The Efficacy of Modified Olfactory Training Method for Patients With Post-viral Olfactory Dysfunction

This olfactory test consists of three subtests that respectively measure odor threshold (T), odor discrimination (D), and odor identification (I). Each subtest has a maximum score of 16, and the sum of the scores from the three subtests provides the global olfactory score (TDI score; Threshold, Discrimination, Identification) with a maximum of 48 points. Patients with a TDI composite score≥30.5 are defined as normosmic. In contrast, those with a TDI composite score between 16.5 and 30.5 are defined as hyposmic, and patients with a TDI composite score<16.5 are defined as functionally anosmic. Based on previous literature, we have established a 5.5 points improvement in the TDI composite score as a significant change.

OB volumetric evaluations will be performed with a 3-Tesla MRI system with coronal T2-weighted fast spin-echo images that included the anterior and the middle parts of the skull base.

The OB volume will be measured using manual segmentation. The contours of the left and the right OBs will be manually delineated. The proximal limit of the OB will be determined on the basis of the sudden change in the diameter at the beginning of the olfactory tract. After all surfaces are added and multiplied by the slice thickness, the volume in cubic millimeters will be obtained for the right and the left OBs, and the total OB volume will be calculated as the sum of the two values.

Measurements will be performed blindly twice by two examiners. When the difference in volume is > 10%, the examiners will perform a third measurement together.

We have interpreted oval, round, triangular, and bean/boat/banana shapes as normal variants of OB shape.Atrophy will be interpreted as flattened OB.

Magnetic resonance imaging (MRI) scans will be performed on a 3T Siemens Verio scanner with a 12-channel phased-array head coil,measuring gray matter(GM) volumes to explore the connection between olfactory function and brain regions.

Magnetic resonance imaging (MRI) scans will be performed on a 3T Siemens Verio scanner with a 12-channel phased-array head coil,measuring white matter(WM) volumes to explore the connection between olfactory function and brain regions.

Magnetic resonance imaging (MRI) scans will be performed on a 3T Siemens Verio scanner with a 12-channel phased-array head coil,measuring cerebrospinal fluid(CSF) volumes to explore the connection between olfactory function and brain regions.

Event-related potentials include olfactory event-related potentials(oERPs) and trigeminal event-related potentials (tERPs).

We will use an OM6b olfactometer to generate ERPs after we have stimulated patients with phenethyl alcohol per standard methods.We infuse olfactory- and then trigeminal-nerve stimuli into the nasal cavity at a constant temperature and flow rate.We will place reference electrodes in the left and right earlobes When analyzing the records offline, we will exclude those contaminated by blinking or other interference . After amplification and filtering, we will obtain stable oERPs and tERPs waveforms.

Questionnaire of Olfactory Disorders (QOD) determines the impact of olfactory dysfunction on daily life (70). The QOD consists of 52 statements, which can be divided into 3 domains: 39 negative statements (degree of suffering; NS), 5 positive statements (positive effects and coping strategies) and 8 socially desired statements ("lie scale") .

Subjective ratings of olfactory function will be also recorded at baseline and follow-up appointments by means of a visual analogue scale, scoring from 0 to 100. On this scale, 0 represents complete olfactory loss and 100 perfect olfactory function. In addition, patients were asked about the presence of qualitative olfactory disorders such as parosmia.