“Eight-and-a-half syndrome” is a rare entity comprising conjugate horizontal gaze palsy, ipsilateral internuclear ophthalmoplegia (INO), and ipsilateral lower motor neuron type of facial palsy, arising due to a lesion affecting the paramedian pontine reticular formation (PPRF), medial longitudinal fasciculus (MLF), and the ipsilateral facial nerve. Dr. Fischer first described the “one and a half syndrome,” which is much more common in occurrence. It is due to a lesion involving the same side of PPRF, abducent nerve nucleus, and the MLF. Since the motor division of the seventh nerve nucleus winds around the motor nucleus of the sixth nerve at the level of the pons, slightly more extensive lesions in the form of infarct and hemorrhage may involve the seventh nerve also leading to this rare entity called the “eight-and-a-half syndrome.”
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