The Musculocutaneous Nerve in a High Resolution MRI

The investigators have made a favourable experience with the in 2006 published transarterial triple injection method [4]. This classic method combines the block effect of an axillary catheter injection (median nerve position) with a double transarterial injection at terminal nerve level in the axilla.

The investigators experience after a recent published MRI study [3], confirms that a proximal axillary local anesthetic injection via an axillary catheter, guided by nerve stimulator, is beneficial for the block effect. The MRI study was conducted using nerve stimulation and a transarterial technique. The proximal injection with an effect at cord level, combined with axillary injections at terminal nerve level, produce an effective block distal to the elbow.

The proximal injection has obviously an effect to the lateral cord and the musculocutaneous nerve (mcn) [3]. Recent studies have advocated that a double axillary injection method is sufficient for the axillary block [5, 6]. Their block techniques included a selective block of the mcn at terminal nerve level. The investigators MRI study [3] demonstrated a successful block effect (analgesia or anaesthesia) of the mcn nerve in all patients (15 of 15 patients) in the triple injection group without a selective block of this nerve. In the 1- deposit (catheter injection) and 2-deposit (transarterial injections) group, 11 of 15 patients (73%) had the mcn successful blocked.

The objective in this study (Article 4) is to examine the mean position of the mcn nerve and its relationship to the coracobrachial muscle. Can MRI indicate / predict that a proximal directed axillary catheter in median nerve position is beneficial in order to provide a successful mcn blockade? Is a selective injection to the mcn at terminal nerve level superfluous when a catheter is used?