Cutaneous vasoconstriction as a measure of incipient autonomic dysreflexia during penile vibratory stimulation in spinal cord injury

Study design:Measurement of haemodynamic responses, cutaneous blood flow and sweat release during penile vibratory stimulation (PVS) in spinal cord-injured men.Objective:To assess the validity of using markers of sympathetic activity (cutaneous blood flow and sweat release) as a measure of incipient autonomic dysreflexia during PVS in spinal cord-injured men.Setting:Prince of Wales Medical Research Institute, Australia.Subjects:Ten spinal cord-injured men with injuries ranging from C3 to T6.Methods:Continuous arterial pressure, intermittent auscultation, heart rate (HR), respiration, cutaneous blood flow and sweat release from both finger and toe were recorded during PVS.Results:Vibration of the penis caused immediate cutaneous vasoconstriction, but negligible sweat release, in the hands and feet of the quadriplegics and the feet of the paraplegics. Systolic blood pressure (BP) increased by up to 90 mm Hg, and a compensatory vagal bradycardia was observed in five of the six quadriplegics and two of the four paraplegic subjects.Conclusion:Given that there wasin generalan inverse relationship between BP and skin blood flow, we conclude that continuous measurements of skin blood flow above and below the lesion can provide important information on the state of the sympathetic nervous system and early identification of reflexly evoked increases in sympathetic vasoconstrictor drive, below a spinal lesion. Coupled with a decrease in HR, this cutaneous vasoconstriction infers an increased BP.