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. Cranial nerve enhancement resulted from RPON would gradually disappear as the symptoms subside after an episode, but spontaneous resolution of nerve enhancement is very unlikely to be seen in neoplastic (e.g. schwannoma), inflammatory and infectious diseases. Contrast-enhanced MRI results can also reveal the location of nerve inflammation for disease diagnosis. Although Tolosa–Hunt syndrome (THS) and RPON share many clinical features, THS can be identified by the presence of granulomatous inflammation in the cavernous sinus, superior orbital fissure, or orbit in MRI scans. Magnetic resonance angiography (MRA) or CT angiography (CTA) can be used to examine cerebral blood vessels and to rule out vascular abnormalities, such as an aneurysm. In cases where intracranial vascular lesions, for example, subarachnoid hemorrhage cannot be completely ruled out after performing MRA or CTA, physicians may consider using traditional digital subtraction angiography (DSA) for more detailed investigation. Laboratory tests Lumbar punctures and blood tests might be performed on those with RPON to identify other possible causes of cranial neuropathy, including diabetes, inflammatory diseases, infections, tumors, and other systemic diseases that involve either the central nervous system or the peripheral nervous system. The detection of abnormalities in these tests suggests that RPON is highly unlikely to be the culprit in cranial neuropathy, and more diagnostic tests should be done to find out the underlying condition.
Recurrent painful ophthalmoplegic neuropathy
Acute visual loss
Visual impairment due to intracranial pressure
Persistent edema of rosacea
Recurrent corneal erosion
Diffuse unilateral subacute neuroretinitis
Chronic progressive external ophthalmoplegia
Facial onset sensory and motor neuropathy