Riechstörungen: Update zur Diagnostik und Therapie

A new perspective on imaging of olfactory dysfunction: Does size matter?

PURPOSE

This study assesses the diagnostic utility of olfactory nerve and bulb morphologies in addition to volumetric analysis in classification of different olfactory dysfunction etiologies.

METHODS

106 patients presenting with olfactory loss and 17 control subjects were included. Based on detailed anamnesis, smell test and ear-nose-throat examination; patients were categorized into four groups as post-viral, post-traumatic, idiopathic, and obstructive olfactory dysfunction. Olfactory region was imaged with paranasal sinus CT and MRI dedicated to olfactory nerve. Olfactory bulb volume and olfactory sulcus depths were calculated on MRI. The olfactory bulb was assessed for morphology, contour lobulations and T2-signal intensity; and olfactory nerve for uniformity and clumping.

RESULTS

Volumetric analysis showed decreased olfactory bulb volume in idiopathic and obstructive group compared to control subjects. Olfactory sulci were shallower in post-viral, post-traumatic, idiopathic, and obstructive group compared to the control group. In post-viral group; olfactory bulbs had lobulated contour and focal T2-hyperintense regions in 67 % of cases, and olfactory nerves had a clumped and thickened appearance in 66 % of cases. In idiopathic group, olfactory bulbs were rectangular shaped with minimally deformed contours, and olfactory nerves were thin and hard to delineate. No specific olfactory bulb or nerve pattern was identified in obstructive and post-traumatic groups, however closed olfactory cleft and siderotic frontobasal changes were helpful clues in obstructive and post-traumatic groups, respectively.

CONCLUSION

In addition to olfactory cleft patency, olfactory sulcus depth and olfactory bulb volume; bulb and nerve morphologies may provide diagnostic information on different etiologies of olfactory dysfunction.

[Temporary hyposmia in COVID-19 patients]

BACKGROUND

This is a report on the high incidence of olfactory dysfunction in COVID-19 patients in the first cohort of COVID-19 patients in Germany (Webasto cluster).

METHODS

Loss of sense of smell and/or taste was reported by 26 of 63 COVID-19 patients (41%), whereas only 31% of the patients experiencing hyposmia had simultaneous symptoms of rhinitis. Smell tests were performed in 14 of these patients and taste tests in 10. The measurements were conducted in a patient care setting in an early COVID-19 cohort.

RESULTS

An olfactory disorder was present in 10/14 patients, before as well as after nasal decongestion. In 2 of these patients, hyposmia was the leading or only symptom of SARS-CoV‑2 infection. All tested patients reported recovery of smell and/or taste within 8 to 23 days.

CONCLUSION

The data imply that a) COVID-19 can lead to hyposmia in a relevant number of patients, the incidence was approximately 30% in this cohort; b) in most cases, the olfactory disturbance was not associated with nasal obstruction, thus indicating a possible neurogenic origin; and c) the olfactory disorder largely resolved within 1-3 weeks after the onset of COVID-19 symptoms. There were no indications of an increased incidence of dysgeusia. These early data may help in the interpretation of COVID-19-associated hyposmia as well as in the counseling of patients, given the temporary nature of hyposmia observed in this study. Furthermore, according to the current experience, hyposmia without rhinitic obstruction can be the leading or even the only symptom of a SARS-CoV‑2 infection.