852 - Botulinum toxin for the treatment of refractory neuropathic facial pain.

Case Diagnosis: Neuropathic pain at the left temporalis muscle.

Case Description: This case report presents a 41-year-old female with a history of pituitary mass, optic neuropathy, meningioma, and R ICA aneurysm status post stent placement who experienced debilitating left-sided facial pain in the distribution of the ophthalmic branch of the trigeminal nerve. The patient was treated with multiple oral medications, from anti-inflammatories, opioids, neuropathic pain medications, and muscle relaxants, without improvement. She also underwent trigeminal nerve block, with worsening of the symptoms. This case explores the use of onabotulinumtoxinA as a part of the treatment of facial pain in the setting of trigeminal neuralgia.

The patient received 25 units of onabotulinumtoxinA injection into the left temporalis muscle, resulting in complete pain resolution for three months. This intervention significantly improved her quality of life and ability to perform activities of daily living.

Discussions: OnabotulinumtoxinA is believed to exert its analgesic effects by inhibiting acetylcholine release at neuromuscular junctions and blocking the release of pain mediators such as substance P and calcitonin gene-related peptides from peripheral nerve endings. This dual action reduces muscular contractions and nerve sensitization, thereby alleviating pain. This case report supports using onabotulinumtoxinA as a promising neuropathic and myofascial pain treatment modality. Further research is warranted to investigate standardized dosing regimens, long-term safety, efficacy, and the biochemical pathways involved in onabotulinumtoxinA's action. Exploring potential synergistic effects with other treatments also presents an exciting avenue for future investigation.

Conclusions: This case report supports using onabotulinumtoxinA as a promising neuropathic and myofascial pain treatment modality. Its mechanisms of action and a well-researched safety profile make it a compelling option for integration into a comprehensive pain management regimen. While preliminary data is encouraging, more extensive trials will be required to establish onabotulinumtoxinA as a standard treatment for these complex and often refractory pain conditions.