To present a case of painful, unilateral trochlear nerve palsy in a patient with anti-GQ1b-positive Miller Fisher syndrome.

Miller Fisher syndrome (MFS) is a rare variant of Guillain Barre syndrome (GBS), an acute-immune-mediated demyelinating polyradiculoneuropathy originally described in 1956 as a triad of total external ophthalmoplegia, ataxia, and areflexia. The presence of the IgG anti-ganglioside (GQ1b) antibodies in serum has been recognized as an excellent diagnostic marker for MFS. This antibody often cross reacts with the GT1a ganglioside and is associated with ophthalmoplegia or ataxia in MFS.

A 21-year-old obese male with no past medical history presented to the hospital with a 3-day history of diplopia, orbital pain when looking to the right, bilateral lower extremity weakness and feeling off balance while ambulating. He experienced an upper respiratory and diarrheal infection one week prior to symptom onset. On exam he was found to have a right trochlear palsy, mild symmetric bilateral lower extremity weakness, absent deep tendon reflexes, dysmetria on finger-to-nose and heel-to-skin bilaterally, and a wide-based, staggering gait. Complete blood count and basic metabolic panel on admission was unremarkable. Magnetic resonance imaging of the brain and spine were unremarkable. CSF analysis was unremarkable. (proteins 30.5 mg/dL [normal, 15–40 mg/dL], glucose 58 mg/dL [normal, 40-70 mg/dL], and white cells 2uL [normal, 0-5 uL]). Serum antiganglioside antibodies (GQ1b and GD1b) IgG/IgM were positive. Patient was treated with IVIG for 5 days with significant improvement in his ocular motor function, bilateral lower extremity strength, and ataxic gait. Patient was discharged home with outpatient therapies.

This case demonstrates that unilateral trochlear nerve palsy can occur as part of the full triad in MFS. Although unilateral ophthalmoplegia is a rare presentation, MFS should remain on the differential diagnosis in patients presenting with a medical history and physical exam features strongly suggestive of MFS.