Radiological evaluation of the craniocervical junction in bone dysplasias and other related syndromes.

The craniocervical junction, a vital but anatomically complex region, presents additional interpretative challenges in patients with skeletal dysplasias and other syndromes involving the musculoskeletal apparatus. Our objective was to review the radiological evaluation used in such conditions; to do so, we identified retrospectively all of the occipitocervical studies done during the last 3 years at our institution on patients with skeletal dysplasias and related syndromes. The 28 cases thus found were reviewed and the different diagnostic modalities identified; the diagnostic findings were summarized and classified into osseous and soft tissue abnormalities. The standard criteria for cervical instability and cord compression were compared with measurements reported in our selected cases. The lateral radiograph of the cervical spine was the first diagnostic test, followed by additional flexion-extension views and sagittal spin-echo magnetic resonance imaging; no conclusive diagnostic criteria for occipitoatlantal instability in children with bone dysplasias were identified.

Diagnostic imaging update in skeletal dysplasias.

The mystique of bone dysplasias is gradually vanishing. A short historical overview introduces the subject of short stature. The pathogenesis and controversial classification of skeletal dysplasias are discussed and summarized in two tables; the use of different imaging modalities is laid out along the sequential diagnostic approach and review of common orthopedic complications. References to such advances in treatment as bone marrow transplantation, bone lengthening, and the encouraging positive effect of growth hormone therapy complete this updated revision.

Neonatal herpes simplex pneumonia: radiographic findings.

The radiologic findings in the lungs of 16 hospitalized neonates with disseminated herpes simplex infection were retrospectively reviewed. A sequential picture was devised of four stages in the evolution of the pneumonitis of this hematogenous infection. The radiologic stages were: Stage I, normal chest; Stage II, prominent perihilar interstitial markings; Stage III, coalescent areas of pulmonary infiltrates; and Stage IV, diffuse alveolar and interstitial disease ("white-out" lungs). In general, the pulmonary abnormalities were widespread and without air trapping. Pleural effusions were noted in one case. All affected neonates died and antemortem clinical and radiological findings were correlated with multiple-organ postmortem histopathologic evidence of viral infection, especially with the associated pneumonia.

A 40-Hz auditory potential recorded from the human scalp.

Computer techniques readily extract from the brainwaves an orderly sequence of brain potentials locked in time to sound stimuli. The potentials that appear 8 to 80 msec after the stimulus resemble 3 or 4 cycles of a 40-Hz sine wave; we show here that these waves combined to form a single, stable, composite wave when the sounds are repeated at rates around 40 per sec. This phenomenon, the 40-Hz event-related potential (ERP), displays several properties of theoretical and practical interest. First, it reportedly disappears with surgical anesthesia, and it resembles similar phenomena in the visual and olfactory system, facts which suggest that adequate processing of sensory information may require cyclical brain events in the 30- to 50-Hz range. Second, latency and amplitude measurements on the 40-Hz ERP indicate it may contain useful information on the number and basilar membrane location of the auditory nerve fibers a given tone excites. Third, the response is present at sound intensities very close to normal adult thresholds for the audiometric frequencies, a fact that could have application in clinical hearing testing.