Cavernous sinus invasion by a pituitary adenoma

Clinical History

A 40-year-old female patient presented with headaches and some memory problems.

Imaging Findings

A 40-year-old female patient presented with headaches and some memory problems. A CT scan was performed, which showed the presence of an intrasellar tumour. An MRI that was done showed that a non-secreting macro-adenoma was present with a right cavernous sinus invasion.

Discussion

Of all pituitary adenomas, 6%–10% involve the cavernous sinus and are considered to be invasive. The clinical signs occur late. Cavernous sinus invasion increases the morbidity and mortality associated with surgical procedures. During MR imaging, the absence of invasion can be assumed if a venous compartment is visible between the tumour and the intracavernous internal cerebral artery (ICA).The content of the cavernous sinus is isointense and is interspersed with small foci of an increased signal intensity which correspond to a slow blood flow or the presence of fat; the ICA is easly identifiable because of its characteristic thin walls surrounding a lumen of a low signal intensity, which is reflective of a high-velocity flow void. After adminstration of a gadolinium contrast, the venous compartments are enhanced strongly, and, thus, the depiction of these structures becomes easy. On the other hand, total encasement of the intracavernous ICA is a very specific sign. Alternative criteria have to be defined by using the limits of the cavernous sinus and the intracavernous ICA. Cottier et al. have divided the cavernous space into five venous compartments: the medial compartment, which is between the ICA and the pituitary fossa; the superior compartment, which is above the ICA; the lateral compartment, which is the venous group lateral to the ICA; the carotid sulcus compartment, which is between the ICA and the carotid sulcus of the sphenoid bone; and the inferolateral compartment, which is between the carotid sulcus and the lateral venous compartment, depending mainly on the loops of the carotid siphon and its position. They found that the best radiological sign of cavernous sinus invasion is obliteration of the carotid sulcus venous compartment and that a percentage of encasement of the intracavernous ICA greater than or equal to 67% corresponds to cavernous sinus invasion. Others have used the intercarotid lines which join the lateral wall, or lateral line (LL); the center, or median line (MdnL); and the medial wall, or medial line (MdlL) of the intracavernous and supracavernous portions of the ICA as shown in Fig. 1b. If the percentage of encasement of the intracavernous ICA is less than 25% or if the tumour does not cross the medial intercarotid line, the cavernous sinus is definitely not invaded. Aside from these two situations, cavernous sinus invasion is very likely to happen if the carotid sulcus venous compartment is obliterated or the lateral intercarotid line is crossed.

Differential Diagnosis List

Final Diagnosis

Pituitary adenoma invading the cavernous sinus.

URL:	https://eurorad.org/case/2141
DOI:	10.1594/EURORAD/CASE.2141
ISSN:	1563-4086