Sympathetic activity influences the vascular axon reflex in the skin.

The interaction between changes of skin blood flow evoked by centrally mediated reflexes and local axon reflexes was studied in healthy subjects. Axon reflexes were evoked on the dorsum of the hand by transcutaneous electrical stimulation and reflex changes of blood flow by changes of ambient temperature, deep breath and emotional changes of blood flow by changes of ambient temperature, deep breath and emotional stress. Skin blood flow was measured by two laser-Doppler flowmeters, the probes of which were situated 6-8 mm from the stimulating electrode (monitoring net flow responses) and several centimetres away (monitoring generalized reflex responses only). The axon reflex responses were markedly diminished by body cooling but did not change during body warming. In warm subjects, a deep breath and emotional stress caused transient reductions of the flow response evoked by the electrical stimulation. Regional anaesthesia of the nerve(s) innervating the stimulated skin area led to marked increases of axon reflex responses in cold subjects, but no changes occurred in warm subjects. The anaesthesia also eliminated the transient flow reductions evoked by deep breaths and emotional stress. Since the applied stimuli are known to change skin sympathetic activity, it is concluded that sympathetic (presumably vasoconstrictor) impulses destined for the skin may reduce axon reflex responses.

Early aneurysm surgery: a 7 year clinical practice report.

One hundred and fifty patients with intracranial aneurysms, operated on consecutively in the early stage in our department, were re-evaluated retrospectively. Seven surgeons operated on 159 aneurysms in 150 patients. Seventy-nine percent of the patients were in grades I-III (scale of Hunt and Hess), 21% in grades IV-V. Seventy-one percent had a severe haemorrhage (classification of Fisher et al.), 21% had an intracerebral haematoma. Intraoperative CSF drainage was an almost indispensable tool while postoperative external drainage did not prove to be helpful in preventing vasospasm and/or hydrocephalus. Induced hypotension was abandoned in favour of temporary clipping. Thirteen percent of the patients suffered a permanent or fatal immediate postoperative deterioration, while 11% developed delayed neurological deficits. Five percent were related to vasospasms alone, they were all transient. Five percent had vasospasm combined with other complications. One of them had permanent and the other one fatal deficits. One percent deteriorated due to embolism or occluded vessels. The results improved with the introduction of the calcium channel blocker nimodipine, induced hypertension and transcranial Doppler sonographic control of the vasospasm. Patients in good preoperative condition had a good early outcome in 69%. The result was fair in 21% and poor in 4%, while 6% of the patients died. In the poor condition group 22% of the patients made a good, 13% a fair, and 59% a poor recovery, 16% of whom died.(ABSTRACT TRUNCATED AT 250 WORDS)