Dose dependent efficacy of adjunctive photobiomodulation with carbamazepine in trigeminal neuralgia: A randomized controlled trial

Source of data- Data will be collected from patients reporting to the Out-Patient Unit of Oral Medicine and Radiology in the Faculty of Dental Sciences, I.M.S., B.H.U. Patients fulfilling the inclusion criteria will be selected. Diagnosis of Trigeminal Neuralgia would be based on the IHS Classification ICHD-3.

Method of collection of data:

Sampling technique- Simple random sampling

Sample size determination- The sample size was estimated using the formula for comparing two independent means, which was rounded up to 16 patients per group. With three treatment groups, the total sample size required was 48. Allowing for an anticipated 20% dropout rate, the final target sample size was set at 20 patients per group, for a total of 60 participants.

**Study design-**Randomized controlled trial

Patient selection criteria:

Inclusion criteria

1. Patients clinically diagnosed with TN according to the IHS Classification ICHD-3.

2. Both males and females.

3. Patients willing to participate who have given informed consent for the study.

4. Patients with blood parameters (CBC, LFT) within normal limits.

Exclusion criteria

1. Pregnant females.

2. Patients with abnormal CBC and liver function tests.

3. Patients with evidence of significant vascular compression of the trigeminal nerve or any other intracranial pathology on 3.0 T MRI brain evaluation.

4. Patients with previous history of treatment for TN within 1 year.

Duration of study– 6 months.

Materials:

1. Basic examination kit

2. 810 nm GaAlAs diode laser device with photobiomodulatory tip and accessories

3. Surgical skin marker

Methods:

1. Diagnosis of trigeminal neuralgia will be made on basis of clinical findings in line with the IHS Classification ICHD-3.

2. The treatment protocol will be explained to patients diagnosed with TN and with normal blood reports. Patients who provide informed consent will undergo a 3.0 T MRI of the brain to rule out significant vascular compression of the trigeminal nerve root or any other intracranial pathology. Only those without detectable abnormalities will be included in the study.

3. Baseline scoring of pain will be recorded using numeric rating scale (NRS) and Barrow Neurological Institute (BNI) Pain Intensity Scale. A baseline scoring of McGill Pain questionnaire (MPQ) will be done. Patients will also be instructed to maintain a daily attack diary recording paroxysm frequency, duration, triggers, and rescue medication use.

4. Patients will be randomized (computer-generated sequence, with allocation concealment) into three treatment arms, with age and sex stratification to ensure balanced distribution.

5. Carbamazepine pharmacotherapy at 200 mg/day will be prescribed to all patients across the groups at the start of treatment. No other centrally acting anticonvulsant or muscle relaxant drugs (e.g., gabapentinoids, baclofen) will be allowed during the study period. As rescue medication during increased pain, tab. acetaminophen (<2g/ day) can be taken and recorded by the patient.

6. All patients will receive an adjunctive photobiomodulation therapy with 810 nm diode laser over trigger zones and involved dermatome, thrice weekly for 3 weeks. Patients in Group 1, Group 2, and Group 3 will receive PBM therapy at 200 mW for 30 s (6 J/point), 45 s (9 J/point), and 60 s (12 J/point) per point, respectively.

7. NRS, BNI and MPQ scoring will be recorded at the end of each week for the first month, then at the end of 2nd and 3rd month for all patients.