(Kiosk 5) Hemidiaphragm Paralysis Following Interscalene Nerve Block: A Case Report

Case Diagnosis: Persistent phrenic nerve paralysis following interscalene nerve block

Case Description or Program Description: A 56 year old male triathlete underwent right shoulder arthroscopic rotator cuff repair with an intraoperative interscalene nerve block (ISB) and noted subsequent dyspnea, orthopnea, and poor exercise tolerance. One year later, he presented to the emergency department for acute dyspnea and pleuritic chest pain. Initial chest x-ray revealed an elevated right hemidiaphragm, which was not visualized on a chest x-ray taken before surgery. Computed tomography of the chest confirmed right hemidiaphragm with right basilar atelectasis. Fluoroscopic sniff test revealed paradoxical motion of the right hemidiaphragm consistent with paralysis. He was recommended strict activity precautions and scheduled for right hemidiaphragm plication.

Setting: Regional Veteran Medical Center

Assessment/Results: ISB causes phrenic nerve paralysis that can be irreversible, affect physical activity and quality of life, and cause detrimental adverse effects.

Discussion (relevance): ISB is commonly administered during shoulder surgery for post-operative pain management. It is performed by injecting anesthetic into the perineural space between the anterior and middle scalene muscles, around the C5-C7 nerve roots of the brachial plexus. As the phrenic nerve is derived from C3-C5 nerve roots, manipulation near the C5 nerve root in ISB causes temporary hemidiaphragmatic paralysis. Chronic phrenic nerve paralysis is rare following ISB and may occur from direct needle trauma, neurotoxicity related to type of anesthetic used, nerve compression related to the quantity of anesthetic injected, or nerve compression due to postoperative hematoma or adhesions. Symptoms of hemidiaphragm with phrenic nerve paralysis include exercise intolerance, dyspnea, and hypoventilation. Diagnostic studies include pulmonary function tests, fluoroscopic sniff test, phrenic nerve stimulation tests, and/or imaging. Depending on symptom severity, management can include observation, surgical plication of the diaphragm, or diaphragmatic pacing.

Conclusions: Though ISB is effective for pain management following shoulder operations, permanent phrenic nerve paralysis should be acknowledged as a rare yet serious risk.