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A tall and thin 15-year-old male patient presents for an arthroscopic capsuloplasty of the right shoulder for instability.


There are anterior, posterior, and multidirectional instabilities, with anterior instability being the most common. Anterior instability happens to young male patients; the humeral head subluxates or dislocates anteriorly and can injure the axillary nerve, which presents as weakness of the deltoid and numbness of the lateral aspect of the shoulder. Atraumatic subluxation is usually multidirectional and is associated with connective tissue disorders like Ehlers-Danlos syndrome, Marfan syndrome, and the like.

An interscalene nerve block will provide superior postoperative pain control. However, the interscalene block is almost 100% associated with a phrenic nerve block, resulting in a paralysis of the ipsilateral hemidiaphragm. This can lead to respiratory failure in patients with marginal pulmonary function. Previous cardiac surgery may cause phrenic nerve injury, which makes careful history taking important.


  • For interscalene block using ultrasound or a nerve stimulator, 15-20 mL of local anesthetic are sufficient for adults. For children, adjust according to the child’s size while following the recommended maximum local anesthetic doses. See Table 64-1 for recommended maximum doses of local anesthetics, Fig. 64-1 for the distribution of the block, and Fig. 64-2 for the ultrasound anatomy.

  • Clonidine may prolong the local anesthesia effect. Add 1 μg/kg.

  • Combine peripheral block with sedation or general anesthesia.


The patient and his family should be given instructions on how to care for the anesthetized arm in order to avoid inadvertent trauma to the anesthetized arm.

TABLE 64-1



Interscalene block: distribution of blockade.


Ultrasound view of the interscalene area. [ASM, anterior scalene muscle; CA, carotid artery; IJV, internal jugular vein; MSM, middle scalene muscle; SCM, sternocleidomastoid muscle; SCP, superficial cervical plexus; T, thyroid gland.]

DOs and DON’Ts

  • ✓ Do evaluate any possible underlying cardiac condition.

  • ⊗ Do not hyperextend the joints of these patients.

  • ✓ Do an interscalene block if appropriate.

  • ✓ Use the shortest needle possible.

  • ⊗ Do not do an interscalene block if the patient has respiratory compromise.


There is a case report of permanent spinal cord injury from an inters-calene block ...

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