To the Editor:—
Spinal analgesia using opioid with or without local anesthetic is commonly used for labor analgesia, usually as part of a combined spinal–epidural technique. Common side effects or complications include pruritus, hypotension, fetal bradycardia or other fetal heart rate tracing alterations, and of course, post–dural puncture headache. We have noted a rare but recurring complication, the loss of swallowing ability and gag reflex. We noted a few cases in the mid-1990s, when the fentanyl doses administered were in a range (25–35 μg) higher than generally given now (10–20 μg). Although this complication has been alluded to in the literature,1–3even most very experienced clinicians have not seen it or heard of it. We therefore present two cases describing the loss of the parturient’s swallowing ability and gag reflex after the administration of subarachnoid fentanyl. In both cases, the gag reflex and the ability to swallow returned after administration of naloxone.
The first case was a 23-yr-old, gravida 1 para 0 woman who received combined spinal–epidural analgesia for labor at cervical dilation of 4 cm. The procedure was uneventful. A 17-gauge Tuohy needle was used to identify the epidural space using loss of resistance to saline 4.5 cm deep to the skin; the subarachnoid space was entered with a 27-gauge Whitacre needle, and 20 μg fentanyl and 2.5 mg bupivacaine were injected into the cerebrospinal fluid. A 20-gauge epidural catheter was threaded into the epidural space. Approximately 10–12 min after spinal injection (with no epidural injection or infusion yet), the patient reported “difficulty breathing.” The oxygen saturation as measured by pulse oximetry throughout the procedure and at this time was 99–100% with the patient breathing room air. It was rapidly determined that the difficulty was not with breathing but rather with swallowing. Sensory block to ice was at about T8 or T7. Motor strength in the upper extremities was completely normal and was 3–4/5 in the lower extremities, as expected with the given dose of bupivacaine. Placing a cotton swab and tongue blade in the posterior pharynx revealed an absent gag reflex. 40 μg naloxone was given intravenously, and within a minute or two, the patient was able to swallow and her gag reflex had returned. Approximately 30 min later, she again noted difficulty swallowing, and again the gag reflex was absent. Another dose of 40 μg naloxone was given, with resolution of her symptoms, and they did not return. Analgesia remained excellent throughout this period. She proceeded to an uneventful delivery with excellent analgesia from both the spinal and epidural portions of her analgesic.
The second case involved a 19-yr-old, gravida 1 para 0 woman undergoing a cesarean delivery for breech presentation. The patient received spinal anesthesia in the sitting position with 12 mg hyperbaric bupivacaine, 0.2 mg preservative-free morphine, and 20 μg fentanyl, resulting in a C4 sensory level and C8 motor level (grip 2/4). Approximately 3 min after the spinal dose, the patient experienced an episode of hypotension that resolved with 160 μg phenylephrine. Approximately 20 min after the spinal dose, the patient reported decreased ability to swallow, and physical examination revealed an absent gag reflex with otherwise intact cranial nerves. Approximately 25 min after the spinal dose, the patient was treated with 80 μg naloxone. Her ability to swallow returned, as did her gag reflex, and she remained without further difficultly swallowing.
This phenomenon has been mentioned in the literature, but never fully described. In a 1993 retrospective review of 90 patients receiving intrathecal sufentanil (10 μg in 1 ml saline), Cohen et al. 2mention a patient who reported “transient difficultly swallowing and taking a deep breath.” The patient was noted to have a loss of pinprick to her face and was unable to swallow water. This event sounds similar to our cases described above. Gadalla et al. 3mention difficulty swallowing as a presumed marker of excessive cephalad intrathecal opioid spread. A large series reported by Albright and Forster1indicates that the phenomenon may occur with a higher frequency than generally appreciated. The authors describe the results of 6,002 combined spinal–epidurals with 10, 15, or 20 μg intrathecal sufentanil with 2.5 mg bupivacaine. The side effects included 71 cases of dysphagia treated with nalbuphine or naloxone. There was an increased prevalence of dysphagia with increasing doses of sufentanil (0.9% vs. 3.8% vs. 3.1%, respectively) and an average onset of symptoms of 24 min.
Despite this incidence, the phenomenon or a potential mechanism for it has not been widely discussed in the literature. Previous reports have focused on the loss of swallowing ability, but the current demonstration of the loss of the gag reflex in association with the swallowing defect suggests that these pregnant patients could be at increased risk of aspiration and that an opioid antagonist should be administered. Both patients were concerned and frightened by the sensation, and therapy was effective. The fact that therapy with opioid antagonists appears to reverse the effect seems to confirm that its mechanism involves the opioid receptor. It is not clear how or why this should be the case, so this observation could also provide some insight into the pathophysiology and treatment of swallowing disorders.
*Columbia University, New York, New York. email@example.com