Baroreflex stimulation shows impaired cardiovagal and preserved vasomotor function in early-stage amyotrophic lateral sclerosis.

OBJECT

In ALS patients, autonomic nervous system dysfunction might account for an additional reduction of the quality and expectancy of life of individual patients and contribute to unexpected early fatalities. This study was undertaken to assess baroreflex-mediated vagal and sympathetic cardiovascular control of the heart and blood vessels in ALS patients.

METHODS

In 12 early-stage ALS patients (age 54 +/- 4 years) and 12 controls (age 55 +/- 3 years) we assessed resting baroreflex sensitivity (BRS) by spectral analysis, then stimulated the carotid baroreflex by oscillating neck suction at 0.1 Hz to assess the autonomic modulation of the heart and blood vessels and at 0.2 Hz to assess the effect of parasympathetic stimulation on the heart.

RESULTS

Resting heart rate was significantly higher in the ALS patients than in the controls (P < 0.05), but resting baroreflex sensitivity did not differ significantly between the groups. Stimulation at 0.2 Hz induced an oscillation in R-R interval that was significantly smaller (P < 0.05) in ALS patients than in controls. R-R interval responses to 0.1 Hz stimulation were significantly (P < 0.01) reduced in ALS patients compared to controls. Responses of blood vessels to 0.1 Hz stimulation did not differ significantly between the groups.

CONCLUSION

In early-stage ALS patients, BRS might be normal at rest. Only baroreflex activation reveals impaired cardiovagal responses while sympathetic vasomotor control is preserved. Treatment to restore sympathetic-parasympathetic balance to the heart could prevent early cardiovascular fatalities in some ALS patients.