View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by HKU Scholars Hub Title Review of Anesthesia for Middle Ear Surgery Author(s) Liang, S; Irwin, MG Citation Anesthesiology Clinics, 2010, v. 28 n. 3, p. 519-528 Issued Date 2010 URL http://hdl.handle.net/10722/142299 NOTICE: this is the author’s version of a work that was accepted for publication in Anesthesiology Clinics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control Rights mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Anesthesiology Clinics, 2010, v. 28 n. 3, p. 519-528. DOI: 10.1016/j.anclin.2010.07.009 ARTICLE IN PRESS 1 2 Review of Anesthesia 3 4 for Middle Ear 5 6 Surgery 7 8 a 9 Sharon Liang, BSc, MBBS , b, 10 Michael G Irwin, MB, ChB, MD, FRCA, FANZCA, FHKAM * ½Q3 ½Q2 11 ½Q6 ½Q4 12 13 KEYWORDS 14 Anesthesia for middle ear surgery Controlled hypotension 15 Postoperative nausea and vomiting 16 17 PROOF 18 The middle ear refers to an air-filled space between the tympanic membrane and the 19 oval window. It is connected to the nasopharynx by the eustachian tube and is in close 20 proximity to the temporal lobe, cerebellum, jugular bulb, and the labyrinth of the inner 21 ear. The middle ear contains three ossicles—the malleus, incus and stapes—which 22 are responsible for transmission of sound vibration from the eardrum to the cochlea. 23 This air-filled cavity is traversed by the facial nerve before it exits the skull via the sty- 24 lomastoid foramen.1,2 The facial nerve provides motor innervation to the muscles of 25 facial expression. 26 27 COMMON MIDDLE EAR SURGERIES 28 29 Middle ear disease affects patients of all ages. Common middle ear pathologic condi- 30 tions requiring surgery in adults include tympanoplasty (reconstructive surgery for the 31 tympanic membrane, or eardrum), stapedectomy or ossiculoplasty for otosclerosis, 32 mastoidectomy for removal of infected air cells within the mastoid bone, and removal 33 of cholesteoma.2 Common middle ear surgery in children includes tympanoplasty, 34 mastoidectomy, myringotomy, grommet insertion. and cochlear implantation.2 35 Some of these procedures can be performed under local anesthesia, although obvi- 36 ously, all surgery can be performed under general anesthesia if necessitated by 37 patient or surgical factors (Box 1). ½Q7 38 39 ANESTHETIC CONSIDERATIONS IN MIDDLE EAR SURGERY 40 41 Given the unique location, size, and delicate content of the middle ear, great care must 42 be taken during the perioperative period. Special considerations include: provision of 43 44 a Department of Anaesthesiology, University of Hong Kong, Queen Mary Hospital, Main Block, 45 Room 43, 2/F, 102 Pokfulam Road, Hong Kong ½Q5 b UNCORRECTED 46 Department of Anaesthesiology, University of Hong Kong, K424, Queen Mary Hospital, 47 Pokfulam Road, Hong Kong * Corresponding author. 48 E-mail address: [email protected] Anesthesiology Clin - (2010) -–- doi:10.1016/j.anclin.2010.07.009 anesthesiology.theclinics.com 1932-2275/10/$ – see front matter Ó 2010 Elsevier Inc. All rights reserved. XATC208_proof ■ 20 July 2010 ■ 10:24 pm ARTICLE IN PRESS 2 Liang & Irwin 49 Box 1 50 Common procedures in middle ear surgery 51 52 Local anesthesia 53 Surgical factors 54 Insertion of grommet 55 56 Myringoplasty 57 Tympanoplasty 58 Stapedotomy 59 Stapedectomy 60 61 Ossiculoplasty (IOFNM) 62 Mastoidectomy (IOFNM) 63 Cholesteoma surgery via intact ear canal (IOFNM) 64 65 Patient factors PROOF 66 Adult 67 Patient must be able to understand, cooperate, hear and communicate 68 General anesthesia 69 70 Surgical factors 71 Cochlear implantation 72 Long operations 73 Complicated surgery (eg, extensive scar tissue in middle ear) 74 75 Patient factors 76 Children 77 Mentally unstable, uncooperative patients 78 79 Patients who request general anesthesia 80 Abbreviation: IOFNM, intraoperative facial nerve monitoring. 81 82 83 a bloodless surgical field, attention to patient’s head positioning, airway management, 84 facial nerve monitoring, the effect of nitrous oxide on the middle ear, a smooth and 85 calm recovery, and prevention of postoperative nausea and vomiting (PONV).2–5 86 A bloodless surgical field is ideal, as even small amounts of blood will obscure the 87 surgeon’s view in microsurgery. A combination of physical and pharmacologic tech- 88 niques is used to minimize bleeding. Attention to patient’s head positioning is impor- 89 tant to avoid venous obstruction and congestion. In addition, extreme hyperextension 90 or torsion can cause injury to the brachial plexus and the cervical spine.4 In patients 91 with carotid atherosclerosis, carotid blood flow may be compromised or plaque 92 emboli dislodged, and it is worth auscultating for carotid bruit before surgery. During 93 general anesthesia,UNCORRECTED the airway can be maintained with a laryngeal mask airway (LMA) 94 or endotracheal intubation; intubation may be more appropriate if extreme neck exten- 95 sion or rotation is required. LMA, however, is a suitable alternative for most middle ear 96 surgery, and a wide range of devices are now available. A well-documented potential 97 complication of otologic surgery is facial nerve paralysis, and a nerve stimulator is 98 often employed for intraoperative monitoring of evoked facial nerve electromyo- 99 graphic activity to aid preservation of the facial nerve. Muscle relaxants should be XATC208_proof ■ 20 July 2010 ■ 10:24 pm ARTICLE IN PRESS ½Q1 Review of Anesthesia for Middle Ear Surgery 3 100 avoided in this circumstance or, if neuromuscular block is needed to facilitate smooth 101 intubation, choose a dose and an agent (eg, mivacurium no longer manufactured in the 102 United States) that ensures the return of function before the need for neuromuscular 103 monitoring arises.3–5 It also should be borne in mind that sudden unexpected patient 104 movement may jeopardize the success of surgery, and depth of anesthesia monitoring 105 may be useful. The use of nitrous oxide in middle ear surgery is controversial. A 106 smooth recovery without coughing or straining is important, especially in patients 107 who have undergone reconstructive middle ear surgery to prevent prosthesis 108 displacement. PONV is a common problem after middle ear surgery that can be mini- 109 mized by appropriate choice of anesthetic technique and antiemetic prophylaxis.3–5 110 Most middle ear procedures can be performed as outpatient surgery; thus rapid ½Q8 111 recovery, good analgesia, and avoidance of nausea and vomiting are essential.6 112 113 PREOPERATIVE ASSESSMENT 114 115 For adults, simple middle ear surgery can be performed under local or general anes- 116 thesia, although complicated or long procedures should bePROOF performed under general 117 anesthesia. Patients who are able to understand the procedure, and to communicate 118 and cooperate throughout the procedure, are suitable candidates for local anesthesia 7 119 with or for foregoing sedation. Patients undergoing middle ear surgery often suffer 120 from extensive hearing loss, thus hindering their ability to cooperate, and in this situ- 121 ation, surgery might be better performed under general anesthesia. Leaving the 122 hearing aid in situ in the nonsurgical ear before induction and replacement before 123 emergence may help to minimize anxiety and ease communication. Oral anxiolysis 124 premedication with benzodiazepines can be considered or standard sedation regi- 125 mens used intraoperatively. A history of cardiovascular disease, hypovolemia, and 126 anemia will limit the degree of hypotension possible. In pediatric patients, in addition 127 to the usual components of preoperative assessment, it is important to check for 6 128 coexisting syndromes and recent upper respiratory tract infection. 129 130 CHOICE OF ANESTHESIA 131 Four nerves provide innervation to the ear. The auriculotemporal nerve supplies the 132 outer auditory meatus; the great auricular nerve supplies the medial and lower aspect 133 of the auricle and part of the external auditory meatus. The auricular branch of the 134 vagus nerve supplies the concha and the external auditory meatus, and the tympanic 135 nerves supply the tympanic cavity.1,4 136 General or local anesthesia has advantages and disadvantages. Uncomplicated 137 middle ear surgery can be performed under local anesthesia. In a study on local anes- 138 thesia in middle ear surgery by Caner and colleagues,8 patients were premedicated 139 with meperidine and atropine intramuscularly 30 minutes before being taken to 140 surgery, and 5 mg to 10 mg diazepam was given intravenously if the patient was still ½Q9 141 agitated in the operating room. Two percent lidocaine with 1:10,000 epinephrine was 142 used for infiltration and auriculotemporal/auricular nerve blocks. Seventy-three of the 143 100 patients said they would prefer local anesthesia for a similar operation in the 144 future. In a similarUNCORRECTED survey, Yung7 found the most common discomforts reported 145 were noise during surgery and anxiety, followed by dizziness, backache, claustro- 146 phobia, and earache. Despite these discomforts, however, 89% of patients said 147 they would prefer local anesthesia for similar operations in the future. Pain was felt 148 mainly at the beginning of surgery when multiple injections of local anesthetic were 149 given, and perhaps the preoperative application of lidocaine and prilocaine (EMLA) 150 could have assisted in this. For the surgeons, the main advantage of performing XATC208_proof ■ 20 July 2010 ■ 10:24 pm ARTICLE IN PRESS 4 Liang & Irwin 151 middle ear surgery under local anesthesia is the ability to test hearing during surgery, 152 and they also report less bleeding. The main concerns of not performing middle ear 153 surgery under local anesthesia are that patients may not tolerate the discomfort and 154 the possibility of sudden movement.