Dynamic CT scanning for visualization of the parasellar carotid arteries

[Giant parasellar aneurysm simulating pituitary tumor]

Seven cases of compromised pituitary fossa at the conventional skull X-ray, who had the final diagnosis of giant aneurysm of the intracavernous portion of the carotid artery (6 cases) and one of the anterior communicating artery, are reported. The main findings were: headache (7/7), complex ophthalmoplegia involving the III, IV and VI cranial nerves (5/7), compromised V cranial nerve (4/7) and eyeball pain (4/7). Other manifestations were: meningeal signs (2/7), unilateral blindness (1/7), hemiparesis (1/7), cacosmia (1/7) and inferior bitemporal quadrantanopsia (1/7). Five patients with intracavernous carotid artery aneurysm showed benefits with progressive occlusion of the internal carotid artery at the cervical level. One died before surgery. The case with anterior communicating artery aneurysm improved after its surgical clipping. Our data, in accord with the literature, support the conclusion that the differential diagnosis of aneurysms in the parasellar region remains a very difficult task. The accurate final diagnosis requires cerebral angiography and the surgical treatment with progressive occlusion at the cervical portion of the internal carotid artery has a relatively low risk with promising results.

Measurement of basilar artery diameter in dogs: CT evaluation correlated with arteriography

In this study we have used a computed tomographic (CT) method using profile analysis to measure the diameter of the basilar artery. In a search for a noninvasive and repeatable method to substitute for the traditional arteriography in the evaluation of the degree of cerebral vasospasm, we employed both CT and arteriography to measure the diameter of the basilar artery in eight adult mongrel dogs weighing between 7 and 12 kg. In three of these animals, assessments were made before and after subarachnoid hemorrhage (SAH) induced by injecting autologous arterial blood into the cistern magna. It was found that the basilar artery diameter as evaluated by CT was 47% larger than that measured by arteriography. However, there was a very good correlation (n = 63, r = 0.75, p less than 0.001) between the two methods. This paper presents a new model for the measurement of the basilar artery diameter, one which may also provide a safer method for the evaluation of vasospasm in humans.

Surgeon's view of the skull base from the lateral approach

This paper presents the surgical anatomy of the skull base and infratemporal fossa. The information has been derived from the author's own experience in surgical and cadaver dissection, standard anatomical references, and selected experience of other skull base surgeons. Because the lateral approach has become the utilitarian method of exposure, the intricate detailed anatomy is demonstrated from this view at five levels of dissection, so the surgeon may gain a practical understanding of the surgical relationship of critical structures. Consistent anatomical landmarks can be used by the surgeon in the location of these critical structures. The styloid process, sphenoidal spine, and middle meningeal artery identify the internal carotid artery as it enters the carotid canal. The bony or fibrous septum that divides the jugular foramen into neural and vascular compartments may be used to better identify nerves IX, X, and XI. The zygomatic root is useful for location of the middle fossa dura. The lateral pterygoid plate leads directly to the foramen ovale. The increased precision of dissection permitted by use of the microscope requires an increased level of knowledge of anatomical structures in this area. It is hoped that the information presented in this paper will assist surgeons in the meticulous and thorough removal of skull base tumors and in the preservation of neural and vascular structures that are presently being sacrificed.

Diagnosis of an "isodense" pituitary microadenoma by dynamic CT scanning. Case report

A case of Nelson's syndrome with an adrenocorticotropic hormone-secreting pituitary chromophobe microadenoma is presented to demonstrate the potential capability of rapid sequential (dynamic) computerized tomography (CT) scanning for the diagnosis of a pituitary microadenoma that was isodense with the adjacent pituitary gland on conventional enhanced CT scanning. The dynamic CT scans showed transient high density in this microadenoma contrasting with the pituitary gland in the early-enhancement phase, and thereafter the contrast density was indistinguishable from that of the pituitary gland in the delayed-enhancement phase. For the detection of pituitary microadenoma, dynamic CT combined with subsequent delayed CT scanning can provide diagnostic and localizing information.