Vertebral collapse in childhood leukemia.

Leukemia is the most common form of cancer in children. At the time of initial presentation, 10% of children have normal peripheral blood counts. Appendicular skeletal involvement occurs in approximately 50% of cases. The literature does not clearly define the incidence of spinal involvement, with only a total of 31 cases located in a review of the literature. If case reports are excluded and series that reported the frequency of spinal involvement are summarized, only 16 of 615 cases had spinal involvement. In only one of 31 was it clear that the patient had a normal peripheral blood count at the time of diagnosis. This article adds to the literature two patients who had normal peripheral blood counts and spinal involvement with acute lymphocytic leukemia. Patients with leukemia may have significant symptoms and radiographic signs with normal peripheral cell blood counts at the time of initial presentation.

Jefferson fractures: the role of magnification artifact in assessing transverse ligament integrity.

Thirty-five consecutive odontoid views were taken using a standardized technique. A 10-mm radiographic marker was positioned lateral to the tip of the C-1 transverse process. Data from three independent readers showed an 18% magnification error inherent to anteroposterior open-mouth odontoid radiographs. Integrity of the transverse ligament after Jefferson fractures has been inferred from the separation of the lateral masses measured on the odontoid view. Spence's anatomic study showed that lateral mass separation of > 6.9 mm implied rupture, but radiograph magnification was not taken into account. Transverse ligament rupture should not be inferred with lateral mass separation of < 8.1 mm.

Pulmonary clearance of encapsulated and unencapsulated Haemophilus influenzae strains.

A mouse model system was employed to investigate the temporal pattern of pulmonary clearance of Haemophilus influenzae and to evaluate the effect of the type b polysaccharide capsule on this clearance pattern. The lungs of BALB/c mice were inoculated with boluses of several different H. influenzae strains via an endobronchial catheter. A fully encapsulated H. influenzae type b strain multiplied readily in the lungs for at least 6 h and then was eventually cleared from the lungs over the next 18 h. The pulmonary clearance pattern obtained with an unencapsulated variant of this H. influenzae type b strain was identical to that obtained with the fully encapsulated parent strain. Two nontypable H. influenzae strains isolated by transtracheal aspiration of patients with acute H. influenzae pneumonia also multiplied in the lung and resisted significant clearance for at least 6 h after inoculation. Bolus deposition of either H. influenzae type b or nontypable H. influenzae in the lungs resulted in an eventual influx of polymorphonuclear leukocytes into the alveoli. The observed delay in clearance of all these strains suggests that resident host defense mechanisms must be augmented for clearance to occur. Furthermore, these data indicate that one or more factors other than the Haemophilus capsule are important bacterial determinants of pulmonary clearance of H. influenzae.