Cavernous Sinus and Superior Orbital Fissure Involvement
Ipsilateral CN dysfunction involving a combination of CNs III, IV, V, and VI, and sympathetic fibers is the hallmark of ophthalmoplegia that is secondary to a cavernous sinus lesion (see Chapter 1 for illustrations). The presence of CN V involvement with facial hypoesthesia, a third-order (postganglionic) Horner syndrome, or both is helpful for localizing the lesion to the cavernous sinus. If only 1 CN is involved, it is usually CN VI, which is the only CN not protected within the lateral dural wall of the cavernous sinus. Aggressive lesions of the cavernous sinus, especially infectious or inflammatory processes, may compromise venous outflow and produce engorgement of ocular surface vessels, orbital venous congestion, increased intraocular pressure, and increased ocular pulse pressure.
It is often impossible to distinguish cavernous sinus lesions clinically from those involving the superior orbital fissure. The CNs pass through this fissure from the cavernous sinus into the orbit, and lesions often cross this anatomical boundary. In recognition of this difficulty, the more general designation of sphenocavernous syndrome or parasellar syndrome may be used. The offending lesion may extend toward the optic canal or into the orbital apex, in which case optic nerve function can be compromised. The designation orbital apex syndrome is then applied.
Tolosa-Hunt syndrome is an idiopathic, sterile inflammation that primarily affects the cavernous sinus. Severe, “boring” pain is almost always present. Neuroimaging may show an enhancing mass within the cavernous sinus. The pain typically responds rapidly and dramatically to corticosteroid therapy, but a positive therapeutic response may also occur with neoplastic mass lesions, especially lymphoma. Frequently, it is later discovered that the cause of the painful ophthalmoplegia in patients initially diagnosed with Tolosa-Hunt syndrome is neoplastic. Therefore, Tolosa-Hunt syndrome is a diagnosis of exclusion. Other causes of cavernous sinus lesions include aneurysm, meningioma, lymphoma, schwannoma, pituitary adenoma (with or without apoplexy), carotid-cavernous fistula, metastasis, sarcoidosis, and cavernous sinus thrombosis.
Hao R, He Y, Zhang H, Zhang W, Li X, Ke Y. The evaluation of ICHD-3 beta diagnostic criteria for Tolosa-Hunt syndrome: a study of 22 cases of Tolosa-Hunt syndrome. Neurol Sci. 2015:36(6):899–905.
Hung CH, Chang KH, Chen YL, et al. Clinical and radiological findings suggesting disorders other than Tolosa-Hunt syndrome among ophthalmoplegic patients: a retrospective analysis. Headache. 2015;55(2):252–264.
Kline LB, Hoyt WF. The Tolosa-Hunt syndrome. J Neurol Neurosurg Psychiatry. 2001;71(5): 577–582.
Carotid-cavernous sinus fistula
Abnormal connections between the cavernous sinus and the carotid artery or its branches introduce high arterial pressure into the normally low-pressure venous circulation of the cavernous sinus. Such a high-pressure connection may reverse blood flow within the superior ophthalmic vein and produce venous congestion within the orbit. Arterialization of conjunctival vessels is a classic sign of this fistula (Fig 7-13). Patients with this condition may have either direct, high-flow connections between the internal carotid artery and the cavernous sinus or indirect, “dural,” low-flow connections mediated by small arterial feeders off the internal or external carotids (Fig 7-14). High-flow, direct fistulas most commonly occur after severe head trauma and produce a cranial bruit, whereas low-flow, indirect fistulas most often occur spontaneously, particularly in older women. The sequence of events leading to indirect fistula formation is not known. Physical examination cannot reliably distinguish between high-flow and low-flow fistulas, aside from a cranial bruit that indicates high flow. MRA, CTA, or cerebral angiography is necessary to make the correct diagnosis.
Figure 7-13 Right carotid-cavernous sinus fistula. A, The elevated orbital venous pressure produces enlarged, corkscrew, arterialized conjunctival blood vessels that extend to the limbus. B, T1-weighted, axial MRI scan reveals an enlarged, dilated superior ophthalmic vein (arrow).
(Courtesy of Karl C. Golnik, MD.)
Figure 7-14 Lateral cerebral angiogram with right common carotid artery injection. Note cavernous sinus fistula (ill-defined area, white arrows) filling from both the external branches (red arrowheads) and internal branches (white arrowheads). The superior ophthalmic vein (red arrow) is markedly enlarged and fills inappropriately during the early arterial phase of this study, consistent with a carotid-cavernous sinus fistula.
(Courtesy of Prem S. Subramanian, MD, PhD.)
Direct and indirect carotid-cavernous sinus fistulas often produce elevated intraocular pressure and proptosis but may also cause the following signs or symptoms:
diplopia resulting from either cranial nerve palsy or orbital congestion
arterial or venous compromise to the retina and eye
ischemic optic neuropathy
choroidal effusions (Fig 7-15)
ocular pain (which may partly result from ocular surface drying if proptosis is significant)
cerebral venous infarction (rare) resulting from venous hypertension
Compression of CN VI due to a posteriorly draining fistula can cause an isolated CN VI palsy. Patients should be asked about pulsatile tinnitus, which is often present. Some indirect fistulas remain stable or close spontaneously; however, both types of fistulas may be successfully treated with interventional radiologic techniques or radiosurgery. Angiographic studies are required to determine the location and configuration of the fistula, and a variety of thrombogenic materials (eg, coils, beads, or balloons) may be employed to eliminate the abnormal vascular flow.
Figure 7-15 Choroidal effusion due to carotid-cavernous fistula. A, Slit-lamp photograph of left eye showing chemosis and arteriolarization of conjunctival vessels from a left carotid-cavernous fistula (arrows point to the shadow corresponding to choroidal effusion). B, Fundus photograph of left eye showing macular-involving choroidal effusion (arrows). C, B-scan demonstrating choroidal effusion (arrows).
(Parts A and B courtesy of Zoë R. Williams, MD; part C courtesy of David A. DiLoreto Jr, MD, PhD.)
Subramanian PS, Williams ZR. Arteriovenous malformations and carotid-cavernous fistulae. Int Ophthalmol Clin. 2009;49(3):81–102.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.