Sympathectomy at the T2 level would block the afferent projection negative feedback to the hypothalamus, since it would section practically all afferent pathways, and would favor CH appearance at the periphery, due to the continuous efferent projections from the hypothalamus. Sympathectomy below this level would section a smaller number of afferent pathways, avoiding the feedback blockage and decreasing CH.
By understanding that CH is a result of a lack of negative feedback to the hypothalamus after sympathectomy, we found out that this side effect is more pronounced when sympathectomy is performed on the T2 ganglion, where there is greater convergence of afferent pathways to the hypothalamus. However, when the sympathectomy is more caudal, the adverse effect is less pronounced.(13,14)
