Pearls & Oy-sters: Supraorbital neuralgia in lepromatus leprosy masquerading as SUNA

Discussion

A triad of spontaneously occurring continuous nonthrobbing pain in the territory of supraorbital nerve, tender nerve in the supraorbital notch, and complete but transient relief from pain by supraorbital nerve block characterizes the supraorbital neuralgia.^1,–,3 Pain in supraorbital neuralgia is usually nonlancinating but it is accompanied by intermittent bursts of periorbital/frontal bursting pain that usually lasts for a few seconds.³ Supraorbital neuralgia is a rare headache. The most common cause of supraorbital neuralgia is forehead trauma and often, these patients will have stich marks above the eyebrow on the affected side. Other causes include tight-fitting helmets and ill-fitting swimming goggles (goggles migraine).^4,5 However, it has never been described secondary to leprosy. Leprosy may have varied manifestations and therefore it is considered to be a great mimic in endemic areas.⁶

The triad for the diagnosis of supraorbital neuralgia requires surpraorbital nerve block to demonstrate transient pain relief. We use nerve block only after failing with medical management. Our patient responded to the multidrug treatment for leprosy after failing a number of antiepileptic medications. Our patient had multiple thickened and tender nerves, suggestive of leprous neuritis. Therefore, we also prescribed oral prednisolone for a 4-week period along with the antileprosy treatment, which might have enhanced the effect of antileprosy treatment. Leprosy is a disease of peripheral nerves caused by Mycobacterium leprae.⁷ It produces thickened and tender nerves. Inadvertent stroking of the enlarged nerve may produce severe lancinating pain in the territory of the nerve that is best explained by the Tinel sign. Therefore, it was not the nerve trauma but the inflammation of supraorbital nerve secondary to leprosy that resulted in Tinel sign in our patient. Supraorbital neuralgia is usually not associated with lacrimation or eye redness. However, some patients report mild transient lacrimation on rare occasions.⁵ Our patient reported an event when he hit his forehead on his friend’s helmet while riding pillion on a bike. He experienced very severe lancinating pain in the eye and forehead region with lacrimation. Possibly, this history of lacrimation from the affected side on a few occasions with episode of triggered pain and the history of intermittent spontaneous burst of periorbital/forehead pains of supraorbital neuralgia mistakenly led to the diagnosis of SUNA in our patient.

SUNA is characterized by multiple daily pain attacks in the eye/periorbital region that last for several seconds and are usually accompanied by lacrimation or redness of the affected eye. The pain attacks are spontaneous as well as triggered. The pain is in the form of single or multiple stabs of lancinating pains.⁸ There is no background continuous pain in SUNA, unlike the continuous pain seen in supraorbital neuralgia. The pain of SUNA is largely indistinguishable from the pain of trigeminal neuralgia of ophthalmic division. The supraorbital neuralgia, however, shares the distribution of pain with SUNA because supraorbital nerve is a terminal branch of frontal nerve, which is a branch of ophthalmic division of trigeminal nerve. The triggered pain in supraorbital neuralgia is always secondary to Tinel sign. In contrast, the pain in SUNA can be triggered by different activities like touching the eyelid or periorbital area, chewing, brushing teeth, yawning, or sometimes by talking.