Interscalene brachial plexus block: can the risk of entering the spinal canal be reduced? A study of needle angles in volunteers undergoing magnetic resonance imaging.

Background: Spinal cord damage during interscalene brachial plexus block has been attributed to needle entry into the spinal canal. The purpose of this study was to identify the angles and depths of needle insertion that increase the likelihood of such an event, using the traditional classic interscalene approach and two more proximal entry points.

Method: Magnetic resonance images of the neck from 10 healthy volunteers were used to obtain the three-dimensional spatial coordinates of three skin markers and the right-sided cervical nerves at the exiting neural foramina.

A study of the characteristics of single-injection insulated block needles in a biologic model.

Background And Objectives: Single-injection block needles are manufactured in many different lengths, diameters, and tip designs, but the literature contains no reports of methods to assess clinical characteristics of regional-block needles. A novel animal model for the assessment of the characteristics of single-injection regional anesthesia needles is described.

Methods: Nine different needles designed for peripheral nerve blocks that were fitted with identical hubs were used.