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Fio. 1. Roentgenogram showing fracture-dislocation of C~ vertebral body anteriorly on C3 with complete avulsion of neural arch of the axis from the body. (Reprinted through the courtesy of Charles C Thomas and Kahn et al. 5} logical correlation has afforded a plausible concept of the mechanism involved in such fracture-dislocations. T h e victims of judicial hanging are naturally not available for study, but traffic victims with " h a n g m a n ' s fracture" m a y survive and thus permit the

We have developed and successfully used the first microprocessor-controlled monitors for collection of data on depth, heart rate, and body temperature of one fetal and five adult male freely swimming Weddell seals. Adult seals almost invariably experienced a prompt bradycardia at the start of each dive, and the mean heart rate during diving was significantly lower for dives greater than 20 min (P greater than 0.999). The heart rate was also significantly greater during the ascent portion of dives when compared with the descent portion (P greater than 0.95). The fetal seal experienced a slow onset of bradycardia when its mother dived; during diving the fetal heart rate decreased by an average of 1.1 beats/min for each minute of the dive. The fetal heart rate generally took approximately 10 min to recover to predive levels after its mother resurfaced to breathe. The body temperature of one adult male Weddell seal showed a decrease of greater than 1.5 degrees C from resting levels before dives of greater than 15 min were initiated and a drop of over 2 degrees C before dives of greater than 30 min duration.

Although the consumption of myoglobin-bound O2 (MbO2) stores in seal muscles has been demonstrated in seal muscles during laboratory simulations of diving, this may not be a feature of normal field diving in which measurements of heart rate and lactate production show marked differences from the profound diving response induced by forced immersion. To evaluate the consumption of muscle MbO2 stores during unrestrained diving, we developed a submersible dual-wavelength laser near-infrared spectrophotometer capable of measuring MbO2 saturation in swimming muscle. The probe was implanted on the surface of the latissimus dorsi of five subadult male Weddell seals (Leptonychotes weddelli) released into a captive breathing hole near Ross Island, Antarctica. Four seals had a monotonic decline of muscle O2 saturation during free diving to depths up to 300 m with median slopes of -5.12 +/- 4.37 and -2.54 +/- 1.95%/min for dives lasting < 17 and > 17 min, respectively. There was no correlation between the power consumed by swimming and the desaturation rate. Two seals had occasional partial muscle resaturations late in dives, indicating transfer of O2 from circulating blood to muscle myoglobin. Weddell seals partially consume their MbO2 stores during unrestrained free diving.

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In 412 patients undergoing surgery for herniated lumbar discs from September 1986 to September 1987 and from January 1988 to July 1989 a microbiological specimen was taken from the intervertebral disc space and from the cover of the operating microscope. Also the tips of the wound drains were examined microbiologically after removal. 17% of the patients had a positive bacteriological culture from their intervertebral disc space; 12% of the specimen from the operating microscope were positive. These results favour the hypothesis that intra-operative contamination of the disc space, in contrast to haematogenous spread, causes spondylodiscitis. On the other hand we saw during this time course only one case of clinical spondylodiscitis, which implies a possible involvement of other predisposing factors such as pre- or perioperative infections or compromised patient immunologically. It is also possible, that the routine application of local antibiotic or antiseptic solutions into the disc space at the end of the operation could decontaminate the operative site and prevent clinical infection despite positive culture findings.

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I N PATIENTS who have concomitant injuries of the head and neck the physician's attention is directed to the cranium when neurologic symptoms are present. This is particularly true when the trauma to the neck is of a blunt nonpenetrating type, and the neurologic manifestations simulating severe craniocerebral injury are not recognized as arising from thrombosis of the internal carotid artery. We wish to report 2 such cases recently encountered which demonstrate the challenge that this type of lesion presents to the physician in diagnosis and treatment. While only an occasional case of thrombosis of the carotid artery secondary to nonpenetrating injuries of the neck has been reported in the literature, the presence of embolism or thrombosis associated with penetrating wounds of the neck or cheek has been more frequently recognized, 2' 3' 4' 11' 16' 17' 18' e1,24,27,28,34 especially in war wounds of the last century22 In addition, 13 since cerebral angiography has been used more widely in the diagnosis of neurological abnormality, certain patients with no apparent trauma are found to have a spontaneous carotid artery thrombosis. Verneuil (187~) 88 was probably the first to report a case of thrombosis following a nonpenetrating injury of the neck: