We read with interest the article on unilateral sensorineural hearing loss after general anaesthesia and the correspondence to this stating that there are only 52 reported cases of sensorineural hearing loss after general anaesthesia [1-2]. We would like to suggest a possible cause of sensorineural hearing loss under general anaesthesia. Bolus intravenous aminoglycoside injections are associated with transient deafness as a reported side-effect that is attributable to the temporary blockage of calcium by gentamicin resulting in low calcium levels and increased acoustic thresholds [3]. Furosemide is thought to cause ototoxicity after a bolus dose when administered at a rate exceeding 4mg.min [4]. Ototoxic drugs have always been associated with sensorineural deafness in the toxic dose range. Although we need more research in the field as to which specific anaesthetic drugs may cause sensorineural hearing loss, we need to be more cautious with bolus administration of drugs such as furosemide and gentamicin that are regularly used and administered by anaesthetists and may have a role in sensorineural deafness after general anaesthesia.

V.Patle, D. Acharya.

Department of Anaesthesia & ITU, Hemel Hempstead General Hospital ,Hemel Hempstead, UK

References

1. Murad NJ, Patel C, Turner CR. Unilateral senorineural hearing loss after general anaesthesia. Anaesthesia 2008; 63: 559-9.

2. Punj J, Pandey R, Darlong V. Sensorineural hearing loss after general anaesthesia: 52 cases reported until now!  Anaesthesia 2009; 64: 2226.

3. Bernard PA, Bourret C. Perilymphatic calcium and VIII nerve action potentials during gentamicin bolus i.v. injections. A preliminary study. Acta Otolaryngology 1987; 103: 400-3.

4. Sasada M, Smith S. Drugs in Anaesthesia and Intensive Care, 3rd edition. US: Oxford Medical Publications, 2003.