An observational study in Trigeminal Neuralgia (TN), Orofacial Pain and Dental Pain, sponsored by University College, London. Not yet recruiting at 1 site in United Kingdom. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-23.
Sponsored by University College, London · Observational
Trigeminal neuralgia (TN) is a severe type of non-dental orofacial pain that can feel like sudden electric shocks in the face and is often mistaken for tooth pain or other dental problems. This can lead to delays in referral and unnecessary, sometimes irreversible, dental treatment. The goal of this observational study is to evaluate how well a new questionnaire (IDentification of possible Trigeminal Neuralgia - IDTN) identifies adults with possible trigeminal neuralgia among patients attending hospital clinics with orofacial pain, with the aim of supporting its use in dental and general medical practice to improve early recognition and referral.
The main questions it aims to answer are:
Participants will:
A subset of participants will also be asked to complete the questionnaire again a few days later to assess test-retest reliability.
Trigeminal neuralgia (TN) is a severe neuropathic facial pain condition that is often difficult to recognize early, especially in primary care and dental settings. Many patients initially present with pain that can be mistaken for dental disease or other types of non-dental pain, such as temporomandibular disorders, which may lead to delays in diagnosis and inappropriate dental treatment. A practical screening tool for use in dental practice may support earlier identification and referral of patients with possible TN.
This study will evaluate the diagnostic accuracy of a newly developed questionnaire, the IDentification of possible Trigeminal Neuralgia (IDTN) tool. The IDTN questionnaire was developed with input from patients, dentists, and clinical experts and is designed to capture key features of TN, including pain quality, paroxysmal attacks, pain location, triggers, and related clinical characteristics. This is the first validation study of this tool in a real-world clinical setting. Currently, there is no similar screening tool that has been validated and widely accepted for use in dental practice.
Study Design This is a single-site, prospective, observational diagnostic validation study conducted at University College London Hospitals (UCLH) NHS (National Health System) Foundation Trust, including the Facial Pain Service and Oral Surgery clinics. Adult patients attending for a first appointment with facial or oral pain will be invited to participate. The study is non-interventional and does not alter routine clinical care.
Study Procedures
Participants will complete the 15-item IDTN questionnaire before their specialist consultation, either:
The treating specialist will be blinded to the completed questionnaire during the consultation. After the appointment, the research team will record the specialist's final diagnosis from the electronic health record. This will serve as the reference standard for evaluating the questionnaire. If diagnostic uncertainty exists, cases may be reviewed through usual multidisciplinary discussion, and the final clinical diagnosis will be used for analysis.
In addition to questionnaire responses, the study team will collect limited clinical and demographic information from the electronic health record, including age, sex, referrer type, year of first symptoms, and diagnosis. Data will be linked using a study ID and analyzed in anonymized form.
Test-Retest Reliability A subset of participants (20%) will be invited to complete the IDTN questionnaire again within a few days (approximately 2-3 days depending on operational feasibility) to assess the stability of responses over time.
Study Objectives
Primary objective To evaluate the diagnostic accuracy of the IDTN questionnaire for identifying possible TN.
Secondary objectives
In the future, the aim is to develop an electronic version of the screening tool with an integrated scoring algorithm, enabling wider use of the tool in the United Kingdom (UK) and internationally.
Outcomes and Analysis Overview
The main diagnostic accuracy measures will include:
A screening threshold will be selected with priority given to high sensitivity, because the tool is intended to support early identification and referral. A secondary threshold based on the Youden Index may also be reported. A scoring algorithm will be explored using regression-based methods, with internal validation to reduce overfitting. Reliability and dimensionality analyses (including test-retest agreement and factor analysis) will also be performed.
Sample Size The anticipated sample size is 250 participants, with an expected 60 participants diagnosed with TN. An interim analysis will be conducted at 6 months, and if recruitment of new TN cases is lower than anticipated, the study may be expanded to additional facial pain or oral surgery centres using the same methodology to achieve the required numbers. This sample size was calculated to estimate the diagnostic accuracy of the screening tool with 95% confidence intervals and a precision of approximately ±10%, assuming expected sensitivity and specificity of 80%.
Significance If validated, the IDTN questionnaire may provide a practical screening tool to help dental and general medical practitioners identify patients with possible trigeminal neuralgia earlier and refer them more promptly for specialist assessment and treatment. This may reduce diagnostic delay and avoid unnecessary and often irreversible dental procedures.
140 studies on the registry are indexed under Trigeminal Neuralgia; 44 are open to participants now.
This study's planned enrollment of 250 is above the median of 84 across 38 observational studies indexed under Trigeminal Neuralgia.
Browse Trigeminal Neuralgia studies →University College, London is the lead sponsor of 651 studies on the registry; 149 are open to participants now.
Of its 6 completed or terminated interventional studies of FDA-regulated products, 2 (33%) have results posted.
Counted across the registry records on this site, refreshed daily.
Participants will be recruited from two clinical settings at University College London Hospitals (UCLH): the Facial Pain Service and the Oral Surgery Clinic. Eligible participants will be identified using clinic codes that indicate first-time attendance for pain-related referrals from primary care. This population includes individuals referred from primary care because of facial pain, dental pain, or suspected orofacial pain conditions, including trigeminal neuralgia.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adults aged 18 years or older attending the University COllege London Hospital (UCLH) Facial Pain Service or the Oral Surgery Clinic for their first appointment for facial or oral pain. All participants will complete the IDTN questionnaire before their routine clinical consultation. Their specialist diagnosis (for example, trigeminal neuralgia or other facial/oral pain condition) will be used as the reference standard to assess the accuracy of the questionnaire.
Other: Completion of the IDTN Questionnaire
There are no interventions because this is an observational validation study. Participants complete a 15-item trigeminal neuralgia screening questionnaire (IDTN) before their clinical appointment.
Diagnostic Accuracy of the IDTN Questionnaire
Sensitivity and specificity of the IDTN screening tool for identifying possible trigeminal neuralgia (TN), using the specialist clinical diagnosis as the reference standard. This will assess how accurately the questionnaire distinguishes between participants with and without possible TN.
Time frame: Day 1 (at the participant's clinic appointment)
Positive and Negative Predictive Values
Positive predictive value (PPV) and negative predictive value (NPV) of the IDTN questionnaire in identifying possible TN compared with the clinical diagnosis.
Time frame: Day 1
Receiver operating characteristic (ROC) curve and area under the curve (AUC)
The AUC-ROC will be calculated to measure how well the IDTN questionnaire discriminates between participants with and without possible TN.
Time frame: Day 1
Internal Consistency Reliability
Internal consistency of the questionnaire items will be evaluated using Cronbach's alpha to assess whether items measure the same underlying construct.
Time frame: Through study completion (after all questionnaires are collected) (average 1 year)
Test - Retest Reliability
Stability of questionnaire responses over time will be assessed in a subsample of participants who complete the IDTN questionnaire twice within a few days. Agreement will be measured using intraclass correlation coefficient or Cohen's kappa.
Time frame: 2-3 days after initial questionnaire completion
Validity
Construct validity will be assessed by comparing IDTN with validated questionnaires. Convergent validity will be evaluated against painDETECT, while divergent validity will be assessed using a TMD screening questionnaire (e.g. American Academy of Orofacial Pain - AAOP). Criterion validity will be based on comparison with the specialist clinical diagnosis.
Time frame: Day 1
Refinement of Questionnaire Items
After data collection is complete, the questionnaire will be reviewed and refined based on diagnostic accuracy findings, test-retest results, and participant/clinician feedback. This may include modifying, removing, or rewording items to improve clarity, usability, and diagnostic performance.
Time frame: Through study completion (on average within 6 months after final participant visit)
Plan to share: Yes — Fully anonymized individual participant data (IPD) that underlie the published results will be shared. This will include anonymized responses to the IDTN questionnaire, demographic variables (such as age and gender), and the final clinical diagnosis used as the reference standard. All direct identifiers will be removed, and data will be de-identified according to UCL/UCLH (University College London/University College London Hospitals) data governance requirements before sharing.
Supporting information: Study protocol, Statistical analysis plan, Analytic code
Time frame: Anonymized IPD and supporting materials will be available 6 months after publication of the main study results and will remain available for up to 5 years thereafter.
Access criteria: Access will be provided to qualified researchers for scientifically justified purposes. Requests must be submitted in writing to the Chief Investigator and will be reviewed jointly by the research team and sponsor (UCL). Approved researchers will sign a data sharing agreement and will receive access to anonymized datasets through a secure transfer mechanism.
Start is estimated for Apr 2026; primary completion for Apr 2027, 12 months later.
Of 19 observational studies under Trigeminal Neuralgia, half reached primary completion within 37 months of starting (the median), counting those still running; a quarter within 24 and three quarters within 59. This study's planned 12 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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