Recurrent painful ophthalmoplegic neuropathy (RPON), previously known as ophthalmoplegic migraine (OM), is a rare neurological disorder that is characterized by repeated headache attacks and reversible ipsilateral paresis of one or more ocular cranial nerves (CN). Oculomotor nerve (CNIII) is by far the most common cranial nerve involves in RPON, while abducens nerve (CNVI) and trochlear nerve (CNIV) involvements are also reported. Globally, RPON was estimated to have an annual incidence rate of 0.7 per million as of 1990, no further epidemiological studies have been conducted. It occurs more often in children and females.Although the etiology of RPON is unknown owing to the rarity of this disease, various potential theories including migrainous and neuropathic mechanisms have been developed. Diagnosis is based on physical examination, magnetic resonance imaging (MRI), and ruling out other possible causes. Despite the fact that there are currently no evidence-based treatment guidelines for RPON, the most commonly used medications are corticosteroids that have been proven effective in alleviating the symptoms. As for people who are unresponsive to steroids, other treatments, such as anti-migraine drugs, botulinum toxin injection and strabismus surgery, may be utilized. For prevention, several medications including calcium channel blockers may be used. However, none have been proved consistently effective. RPON has a good overall prognosis as a result of the self-limiting nature of the condition, but permanent neurological damage may accumulate over repeated episodes. Signs and symptoms
The typical symptoms of RPON are recurrent headaches and ipsilateral paralysis of the extraocular muscles (ophthalmoplegia) that are responsible for controlling eye movements.
Inflammatory demyelination of the ocular cranial nerves would likely lead to the release of neuropeptides, such as calcitonin gene-related peptide, to the trigeminovascular system. This would irritate the trigeminal sensory fibers, and consequently, a headache as manifested in RPON is triggered. Diagnosis
Diagnostic criteria
To be diagnosed with RPON, a person must have a minimum of 2 unilateral headache attacks with ipsilateral ocular cranial nerve paralysis that cannot be explained by other causes of headache in ICHD-3 after investigation. Diagnostic tests
RPON is a diagnosis of exclusion, meaning that other conditions with similar clinical presentation, such as vascular, inflammatory, neoplastic, and infectious causes, must be ruled out before the confirmation of RPON diagnosis. Physical examination, neuroimaging, and laboratory tests are routinely conducted in clinical practice to evaluate this disease. Physical examination
After obtaining the medical history of people with suspected RPON, thorough eye examination and neurological examination are usually performed to assess the extent of neurological impairment, localize the brain regions being affected, and rule out other possible causes for the symptoms. These involve the assessments of visual acuity, eye movements and alignment, pupillary responses, and mental status. Neuroimaging
Contrast-enhanced magnetic resonance imaging (MRI) is a diagnostic tool that can facilitate the differentiation of RPON from other diseases. The transient, reversible enhancement or thickening of the ocular motor nerve(s), which can be observed in the MRI scans of a small proportion of affected individuals during acute attacks, is a distinguishing feature of RPON.