Ophthalmoplegic migraine: migraine variant or cranial neuralgia?

Ophthalmoplegic migraine (OM) is a rare headache disorder, which usually starts in childhood but sometimes first appears in adulthood. The typical clinical presentation is migraine-like headache accompanied or followed by transient extraocular muscle paresis, mostly involving the oculomotor nerve but sometimes the abducens or trochlear nerves. Ophthalmoplegia recovers spontaneously within weeks. OM was initially classified as a migraine variant in the International Classification of Headache Disorders, 1st edition (ICHD-1) (1). In 1992, Mark et al. (2) described the first OM patient with reversible gadolinium enhancement of the oculomotor nerve on magnetic resonance imaging (MRI). Thereafter, several case reports followed. Because of the self-limiting clinical characteristics, the disease was suspected to be related to recurrent demyelinating neuropathy. In 2004, the International Headache Society (IHS) Classification Committee moved this headache disorder to the group of ‘cranial neuralgias’ in the International Classification of Headache Disorders, 2nd edition (ICHD-2) (3); nonetheless, the terminology of ‘ophthalmoplegic migraine’ remained in use (Table 1). In this issue of Cephalalgia, Akimoto et al. (4) report on a 54-year-old man, who experienced attacks of OM for more than 45 years. The MRI examination in the acute phase showed an enhanced nodular lesion in the root exit zone (REZ) of the left oculomotor nerve. Because the clinical symptoms were progressive, a biopsy was performed. Intriguingly, the biopsy did not show inflammatory cell infiltration or demyelination but neuromuscular hamartoma. This finding obviously does not support a prior belief that the MRI findings imply demyelination as the underlying cause for OM. Even though enhancement of the cisternal portion of the oculomotor nerve is the most common MRI finding for OM, it is not specific. Certain causes can present similar pictures, such as trauma, inflammation, demyelination, small vessel ischemia, tumor (schwannoma, lymphoma, hemangioma and carcinomatous meningitis), postviral syndrome and systemic lupus erythematosus.