Evaluation of Lamotrigine on Neuropathic Facial Pain Using fMRI

Pain and Analgesia Imaging and Neuroscience Group6 enrolled

Overview

The aim of this project is to evaluate the effects of the anticonvulsant drug lamotrigine (trade name Lamictal) on neuropathic facial pain or neuralgia using functional magnetic resonance imaging (fMRI).

Currently there are no pharmacological agents that can control neuropathic pain akin to the efficacy of antibiotics for bacterial infection. All current neuropathic pain drugs have approximately the same efficacy of less than 30% in controlled trials, and many of these drugs do not have known mechanisms of action. fMRI studies may provide insight into how brain circuitry is altered by chronic pain, and how these drugs act on altered circuitry. The trigeminal system in particular offers unique advantages for studying such alterations, including a large central representation and high degree of somatotopy. The administration of lamotrigine to neuropathic pain patients in conjunction with fMRI will allow us to compare subjective ratings of pain with objective measures of neural activity during increased conditions of allodynia/hyperalgesia.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Facial Neuropathy

Interventions

LamotrigineDRUG

: 25mg and 50mg tablets

Placebo (for Lamotrigine)DRUG

Sugar pill manufactured to mimic Lamotrigine tablets

Eligibility

Sex: ALLMin age: 18 YearsMax age: 60 Years

Medical Language ↔ Plain English

Inclusion Criteria: * 18-60 years of age * Right-handed non-smokers * Diagnosed with facial pain * Continuous pain for more than 3 months * Spontaneous pain greater than 3 of 10 * Allodynia to brush greater than 5 of 10 Exclusion Criteria: * Medications * Depression * Significant medical problems * Claustrophobia * Abnormal EKG * Significant drug or alcohol history * Positive drug screen * Weight greater than 285 lbs * History of allergy to anticonvulsants * Tattoos with metallic ink on upper body * Any neurostimulator devices, or metal cochlear, ocular, or cardiac implants or other metal near vital areas * Exposure to shrapnel or metal filings * Other metallic surgical hardware

Locations (1)

McLean Hospital Neuroimaging Center, 115 Mill Street

Belmont, Massachusetts, United States

Outcomes

Primary Outcomes

Blood Oxygenation Level-dependent (BOLD) Changes in Neural Pain Circuitry Following Treatment With Lamotrigine During Experimentally Induced Pain States

fMRI scans acquired Stimuli Type: Brush Stimulation Regions: Face (V2) Right and Left Sides Rating: Pain/ unpleasantness fMRI scans acquired Stimuli Type: Cold, threshold -1°C Stimulation Regions: Face (V2) Right and Left Sides Rating: Pain/ unpleasantness \*\*Extra time allotted for probe repositioning\*\* fMRI scans acquired Stimuli Type: Heat, threshold +1°C Stimulation Regions: Face (V2) Right and Left Sides Rating: Pain/ unpleasantness \*\*Extra time allotted for probe repositioning\*\* Cortical, subcortical, and brain stem sensory regions Z-scores Increase or decrease in activation as affected by the drug

Time frame: Week 10 during scanning session

Secondary Outcomes

Subjective Ratings of Pain During Magnetic Resonance Scanning

Quantitative Sensory Testing (QST) Stimuli Type: Heat, Cold, Brush Stimulation Regions: Face Affected and contralateral Unaffected mirror area Rating: Pain/ unpleasantness Stimuli Type: Cold, threshold -1°C Stimulation Regions: Face Affected and contralateral Unaffected mirror area Rating: Pain/ unpleasantness Stimuli Type: Heat, threshold +1°C Stimulation Regions: Face Affected and contralateral Unaffected mirror area Rating: Pain/ unpleasantness Ratings on a likert scale of 0-10 with 0 being defined as no pain and 10 being defined as worst possible pain

Time frame: week 10 (during the scan)

Data from ClinicalTrials.gov

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