Neural reflex pathway between cervical spinal and sympathetic ganglia in rabbits: implication for pathogenesis of cervical vertigo

BACKGROUND CONTEXT: A functional association between cervix and vertigo has been observed in patients with cervical vertigo, implicating correlation between cervical spinal and sympathetic ganglia. However, it is unclear where there is an anatomic connection between those two groups of ganglia. PURPOSE: This study aimed to investigate the existence of the neural connections between cervical spinal and sympathetic ganglia. STUDY DESIGN/SETTING: FluoroGold staining patterns in cervical spinal and sympathetic ganglia were evaluated using FluoroGold retrograde tracing in New Zealand rabbits. METHODS: New Zealand rabbits were randomly divided into superior cervical spinal ganglion injection groups, inferior cervical spinal ganglion injection groups, superior cervical sympathetic ganglion injection group, and inferior cervical sympathetic ganglion injection group. Four percent FluoroGold solution was injected into these ganglia. Distribution of FluoroGold in cervical spinal and sympathetic ganglia was observed under a microscope. RESULTS: When FluoroGold solution was injected into C2 and C3 superior cervical spinal ganglia or C5-C6 inferior cervical spinal ganglia, fluorescence was only observed in the ipsilateral superior or inferior cervical sympathetic ganglia, respectively. When FluoroGold solution was injected into superior or inferior cervical sympathetic ganglia, fluorescence was found mainly in the ipsilateral C3-C4 superior or C5-C8 inferior spinal ganglia. No fluorescence was observed in contralateral ganglia of experimental animals and all ganglia of matched control animals injected with physiological saline. CONCLUSIONS: Bidirectional nerve fiber connections between cervical spinal and sympathetic ganglia were observed, and these connections are arranged in a segmental distribution. This observation may provide a possible neuroanatomic basis for the pathogenesis of cervical vertigo. (C) 2014 Elsevier Inc. All rights reserved.