[Advantages of the L-menthol test in assessing chronic nasal obstruction]

In normal and anosmic patients, l-menthol inhalation is responsible for the subjective sensation of increased nasal permeability, related to a stimulation of the internal nasal nerve (branch of trigeminal nerve) endings connected with cold pressor receptors. At present, routine assessment of nasal obstruction does not include the l-menthol test. The aim of this case report was to show the advantages of this test in chronic nasal obstruction evaluation.

The example of a patient with a medical history of facial trauma and anosmia for sequela is reported. This patient complained of chronic nasal obstruction that persisted despite several septorhinoplasties and that conflicted with clinical examination and rhinomanometry data.

An l-menthol test did not induce any mint smell recognition, any improvement of nasal permeability sensation, or any freshness sensation.

The authors suggest that the nasal obstruction sensation could result, in this case, from post-trauma anesthesia of the trigeminal nerve, particularly its internal nasal nerve branch. The l-menthol test could be a predictive test that may prevent recurrent functional failures of surgical treatment proposed for nasal obstruction.