Metastasen der Schädelbasis

A radiologic

review of hoarse voice from anatomic and neurologic perspectives. Skull base metastasis. A 63-year-old woman with several weeks of right-sided ear infection and hoarseness, followed by sudden onset right facial droop. Axial post-contrast T1-weighted (a) and DWI/ADC (b, c) MR images reveal a large enhancing infiltrative lesion with diffusion restriction at the skull base (arrows). Axial CTA image (d) demonstrates osseous destruction and obliteration of the right internal jugular vein (arrowheads). This was found to be metastatic adenocarcinoma of unknown primary

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Metastases to the skull are very common in patients with disseminated skeletal metastatic disease, although they are often asymptomatic. For a more detailed general discussion please refer to the article on skeletal metastatic disease.

Epidemiology

Skull metastases are seen in ~20% (range 15-25%) of all cancer patients . The demographics of patients with skull metastases will mirror those of the primary tumor, and as such in general they are found in the older population.

Clinical presentation

Although over half of all skeletal metastases are asymptomatic, they can cause symptoms in a number of scenarios :

mass effect on adjacent structures
- compression of brain/brainstem
  - focal neurological deficits
  - seizures
- compression of exiting cranial nerves
- compression/invasion/occlusion of dural venous sinuses
  - dural venous sinus thrombosis
- proptosis
mechanical instability
- occipital condyle compression fracture
- temporomandibular joint instability

Pathology

Primary tumors most frequently encountered as metastases to the skull include :

In children both neuroblastoma (skull metastases are not infrequently the first sign of disease) and Ewing sarcoma are encountered.

Radiographic features

Skull metastases have the same range of appearances as skeletal metastases elsewhere, and in 90% of cases other skeletal metastases are evident:

lytic metastases: most common
sclerotic metastases
- can particularly occur from breast and prostate cancers
mixed lytic and sclerotic metastases

It is worth remembering that occasionally a solitary skull metastasis may be the only evidence of metastatic disease. This is particularly the case with renal cell carcinoma and thyroid carcinoma .

Treatment and prognosis

For asymptomatic lesions, no specific treatment is required above or beyond systemic treatment being administered. Even when symptomatic, in many instances patients are being palliated and as such no focal therapy is instituted.

In instances where symptoms are significant and the general health and prognosis warrants intervention, a number of options exist :

radiotherapy
- whole brain radiotherapy if cerebral or leptomeningeal metastases are present
- focal radiotherapy for single/symptomatic lesions
chemotherapy
- usually already instituted for systemic disease
surgery
- reserved for larger symptomatic lesions
- has a role in diagnosis, when the lesion is solitary or diagnosis not established

It is difficult to say anything sensible when discussing prognosis, as clearly the degree of systemic disease, and the primary tumor and its response to therapy is going to have a huge impact. In general, it is safe to say however that in most instances, skeletal metastases represent advanced disease with poor prognosis, typically measured in weeks and months.