Trigeminal Evoked Responses to Improve Rhizotomy

Study Overview
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Brief Summary
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Trigeminal neuralgia (TGN) is a debilitating pain syndrome where electrical, shock- like jolts of pain affect the face. Trigeminal somatosensory evoked potentials (TSEPs) provide a promising modality for measuring the trigeminal sensory and nociceptive pathway by using peripheral stimulation of the trigeminal nerve (on the skin) and measuring low latency evoked potentials on the scalp (contralateral sensory cortex). While TSEPs have been measured in the past, it is not clear if implementing TSEPs into a routine neurosurgical rhizotomy procedure will be feasible. This is a prospective cohort study examining the feasibility of routinely performing TSEPs during rhizotomies for TGN.

Official Title
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Trigeminal Evoked Responses to Improve Rhizotomy

Conditions
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Trigeminal Neuralgia, Rhizotomy

Intervention / Treatment
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* Other: TSEP + rhizotomy surgery
* Other: TSEPs recording only


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults of 18 years or older Scheduled to undergo percutaneous rhizotomy for facial pain Exclusion Criteria: For TGN: Facial pain of unclear origin (i.e. not clearly TGN pain) or Rhizotomy procedure canceled For Healthy control: Diagnosis or history of facial pain such as TMD or TGN, History of migraine, History of any functional pain disorder: fibromyalgia, IBS, CRPS or Recent chronic pain (within last month)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: TGN patients<br>Patients with TGN who will undergo rhizotomy surgery as the standard of care | Other: TSEP + rhizotomy surgery<br>* TGN patients recruited for this study will already be undergoing percutaneous rhizotomy surgery. TSEPs will be measured at baseline prior to surgery. During the rhizotomy procedure, an electrode or balloon is placed through a metal sheath to then damage the nerve. A stylet is introduced to clear tissue from the sheath in preparation for the electrode or balloon. Prior to the final insertion of the RF electrode where the gasserian ganglion will be damaged, we will place a standard stereotactic EEG electrode (SEEG). Following damaging the nerve (clinical procedure), we will record again to measure differences in the TSEPs following cell body damage. The Neuralynx system will be used to record the potentials at 40 KHz.<br>|
| Active Comparator: Healthy volunteers<br>Healthy volunteers for whom TSEPS will be recorded in a lab setting | Other: TSEPs recording only<br>* TSEPS will also be recorded from healthy controls in a lab setting; all procedures for the healthy controls will be non-invasive.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Feasibility | total study procedure completion rate | 3 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| TSEPS peak to peak amplitude within TGN | difference in measured peak to peak amplitude between normal and TGN side | 1 day | 
| TSEPS latency within TGN | difference in measured TSEPS latency between normal and TGN side | 1 day | 
| TSEPS peak to peak amplitude between control and TGN patients | difference in measured peak to peak amplitude between healthy participants and TGN patients | 1 day | 
| TSEPS latency between control and TGN patients | difference in latency between healthy participants and TGN patients | 1 day |