Eight Syndrome - Horizontal Gaze Palsy Plus Ipsilateral Seventh Nerve Palsy

A 62-year-old woman developed a right horizontal gaze palsy and ipsilateral facial nerve palsy due to a right pontine tegmentum infarct. This constitutes a forme fruste of the eight-and-a-half syndrome that we have termed the eight syndrome.

Photo Essay Section Editor: Timothy J. McCulley, MD Eight Syndrome: Horizontal Gaze Palsy Plus Ipsilateral Seventh Nerve Palsy Kemar E. Green, DO, David P. W. Rastall, PhD, Eric R. Eggenberger, DO FIG. 1. Patient has a partial right gaze palsy with an esotropia on attempted right gaze. Abstract: A 62-year-old woman developed a right horizontal gaze palsy and ipsilateral facial nerve palsy due to a right pontine tegmentum infarct. This constitutes a forme fruste of the eight-and-a-half syndrome that we have termed the eight syndrome. Journal of Neuro-Ophthalmology 2018;38:347-349 doi: 10.1097/WNO.0000000000000651 © 2018 by North American Neuro-Ophthalmology Society addition, she had a right lower motor neuron facial palsy (Fig. 2). Diffusion-weighted imaging identified a small area of restricted diffusion in the dorsal portion of the right pons at the level of the sixth nucleus and facial colliculus consistent with acute ischemia (Fig. 3). The patient's gaze palsy was resolved at 2 weeks and at 6 months, no facial weakness was present. CASE REPORT A 62-year-old woman with hypertension developed nausea, vomiting, right facial droop, and horizontal diplopia. Examination revealed a partial right gaze palsy with a small angle esotropia on attempted right gaze (Fig. 1). In Departments of Neurology and Ophthalmology (KEG), Michigan State University, East Lansing, Michigan; College of Osteopathic Medicine (DPWR), Michigan State University, East Lansing, Michigan; and Departments of Ophthalmology and Neurology (ERE), Mayo Clinic Florida, Jacksonville, Florida. The authors report no conflicts of interest. Address correspondence to Kemar E. Green, DO, Departments of Neurology and Ophthalmology, Michigan State University Clinical Center, Michigan State University, A-217, 804 Service Road, East Lansing, MI 48824; E-mail: [e-mail] Green et al: J Neuro-Ophthalmol 2018; 38: 347-349 FIG. 2. A right lower motor neuron facial palsy is present. 347 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay FIG. 3. Diffusion-weighted imaging (A) with accompanying apparent diffusion coefficient map (B) shows an area of restricted diffusion (arrows) in the right dorsal pontine tegmentum. DISCUSSION The one-and-a-half (1 ½) syndrome was originally described by Freeman et al (1) and the term was coined by Fisher (2). It results from lesions of the sixth nerve nucleus or paramedian pontine reticular formation (PPRF) and the adjacent medial longitudinal fasciculus (MLF). This produces a combination of an ipsilateral gaze palsy and internuclear ophthalmoplegia (INO); the only remaining horizontal eye movement is abduction of the contralateral eye (2,3). These lesions most frequently arise from stroke or TABLE 1. Localization and clinical findings in one-and-a-half syndrome, eight-and-a-half syndrome, and variants Syndrome One-and-a-half (1,2) Eight-and-a-half (4) Lesion Clinical Findings 6NN/PPRF plus MLF. 6NN/PPRF plus MLF plus ipsilateral 7N fascicles. Conjugate horizontal gaze palsy and ipsilateral INO. Conjugate horizontal gaze palsy associated with an ipsilateral INO and lower motor neuron facial palsy. Eight (15) (present case)Partial 6NN plus ipsilateral 7N fascicles. Partial conjugate gaze palsy, lower motor neuron facial palsy, and ipsilateral small angle esotropia. Nine (5) 6NN/PPRF plus MLF, ipsilateral 7N fascicles, and Conjugate horizontal gaze palsy, ipsilateral INO, ipsilateral corticospinal tract and medial lemniscus. ipsilateral lower motor neuron facial palsy, and contralateral hemiparesis and hemihypesthesia. Nine (6) 6NN plus MLF, ipsilateral 7N fascicles, and ipsilateral Conjugate horizontal gaze palsy, ipsilateral INO, ipsilateral lower motor neuron facial palsy, and an inferior cerebellar peduncle or midbrain ipsilateral (inferior cerebellar peduncle lesion) or tegmentum/red nucleus. contralateral (midbrain tegmentum/red nucleus lesion) hemiataxia. Thirteen-and-a-half (7) 6NN plus MLF, ipsilateral 7N fascicles, and ipsilateral Conjugate horizontal gaze palsy, ipsilateral INO, trigeminal nerve. ipsilateral lower motor neuron facial palsy, and an ipsilateral facial numbness. Fifteen-and-a-half (8) 6NN/PPRF plus MLF and bilateral 7N fascicles. Conjugate horizontal gaze palsy, ipsilateral INO, and facial diplegia. Sixteen (9) 6NN/PPRF, bilateral MLF, and bilateral 7N fascicles. Bilateral horizontal gaze palsy, bilateral INO, and facial diplegia. Sixteen-and-a-half (10) 6NN/PPRF plus MLF, ipsilateral 7N fascicles, plus Conjugate horizontal gaze palsy, ipsilateral INO, ipsilateral cochlear nuclear complex (8N). ipsilateral lower motor neuron facial palsy, and ipsilateral sensorineural hearing loss. Twenty-four-and-a-half 6NN/PPRF plus MLF, ipsilateral 7N fascicles, plus Conjugate horizontal gaze palsy, ipsilateral INO, (11) bilateral cochlear nuclear complex (8N). ipsilateral lower motor neuron facial palsy, and bilateral sensorineural hearing loss. 6NN, sixth nerve nucleus; 7N, facial nerve; 8N, vestibulocochlear nerve; INO, internuclear ophthalmoplegia; MLF, medial longitudinal fasciculus; PPRF, paramedian pontine reticular formation. 348 Green et al: J Neuro-Ophthalmol 2018; 38: 347-349 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo Essay demyelinating disease, although other causes have been reported (3). The eight-and-a-half (8 ½) syndrome is a combination of the 1 ½ syndrome with the addition of a seventh nerve facial palsy (4). Because of the close proximity of the seventh nerve fascicles to the sixth nerve nucleus and fascicles as well as the MLF and the PPRF, a single lesion may affect these and adjacent structures, leading to several variations as shown in Table 1 (4-11). Our patient had a partial right horizontal gaze palsy without an INO (1 ½2½ = 1) coupled with ipsilateral intra-axial fascicular seventh nerve palsy. The combination produces a variant of the eight-and-a-half syndrome, the eighth syndrome. A lesion in the region of the facial colliculus may affect both the sixth nerve nucleus and fascicle. The absence of an INO indicates sparing of MLF fibers. The sixth nerve nucleus contains at least 3 functional cell groups: motorneurons, internuclear neurons, and cerebellar projecting neurons (12), although the exact topographical localization of the individual fibers in humans remains uncertain. The sixth nerve nucleus vascular supply arises from both the anterior inferior cerebellar artery (posterolateral) and basilar pontine perforators (ventromedial), creating the possibility of partial nuclear ischemia (13,14). We postulate that in our patient, a partial sixth nerve nuclear lesion produced a mixed nuclear/fascicular palsy. A similar picture could result from the combination of a sixth nerve fascicular lesion with an INO; these would be indistinguishable on neuroimaging. Because the seventh nerve segment that forms the facial colliculus lies posterior to the sixth nerve nucleus, its involvement suggests a posterior pontine tegmental insult, as in our patient. Tsuda et al (15) described a similar case of sixth nuclear palsy and fascicular seventh nerve palsy occurring without an INO from a facial colliculus lesion. We have named this pattern of an MLF-sparing nuclear and seventh nerve fascicular palsy as the "eight syndrome"-a neuroanatomical variant of the eight-and-a-half syndrome. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: K. E. Green, D. P. W. Rastall, and E. R. Eggenberger; b. Acquisition of data: K. E. Green and D. P. W. Rastall; c. Analysis and interpretation of data: K. E. Green and E. R. Eggenberger. Category 2: a. Drafting the manuscript: K. E. Green et al: J Neuro-Ophthalmol 2018; 38: 347-349 Green, D. P. W. Rastall, and E. R. Eggenberger; b. Revising it for intellectual content: K. E. Green, D. P. W. Rastall, and E. R. Eggenberger. Category 3: a. Final approval of the completed manuscript: E. R. Eggenberger. REFERENCES 1. Freeman W, Ammerman HH, Stanley H. 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