Post-stroke autonomic nervous system function: palmar sympathetic skin responses thirty or more days after...

We studied sympathetic nervous system (SNS) function after cerebrovascular accident (CVA) by measuring hypothenar sympathetic skin responses (SSR) to normal or hemiplegic arm electrical stimulation. We anticipated SNS function after CVA to be asymmetric and selected null hypotheses of bilaterally symmetric SSR latencies and amplitudes irrespective of side of stimulation and/or recording. Thirteen patients between ages 44 and 77 years (median 59) were tested between 1 and 72 months (median 15) after CVA. Hypothenar recording and dorsal reference surface electrodes were used. Amplifier bandwidth was set from 0.5 to 100 Hz. Gain was adjusted to allow adequate recognition of the waveforms. Sweep speed was set to 500ms/div. Stimulus width was set to 0.2 ms and intensity was increased stepwise from 10mA initially until optimum responses were obtained. Nonparametric statistics were used to analyze the data. SSRs were present in all patients on both the normal and the hemiplegic sides irrespective of the side of stimulation. Median SSR latency recorded homolaterally to the stimulus site was found to be 80ms shorter than median SSR latency recorded heterolaterally. Median SSR latency in left hemiplegics was found to be 16% longer than in right hemiplegics. Otherwise, neither side of hemiplegia, side of stimulation, side of recording nor any paired combination thereof were found to be significant. Our finding of bilaterally obtainable SSRs after CVA diverges from that of Uncini and colleagues but presumably only reflects the difference in poststroke chronology between the respective samples.