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Correspondence |
Hôpital de Bicêtre, Le Kremlin-Bicêtre, France, E-mail: dan.benhamou{at}bct.ap-hop-paris.fr
To the Editor:
A 30-yr-old man presented with a traumatic injury of his clavicle. An upper respiratory tract infection was noted during the preanesthetic interview. Anesthesia was provided with a right interscalene plexus block, using a 22-G needle and nerve stimulation. A muscular response of the deltoid and biceps was easily obtained at 0.7 mA, and 30 mL of ropivacaine 0.75% were injected after negative aspiration. Horner’s syndrome was not recorded and no complication occurred. Shoulder surgery was started after induction of general anesthesia using nitrous oxide in oxygen, propofol, sufentanil, and placement of a laryngeal mask airway. Upon emergence, the patient complained of a profound hearing loss of the ear ipsilateral to the block. This hearing loss was not associated with fullness in the ear, tinnitus, vertigo or headache. Immediate ear examination performed by an otorhinolaryngologist confirmed a bilateral serous otitis media with effusion and retracted tympanic membranes. Audiometric testing performed on the same day disclosed a conductive deficit (homogeneous decrease of 30 dB in all frequencies for air conduction with normal and symmetric bone conduction) and was normal for the opposite ear. Motor block lasted six hours, while hearing loss notably improved within a few hours after recovery of motor function and completely disappeared within four days. An audiogram repeated one month later showed complete recovery.
General anesthesia using nitrous oxide may have impacted on the movement of the tympanic membrane and thus the stapes.1 However, we believe that regional anesthesia was the triggering factor, as hearing loss was experienced only ispislateral to the block while otitis media was detected bilaterally. One would have expected nitrous oxide to alter hearing bilaterally. Moreover, hearing recovered with the same time profile as the interscalene block. Rosenberg has described a case of hearing impairment after interscalene brachial plexus block anesthesia.2 Sympathetic block-induced vasodilatation induced edema of the mucosal membranes of the Eustachian tube (ET) and the middle ear, thereby producing a hearing decrement on that side.
Otitis media also contributed to hearing impairment by obstructing the ET and by causing tympanic cavity mucosal edema.3,4 In this patient with otitis media, vasodilatation of the ET and the tympanic cavity associated with an interscalene block led to complete obstruction of an already partially obstructed ET, thus creating acute transient hearing loss.
References
1 Sprung J, Bourke DL, Contreras MG, Warner ME, Findlay J. Perioperative hearing impairment. Anesthesiology 2003: 98: 241–57.[Medline]
2 Rosenberg PH, Lamberg TS, Tarkkila P, Marttila T, Björkenheim JM, Tuominen M. Auditory disturbance associated with interscalene brachial plexus block. Br J Anaesth 1995: 74: 89–91.
3 Ars B, Ars-Piret N. Middle ear pressure balance under normal conditions. Specific role of the middle ear structures. Acta Otorhinolaryngol Belg 1994: 48: 339–42[Medline]
4 Sadé J, Luntz M. Dynamic measurement of gaz composition in the middle ear. II: steady state values. Acta Otolaryngol (Stockh) 1993: 113: 353–7.
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