A 25-Year-Old Woman With a Droopy Eyelid and Double Vision

Monica Saini, MD, MBBS

Disclosures

March 20, 2020

Discussion

Painful third nerve palsy is a neurologic emergency. The patient in this case had recurrent episodes of unilateral ptosis and diplopia, in association with migraine. Clinically, these episodes were thought to be consistent with RPON, which was previously termed "ophthalmoplegic migraine." However, incomplete recovery and persistent neuroimaging abnormalities (Figure) indicated a mass lesion of the left oculomotor nerve, which is believed to be a schwannoma.

MRI of the patient's brain revealed an enhancing, nodular lesion (red arrow) at the cisternal segment of the left oculomotor nerve (green arrowheads), just distal to the nerve root exit. The left posterior communicating artery (blue dashed arrow) and the left posterior cerebral artery (short blue arrows) were identified in relation to the left oculomotor nerve.

RPON is a controversial disorder and was previously considered to be a migraine variant.[1] After ophthalmoplegic migraine was found to be associated with enhancement of the oculomotor nerve, a neuropathic etiology was put forth. Although ophthalmoplegic migraine has been renamed RPON by the International Headache Society,[2] some researchers still support the classification of RPON as a migraine variant. Whether RPON is truly neuropathic or migrainous is an ongoing subject of debate.

Ophthalmoplegic migraine was originally described as one or more ocular cranial nerve palsies (> 60% oculomotor nerve) that occur in association with, or within several days of, episodic headache (usually severe), with gradual resolution of symptoms over time. In a prospective cohort of 62 patients, ophthalmoplegic migraine was reported in predominantly young individuals (mean age 36.4 ± 12.8 years), with 95% of patients developing ophthalmoplegia during a severe attack of migraine without aura.[3] More than 80% of patients reported an increase in migraine severity in the preceding ≥ 2 weeks. Ophthalmoplegia occurred ipsilateral to a unilateral headache in 75% of patients, whereas bilateral headaches were noted in the rest. Only 22.5% patients had more than one attack of ophthalmoplegic migraine. No nerve abnormalities were noted in any of the patients who underwent contrast-enhanced MRI.

The presence of nerve enhancement, a relapsing-remitting course of progression, response to steroids, and absence of headache in some patients led to reclassification of ophthalmoplegic migraine as a neuropathic disorder (RPON). The diagnostic criteria for RPON include the following:

  • At least two attacks that include both a unilateral headache and ipsilateral paresis of one, two, or three ocular motor nerves

  • Exclusion of orbital, parasellar, or posterior fossa lesion using appropriate investigation

  • Symptoms not better explained by another diagnosis in the third edition of the International Classification of Headache Disorders (ICHD-3)

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