IMPAIRMENT OF AUTONOMIC CARDIAC CONTROL IN PATIENTS WITH BULBAR AND SPINAL ONSET OF AMYOTROPHIC LATERAL SCLEROSIS
Background: Bulbar onset is associated with shorter survival than spinal onset ALS. The purpose of this study was to investigate differences of autonomic cardiac control between patients with bulbar and spinal onset.
Methods: Fifty five patients with sporadic ALS (28 women and 27 men; average age 56,00+10,34) were compared to 30 healthy controls (17 women and 13 men; average age 49,50+11,15). Fourty five patients had spinal and 18 patients had bulbar onset of ALS. Patients with previous history of cardiac disease and impaired respiratory function were excluded from the study. Cardiovascular autonomic reflex tests according to Ewing, five minute power spectrum analysis of heart rate variability (HRV), ten minute real time beat-to-beat ECG and blood pressure signal monitoring with HRV analysis at rest and baroreceptor function analysis were carried out in all patients at the beginning of the study. Time domain parameters of HRV, mean RR interval as well as presence of ectopic activity were obtained from 24-hour ECG monitoring.
Results: ALS patients with bulbar onset had a significantly higher score of parasympathetic dysfunction (p<0,05). Response to standing up was significantly altered in comparison to spinal onset patients (p<0,01). In contrast, sympathetic function. The overall score of autonomic dysfunction was also significantly higher in bulbar onset ALS patients (p<0,01). Both spectral and time domain parameters of HRV showed a more pronounced decrease of HRV in patients with bulbar onset, however these differences were not statistically significant. Baroreflex activity was lower in patients with bulbar onset in comparison to patients with spinal onset, but this difference was also not statistically significant.
Conclusion: The results of this study indicate that bulbar onset is associated with more pronounced parasympathetic dysfunction suggesting that the pathological process affects both motor and parasympathetic neurons in brainstem nuclei simultaneously.