16 Syndrome in a Patient With Multiple Sclerosis

Abstract

We read with interest the report of Connors et al (1) of a case of 16 syndrome with complete horizontal gaze paralysis and facial diplegia caused by a pontine hemorrhage. We describe a patient with multiple sclerosis (MS) who experienced an evolving eye movement disorder, which included internuclear ophthalmoplegia, one-and-a-half syndrome, eight-and-a-half syndrome, fifteen-and-a-half syndrome, and finally 16 syndrome. A 44-year-old man with a history of hypertension, heavy smoking, and a positive family history of cardiovascular disease complained of double vision upon awakening. Neurological examination revealed bilateral internuclear ophthalmoplegia (INO), which was attributed to a brainstem infarction given the sudden onset and patient’s vascular risk factors. Magnetic resonance imaging (MRI) of the brain and the intracranial vessels revealed several periventricular white matter lesions but no brainstem abnormality. Three days later, the patient developed drooping of the right corner of his mouth and complained of drooling. Examination revealed a right lower motor neuron facial nerve paresis in addition to bilateral INO. Repeat MRI revealed a nonenhancing lesion in the midline of the dorsal pons (Fig. 1). Two days later, he developed a complete right conjugate horizontal gaze palsy which, coupled with his left INO, produced a one-and-a-half syndrome. Concurrently, he also experienced bilateral facial paresis.FIG. 1: Axial fluid-attenuated inversion recovery (A) and sagittal T2 (B) MRI show an area of high signal (arrows) in the dorsal pons ventral to the fourth ventricle.Evaluation for stroke including extensive hematological tests, Holter cardiac monitoring, and transesophageal echocardiography was normal. Cerebrospinal fluid analysis for IgG, oligoclonal bands, and aquaporin-4 antibodies as well as visual evoked responses were normal. MRI of the cervical spinal cord revealed no lesions. On the 11th day of hospitalization, the patient developed bilateral horizontal gaze palsies with worsening of his facial diplegia. His clinical course in combination with the periventricular white matter lesions was highly suggestive of demyelinating disease. Treatment with methylprednisolone was begun, and 3 weeks later, he had recovered completely. Several follow-up MRIs were performed. The most recent MRI, 1.5 years after the onset of symptoms, revealed an increase in number and extent of the white matter hyperintensities (Fig. 2). Glatiramer acetate therapy was initiated.FIG. 2: Axial fluid-attenuated inversion recovery (A) and sagittal T2 (B) scans reveal several areas of high signal intensity in the periventricular region and corpus callosum.On occasion, a one-and-a-half syndrome can be accompanied by a facial paresis if the fascicle or nucleus of the seventh cranial nerve in the lower part of the dorsal pontine tegmentum is also affected. Eggenberger (2) designated this as eight-and-a-half (1.5 + 7) syndrome. As mentioned by Connors et al (1), variations of this syndrome caused by pathology of the dorsal pontine tegmentum have since been described including a combination of a one-and-a-half syndrome and a bilateral peripheral facial paresis which Bae and Song (3) designated fifteen-and-a-half (1.5 + 7 + 7) syndrome. Only 3 cases of isolated eight-and-a-half syndrome caused by MS have been described in the literature (4,5). In one of these cases (4), the eight-and-a-half syndrome was, as in our patient, the initial symptom of MS. A 16 syndrome caused by MS has not been reported previously.