Surgical decompression of thoracic outlet syndrome; is it a worthwhile procedure?

During a 20-year period from 1974 to 1994, 37 thoracic outlet decompressions were performed. There were 28 females and six males (ratio 5:1). The median age was 37 years (range 15-64). Symptoms were predominantly neurological in 29 limbs (78%), arterial in five limbs (14%) and venous in three limbs (8%). Limb pain and paraesthesia were the most common symptoms. Surgical decompression was performed via a supraclavicular approach in 24 limbs (65%) and a transaxillary approach in 13 limbs (35%). A cervical rib was excised in 21 limbs (57%), a first rib in 10 limbs (27%), a cervical and first rib in one limb (3%) and a cervical band in five limbs (13%). Arterial reconstruction was only required in three limbs (8%). There were a total of four complications (11%). The outcome of surgical decompression was assessed by using a questionnaire completed by the patient. Overall 27 patients (87%) felt that the operation was worthwhile. These results show that surgical decompression for thoracic outlet syndrome is a worthwhile procedure and is associated with relatively few complications.

Trends in abdominal aortic aneurysms: a 13 year review.

AIM: To assess changing trends of abdominal aortic aneurysms 1979-1991. DESIGN: Retrospective study from the Leicestershire Health Authority. RESULTS: 727 patients with abdominal aortic aneurysm were treated. Of these 56.4% were admitted for elective repair and 43.6% presented with rupture. There was a significant increase in the number of ruptured aortic aneurysms over this period despite an increase in the number of elective repairs. The overall 30-day mortality of elective repair (including patients with symptomatic but non-ruptured aneurysms) was 8.8%. The overall 30-day mortality of ruptured aneurysms (including patients who were deemed medically too unfit for surgery) was 57.7%. There has been no significant change in elective and ruptured mortality over the study period. There was a significant increase in the median age of patients (69.5 yrs in 1979 to 74 yrs in 1991). CONCLUSION: The increasing incidence of abdominal aortic aneurysms may reflect better diagnostic methods, greater clinical awareness of the condition and increase in the proportion of elderly people in the population.

Metabolic effects of neuropeptide Y injections into the paraventricular nucleus of the hypothalamus.

The metabolic effects of single injections of neuropeptide Y (NPY) into the paraventricular hypothalamus were investigated in an open-circuit calorimeter. Wistar rats were tested, with no food available during the tests. Over the dose range of 10-156 pmol NPY had large effects on respiratory quotient (RQ) while having no effect on energy expenditure or locomotor activity. The effects of NPY on RQ were unusual both in respect to their dose-response and time-dose-response characteristics. The lowest dose (10 pmol) produced a very low latency reduction in RQ which indicates a decreased utilization of carbohydrates as an energy substrate. The next higher dose (20 pmol) had no effect, whereas the next three doses (39, 78 and 156 pmol) produced increases in RQ which indicate an increased utilization of carbohydrates as an energy substrate. Surprisingly, the latencies of the increased RQs were dose-dependent over the range of 30 min to 20 h with the highest dose producing the longest latency effect. The finding of a positive relation of dose to response latency over a time range of from a few minutes to 20 h is unprecedented and appears to represent a neuromodulatory effect of NPY that acts in concert with its neurotransmitter effects. These data highlight the central role of NPY in modulating energy substrate utilization and indicate the importance of elucidating time-dose-response relationships when investigating the effects of NPY.

Environment-specific conditioning produced by electrical stimulation of the lateral hypothalamus.

Rats received noncontingent electrical stimulation of the lateral hypothalamus on one side of a place preference apparatus and no stimulation on the other side. Subsequently, when allowed access to both sides, the rats spent more time on the side associated with stimulation. This change in preference was only found in rats receiving stimulation in the side least preferred prior to conditioning trials. It was further shown that the place preference conditioning procedure produces increased locomotor activity. Thus, the place preference obtained was not an artifact produced by a conditioned freezing response. These data suggest that both the reinforcing and activating effects of lateral hypothalamic stimulation may be conditioned to a specific environment. Some methodological problems of the place preference paradigm are discussed.

The intrinsic and interactive effects of RO 15-4513 and ethanol on locomotor activity, body temperature, and blood glucose concentration.

The ability of the putative ethanol antagonist RO 15-4513 to antagonize ethanol - induced hypoactivity, hypothermia and hyperglycemia was investigated in rats. Although RO 15-4513 produced hypoactivity by itself, it attenuated ethanol - induced hypoactivity. This antagonism suggests that ethanol - induced hypoactivity is mediated by the GABA-benzodiazepine receptor complex which is thought to be the site of action of RO 15-4513. In contrast, although RO 15-4513 produced hypothermia by itself, it had no significant effect on ethanol - induced hypothermia. This suggests that the hypothermic effect of ethanol is not mediated by the GABA-benzodiazepine receptor complex. The fact that RO 15-4513, ethanol and the vehicle all produced hyperglycemia suggests a common stress effect and does not permit any firm conclusions to be drawn as to the interaction between ethanol and RO 15-4513 in modulating glycemic responses. These data indicate that the ethanol antagonism of RO 15-4513 is primarily confined to ethanol's behavioural effects and that ethanol's behavioural and physiological effects are mediated by neurochemically distinct mechanisms.