One and Half Syndrome With Supranuclear Facial Palsy and Horner Syndrome

One and a half syndrome in combination with lower motor neuron facial palsy defines the eight and half syndrome. It is caused due to a dorsal pontine tegmentum lesion affecting the abducens nucleus/paramedian pontine reticular formation, medial longitudinal fascicle and the facial nerve nucleus/fascicle. We present a case of one and a half syndrome associated with ipsilateral supranuclear facial weakness and an incomplete Horner syndrome.

Poster 169 One and half syndrome with supranuclear facial palsy and Horner syndrome Fernando Labella1, María del Carmen Blanco-Valero1, Alejandro Quirós Peral1, Irene Rivero Martínez1, Alba Rodríguez Martín1, Fernando Acebrón1, Eduardo Agüera Morales1 1 Reina Sofía University Hospital, Cordoba, Spain Introduction: One and a half syndrome in combination with lower motor neuron facial palsy defines the eight and half syndrome. It is caused due to a dorsal pontine tegmentum lesion affecting the abducens nucleus/paramedian pontine reticular formation, medial longitudinal fascicle and the facial nerve nucleus/fascicle. We present a case of one and a half syndrome associated with ipsilateral supranuclear facial weakness and an incomplete Horner syndrome. Description of Case(s): A right-handed 27-year-old male presented to the emergency deparment complaining about 3 weeks duration of progressive binocular diplopia. He was smoker and he was not taking any treatment. He started with spontaneous cervical discomfort which was followed by whistle difficulty, dizziness and binocular horizontal diplopia in the next weeks. Examination showed left conjugate gaze palsy, left internuclear ophthalmoplegia, upbeating nystagmus on upward gaze and left eye miosis anisocoria which increased under low light conditions and inversed after apraclonidine 1% test. A left orbicularis oris weakness greater than left orbicularis oculi paresis with spared forehead mucles was detected. Brain CT and supra-aortic vessels CT angiograhy were normal. During hospitalization brain MRI showed a left periventricular dorsal pontine tegmentum lesion, besides periventricular and contrastenhacing corpus callosum lesions suggesting a demyelinating disease. Blood lab tests with serology and autoimmunity, including AQP4 and MOG antibodies, were normal. After normal CSF cytochemestry he initiated corticosteroids treatment achieving partial improvement. He was diagnosed with relapsing- remitting multiple sclerosis after excluding other etiologies. Conclusions, including unique features of the case(s): The most frequent facial palsy associated with one and half syndrome is due to lower motor neuron engagement. However, a supranuclear pattern can be observed owing to corticobulbar fascicle involvement once they have decussated and before they reach the facial nucleus. On the other hand, descending sympathetic fibers can also be damaged at this level explaining the Horner syndrome development. References: None. Keywords: ocular motility Financial Disclosures: The authors had no disclosures. Grant Support: None. Contact Information: None provided. 2021 Annual Meeting Syllabus | 169