Trochlear Nerve Palsy Due to Quadrigeminal Plate Cistern Lipoma

Intracranial lipomas are rare, accounting for <0.1% of primary brain lesions. The majority are interhemispheric (45%) followed by a quarter that are quadrigeminal or superior cerebellar (25%). Intracranial lipomas are most often asymptomatic incidental imaging findings. 55% of patients have associated brain malformations as the primary source of neurologic symptoms. Prior case reports and literature reviews have shown that isolated symptomatic quadrigeminal plate cistern lipomas can result in obstructive hydrocephalus, elevated intracranial pressure, and seizures. In this case report, we present a rare clinical presentation for a classically asymptomatic brain lesion.

Poster 69 Trochlear Nerve Palsy due to Quadrigeminal Plate Cistern Lipoma Sara Francomacaro1, Tiffany Tolbert2, Vivian Rismondo2 1 University of Maryland Medical Center, Baltimore, Maryland, USA, 2Greater Baltimore Medical Center, Towson, Maryland, USA Introduction: Intracranial lipomas are rare, accounting for <0.1% of primary brain lesions. The majority are interhemispheric (45%) followed by a quarter that are quadrigeminal or superior cerebellar (25%). Intracranial lipomas are most often asymptomatic incidental imaging findings. 55% of patients have associated brain malformations as the primary source of neurologic symptoms. Prior case reports and literature reviews have shown that isolated symptomatic quadrigeminal plate cistern lipomas can result in obstructive hydrocephalus, elevated intracranial pressure, and seizures. In this case report, we present a rare clinical presentation for a classically asymptomatic brain lesion. Description of Case(s): A 71 year old male with past medical history of hypertension, ocular migraines, Sjogren's syndrome, and stage 3 chronic kidney disease, presented for consultation of worsening binocular oblique diplopia since onset 3 years prior, without preceding head trauma. Extraocular muscle examination revealed right hypertropia of 18 prism diopters in primary gaze, worse in left gaze, down gaze, and right head tilt. Magnetic resonance imaging of the brain without contrast revealed a left-sided quadrigeminal plate cistern lipoma, without mass effect or hydrocephalus, in close proximity to cranial nerve IV at its exit from the left dorsal midbrain at the level of the inferior colliculi. Conclusions, including unique features of the case(s): In a patient with progressive trochlear nerve palsy without preceding head trauma, imaging revealed lipomatous cranial nerve IV impingement. This is the first reported case of a trochlear nerve palsy secondary to a quadrigeminal plate cistern lipoma. There are only 3 reported cases to date of quadrigeminal lipomas resulting in strabismus: one unspecified, one with upgaze restriction, and one with abducens palsy. This case demonstrates that, while the vast majority of cranial nerve IV palsies are secondary to trauma the nerve is also susceptible to impingement by space occupying lesions as we demonstrate in this unusual patient scenario. References: Truwit, Barkovich. Pathogenesis of intracranial lipoma: An MR study in 42 patients. American Journal of Neuroradiology, 11(4), 665-674, 1990. Ono, Ikeda, Imai, Mano, Matsuoka, Nagai, Okada. Intracranial lipoma of the quadrigeminal region associated with complex partial seizures. Pediatric radiology, 28(9), 729-731, 1998. Ambrosetto, Martinelli, Bacci, Daidone. Lipoma of the quadrigeminal plate cistern. The Italian Journal of Neurological Sciences, 6(3), 347-349, 1985. Yilmaz, Egemen, Tekiner. Lipoma of the quadrigeminal cistern: report of 12 cases with clinical and radiological features. Turkish neurosurgery, 25(1), 16-20, 2015. Nikaido, Imanishi, Monobe. Lipoma in the quadrigeminal cistern. Neurologia medico-chirurgica, 35(3), 175-178, 1995. Keywords: Tumors, Neuroimaging, Ocular motility, Adult strabismus with a focus on diplopia Financial Disclosures: The authors had no disclosures. Grant Support: None. Contact Information: [e-mail] 124 | North American Neuro-Ophthalmology Society