This article includes discussion of calvarial, skull base, dural, and nasopharyngeal metastases; calvarial and skull base metastases; bone metastases; and skull metastases. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
This chapter describes the clinical manifestations, epidemiology, diagnosis, and management of calvarial and skull base metastatic lesions. It also discusses various skull base syndromes and provides examples. In this article, the author adds information about the role of stereotactic radiotherapy in skull base metastases.
• Several skull base syndromes have been described that are uncommon and require a high index of suspicion.
• Lung, breast, prostate, and head/neck cancer account for most of the cases of skull metastases.
• Radiation therapy remains the mainstay of palliative care in most patients.
Historical note and terminology
The calvarium is composed of the bones forming the convexity of the skull, periosteum, and soft tissue coverings. It consists of parts of the frontal, parietal, temporal, and occipital bones. The calvarial bone consists of inner and outer tables that enclose marrow containing diploic space in between. The skull base separates the brain from the neck, orbit, and air containing spaces below. It is composed of the orbital plates of the frontal bone, the greater and lesser wings of the sphenoid bone, the temporal bone, and the basisphenoid and basiocciput (that constitutes the clivus). The skull base is divided into the anterior, middle, and posterior cranial fossae. The roof of the orbit and the cribriform plate form the anterior fossa. The middle fossa consists of body and wings of sphenoid bone and overlies the infratemporal fossa. This includes the contents of pituitary fossa and cavernous sinus. The posterior fossa is composed of basiocciput, occipital bones, and petrous parts of the temporal bone. The posterior fossa is the deepest and largest of all cranial fossae (Fagan et al 1992; Grossman 1996; Rodas and Greenberg 1997).
Both the calvarium and skull base can be affected by a variety of benign and malignant processes. Calvarial metastases, which tend to be less symptomatic than brain metastases, are frequent and probably more common than brain metastases (Posner 1995a).
|Image: Poorly differentiated carcinoma from an unknown primary presenting with occipital condyle syndrome (|
|Image: Solitary lung cancer metastasis to the sphenoid bone with secondary extension into the local dura (C|
|Image: Breast cancer metastatic to the sphenoid and ethmoid bones with direct extension into the orbital ap|
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