Abstract

An 85-year-old lady presented with a 12-month history of progressive intermittent speech difficulties. At review, wasting and fasciculations of the right side of the tongue was noted. A diagnosis of isolated hypoglossal nerve palsy was made. An MRI demonstrated a lobulated non-enhancing mass centred on the right hypoglossal canal with both intra and extracranial spread in keeping with a synovial cyst of the occipito-cervical junction. Isolated hypoglossal nerve palsy is an uncommon diagnosis. The aetiology is wide-ranging (demonstrated in a table) though its presentation should raise concerns of malignancy. In the absence of an obvious iatrogenic aetiology, a malignant cause has been reported in 20% of truly isolated hypoglossal nerve palsies. Synovial cysts of the vertebrae are benign fluid filled sacs that are mostly found in the lumbar spine, usually arising from the facet joints laterally or dorsolaterally of the lumbar spine associated with degeneration. Synovial cysts of the cervical spine are rare. Most are seen at the neurologically delicate cervico-medullary junction. To our knowledge this is the first documented case of isolated hypoglossal nerve palsy associated with a synovial cyst of the occipito-cervical junction.