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Correspondence |
Mayo Clinic College of Medicine, Mayo Clinic, Rochester, USA, E-mail: sprung.juraj{at}mayo.edu
To the Editor:
The acute onset of aphonia after surgery is a worrisome event, and the differential diagnosis include cerebral vascular events, laryngeal trauma during endotracheal intubation, and rarely paralysis caused by local anesthetic administered in the vicinity of the laryngeal nerves. We describe a patient who developed transient aphonia after emerging from general anesthesia. Consent for publication of this report was obtained in accordance with our Research Ethics Board guidelines.
A 58-yr-old female underwent left shoulder arthroscopy under general anesthesia. The vocal cords were visualized and tracheal intubation was atraumatic. In order to facilitate postoperative rehabilitation, the surgeon implanted a catheter into the shoulder joint for local anesthetic administration. Before the end of surgery we injected 20 mL of 0.5% bupivacaine with 1:200,000 epinephrine through the catheter and then started an infusion of the same solution at a rate of 2 mL·hr–1. In the recovery room, the patient was talking and reported no pain. Thirty-six minutes later she became visibly upset, and then was suddenly unable to speak. Vital signs, electrocardiogram, chest radiogram, and electrolytes were all within normal limits. She was able to follow commands and express her thoughts in writing. She was able to move her lower extremities on command as well. Cranial nerve examination revealed no deficits. Pupils were equal and reactive with no gaze deviation, and funduscopic examination was normal. Deep tendon reflexes in her right arm and lower extremities were within normal limits. She understood and followed commands, but was unable to vocalize. The neurologist further noted that she had preserved sensation to pinprick in both legs and left hand, but somewhat diminished in the right arm, therefore, he ordered a computerized tomography scan, magnetic resonance imaging of the head, and a cerebral angiogram, all of which were normal. Approximately seven hours after the initial onset of aphonia she started to vocalize words, and by the eighth hour, full function of speech had returned.
The acute inability to speak has rarely been reported in association with the use of local anesthetics, i.e., after axillary block,1 following release of tourniquet in a patient receiving iv regional anesthesia,2 during retrobulbar nerve block,3 or stellate ganglion block.4 In this patient, transient aphonia presented as an isolated sign upon emergence from general anesthesia and lead to an extensive "negative" neurological work-up. The resolution of aphonia within the expected duration of bupivacaine block, as well as absence of obvious neurologic findings during diagnostic work-up, suggests a possible underlying mechanism of laryngeal nerve paralysis from the local anesthetic bolus, which diffused to the laryngeal nerve causing immobility of the vocal cords.
Footnotes
Accepted for publication September 21, 2005.
References
1 Schneider H, Paul A. Transient total motor aphasia. A complication of an axillary brachial plexus block (German). Anaesthesist 1992; 41: 423–5.[Medline]
2 Cherng CH, Wong CS, Ho ST. Acute aphasia following tourniquet release in intravenous regional anesthesia with 0.75% lidocaine. Reg Anesth Pain Med 2000; 25: 211–2.[Medline]
3 Nicoll JM, Acharya PA, Ahlen K, Baguneid S, Edge KR. Central nervous system complications after 6000 retrobulbar blocks. Anesth Analg 1987; 66: 1298–302.
4 Scott DL, Ghia JN, Teeple E. Aphasia and hemiparesis following stellate ganglion block. Anesth Analg 1983; 62: 1038–40.
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