An interview with Professor Thomas Hummel of the Interdisciplinary Center for Smell and Taste in Dresden, Germany

Professor Hummel, it is a great pleasure to have you answer some questions for the Smell Training Facebook Group. As one of the leaders in the field of olfactory dysfunction and smell loss, your comments will be invaluable to readers, who often do not have access to the most recent information.

Q. The readers of these pages are often told by their doctors that nothing can really be done for patients with smell loss. Can you update us on recently published works that may offer help?

A. There are things that can be done about smell loss, although the success rate certainly depends on the cause of olfactory loss. For example, in the case of chronic rhinosinusitis, one can treat the sinusitis with surgery or medication and this is often successful. In other cases of olfactory loss, it is important to counsel people. There is spontaneous recovery which is in the range of 20% or more of people with olfactory loss after head trauma, and the spontaneous recovery rate of people with olfactory loss after an infection of the upper respiratory tract is in the range of 50% or higher. This recovery is slow over months and years, and it can be supported by smell training – we just published a review on that. In addition, we published research on the possible effectiveness of retinoic acid. And we currently work on sodium citrate which may be helpful in olfactory loss after an infection of the upper respiratory tract – but this is not ready for routine application. Here is a list of most recent research, including a position paper, recently published: 

1. Effects of olfactory training: a meta-analysis. Rhinology 55:17-26 Sorokowska A, Drechsler E, Karwowski M, Hummel T (2017) 

2. Intranasal vitamin A is beneficial in post-infectious olfactory loss. Eur Arch Otorhinolaryngol 274(7):2819-2825. Hummel T, Whitcroft KL, Rueter G, Haehner A (2017)

3. The effect of intranasal sodium citrate on olfaction in post-infectious loss: results from a prospective, placebo-controlled trial in 49 patients. Clin Otolaryngol 42:557-563. Whitcroft K, Ezzat M, Cuevas M, Andrews P, Hummel T (2016)

4. A Randomised Controlled Trial of Sodium Citrate Spray for Non-Conductive Olfactory Disorders. Clin Otolaryngol Mar 24. doi: 10.1111/coa.12878. Philpott C, Erskine S, Clark A, Leeper A, Salam M, Sharma R, Murty G, Hummel T (2017)

5. Intranasal sodium citrate solution improves olfaction in post-viral hyposmia. Rhinology 54: 368-374. Whitcroft K, Merkonidis C, Cuevas M, Haehner A, Philpott C, and Hummel T (2016)

6. Position Paper on Olfactory Dysfunction. Rhinology Jun 17. doi: 10.4193/Rhin16.248.  Hummel T, Whitcroft KL, Andrews P, Altundag A, Cinghi C, Costanzo RM, Damm M8, Frasnelli J, Gudziol H, Gupta N, Haehner A, Holbrook E, Hong SC, Hornung D, Hüttenbrink KB, Kamel R, Kobayashi M, Konstantinidis I, Landis BN, Leopold DA, Macchi A, Miwa T, Moesges R, Mullol J, Mueller CA, Ottaviano G, Passali GC, Philpott C, Pinto JM, Ramakrishnan VJ, Rombaux P, Roth Y, Schlosser RA, Shu B, Soler G, Stjärne P, Stuck BA, Vodicka J, Welge-Luessen A (2017)

Q. What do you see coming that may be promising for smell dysfunction? Are there new treatments in the pipeline? 

A. For chronic rhinosinusitis and polyposis a number of new drugs are about to reach the routine clinic. They seem to be very effective, but I guess more studies still need to be done. For other causes of olfactory loss there may be different solutions, including transplantation of olfactory epithelium, or theophylline applied to the olfactory nerves. Maybe one day we will have an “olfactory implant”, similar to cochlear implants. Overall, I guess there will be never one cure for all types of smell loss, but probably this will boil down to solutions for the various causes of olfactory loss.

Q. What are the most important kinds of self-help that patients can do themselves?

A. During the last 10 years “smell training” has been studied quite a bit, and it seems to be helpful, at least for certain types of olfactory disorders. The simple advice for people with olfactory loss after an infection or head trauma would be to smell 4 different odors twice daily, 20 seconds each. And do that regularly for 6-12 months! But before you start, please see an ENT doctor or a neurologist so that the diagnosis can be established and a proper smell test can be done.

Q. Finally, do you have any general advice to patients about smell loss?

A. As I said earlier, I think it is very important to see an ENT or a neurologist and ask for advice, and have the sense of smell was tested with a standardized olfactory test. 

Thank you, Professor Hummel!

Read another of our interviews with leaders in the field of olfactory dysfunction by clicking here