October 2021

Smell Responses to Hyposmia Treatment are Nonlinear

We have used four odors in the Henkin test to measure smell function. These odors are pyridine (pungent), nitrobenzene (sweet, almond-like), thiophene (putrid, petroleum-like) and amyl acetate (banana oil). Each of these odors are used to generate specific parameters of smell function – detection thresholds, recognition thresholds, magnitude estimations and hedonic values in order to measure quantitatively these several aspects of smell function in humans.

Responses to each odor differ in sensitivity. Initial responses before treatment are non-linear. Thus, while a patient may respond normally to thiophene there may be an abnormality to amyl acetate; overall, the patient may consider their smell function impaired although only one odor may be impaired.

Responses to treatment which improve smell function are also not uniform – they are non-linear. Thus, patients may improve function with one odor and not with another but consider their smell function to be either impaired or improved. Patients may exhibit improvement in one, two, three or all parameters with one odor but not with others. Thus, the patient may consider these changes consistent with overall improvement in their smell function although there may be abnormalities in one or more odors.

It is critical to recognize that non-linearity markers occur which help to understand patient improvement or lack thereof with treatment.