ABSTRACT
Purpose:
Myofascial
trigger points (MTrPs) are the main cause of
myofascial pain syndrome (MPS), and
patients with MPS also have symptoms of sympathetic
abnormalities. Consequently, this study aimed to investigate the potential relationship between MTrPs and sympathetic nerves. Materials and
Methods:
Twenty-four seven-week-old
male rats were randomly divided into four groups (six
rats every group). Groups I and II were kept in normal condition (n=12), and groups III and IV underwent MTrPs modelling (n=12). After successful MTrPs modelling, differences in sympathetic outcomes between the MTrPs groups (III and IV) and non-MTrPs groups (I and II) were observed. Sympathetic blockade was then applied to groups III and I (n=12). Data were collected on peak inversion spontaneous potentials (PISPs) and the
H-reflex-evoked
electromyography during spontaneous discharge at the MTrPs before and after sympathetic blockade.
Results:
Systolic
blood pressure, diastolic
blood pressure,
mean arterial pressure, and
heart rate were significantly higher in the MTrPs group than in the non-MTrPs group (P<0.05). Compared with group I, group III had the PISPs potential lower
wave amplitude, shorter duration and amplitude-to-duration ratio, and lower H latency and latency difference H-M (P<0.05). Compared with group IV, group III had the PISPs potential lower
wave amplitude, duration, amplitude-to-duration ratio, M-
wave latency, H maximum
wave amplitude, and maximal
wave amplitude ratio H/M (P<0.05). The changes before and after sympathetic blockade in the MTrPs group were significant, and the amplitude, duration, and amplitude-to-duration ratio of the PISPs potentials were lower after the blockade (P<0.05).
Conclusion:
MTrPs and sympathetic nerves interact with each other forming a specific relationship. MTrPs sensitize sympathetic nerves, and sympathetic nerve
abnormalities affect local
muscle myoelectric hyperactivity, leading to MTrPs. This finding is instructive for the clinical management of sympathetic disorders.