Anterior Scalene Block Test for Thoracic Outlet Question

I have a thoracic surgeon sending me these for diagnostic purposes prior to first rib resection. Pts are very legit and have extensive imaging/workup with positive findings ahead of time. My question is this. On review of the literature, it seems there is some ambiguity. At times both the middle and anterior scalene muscles are blocked, and at times only the anterior scalene muscle. I am not sure which has better diagnostic value?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Pain Medicine Source Type: forums