Sympathetic vascular response to facial cooling is increased in flail phenotypes of amyotrophic lateral sclerosis.

Objective: To assess cardiovascular responses to cold face test (CFT) in patients with classic-onset ALS (bulbar or limb onset, ALS-C) and in patients with flail arm and flail leg phenotypes (FA/FL). Methods: In 18 ALS-C, eight FA/FL patients and 10 age-matched controls we continuously monitored heart rate (HR), systolic (SBP), diastolic (DBP) and mean blood pressure (MBP) during two-minute baseline and one-minute cold stimulus application. HR and BP responses to CFT were calculated as differences between the peak responses and baseline values (dHR, dSBP, dDBP, dMBP), as percent changes from baseline (dHR%, dSBP%, dDBP%, dMBP%), and also latencies and durations of HR and BP responses were assessed (Lat(HR), t(HR), Lat(BP), t(BP)). Results: There were no differences in baseline values of HR, SBP, DBP and MBP among ALS-C, FA/FL and controls (p>0.05). A decrease in HR and increases in SBP, DBP and MBP were observed in all subjects (p<0.05). However, in FA/FL, the magnitude of BP responses, i.e. dSBP, dSBP%, dDBP, dMBP, and dMBP% were significantly higher than in controls. Moreover, these BP responses occurred with a significantly shorter latency in FA/FL than in controls and ALS-C. Furthermore, duration of the BP changes was significantly longer in FA/FL than in ALSC. In contrast, ALS-C patients had a significantly longer Lat(HR) and shorter t(HR) than healthy persons. However, no significant differences were observed in dHR or dHR% among the three groups. Conclusions: Sympathetic vascular response to facial cooling is increased in flail phenotypes of ALS.