A Simple Interscalene Block: The Manani's Technique. Some Elements of Distinction from Supraclavicular Perivascular Techniques

Aim: The aim of this study is an anatomical review regarding the brachial plexus and its relationships with contiguous anatomical structures to better define the Interscalene Brachial Plexus Block Technique already described by Manani (IBPBTM), specifically concerning the point of needle penetration, needle direction and its relationship with OmoClavicular Triangle (OCT) and the inferior belly of omohyoid muscle. Moreover, IBPBTM was compared with other Supraclavicular Perivascular Brachial Plexus Block Techniques (SPBPBT). Materials and methods: The IBPBTM was performed in 80 randomly selected patients scheduled for shoulder surgery. After identification of the OCT and inferior belly of omohyoid muscle, fascial click perception and evocation of adequate muscular contractions, injection of 30 ml of 0.5% bupivacaine in the interscalene space (IS) was performed; the angles delimited by the penetrating needle on the transverse and frontal planes, going across the cutaneous penetration point, were measured and recorded. Moreover, the time of complete anaesthetic block development and failure rate were evaluated by means of an electric stimulation applied on the skin of C3-T1 dermatomes. Results: In almost all patients identification of the OCT, omohyoid inferior belly muscle and fascial click perception were possible. The stimulating needle resulted to be directed with a 14.0±5.2 and -5.1±1.3 degree angle to the frontal and transverse planes going across the cutaneous penetration point, respectively. Deep surgical blocks developed more rapidly on C3, C4 and C5 dermatomes, with respect to the C6, C7, C8-T1 dermatomes. Failure rate was about 8%. Discussion and conclusions: Our results confirm the efficacy of the IBPBTM and provide new insight for a better performance of this block, specifically regarding to the needle penetration angles, the identification of precise anatomical landmarks (OCT and omohyoid inferior belly muscle). The block efficacy was dependent on a correct performance, including the identification of the IS located medially, behind and above the OCT; on the contrary, in the SPBPBT the needle penetration points are located inside the OCT. From this comparison IBPBTM seems to be superior to SPBPBT in shoulder and peri-shoulder surgery.