Skull-base metastases.

Metastasis to the skull-base particularly affects patients with carcinoma of the breast and prostate. Clinically, the key feature is progressive ipsilateral involvement of cranial nerves. Five syndromes have been described according to the metastatic site including the orbital, parasellar, middle-fossa, jugular foramen and occipital condyle syndromes. Magnetic resonance imaging (MRI) is nowadays the most useful examination to establish the diagnosis but plain films, CT scans with bone windows and isotope bone scans remain helpful to demonstrate bone erosion. Normal imaging studies do not exclude the diagnosis. The treatment depends on the nature of the underlying tumor. Radiotherapy is generally the standard treatment, while some patients with chemosensitive or hormonosensitive lesions benefit from chemotherapy or hormonotherapy and selected patients from surgical removal. Gamma Knife radiosurgery is sometimes a useful alternative, particularly for previously irradiated skull-base regions, and for small tumors (diameter < 30 mm). The overall prognosis is poor, with an overall median survival of about 2.5 years, probably because skull-base metastases appear late in the course of the disease.