Evaluation with Heart Rate Variability for the Treatment Effect of Aminophylline in Patients with Bradycardia after Cervical Spinal Cord Injury: A Preliminary Study

After cervical spinal cord injury (SCI), the autonomic nervous system (ANS) becomes impaired and then, bradycardia can develop. In view of this, we performed to prescribe aminophylline as pharmacotherapy for bradycardia. The study population consisted of 36 patients with cervical SCI. Bradycardia developed in 20 patients (55.6%), of these patients, 8 showed spontaneous recovery. Twelve patients had persistent bradycardia, therefore, aminophylline was administered at 0.5 mg/kg/hr by intravenous infusion. Their average heart rate increased within 24 hours after the start of infusion. In heart rate variability analysis for 7 preliminarily selected patients, the spectral waveforms of “oligowave type” indicating ANS impairment tended to appear in relatively early phase after injury (i.e., 2 days to 2 weeks after injury), whereas “normal type” was observed in the late phase (i.e., at 4 weeks). “Sympathetic block type” was observed throughout the follow-up period (2 days to 4 weeks). “Sympathetic block type” was also observed in a non-bradycardic patient on day 2. These results underscore the importance of treating ANS impairment with aminophylline while keeping in mind that bradycardia can occur even in post-SCI patients without clinical manifestations.