Surgical treatment of permanent diaphragm paralysis after interscalene nerve block for shoulder surgery.

U NILATERAL diaphragm paralysis after interscalene nerve block can result in respiratory disturbances that may have a substantial impact on quality of life and increased prevalence of respiratory infections. Several reports have estimated the incidence of transient diaphragm paralysis after routine interscalene blocks for shoulder surgery to be 100%, 3 however, with modified local anesthetic dosing and ultrasound-guided needle placement, more recent data suggest this rate to be lower. Of greater concern is permanent diaphragm paralysis after interscalene nerve block for shoulder surgery. There are isolated reports in the literature regarding long-standing postprocedural diaphragm paralysis , 6,7 yet the underlying causative mechanism has not been previously sought. Peripheral nerve injury may occur from a variety of mechanical causes, including: transection, piercing , stretching, thermal injury, and compression. Alternatively , a nonmechanical injury can result from the toxic or ischemic effects of pharmacologic agents, such as local anesthetics , epinephrine, or chemotherapeutic agents. Phrenic nerve injury from many of these causes may be repaired using nerve-reconstruction techniques. We report our experience with 14 patients suffering permanent diaphragm paralysis after interscalene nerve blocks evaluated and treated between 2009 and 2012 at a tertiary referral center for peripheral nerve injuries with a catchment area that includes the entire United States. Parameters for review included: results of comprehensive evaluation, intraoperative findings during phrenic nerve surgery, and outcomes of surgical intervention (using our previously reported surgical treatment algorithm and outcomes study 8). Successful treatment of the paralyzed diaphragm was based on improvements on: sniff testing, spi-rometry, nerve conduction testing, electromyography, and patient reporting. Case 1 The patient is a 58-yr-old man (patient 4; table 1) with a 2-yr history of chronic dyspnea and orthopnea noted immediately after an interscalene nerve block administered for rotator cuff repair. Left diaphragm paralysis was confirmed on chest fluoroscopy, and a phrenic neuropathy was documented based on a prolonged conduction latency and reduced motor amplitude on nerve-conduction testing. Given the significant impact on his quality of life, and the absence of any spontaneous improvement, the patient desired definitive repair of his phrenic nerve. During surgery, the phrenic nerve was found to be adherent to dense scar tissue consistent with chronic inflammation. A complete neurolysis was performed from the nerve root through the level of the subclavian vessels. A partial sca-lene muscle excision was also performed to permit complete decompression. Before decompression of the nerve, stimulation at 2 mA did not …