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Anterior access (according to Meier)

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The interscalene nerve block is a modification of the technique described by Winnie in 1970. In the classical technique of Winnie, the interscalene nerve block is performed at the posterior scalene gap. This puncture site is thus at the level of the cricoid. The puncture is made in the medial, dorsal and caudal direction. In the modified technique, by contrast, the puncture point is located at the height of the superior thyroid notch at the posterior edge of the sternocleidomastoid muscle. The puncture is directed caudad, slightly to the lateral and aims at the puncture site of the vertical-infraclavicular blockade (see Chapter 2.2). There are several reasons to prefer the modified technique: a lower risk of inadvertent vessel puncture (of the vertebral artery), the production of high spinal or peridural anaesthesia and the fact that more favourable conditions are created for placement of a catheter for the continuous block technique. In our department, we have replaced the classical interscalene technique according to Winnie with the modified technique for those reasons.

 

 

Anatomical landmarks

Superior thyroid notch, sternocleidomastoid muscle (posterior scalene gap)

interscalene

 

 

Block technique

The patient lies supine (without a pillow!) and the arm that is to be blocked is positioned comfortably on the abdomen. The head is turned slightly to the side. Briefly raising the head from the table may help to identify the posterior edge of the sternocleidomastoid muscle. The puncture point is located at the level of the superior thyroid notch at the posterior edge of the sternocleidomastoid muscle. Care should be taken with the external jugular vein, which is to be found in this region with a relatively high frequency. The direction of insertion is caudad, however with a discrete dorsal orientation relative to the body axis. After 3-4 cm, the upper trunk or portions of the lateral sheath are reached which becomes evident by contractions in the region of the biceps brachii muscle (musculocutaneous nerve). Inject the local anaesthetic after the threshold current (0.2-0.3 mA) is reached. Complete dissemination of the blockade takes between 10-15 minutes.