Electrooculography and discriminant analysis in Duane's syndrome and sixth-cranial-nerve palsy

Eye-movement recordings may be helpful in the differentiation of Duane's syndrome from sixth-cranial-nerve palsy. Voluntary horizontal saccades were recorded and quantitated by electrooculography in 18 patients with unilateral type I Duane's syndrome and in 25 patients with sixth-nerve palsy. When ranges of abduction were matched, the peak velocities of abducting saccades in affected eyes were decreased equally in both groups. However, the peak velocities of adducting saccades in sound eyes were slowed in patients with Duane's syndrome. Because the standard deviations in saccadic velocities are large, computer-based, stepwise discriminant analyses were performed to identify the variables that proved to be useful in differentiating the two disorders. By entering these variables into the discriminant functions that were created, we could distinguish Duane's syndrome from sixth-nerve palsy in a statistically significant manner.This research was supported in part by a Manpower Award from Research to Prevent Blindness, Inc. (J.B.B.), the Dolly Green Research Scholar Award, RPB Inc. (R.D.Y.), and NEI grant EY068772 (J.B.B.) Offprint requests to: J. Bronwyn Bateman     

Predicting ocular irritancy and recovery from injury using Madin-Darby canine kidney cells

Two promising cell culture assays, using Madin-Darby canine kidney cells, for predicting eye irritancy, the fluorescein leakage assay and the neutral red release assay, have been adapted to try and assess the ability of damaged cells to recover from chemical-induced injury. The fluorescein leakage and neutral red release protocols are similar but measure injurious effects on different parts of the cells, namely the tight junctions and the cell membrane, respectively. Both endpoints have previously given equivalent rankings of chemicals in order of their eye irritancy potential. Sixteen compounds of varying irritancy potential and chemical nature were tested using the two assays. In both assays, little or no cell recovery was measured 72 hr after a mildly injurious exposure, although using the fluorescein leakage assay, five test agents displayed substantial recovery and two displayed significant deterioration of the cell layer after removal of the test material. Comparing these in vitro results with in vivo data suggests that the fluorescein leakage assay, in its current format, does not predict the likely recovery rate of ocular tissue after chemical damage.     

Acute unilateral pulmonary nonventilation due to mucous plugs

Acute bronchial obstruction by mucous plugs may be manifested clinically by dyspnea, hypoxemia, and respiratory alkalosis mimicking pulmonary thromboembolism. In eight cases with complete interruption of ventilation to an entire lung, chest radiography failed to reveal the extent of the obstruction. Perfusion was substantially less affected than ventilation. Routine ventilation-perfusion scintigraphy with technetium-99m DTPA aerosol aids in the diagnosis of acute major bronchial obstruction in patients with suspected pulmonary thromboembolism.