The clinical spectrum of tegmental pontine syndromes is richly described. Horizontal gaze palsy is rarely complete. To our knowledge, there is only one other published case of complete bilateral, horizontal gaze paralysis and facial diplegia caused by tegmental pontine infarction (1).
A previously healthy 39-year-old man developed dyspnea and parasthesias in his fingers. Admission blood pressure was 240/140. Neurological examination revealed fluctuating alertness, ocular bobbing, bilateral, horizontal gaze palsies and facial diplegia. Caloric testing and oculocephatic maneuvers failed to elicit horizontal eye movements. Vertical gaze and convergence were normal. Magnetic resonance image (MRI) of the brain revealed a midline tegmental pontine hemorrhage (Fig. 1). The patient was intubated and transferred to the intensive care unit. During his hospital course, he became fully alert. He was able to breathe without assistance and his appendicular function markedly improved. However, severe dysarthria, bilateral horizontal gaze palsy, and facial diplegia remained (see Video, Supplemental Digital Content, http://links.lww.com/WNO/A57).
Disorders of the pontine tegmentum are characterized by the anatomic relationship of the genu of the intrapontine facial nerve fascicle to structures mediating horizontal gaze including the sixth nerve nucleus and the pontine paramedian reticular formation. Structures mediating vertical gaze and convergence are spared as they are located in the midbrain.
Fisher (2) described the one-and-a-half syndrome because of the involvement of a horizontal gaze center and ipsilateral medial longitudinal fasciculus. Variations of that classic tegmental pontine syndrome have since been described. Eggenberger (3) reported a patient with one-and-a-half syndrome and ipsilateral facial palsy and coined the term the eight-and-a-half syndrome (7 + 1½ = 8½). An eight-and-a-half syndrome associated with contralateral facial paralysis was designated as the fifteen-and-a-half syndrome (7 + 1½ + 7 = 15½) by Bae et al (4). These pontine syndromes usually are the result of ischemic cerebrovascular disease and demyelination.
Pontine lesions causing nuclear–fascicular facial diplegia without gaze palsy have been described as a consequence of infarction, hemorrhage, glioma, and brainstem encephalitis (4,5). Facial weakness is almost always unilateral if associated with horizontal gaze palsy (6). We are aware of only one other case report of facial diplegia and bilateral, horizontal gaze palsies. Utku et al (1) documented these clinical findings in a 43-year-old hypertensive woman. MRI showed an ischemic lesion in the paramedian tegmentum at the midpontine level.
The precise cause of the pontine stroke was not established in the case reported by Utku et al (1). Of note, the pontine tegmentum may be supplied bilaterally by a single arteriole with a late bifurcation, obviating the need to posit tandem occlusion of adjacent paramedian arteries in cases of bilateral ischemic tegmental disease (7).
1. Utku U, Celik Y, Balci K. Bilaterally persistent horizontal gaze palsy and facial palsy caused by pontine infarction. J Stroke Cerebrovasc Dis. 2001;10:242–243.
2. Fisher CM. Some neuro-ophthalmological observations. J Neurol Neurosurg Psychiatry. 1967;30:383–392.
3. Eggenberger E. Eight-and-a-half syndrome: one-and-a-half syndrome plus cranial nerve VII palsy. J Neuroophthalmol. 1998;18:114–116.
4. Bae JS, Song HK. One-and-a-half syndrome with facial diplegia: the 15 1/2 syndrome? J Neuroophthalmol. 2005;25:52–53.
5. Keane JR. Bilateral seventh nerve palsy: analysis of 43 cases and review of the literature. Neurology. 1994;44:1198–1202.
6. Felicio AC, Bichuetti DB, Marin LF, dos Santos WA, Godeiro-Junior C. Bilateral horizontal gaze palsy with unilateral peripheral facial paralysis caused by pontine tegmentum infarction. J Stroke Cerebrovasc Dis. 2009;18:244–246.
7. Fisher CM. Neuroanatomic evidence to explain why bilateral internuclear ophthalmoplegia may result from occlusion of a unilateral pontine branch artery. J Neuroophthalmol. 2004;24:39–41.