Eight-and-a-Half Syndrome: A Rare Presentation of Pontine Infarction N. S. Sampath Kumar, DM, C. Govinda Raju, DM, P. Ravi Kiran, MD, T. Anil Kumar, MD, B. Venu Gopal, MD, and D. Bala Khaseem, MD
‘‘Eight-and-a-half’’ syndrome is ‘‘one-and-a-half’’ syndrome (conjugated horizontal gaze palsy and internuclear ophthalmoplegia) plus ipsilateral fascicular cranial nerve seventh palsy. This rare condition, particularly when isolated, is caused by circumscribed lesions of the pontine tegmentum involving the abducens nucleus, the ipsilateral medial longitudinal fasciculus, and the adjacent facial colliculus. Its recognition is therefore of considerable diagnostic value. We report a case of a 65year-old man who presented with eight-and-a-half syndrome in which brain magnetic resonance imaging scan revealed a lacunar pontine infarction. Key Words: Eight-and-a-half syndrome—pons—infarct—medial longitudinal fasciculus— abducens nucleus—facial colliculus. Ó 2014 by National Stroke Association
Introduction Freeman et al first described the unusual and remarkable disorder of eye movement consisting of a lateral gaze palsy in one direction and an internuclear ophthalmoplegia (INO) in the other eye.1 This was later coined as one-and-a-half syndrome by C. Miller Fisher to describe a combination of horizontal gaze palsy and INO caused by a lesion in medial longitudinal fasciculus (MLF) or parapontine reticular formation.2 The constellation of one-and-a-half syndrome plus cranial nerve seventh palsy was referred to eightand-a-half syndrome (11/2 1 7) by Eggenberger.3
Case Report A 65-year-old male patient who was chronic smoker, alcoholic, and a known hypertensive presented with a From the Department of Neurology, Narayana Medical College, Nellore, Andhra Pradesh, India. Received December 17, 2013; accepted January 7, 2014. Address correspondence to N.S. Sampath Kumar, DM, Department of Neurology, Narayana Medical College, Nellore 524003, Andhra Pradesh, India. E-mail: [email protected]
1052-3057/$ - see front matter Ó 2014 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2014.01.002
history of deviation of mouth to the left side, drooling of saliva from the right angle of the mouth, excess tears from the right eye, and double vision of the left eye. All the symptoms started with sudden onset and had nonprogressive course. The general examination results were as follows: Glasgow coma scale: E4 M6 V5, pulse: 82/minute, regular, blood pressure: 150/100 mm Hg, and respiratory rate: 24/minute. On central nervous system examination, it was found that the patient had total right eye horizontal gaze palsy and limitation of adduction of the left eye with horizontal nystagmus on abduction. Diplopia on abduction of the left eye was also observed. Left eye abduction and vertical eye movements were preserved. Pupillary reflex was normal on both sides. Further examination revealed right lower motor neuron facial palsy. Rest of the neurologic examination was normal. All serum laboratory values are normal. A diffusion-weighted magnetic resonance imaging showed hyperintensity in lower pons (Fig 1 A-G). Patient was treated with antiplatelets and antihypertensives.
Discussion Eight-and-a-half syndrome is caused by a lesion in the dorsal tegmentum of the caudal pons involving
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Figure 1. (A-C) Combination of total right gaze paresis along with adduction lag in left eye and suggestive of right horizontal one-and-half syndrome. Note the normal vertical eye movements from the primary position of gaze (D and E). (P, Primary position of gaze; arrows point toward the direction of gaze shifts.) (F) Right lower motor neuron facial weakness. (G) Diffusion-weighted image showing hyperintensity in lower pons.
the parapontine reticular formation or abducens nucleus and the MLF, and the nucleus and fasciculus of the facial nerve.3 It is characterized by INO in addition to horizontal gaze palsy (one-and-a-half syndrome) and ipsilateral lower motor neuron-type facial palsy. The syndrome is a combination of ipsilateral seventh lower motor neuron paresis associated with partial horizontal gaze palsy.4 The affected nuclei may include either a combination of the ipsilateral seventh and sixth nerve nucleus and the ipsilateral MLF or a combination of ipsilateral seventh and ipsilateral paramedian pontine reticular formation along with the ipsilateral MLF.5 This results in complete ipsilateral horizontal gaze paresis and partial gaze paresis of the opposite eye (spared contralateral abduction). The condition is often caused by a lesion (vascular or demyelinating) in the dorsal tegmentum of the caudal pons.6-8 The oneand-a-half syndrome is most often caused by multiple sclerosis, infarcts, hemorrhages, trauma, basilar artery aneurysms, brainstem arteriovenous malformations, and tumors.9,10
Conclusions A rare case of ‘‘eight-and-a-half’’ syndrome is ‘‘oneand-a-half’’ syndrome plus ipsilateral fascicular cranial nerve seventh palsy, a unique combination of rightsided horizontal one-and-a-half syndrome and lower motor neuron seventh cranial nerve palsy. The involvement of right abducens nucleus, right MLF, and right facial nucleus/fascicles in the lower pontine tegmentum contributed to the observed clinical signs. Thus, the recognition of this syndrome allows precise localization of the lesion to lower pontine tegmentum ipsilaterally. Magnetic resonance imaging of brain has shown hyperintensity in lower pons. Etiology attributed to lower pontine tegmental infarct is because of occlusion of right paramedian pontine perforators.
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EIGHT-AND-A-HALF SYNDROME 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-ahalf syndrome plus cranial nerve VII palsy. J Neuroophthalmol 1998;18:114-116. 4. Sarwal A, Garewal M, Sahota S, et al. Eight-and-a-half syndrome. J Neuroimaging 2009;19:288-290. 5. Sharpe JA, Rosenberg MA, Hoyt WF, et al. Paralytic pontine exotropia: a sign of acute unilateral pontine gaze palsy and internuclear ophthalmoplegia. Neurology 1974;24:1076-1081. 6. Felicio AC, Bichuetti DB, Marin LF. Bilateral horizontal gaze palsy with unilateral peripheral facial paralysis caused by pontine tegmentum infarction. J Stroke Cerebrovasc Dis 2009;18:244-246.
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