Background and Objectives The precise fascial space through which the injectate spreads during stellate ganglion block (SGB) remains unclear. Recent studies using magnetic resonance imaging or computed tomography have suggested that the injectate is deposited around and/or within the longus colli muscle during SGB. However, a fascial space, close to the longus colli, is the most likely route of spread. We identified the prevertebral interlaminal space (PVILS), situated between the anterior and posterior laminae of the prevertebral layer of the fascia, as an important route for the spread of the injectate and as a potential pathway to the ganglion. The danger of downward spread of deep infections through this space has previously been recognized.

Methods and Results Using the 6th cervical vertebra paratracheal approach technique, we performed experimental SGB with 10 mL latex on donated cadavers. Spreading of latex into the PVILS was observed in 45 of 52 (86.5%) cadavers that had been fixed with formaldehyde after death, and 5 of 8 (62.5%) fresh cadavers. In these experiments, the latex usually reached the ganglion via the PVILS (39 of 45 and 5 of 5, respectively). Moreover, after direct injection into the PVILS, latex reached the ganglion in 13 of a further 19 (68.4%) postmortem-fixed donated cadavers.

Conclusion These results suggest that the PVILS plays a critical role in the spread of injectate as well as being a potential pathway to the stellate ganglion during SGB.