was noted. Such obstruction was significantly less frequent in patients with normal filling pressures (10 of 17, 59 percent; P less than 0.001). Compared with patients with coronary artery disease, patients with passive pulmonary hypertension due to aortic stenosis or mitral stenosis had significantly greater degrees of pulmonary hypertension (P less than 0.05) yet slightly lesser elevations of right ventricular end-diastolic pressure. These data suggest that in patients with ischemic heart disease the right ventricle exhibits diastolic dysfunction at lower levels of afterload stress than it would with normal coronary blood flow.

A multivariate approach for interpreting treadmill exercise tests in coronary artery disease.

To determine the value of a multivariate approach for the analysis of the treadmill exercise tolerance test (ETT), 237 patients referred for evaluation of chest pain who underwent a standard Bruce protocol ETT and coronary arteriography were studied. Predictive value of a positive ETT was 0.78 (43/55) using 1.0--1.9 mm ST segment depression criterion, 0.97 (59/61) using greater than or equal to 2.0 mm ST segment depression. When the 1.0--1.9 mm ST criterion was combined with peak systolic blood pressure-heart rate product (double product) less than or smaller than 23,000, exercise duration less than 6 minutes, and ST depression for greater than 3 minutes into recovery, predictive value improved to 0.89 in 18 patients with any two of the above. Predictive value for multivessel disease was also improved using non-ST criteria. Predictive value of a negative ETT for absence of coronary artery disease was 0.60 (29/48), and was 0.86 (12/14) if double product was greater than or equal to 30,000. Presence of chest pain during ETT did not improve predictive value of any type of test. Digitalis ingestion in 33 patients was not associated with decreased predictive value of a positive test. These data suggest that the predictive value of both positive and negative ETT in a symptomatic population can be improved with a multivariate approach.

Phenylalanine metabolism and intellectual functioning among carriers of phenylketonuria and hyperphenylalaninaemia.

All members of 63 families who had phenylketonuric or hyperphenylalaninaemic offspring received a phenylalanine tolerance test and an individual intelligence test. Parent carriers (heterozygotes, n=115) displayed a significant relationship (canonical correlation R=0.75, P is less than 0.05) between their ability to metabolise phenylalanine and their intellectual strengths and weaknesses. Mothers of hyperphenylalaniaemic children did not show this relationship. The number of carrier children (n=40) was too small for multivariate or sex analysis, but significant bivariate correlations were found for this group.