Specific Imaging Findings

A unilateral, poorly defined cavernous sinus lesion is characteristic for Tolosa–Hunt syndrome (THS). The lesions are usually slightly dark on T2-weighted images, hypointense to gray matter, and cause increase in size of the sinus with convex bulging of the dural contour. Blurring or complete effacement of the normally hypointense lateral dura may also be present on T2-weighted images. Uniform enhancement is typical, but the degree of enhancement is usually less compared to the unaffected contralateral sinus. Dynamic post-contrast imaging may show small areas of delayed enhancement which gradually fill in on the delayed images. The ipsilateral internal carotid artery will be narrowed in almost one half of patients. In over a third of cases, the process extends anteriorly into the orbital apex via the superior orbital fissure, with abnormal enhancement best seen on fat-saturated post-contrast images. Optic nerve sheath may also be involved.

Pertinent Clinical Information

Painful ophthalmoplegia is the clinical hallmark of THS. Patients classically present with acute, severe periorbital or retroorbital pain followed within days by the onset of diplopia. Visual loss can occur if there is optic nerve involvement. The process is usually unilateral and the diagnosis is based on criteria established by the International Headache Society: (1) one or more episodes of unilateral orbital pain persisting for weeks if untreated; (2) paresis of one or more of the cranial nerves III, IV, or VI and/or demonstration of a granuloma by MRI or biopsy; (3) paresis coinciding with the onset of pain or following it within 2 weeks; (4) resolution of pain and paresis within 72 h of adequate treatment with corticosteroids; and (5) exclusion of other causes with appropriate investigations.