Peripheral trigeminal nerve block improves symptoms of chronic orbital pain: Study

USA: Modulating trigeminal afferent nerve activity with peripheral trigeminal nerve blocks may be a favorable treatment strategy for multifactorial chronic orbital pain, states an article published in the Ophthalmic Plastic and Reconstruction Surgery.

Chronic ocular pain can be seen as a manifestation of several clinical scenarios.  Patients often describe ocular pain as "dryness", "burning", "tenderness", and "aching". Pain in the eye can arise from chronic ocular surface disruption and inflammation, from neuropathic processes, or frequently from mixed mechanisms. The trigeminal nerve also called the fifth cranial nerve, mediates sensations of the face and eye. A trigeminal nerve block is a type of therapeutic pain block that involves injecting a local anesthetic into the trigeminal nerve, which carries sensation from the face to the brain.

Grace Lee, University of Iowa, Iowa City, USA,  and colleagues conducted a retrospective study to characterize chronic orbital pain in patients who benefitted from peripheral trigeminal nerve blocks and to explore the relationship between pain etiologies and phenotypes, injection attributes, and positive response to treatment.

Investigators included 19 patients who underwent a total of 94 peripheral trigeminal nerve blocks for chronic orbital pain in the study. Data reviewed included inciting factors, neuropathic symptoms of orbital pain, injection composition (anesthetic alone versus anesthetic + dexamethasone), and corneal epitheliopathy grades. Primary outcomes assessed were a response to injection, duration of injection effectiveness, and overall treatment efficacy. Associations between subgroups of chronic orbital pain, injection attributes, and treatment outcomes were examined. During a mean follow-up period of 2.4 years after initial injection (range 7 days-4.6 years),

Key findings of the study,

• Out of the total, 84.2% of the patients achieved either partial or complete improvement.

• Ocular versus nonocular origin of orbital pain or the presence of neuropathic sensory characteristics were not associated with a treatment outcome.

• Injections containing dexamethasone had a lower positive efficacy (relative risk-0.88) and no statistically significant association with prolonged effect.

• 50.9% of the injections for which effect duration was recorded produced a response lasting greater than 6 weeks.

Investigators conclude that giving peripheral trigeminal nerve blocks for modification of trigeminal afferent nerve activity may be a good treatment strategy for chronic orbital pain of diverse etiologies and phenotypes.

Reference:

Lee G, Pham CM, Kardon RH, Shriver EM. Peripheral Trigeminal Nerve Blocks for Chronic Orbital Pain: Clinical Features and Outcomes. Ophthalmic Plast Reconstr Surg. 2022 Jul-Aug 01;38(4):369-376. doi: 10.1097/IOP.0000000000002120