Cardiovascular responses to static muscle contraction in patients with brachial plexus injury treated with intercostal nerve transfer

 

Katsuya Yamauchi¹,Yukihide Nishimura², Takashi Mizushima¹, Fumihiro Tajima³, Hiroshi Irisawa¹, Fumie Kajiwara⁴, Hiroshi Koyama², and Akira Nagano²

¹Department of Rehabilitation Medicine, Hamamatsu University School of Medicine; ²Department of Orthopedic Surgery, Hamamatsu University School of Medicine; ³Department of Rehabilitation Medicine, Wakayama Medical University; ⁴Department of Rehabilitation, Seijo University

 

Pressor response is carried in afferent fibers of somatic nerves to increase blood pressure (BP) and heart rate (HR) on static exercise in human. However there is no information of peripheral responses restore muscle contraction with nerve transfer operation. We assessed isometric exercise-induced pressor responses in patients with brachial plexus injury (BPI) after intercostal nerve transfer (ICNT) to restore elbow flexor muscles.  Seven subjects with BPI treated with ICNT were measured BP and HR during 2-minute sustained isometric muscle contraction of elbow flexors at 20% and 35% of maximal voluntary contraction (MVC) on the unaffected side and ICNT side.  BP and HR during elbow flexors at 20% of MVC on the unaffected side were similar to those recorded before and after the exercise.  However, the same variables increased significantly during similar type exercise at 35% MVC on the unaffected side. On the ICNT side, no significant differences were noted at 20% and 35% MVC. Exercise at 35% of MVC did not induce pressor and HR changes on the ICNT side. The difference could be due to incomplete recovery of afferent nerve function following nerve repair, despite the restoration of efferent nerve function.

 

Keywords: exercise-induced pressor responses, brachial plexus injury, afferent nerve