EIGHT-AND-A-HALF-SYNDROME: A RARE NEURO-OPHTHALMIC SEQUELAE OF PONTINE INFARCT
Background: “Eight-and-a-half” syndrome is an unusual neuro-ophthalmic clinical entity which comprises of “one-and-a-half” syndrome (conjugated horizontal gaze palsy and internuclear ophthalmoplegia) with ipsilateral fascicular seventh cranial nerve palsy. This condition is caused by circumscribed lesions of the pontine tegmentum involving the abducens nucleus, the ipsilateral medial longitudinal fasciculus, and the adjacent fascial colliculus. Here, we report a case of “eight-and-a-half” syndrome.
Materials and Methods: Case Report
Result: A 62-year old gentleman with hypertension, diabetes mellitus and paroxysmal atrial fibrillation presented with sudden onset of binocular diplopia and facial asymmetry. Examination showed right eye exotropia at primary gaze. He had conjugate horizontal gaze palsy to the left. On right gaze, the patient had restricted left eye adduction with retained ability to abduct the right eye, which evoked a right horizontal nystagmus. Convergence with near fixation were spared. Vertical eye movements were also normal. In addition, he had left lower motor neuron facial weakness with no other neurological deficit. Computed tomography scan showed a left paramedian pontine infarct. A diagnosis of eight-and-a-half syndrome was made.
The patient was referred to neuromedical team for treatment of acute stroke in which he was treated conservatively. Evaluation after 4 weeks showed slight improvement in adduction lag of the right eye.
Conclusion: Our patient presented with the unique combination of left sided horizontal one-and-a-half syndrome and lower motor neuron seventh cranial nerve palsy. Combination of these signs (seven plus one-and-a-half) is known as eight-and-a-half syndrome. Recognition of the spectrum of eight-an-a-half syndrome allows precise anatomic localisation of the lesion to pontine tegmentum region.Keywords: eight-and-a-half syndrome, one-and-a-half syndrome, internuclear ophthalmoplegia, pontine infarct, pontine tegmentum