Evaluation of Lamotrigine on Neuropathic Facial Pain Using fMRI

Pain and Analgesia Imaging and Neuroscience Group

Status: Completed

Conditions: Facial Neuropathy

Treatments: Drug: Placebo (for Lamotrigine); Drug: Lamotrigine

Study type: Interventional

Funder types: Other; Industry

Identifiers

NCT00243152

Facial Neuropathy/lamotrigine

Details and patient eligibility

About

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).

Full description

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.

Enrollment: 6 patients

Sex: All

Ages: 18 to 60 years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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6 participants in 2 patient groups

Lamotrigine to Placebo Crossover

Active Comparator group

Description:

The drug lamotrigine will be given for 9 weeks prior to imaging session 1. A rescue drug, Gabapentin, will be provided for pain control. Patients will taper off the Gabapentin 2 weeks before each scan date. After a taper and washout, placebo (cross over) will be administered. At the end of the trial (after imaging session 2), a taper for placebo will be given. Patients will be required to maintain a pain diary during the study, documenting the perceived effects of the drug on the severity of their pain and keeping track of their subjective pain ratings day to day. Patients will also complete the McGill Pain Questionnaire at each visit.

Treatment:

Drug: Lamotrigine

Placebo to Lamotrigine Crossover

Active Comparator group

Description:

The placebo will be given for 9 weeks prior to imaging session 1. A rescue drug, Gabapentin, will be provided for pain control. Patients will taper off the Gabapentin 2 weeks before each scan date. After a taper and washout, the drug lamotrigine (cross over) will be administered. At the end of the trial (after imaging session 2), a taper for drug will be given. Patients will be required to maintain a pain diary during the study, documenting the perceived effects of the drug on the severity of their pain and keeping track of their subjective pain ratings day to day. Patients will also complete the McGill Pain Questionnaire at each visit.

Treatment:

Drug: Placebo (for Lamotrigine)