Pediatric patients with achondroplasia: CT evaluation of the craniocervical junction

Twenty-six patients (4 months to 6 years old) with achondroplasia complicated by sleep apnea and/or other neurologic manifestations underwent plain computed tomography (CT) of the craniocervical junction; six also underwent CT myelography. For objectification, multiplanar reconstruction was used to complement axial plane measurements by providing coronal and sagittal measurements; multiplanar reconstruction also improved perception of the longitudinal relationships between the brain stem and subarachnoid space. A narrow subarachnoid space was found in all 26 patients; marked cord compression was present in nine, six of whom underwent CT myelography. These six had marked focal obliteration of the subarachnoid space on both plain CT and CT myelography. Since the subarachnoid space immediately above and below the craniocervical junction is normally capacious, when marked constriction was present, no additional information could have been gained from CT myelography. Thus, plain CT was shown to be sufficient for surgical planning (suboccipital decompression) in nine patients with cord compression due to achondroplasia.     

Thrombosis at venous insertion sites after inferior vena caval filter placement

Color Doppler flow imaging or compression ultrasound (US) was used to prospectively determine frequency of thrombosis at 54 venous insertion sites (47 in common femoral veins, seven in right internal jugular veins) after percutaneous placement of Greenfield filters for interruption of the inferior vena cava. Fifty-one filters were successfully placed in 51 patients with a dilator set or a balloon angioplasty catheter. Nine focal thrombi were detected in the common femoral vein (19%) and one in the right internal jugular vein (14%). Use of dilators induced eight thrombi (24%), compared with two (10%) from balloon catheters. The left common femoral vein had a high frequency of thrombosis, regardless of dilation technique (five of nine). Of nine patients with acute common femoral vein thrombosis, four became symptomatic within 10 days after the procedure. Patients may remain asymptomatic or have delayed symptoms; thus, US is valuable for determining patients at risk of thrombosis of the common femoral vein.     

Role of genetic factors in the etiology of juvenile-onset myopia based on a longitudinal study of refractive error.

In an attempt to determine the role of genetic factors in the development of myopia, we examined the relationship of infantile refractive error and parental history to juvenile-onset myopia and analyzed 43 pedigrees affected by juvenile-onset myopia. Refraction data collected at regular intervals from a sample of juvenile subjects participating in a 24-year longitudinal study of refractive error were used. Results showed that children with two myopic parents were 6.42 times as likely to become myopic as children with one or no myopic parents. Furthermore, children who had refractions in the lower half of the distribution at 6 to 12 months of age were 4.33 times as likely to develop myopia as children who had refractions in the upper half of the distribution at 6 to 12 months of age. The pedigree analysis indicated that 63% of individuals considered at risk for developing juvenile-onset myopia actually became myopic, with an equal number of affected males and females. These results suggest that juvenile-onset myopia of moderate amounts may be inherited as a complex trait involving both genetic and environmental factors.     

Epinephrine enhances analgesia produced by epidural bupivacaine during labor

Reports on the analgesic and hemodynamic effects of epinephrine added to bupivacaine for epidural use in obstetrics are conflicting. In this study, healthy parturients received in a random manner either 10 ml of 0.25% bupivacaine (n = 50) or 10 ml of 0.25% bupivacaine with 1:300,000 epinephrine (n = 50) epidurally. Epinephrine enhanced the analgesia produced by bupivacaine: onset was hastened (5.8 +/- 0.6 vs 8.7 +/- 0.8 min, mean +/- SEM, P less than 0.05), duration prolonged (123 +/- 7.0 vs 92 +/- 5.0 min, P less than 0.05), and the number of women requiring additional local anesthetic for analgesia decreased (9 vs 18, P less than 0.05) compared to the group receiving plain bupivacaine. The incidence of hypotension did not differ between groups. Maternal heart rate increased only after injection of the epinephrine-containing solution. The authors conclude that epinephrine 1:300,000 modestly but statistically significantly improves the analgesic efficacy of epidurally administered 0.25% bupivacaine during labor.