Study of EEG and Nasal Stimulus in Olfactory Disorders

Browse trials for

• Olfaction Disorders 70
• Tinnitus 444

Keywords

• Olfactory stimuli
• EEG
• Tinnitus
• Olfactory disorders
• Smell impairment
• Olfactometry
• Brain waves

Olfaction Disorders

70 studies on the registry are indexed under Olfaction Disorders; 18 are open to participants now.

This study's planned enrollment of 1,000 is above the median of 60 across 49 interventional studies indexed under Olfaction Disorders.

Lead sponsor

Fondazione Policlinico Universitario Agostino Gemelli IRCCS is the lead sponsor of 952 studies on the registry; 541 are open to participants now.

Study arms

• Active comparator
  Normosmic

  Participants in this group have normal olfactory function, as determined by the Sniffin' Sticks test. They will undergo EEG analysis while being exposed to various olfactory stimuli to establish baseline brain wave patterns for normal olfactory responses. (n=550)

  Diagnostic Test: Sniffin'Sticks

• Active comparator
  Hyposmic

  Participants in this group have impaired olfactory function (hyposmia), confirmed through the Sniffin' Sticks test. They will undergo EEG analysis during olfactory stimulation to identify differences in brain wave patterns compared to normosmic individuals. (n=150)

  Diagnostic Test: Sniffin'Sticks

• Active comparator
  Tinnitus Patients with Hyposmia

  This group includes participants who have both tinnitus and hyposmia. They will be subjected to EEG analysis during olfactory testing to investigate the interaction between olfactory and auditory disorders and how these conditions may influence brain wave responses. (n=150)

  Diagnostic Test: Sniffin'Sticks

• Active comparator
  Tinnitus Patients without Hyposmia

  Participants in this group have tinnitus but normal olfactory function. They will undergo the same EEG and olfactory tests to explore the impact of tinnitus on brain wave patterns in the absence of olfactory disorders and to compare their responses with those of other groups. (n=150)

  Diagnostic Test: Sniffin'Sticks

Interventions

• Diagnostic testSniffin'Sticks

  The Sniffin' Sticks test, a validated method to evaluate olfactory functions, utilizes pen-like devices to dispense scents for testing identification, discrimination, and detection of odors. In this study, participants' responses to various scents are recorded. EEG (Electroencephalography) captures electrical activity in the brain during exposure to these odors by using an EEG cap fitted with electrodes on the scalp. This allows for the monitoring of brain wave patterns in response to olfactory stimuli. Both the Sniffin' Sticks test and EEG recordings are conducted simultaneously, providing a dual assessment of behavioral reactions and brain activity to odors. The goal of the study is to compare brain wave patterns and olfactory function in normosmic (normal smell), hyposmic (reduced smell), and tinnitus patients with and without olfactory impairments, delivering comprehensive insights into the neural basis of olfactory perception.

  Also known as: EEG

Primary outcomes

1. Enrollment and data collection

   During this period, 1000 participants \> 18 y/o will be recruited and divided into four distinct groups: normosmics (550), hyposmics (150), tinnitus patients with hyposmia (150), and tinnitus patients without hyposmia (150). The primary outcome of the Neuroscent project is to assess the ability of EEG analysis to distinguish between normosmic and hyposmic participants during olfactory stimulation using the Sniffin' Sticks test.

   Time frame: 22 months

2. EEG Parameters (in µV²)

   Alpha Power: Measured in microvolts squared (µV²), representing the magnitude of Alpha wave activity during olfactory stimulation. Theta Power: Measured in microvolts squared (µV²), representing the magnitude of Theta wave activity during olfactory stimulation. We will make use of the Fourier transform as well, which is inherently dimensionless. The data acquisition setup involves placing blindfolded participants in an isolated room and administering three randomized olfactory stimuli (pure olfactory, trigeminal, and olfactory-gustatory) while collecting EEG data. Sessions start and end with a 30-second resting state.

   Time frame: 22 months

3. Behavioral/Performance Measures (Scores)

   Olfactory Threshold Scores (as per routinary diagnosis of olfactory performances): Derived from the Sniffin' Sticks test, these scores quantify participants' ability to detect odors, classifying them as normosmic or hyposmic. All the participants will undergo a complete olfactory assessment through the Sniffin' Sticks test. These are represented as numerical scores. The maximum score obtainable in the full Sniffin' Sticks test, which includes the three sub-tests (Threshold, Discrimination, Identification - TDI), is 48. This maximum score is achieved by summing the highest possible score from each of the three components: 16 for olfactory threshold (Threshold), 16 for olfactory discrimination (Discrimination), and 16 for olfactory identification (Identification).

   Time frame: 22 months

4. Model Performance Metrics (Accuracy)

   Random Forest Model Classification Accuracy: The accuracy of the classification model used to distinguish between normosmic and hyposmic participants based on EEG data, usually expressed as a percentage or a value between 0 and 1.

   Time frame: 22 months

5. Dimensionality Change Outputs (t-SNE)

   t-SNE Features: Although these don't have a specific unit, they represent the reduced dimensional data points used as features in the Random Forest model. These are typically dimensionless and used in the context of visualizing and improving model performance.

   Time frame: 22 months

Secondary outcomes

1. Pure Tone Audiometry Test

   Pure Tone Audiometry (PTA), as per routinary diagnosis of Tinnitus: Measures hearing thresholds across frequencies, reported in decibels Hearing Level (dB HL) to determine the degree of hearing loss. The results are plotted on an audiogram, which shows the person's hearing threshold at different frequencies; a normal audiogram threshold is 0-20 dB HL between 250 and 8k Hz.

   Time frame: 22 months (Simultaneously with the primary outcome)

2. Behavioral/Performance Measures (Scores)

   Tinnitus Handicap Inventory (THI): Scores the impact of tinnitus on a scale from 0 to 100, where a higher score indicates a worse impact of tinnitus.

   Time frame: 22 months (Simultaneously with the primary outcome)

3. EEG Parameters

   EEG Data: Analyzed during exposure to olfactory stimuli (as per Primary Outcome), with features reduced via t-SNE and classified using a Random Forest algorithm.

   Time frame: 22 months (Simultaneously with the primary outcome)

4. Model Performance Metrics

   Random Forest Model Classification Accuracy: Measures the accuracy of the model used to classify participants across the four groups. This is typically expressed as a percentage or a value between 0 and 1. Fleiss' Kappa Statistic: Used to evaluate the agreement of classification, reported as a kappa coefficient.

   Time frame: 22 months (Simultaneously with the primary outcome)

5. Power Analysis and Post-hoc Analyses

   Power Analysis: Ensures the sample size is adequate to detect significant effects. This is typically expressed in terms of statistical power (e.g., 0.8 or 80%). Post-hoc Analyses: Conducted if significant differences are found, usually involving p-values or effect sizes.

   Time frame: 22 months (Simultaneously with the primary outcome)

6. Auditory Brainstem Response (ABR)

   Auditory Brainstem Response (ABR) as per routinary diagnosis of Tinnitus: Assesses the auditory nerve and brainstem's response to sound stimuli by measuring electrical activity in the brain. Results are typically presented as waveforms, with particular focus on latency and amplitude of specific waves, measured in milliseconds (ms) and microvolts (µV) respectively, to evaluate neural pathways involved in hearing.

   Time frame: 22 months (Simultaneously with the primary outcome)

7. Tympanometry

   Tympanometry, as per routinary diagnosis of Tinnitus: Evaluates middle ear function by measuring tympanic membrane mobility, with results reported in decapascals (daPa) and milliliters (mL). The pressure reading in tympanometry reflects the air pressure in the middle ear cavity. A normal tympanogram shows peak compliance when the pressure in the ear canal matches the pressure in the middle ear, indicating normal middle ear function. The two units of measurement, pressure and compliance, are plotted on a two-dimensional graph. Pressure (daPa) is plotted on the x-axis and compliance, measured in mL, is plotted on the y-axis in the two-dimensional graph

   Time frame: 22 months (Simultaneously with the primary outcome)

Other outcomes

1. Predicting Odor Categories in Tinnitus and Non-Tinnitus Groups Using EEG and Machine Learning

   The final outcome will involve comparing olfactory perception across four participant groups (normosmic, normosmic with tinnitus, hyposmic, and hyposmic with tinnitus) using EEG features derived from Fourier analysis, reduced via t-SNE, and classified with a Random Forest algorithm. The model's accuracy in predicting odor categories (based on EEG data) will be evaluated using metrics such as accuracy, precision, recall, specificity, and F1 score. Fleiss' kappa statistic will assess agreement across groups, comparing the algorithm's predictions with the Sniffin' Sticks test results. Statistical power analysis ensures adequate sample sizes for reliable comparisons, with post-hoc analyses conducted if significant differences are detected.

   Time frame: 2 months

Individual participant data

Plan to share: No