T2-weighted three-dimensional turbo spin-echo MR of intracranial aneurysms.

A T2-weighted three-dimensional turbo spin-echo sequence is described that accurately depicted the anatomy of 18 intracranial aneurysms in 10 patients.

Anatomy of the facial and vestibulocochlear nerves in the internal auditory canal.

PURPOSE: To define the anatomy of the facial and vestibulocochlear nerves in the internal auditory canal on parasagittal CT scans of cadaveric specimens and to compare this anatomy with findings on in vivo T2-weighted two-dimensional fast spin-echo and three-dimensional turbo spin-echo MR images. METHODS: Thirty-eight formalin-fixed cadaveric temporal bones were examined with 1-mm-thick contiguous parasagittal CT sections to determine the anatomy of the nerves in the internal auditory canal. Ten specimens underwent limited dissection. Fourteen canals in 12 patients were examined with T2-weighted two-dimensional fast spin-echo oblique parasagittal MR imaging and 12 canals in 8 patients were examined with T2-weighted three-dimensional turbo spin-echo MR imaging. The anatomy depicted on MR images was compared with the cadaveric anatomy. RESULTS: On cadaveric specimens, the facial nerve coursed superior and anterior to the vestibulocochlear nerve as a tubular structure throughout the length of the canal. The vestibulocochlear nerve entered the canal as a tubular structure but became crescent shaped in cross section in the middle portion of the canal and separated into individual nerves only in the most lateral portion of the canal. The anatomy of the nerves differed among the specimens. Similar anatomy was demonstrated by MR imaging. CONCLUSION: The ability to define the nerves in the internal auditory canal in the parasagittal plane may provide greater sensitivity and specificity in identifying abnormalities of this anatomic structure.

Analytic framework for evaluation of telemedicine.

This paper discusses two conceptual models intended to facilitate research on the effects and effectiveness of telemedicine. The first is a conceptual framework to study the efficacy of telemedicine as a diagnostic medium. Using conditions that are carefully chosen to serve as indicators of effectiveness, we recommended the analysis of sensitivity and specificity to establish the accuracy of telemedicine in relation to conventional health care delivery. Suggested guidelines for interpretation of the results are discussed. The second model is a scheme for classification of telemedicine applications that is based on processes of care rather than on specialties or disorders. The purpose of this classification scheme is to facilitate research on such variables as costs, access, acceptability, and effects on practice patterns.

Effects and effectiveness of telemedicine.

The use of telemedicine has recently undergone rapid growth and proliferation. Although the feasibility of many applications has been tested for nearly 30 years, data concerning the costs, effects, and effectiveness of telemedicine are limited. Consequently, the development of a strategy for coverage, payment, and utilization policy has been hindered. Telemedicine continues to expand, and pressure for policy development increases in the context of Federal budget cuts and major changes in health service financing. This article reviews the literature on the effects and medical effectiveness of telemedicine. It concludes with several recommendations for research, followed by a discussion of several specific questions, the answers to which might have a bearing on policy development.

Influences of NREM sleep on the activity of tonic vs. inspiratory phasic muscles in normal men.

Studies of sleep influences on human pharyngeal and other respiratory muscles suggest that the activity of these muscles may be affected by non-rapid-eye-movement (NREM) sleep in a nonuniform manner. This variable sleep response may relate to the pattern of activation of the muscle (inspiratory phasic vs. tonic) and peripheral events occurring in the airway. Furthermore, the ability of these muscles to respond to respiratory stimuli during NREM sleep may also differ. To systematically investigate the effect of NREM sleep on respiratory muscle activity, we studied two tonic muscles [tensor palatini (TP), masseter (M)] and two inspiratory phasic ones [genioglossus (GG), diaphragm (D)], also measuring the response of these muscles to inspiratory resistive loading (12 cmH2O.l-1.s) during wakefulness and NREM sleep. Seven normal male subjects were studied on a single night with intramuscular electrodes placed in the TP and GG and surface electrodes placed over the D and M. Sleep stage, inspiratory airflow, and moving time average electromyograph (EMG) of the above four muscles were continuously recorded. The EMG of both tonic muscles fell significantly (P less than 0.05) during NREM sleep [TP awake, 4.3 +/- 0.05 (SE) arbitrary units, stage 2, 1.1 +/- 0.2; stage 3/4, 1.0 +/- 0.2. Masseter awake, 4.8 +/- 0.6; stage 2, 3.3 +/- 0.5; stage 3/4, 3.1 +/- 0.5]. On the other hand, the peak phasic EMG of both inspiratory phasic muscles (GG and D) was well maintained.(ABSTRACT TRUNCATED AT 250 WORDS)