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.
Even though various studies have documented the success of using this medication to induce symptomatic relief in affected individuals, the improvement is not as rapid and significant as observed in other inflammatory diseases, such as THS and temporal arteristis. In addition, some steroid non-responders may have worsened RPON symptoms after taking these drugs, suggesting that corticosteroids are not suitable for treating every patient with the condition.Other drugs, such as nonsteroidal anti-inflammatory drugs (NSAIDs), ergotamine, triptan and acetaminophen, have been investigated for the acute treatment of RPON. However, their efficacy is currently unknown. Management of residual symptoms
Depending on the severity of symptoms, various treatment options are available to people with persistent ophthalmoplegia. For mild conditions, prism glasses can be prescribed to correct specific types of double vision. In more extreme cases, additional intervention such as botulinum toxin injection and strabismus surgery, might be required to rebalance the actions of the extraocular muscles. This would improve the alignment of the eyes when they are in primary position. Similarly, surgical correction can be performed on individuals with severe ptosis. Prognosis
The prognosis of RPON is generally considered favorable, with most affected individuals having spontaneous symptom resolution after an attack. However, the accumulated nerve damage from repeated RPON attacks might increase the severity and persistence of ophthalmoplegia. Among people with recurrent episodes of RPON, about 30-54% develop permanent neurological sequelae, such as persistent mydriasis, ptosis, strabismus and double vision. == References ==