Quantitative Assessment of Subjective Symptoms and Corneal Sensitivity in Chronic Orbital Pain Patients.

PURPOSE: To objectively evaluate the subjective symptoms and characteristics of chronic orbital pain as well as to quantify sensitization of peripheral trigeminal nerves.

METHODS: In this prospective cohort study, patients who previously showed a response to peripheral trigeminal nerve blocks for unilateral, idiopathic chronic orbital pain and healthy subjects completed validated questionnaires assessing headaches, neuropathic signs and symptoms, photophobia, and pain qualities. Corneal sensitivity was measured in both eyes for all subjects with a Cochet-Bonnet aesthesiometer. For pain patients, the full assessment protocol was repeated 2-4 weeks after the study injection, and corneal sensitivity was also measured 30 minutes postinjection. Outcomes assessed were headache, neuropathic pain, and photophobia scores; pain qualities; and corneal sensitivity.

RESULTS: Six female chronic orbital pain patients (mean age 48.2 years) and 11 female controls (mean age 47.5) were included. The mean headache, neuropathic pain, and photophobia questionnaire scores were significantly higher for pain patients than for controls (p < 0.001). On sensory testing, 5 pain patients (83.3%) endorsed allodynia, and all 6 (100%) had hyperalgesia in the ipsilateral frontal nerve dermatome. No controls had allodynia or hyperalgesia. Corneal sensitivity was similar between eyes in pain patients and between groups. Questionnaire scores and corneal sensitivity did not change significantly after the injection.

CONCLUSIONS: Chronic orbital pain patients have a measurable reduction in quality of life due to headaches and photophobia. The supraorbital and supratrochlear nerves are sensitized, resulting in cutaneous hypersensitivity in the corresponding dermatome, but corneal nerves have normal sensitivity.