Sixteen syndrome: a rare presentation of central demyelination.

This case illustrates two diagnostic challenges for clinicians: the rarely described sixteen syndrome and the relationship between tumour necrosis factor (TNF)-alpha inhibitors and central demyelination. Sixteen syndrome affects horizontal eye movements and the facial nerve bilaterally reflecting a lesion in the posterior pontine tegmentum, adjacent to the fourth ventricle. Given its rarity and complexity of clinical signs, this syndrome risks misdiagnosis and mismanagement. The relationship between TNF-alpha inhibitors and demyelination is a complex issue in which causality is yet to be established. This diagnostic challenge poses a management dilemma for clinicians.