of study. The admission rate of those not wearing seat belts was 20%, compared to 9% among those who wore seat belts. The authors also noted that the number of internal injuries, fractures, and wounds was decreased, except for soft-tissue injuries of the neck and chest. Compliance rate has increased from 31% to 88% since the compulsory seat belt law began.

Douglas W Davenport, MD

scaphoid fracture, soft-tissue changes

Soft- t issue changes accompany ing recent scaphoid injuries Carver RA, Barrington MA Clin Radiol 36:423-425 Jul 1985

Two hundred consecutive cases of suspected scaphoid fracture were evaluated radiologically to correlate the pres- ence of fracture with soft-tissue signs on radiograph. Of 88 patients with normal soft tissues, none demonstrated a frac- ture on follow-up examination, although 54 wrists were casted for a min imum of 10 days. Of 27 patients with docu- mented scaphoid fractures, most had definitely abnormal soft-tissue findings over the dorsum of the wrist, and only 3 were equivocal. Dorsal wrist swelling was believed to be a more reliable radiographic sign for scaphoid fracture than was scaphoid fat pad. It was concluded that no fracture of the scaphoid is present if the soft tissues are totally normal and the injury is less than 48 hours old./Editor 's note: This appears to have been a retrospective radiological analysis with no direct correlation with the history or physical ex- amination. The standard of care, however, is to immobilize the wrist and thumb with a thumb spica cast or splint if snuff-box tenderness is present. Perhaps this practice could be modified in the future if further studies confirm that the absence of soft-tissue abnormalities indeed rules out a scaphoid fracture.]

Michael Hunt, MD

Trendelenberg position

Effect of body inversion on hemodynamics determined by two-dimensional echocardiography Jennings 7-, Seaworth J, Howell L, et al Crit Care Med 13:760-762 Sep 1985

Eight healthy normovolemic men were studied to deter- mine the effect of the Trendelenberg position on left yen-

t r icu la r f i l l ing pressure in the hear t . Blood pressure measurements and two-dimensional echocardiograms were obtained at baseline supine positions and immediately after inversion to 10 °, 30 °, 60 °, and 90 ° head-down positions in all subjects. Stroke volume and cardiac output calculations were d e t e r m i n e d for each p o s i t i o n t h r o u g h echocar- diographic measurements. There were no statistically sig- nificant differences in stroke volume, cardiac output, or blood pressure at any position except 60 °, at which a signifi- cant increase in diastolic pressure was noted. The authors postulate that an increase in left ventricular preload does not occur in normal patients placed in a head-down posi- tion because the heart is above the point of maximal ven- ous pooling. /Editor's note: In the setting of hypotension secondary to hypovolemia, left ventricular filling pressures will be decreased. This study does not address the poten- tial changes in stroke volume, cardiac output, or blood pressure produced by a head-down position in the hypo- volemic state. Left ventricular filling pressures may be m- creased to normal values in this setting.]

Kurt Duffens, MD

mitral valve prolapse, cerebral ischemic events

'~ Associat ion of mitral valve leaf let prolapse wi th cerebra l ischemic events in the young and early middle-aged pat ient Kouvaras G, Bacoulas G Q J Med 55:387-392 Jul 1985

The authors carried out a prospective study to determine an association between mitral valve prolapse and cerebral ischemic events in patients less than 50 years old. Twenty- three of 66 (35%) who suffered transient ischemic attacks on completed strokes were found to have mitral valve pro- lapse by echocardiogram. Eighteen (78%) of these 23 pa- tients had the typical auscultatory findings of a mid- to late systolic murmur and a midsystolic click at the left stemal border and apex. All of the others had either a murmur or click. In 16 (24%) of these, no other cause for the cerebral i schemia could be found. Three mechan i s ms , t h rom- bogenesis, bacterial endocarditis, and arrhythmia, are postu- lated. Noninfective thromboembolism is the most probable mechanism. No positive blood cultures were found, and the occurrence of focal neurological signs mitigates against ar- rhythmias. The authors conclude that mitral valve prolapse may be associated with cerebral ischemic event and should be looked for, but more studies are needed to evaluate treat- ment and the role of antithrombotic drugs.

Gerald J Estep, MD

15:1 January 1986 Annals of Emergency Medicine 97/155