EditorA 62-yr-old male patient presented with nasal breathing impairment, cough and facial pain without olfactory discomfort. Fibreoptic flexible endoscopy of the nasal passages was performed, preceded by endonasal topical local anaesthesia (ETLA) with lidocaine 4% spray (two puffs in each nostril), using a plastic dispensing apparatus, with no propellant gas. Inferior turbinate hypertrophy and nasal septal deviation were found. About 10 min later the patient mentioned the onset of anosmia. Olfactory impairment was confirmed by a Sniffin'SticksTM test battery1 score <16. Head computed tomography (CT) scan was performed to rule out tumour, infection and obstruction. Three months later the patient was still anosmic and the Sniffin'Sticks test battery confirmed previous findings.
Establishing a direct relationship between drug exposure and anosmia is often difficult, and it is frequently hard to determine with certainty the causative role of specific drugs in the development of such a disorder. In this case lidocaine seems the likely cause of the patient's anosmia, as no other substance either included in the original lidocaine solution or coming from the dispensing apparatus came into contact with the nasal mucosa. Mitochondrial dysfunction with activation of apoptotic pathways2 is the likely mechanism of lidocaine neurotoxicity. Furthermore, ETLA in the supine position and/or in a head-down position can favour contact of the anaesthetic to the olfactory cleft with consequent higher risk of anosmia.3 Smell disorder after ETLA, though usually reversible,4 is a cause of dissatisfaction and fears for the patient and the clinician, with possible legal consequences.5
In conclusion, we suggest performing ETLA with the subject in the sitting position and the head upwards to reduce contact of the anaesthetic with the olfactory cleft. Written informed consent should be obtained from each patient, considering that ETLA will render the procedure more comfortable but may cause transient or, as in this unique case, permanent olfactory dysfunction.
Rome, Italy
References
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