Sixth Cranial Nerve Palsy and Craniocervical Junction Instability due to Metastatic Urothelial Bladder Carcinoma.

Metastases involving the clivus and craniocervical junction (CCJ) are extremely rare. Skull base involvement can result in cranial nerve palsies, while an extensive CCJ involvement can lead to spinal instability. We describe an unusual case of clival and CCJ metastases presenting with VI cranial nerve palsy and neck pain secondary to CCJ instability from metastatic bladder urothelial carcinoma. The patient was first treated with an endoscopic endonasal approach to the clivus for decompression of the VI cranial nerve and then with occipitocervical fixation and fusion to treat CCJ instability. At the 6-month follow-up, the patient experienced complete recovery of VI cranial nerve palsy. To the best of our knowledge, the simultaneous involvement of the clivus and the CCJ due to metastatic bladder carcinoma has never been reported in the literature. Another peculiarity of this case was the presence of both VI cranial nerve deficit and spinal instability. For this reason, the choice of treatment and timing were challenging. In fact, in case of no neurological deficit and spinal stability, palliative chemo- and radiotherapy are usually indicated. In our patient, the presence of progressive diplopia due to VI cranial nerve palsy required an emergent surgical decompression. In this scenario, the extended endoscopic endonasal approach was chosen as a minimally invasive approach to decompress the VI cranial nerve. Posterior occipitocervical stabilization is highly effective in avoiding patient's neck pain and spinal instability, representing the approach of choice.