Delhi Journal of Ophthalmology

Eight and A Half: A Rare Neuro Ophthalmological Syndrome

Ekta Syal, Rajwinder Kaur, Harjeet Kaur Sidhu
Department of Ophthalmology, Adesh Institute of Medical Sciences and Research, Bathinda, Punjab, India

Corresponding Author:

Rajwinder Kaur 
Department of Ophthalmology, 
Adesh Institute of Medical Sciences and Research, Bathinda, Punjab, India
Email id:

Published Online: 01-NOV-2018


Eight-and-a-half syndrome is a rare clinical entity comprised of one-and-a-half syndrome with ipsilateral facial palsy. We present a clinical case of a 45 year old male who presented with left eight and a half syndrome. Contrast MRI brain showed the constellation of findings with diffusion weighted images (DWI) and apparent diffusion coefficient (ADC) changes corresponding to the anatomical correlation in the dorsal pontine tegmentum. Treatment with antihypertensive and antiplatelets showed significant improvement in symptoms. Our report aims to raise awareness about this rare neuro-ophthalmological syndrome, as early recognition can accelerate diagnosis and decrease the morbidity.

Keywords :Diplopia, Pontine infarct, Eight and a half, Hypertension

“One-and-a-half” syndrome refers to a gaze disorder characterized by ipsilateral gaze paresis or palsy, and internuclear ophthalmoplegia on contralateral gaze resulting in loss of all horizontal movements in the ipsilateral eye, except-abduction of the contralateral eye. The syndrome was first described by Fisher in 1967.1 The so-called “Eight-and-a-half” syndrome, originally proposed by Eggenberger in 1998, refers to one-and-a-half syndrome combined with ipsilateral fascicular seventh cranial nerve palsy, which is caused by circumscribed lesions of the pontine tegmentum involving the abducens nucleus, the adjacent facial colliculus, and the ipsilateral medial longitudinal fasciculus (MLF).2 Due to its extreme rarity, the clinical course, radiological characteristics and outcomes of this specific disease are not well-characterized. Herein, we report a case of eight-and-a-half syndrome.

Case Report
A 45-year-old male presented in the emergency with a 2-day history of headache preceded by nausea and vomiting. He complained of sudden decrease in vision with double vision in the horizontal gaze since the last 2 days. He was a known case of hypertension since 4 years and was on regular treatment. The patient was conscious and oriented. On admission, his blood pressure was 180/100 mmHg, and heart rate was 78 beats per minute. On motor system examination, the bulk was normal, the tone was normal in left upper and lower limb, power was 5/5 in upper limb and 5/5 in lower limb on the left side while deep tendon reflexes were 3+ but left plantar reflex was decreased. The respiratory system, cardiovascular system and abdomen were all normal.
Oculomotor examination showed complete left horizontal conjugate gaze palsy (Figure 1) and a right adduction deficit with nystagmus in abduction (Figure 2). It was accompanied with left seventh nerve palsy which was lower motor neuron type (Figure 3). Vertical ocular movements were normal. Pupils were equal in size and reactive to light. Fundoscopy revealed bilateral disc edema with disc pallor in the right eye and hypremia in the left eye. Contrast MRI revealed pontine tegmentum infarct (Figure 4) along with acute infarct of splenium of corpus callosum indicative of occlusion of pericallosal artery- a branch of posterior cerebral artery. Laboratory investigations showed a raised WBC count of 15000/mm3 with platelet count of 345000 and raised blood urea of 63mg/dl. Serum creatinine, HbsAg, Anti HCV, LFTs, electrolytes, APPT, PT-INR, bleeding and clotting time, ESR, random blood sugar and serum electrolytes were normal. The patient was started on intravenous antibiotics, antihypertensive and antiplatelet medication. On the next day, visual examination showed similar oculomotor status with uncorrected vision of 6/9 in both eyes. Half a month later, there was significant improvement in extraocular movements (Figure 5, 6) and lagophthalmos (Figure 7). The patient was discharged on antihypertensive and antiplatelet drugs to follow up in Neurology and Ophthalmology OPD.

One-and-a-half syndrome refers to conjugate horizontal gaze palsy (one) with inter nuclear opthalmoplegia (half) due to a lesion of the paramedianpontine reticular formation (PPRF) and medial longitudinal fasciculus.1 The isolated form of one-and-a-half syndrome is uncommon, and this syndrome is usually accompanied by cranial nerve palsies, hemiplegia, or hemihypesthesia. When one-and-a-half syndrome is associated with other cranial nerve involvement, the number of the cranial nerve is added to one-and-a-half to describe the clinical syndrome like five and a half syndrome ((1½ + 4-trochlear nerve), seven and a half (1½ + 6-abducens), eight and a half syndrome2-3 nine syndrome (eight-and-a-half syndrome and an additional lesion in the midbrain tegmentum/red nucleus causing contralesional hemiataxia4, eleven and a half syndrome (1½ + facial nerve + oculomotor nerve), fifteen and a half syndrome (bilateral seventh nerve palsy and one-and-a-half syndrome)5 sixteen and a half syndrome (bilateral seventh nerve palsy + one-and-a-half syndrome + hemiparesis).6 Hence, eight and a half syndrome is a combination of ipsilateral seventh lower motor neurone paresis associated with partial horizontal gaze palsy. Eight-and-a-half syndrome is caused by a lesion in the dorsal tegmentum of the caudal pons involving the PPRF or abducens nucleus and the medial longitudinal fasciculus (MLF), as well as the nucleus and fasciculus of the facial nerve.3 The facial nucleus lies adjacent to the PPRF and gives rise to cranial nerve VII (CN7) which courses through the PPRF before circling the abducens nucleus and exiting the brainstem. The rare condition is often caused by a infarction, haemorrhage, demyelination, gliomas, and cystic lesions in the dorsal tegmentum of the caudal pons.7,8 In our patient, Magnetic Resonance Imaging revealed a left caudal pontine infarct involving the para pontine reticular formation, medial longitudinal fasciculus and VII nerve nucleus, An almost similar clinical entity has been termed as “Nine syndrome” previously reported by Rosni at al4 resulting from lacunar pontine infarction. Our patient was younger who developed pontine tegmentum infarction as a result of high blood pressure. Pons is one of the most common sites for hemorrhagic stroke apart from putamen, thalamus and cerebellum. This is an addition in the spectrum of brainstem syndromes which not only have clinical importance but also help anatomic localization from a student’s point of view as well as in order to have appropriate imaging. We present this case to highlight the fact that interpretation of eye movement abnormalities in brainstem strokes can be difficult yet fascinating.

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  5. Bae JS, Song HK. One-and-a-Half Syndrome with Facial Diplegia: The 15 1/2 Syndrome? Journal of Neuro-opthmology 2005; 25:55-53.
  6. Cummins G, O’Hare A, Dunne R, et al. "Sixteen and a half": A novel pontine neuro ophthalmological syndrome. J Neurol 2011; 258:1347-8.
  7. Wall M, Wrauy SH. The one-and-a-half syndrome–a unilateral disorder of the pontine tegmentum: a study of 20 cases and review of the literature. Neurology 1983; 33:971-80
  8. Martyn CN, Kean D. The one-and-a-half syndrome. Clinical correlation with a pontine lesion demonstrated by nuclear magnetic resonance imaging in a case of multiple sclerosis. Br J Ophthalmol 1988; 72:515-7.


Ekta Syal, Rajwinder Kaur, Harjeet Kaur SidhuEight and A Half: A Rare Neuro Ophthalmological Syndrome.DJO 2018;29:67-69


Ekta Syal, Rajwinder Kaur, Harjeet Kaur SidhuEight and A Half: A Rare Neuro Ophthalmological Syndrome.DJO [serial online] 2018[cited 2019 Apr 25];29:67-69. Available from: