Anesth Analg 2003;96:1191-1192
© 2003 International Anesthesia Research Society
REGIONAL ANESTHESIA
Airway Difficulty After a Brachial Plexus Subclavian Perivascular Block
Mark Rollins, MD,
Warren R. McKay, MD, and
Rachel Eshima McKay, MD
Department of Anesthesia and Perioperative Care, University of California, San Francisco, California
Address correspondence and reprint requests to Rachel Eshima McKay, MD, University of California, San Francisco, Department of Anesthesia and Perioperative Care, 521 Parnassus Ave., Room C-450, Box 0648, San Francisco, CA 94143-0468. Address e-mail to eshimar{at}anesthesia.ucsf.edu
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Abstract
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IMPLICATIONS: We report a case of upper airway obstruction after subclavian perivascular block in a patient with a preexisting unrecognized paralyzed vocal cord on the opposite side. We discuss the incidence of vocal cord paralysis after subclavian perivascular block and the risk of airway compromise if contralateral vocal cord paralysis is known or suspected.
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Introduction
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Brachial plexus anesthesia carries the risk of clinically threatening complications (pneumothorax, nerve injury, and intravascular injection) in addition to common, well described side effects (Horner’s syndrome, unilateral phrenic or recurrent laryngeal nerve involvement) (1–5) . Fortunately, the clinical significance of hemidiaphragmatic paralysis or hoarseness is usually minimal in a patient who is otherwise neurologically intact. We report a case of severe stridor and airway compromise in a patient with unrecognized, preexisting left vocal cord paralysis after right-sided subclavian perivascular block.
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Case Report
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A 71-yr-old, 68-kg woman with squamous cell carcinoma of the tongue presented for open reduction and internal fixation of a pathologic right midshaft humerus fracture. Her primary tumor was diagnosed 18 mo earlier, at which time she had undergone partial glossectomy and neck dissection. Over subsequent months, the tumor invaded structures on the left side of her neck, requiring more extensive surgical resection and radiation treatment. Besides pain from the broken arm, she denied other symptoms.
On examination, she had a gross deformity from a tissue defect on the left side of her neck. She had a small, recessed jaw, with a thyromental distance of less than two finger breadths. The submandibular tissue was extensively scarred and noncompliant. With maximum effort she was able to open her mouth 2 cm, revealing only the tongue and a portion of the hard palate. Her neck extension was extremely limited. The patient’s voice was soft and coarse. A preoperative chest radiograph was not obtained.
Given her severe scarring and limited neck mobility, we planned an awake fiberoptic intubation technique. Before the induction of general anesthesia, we planned to perform a subclavian perivascular block.
After IV administration of 2 mg of midazolam and 25 µg of fentanyl, a supraclavicular brachial plexus block was performed by using a 21-gauge stimulator needle. The subclavian artery pulse was palpated medial to the midclavicle, and the stimulator needle was inserted just posterior to the pulse and advanced caudally. Biceps muscle stimulation was noted at 0.5 mA of current. The muscle response was abolished after 1 mL of local anesthetic solution was injected. A total of 30 mL of 0.75% ropivacaine with 1:200,000 epinephrine and 40 mg of tetracaine were injected in divided doses.
Oxygen by nasal cannula and an additional 50 mg of fentanyl IV were administered while preparing for fiberoptic intubation. During the administration of nebulized local anesthetic to the oropharynx, the patient began to exhibit increasing ventilatory difficulty, with audible inspiratory stridor. The oxygen saturation measurement decreased to 86%–89% while oxygen was delivered by face mask. Oxygenation improved to 100% SpO2 after the application of mask continuous positive airway pressure. Successful nasal fiberoptic intubation was achieved with a 5.5 endotracheal tube (ET) after attempts to pass a 6.5 ET tube over the fiberscope failed when resistance was met. During intubation, the cords were observed to be in a paramedian position.
Surgery proceeded uneventfully. Given the onset of inspiratory stridor soon after completion of the subclavian perivascular block, we suspected that the patient might have had an underlying dysfunction of the contralateral vocal cord, where the surgery and radiation had taken place. Our suspicions were confirmed after contacting the otorhinolaryngology (ENT) surgeons who were involved in her prior neck dissection and postoperative radiation therapy. Our patient remained intubated overnight after surgery. The following day, when she was tracheally extubated over a fiberoptic scope, the right vocal cord was mobile, whereas that on the left remained at midposition and immobilized. Chest radiograph findings were unremarkable, and the patient’s voice had a soft, coarse quality. A formal ENT consultation confirmed the finding of left vocal cord paralysis.
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Discussion
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The onset of respiratory difficulty after a brachial plexus block brings to mind a differential of complications, including pneumothorax, phrenic nerve block, recurrent laryngeal nerve block, direct spinal root neurologic injury, bronchospasm, and allergic reaction. Nebulized local anesthetic has remote potential to cause laryngospasm (6). An evolving phrenic nerve block may have contributed to the patient’s symptoms, as increased ventilatory efforts and anxiety from a sensation of weakness may have caused increased negative pressure in the upper airway. Complete or partial paralysis of the hemidiaphragm after subclavian perivascular block had a 40%–70% incidence in two studies (3,4) . However, a right recurrent laryngeal nerve block on top of a preexisting left vocal cord paralysis appears to be the most likely explanation for our patient’s severe respiratory difficulty given the onset and persistence of inspiratory stridor, lack of pain with needle placement, absence of pneumothorax on chest radiograph, absence of airway edema, and maintenance of excellent saturation after intubation.
The recurrent laryngeal nerve supplies all of the intrinsic muscles of the larynx, with the exception of the cricothyroid muscle (6). Airflow during inspiration causes decreased lateral pressure in the upper airway, in proportion to the flow rate and inspiratory effort. In the narrow, flexible airway, closure tends to occur during inspiration without the well timed, coordinated contraction of the posterior cricoarytenoid muscle (innervated by the ipsilateral recurrent laryngeal nerve) allowing abduction of the vocal cords and arytenoids cartilages. The ipsilateral recurrent laryngeal nerve also provides vocal cord adduction, necessary for airway protection and modification of phonation, through the thyroarytenoid and lateral cricothyroid muscles. The gap in the posterior larynx is closed by the interarytenoid muscles, which receive bilateral innervation from the recurrent nerve. The cadaveric position of the cords is paramedian. A unilateral recurrent laryngeal nerve lesion may have clinical manifestations of dysphagia, dyspnea on exertion, dysphonia, or aspiration or, more rarely, may be asymptomatic (7). The cricothyroid muscles lengthen and allow isotonic contraction of the vocal cords for pitch modulation of the voice.
Recurrent laryngeal nerve paralysis after a brachial plexus block is a well described complication and normally presents as hoarseness after the ipsilateral involvement. Ward (8) detailed 1 (3%) incident of right-sided recurrent laryngeal nerve palsy out of 34 consecutive patients receiving an interscalene-approach brachial plexus block for upper extremity procedures. Hickey et al. (9) described 2 (1.3%) incidents of right-sided recurrent laryngeal nerve palsy out of 156 consecutive patients receiving a subclavian perivascular block for upper extremity procedures. Winnie (1) references a series of 100 subclavian perivascular brachial plexus blocks that Seshadri analyzed and described to him through personal communication, which showed a 6% incidence of hoarseness. Winnie points out that although recurrent laryngeal nerve involvement is theoretically possible on either side, hoarseness has been reported after brachial plexus blocks only on the right, most likely because the injected anesthetic can travel along the subclavian artery to the position where the nerve loops under the vessel (1). These observations suggest that the risk of unilateral vocal cord paralysis may be more frequent than previously reported incidences (1.3%–6%) when we consider individuals receiving right-sided blocks.
Although infrequent, ipsilateral recurrent laryngeal nerve paralysis in a patient with a preexisting contralateral vocal cord paralysis can create an airway emergency. Before performing a brachial plexus block, a thorough preoperative evaluation for vocal cord paralysis should be stressed in patients who have received any type of neck surgery or radiation treatment to the neck or upper chest. In a patient with equivocal symptoms, an awake examination of the vocal cords should be considered.
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References
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- Ward ME. The interscalene approach to the brachial plexus. Anaesthesia 1974; 29: 147–57.[Web of Science][Medline]
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Accepted for publication December 10, 2002.
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Abstract
Introduction
