Functional Pathway Between Cervical Spinal and Sympathetic Ganglia: A Neurochemical Foundation Between Neck Pain and Vertigo

Abstract

Background: Cervical vertigo commonly concurs in patients with neck pain, but the concurrent mechanism of these 2 symptoms still remains unclear. We previously reported a bidirectional segmental nerve fiber connection between cervical spinal and sympathetic ganglia, which provided a hypothesis that this connection between the 2 ganglia may be the anatomic basis for the concurrence of neck pain and cervical vertigo. However, this concurrent mechanism needs biochemical and functional evidence. Objectives: This study aimed to investigate a possible noradrenergic pathway between cervical spinal and sympathetic ganglia. Study Design: We performed both clinical and laboratory research. Clinical observation was a prospective case–control study. Setting: Clinical study took place in our hospital; laboratory study was in an orthopedic laboratory. Methods: Cervical lamina block therapy used in patients with cervical vertigo was clinically evaluated; norepinephrine (NE) expressions in cervical sympathetic ganglia were analyzed using immunohistochemical staining after electrical stimulation to the cervical spinal ganglia; the influence of phentolamine local injection to the vertebrobasilar artery flow was experimentally measured. Results: Cervical lamina block therapy could significantly shorten the clinical hospital stays of patients with cervical vertigo (P = 0.000) and improve vertebral artery flow (P < 0.05). NE expressions in superior cervical sympathetic ganglia (SCG) or inferior cervical sympathetic ganglia (ICG) increased significantly when ipsilateral C2 to C3 or C6 to C8 spinal ganglia were electrically stimulated, respectively. Adrenergic receptor block with phentolamine significantly inhibited the decrease of basilar artery (BA) flow induced by electrical stimulation of the cervical spinal ganglia. The change range of BA flow caused by stimulations of C2 to C3 and C6 to C8 spinal ganglia was more than that of C4 and C5. Limitations: The inpatients observed in this clinical study might be influenced by some factors including emotion, diet, sleep, and others. The limitations of the laboratory study included animal species and small sample size. Conclusions: Adrenergic system could play a part in cervical spinal ganglia altering the vertebrobasilar artery system. It could provide a neurochemical foundation between neck pain and vertigo, and that segmental functional connections exist between cervical spinal and sympathetic ganglia.