Conditions: Facial Neuropathy
Keywords: pain neuropathic face trigeminal
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 6
Healthy volunteers: no

Brief summary:
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).

Detailed 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.

Arms:
arm 1: 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. arm 2: 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.

Interventions: intervention 1: Lamotrigine intervention 2: Placebo (for Lamotrigine)
Intervention descriptions: intervention 1: : 25mg and 50mg tablets intervention 2: Sugar pill manufactured to mimic Lamotrigine tablets

Protocol document: