Graves orbitopathy: correlation of CT and clinical findings.

Abstract

The clinical and high-resolution computed tomographic (CT) findings in 71 patients (142 orbits) with Graves orbitopathy and 20 healthy patients (40 orbits) were retrospectively reviewed. The orbits with orbitopathy were subgrouped at clinical examination into those with (n = 18) and those without (n = 124) optic neuropathy. Mean extraocular muscle diameters and the calculated muscle diameter index were significantly increased in all orbits with ophthalmopathy, particularly in those with optic neuropathy. Graves orbitopathy affected the superior muscle group (63.4%) more than the medial (61.3%) or inferior (57%) recti. The most common pattern of muscle involvement involved all five measured extraocular muscles. Solitary muscle involvement most frequently involved the superior muscle group (6.3%). Significant enlargements of the retrobulbar optic nerve sheath and superior ophthalmic vein were noted only in orbits with optic neuropathy. Anterior displacement of the lacrimal gland at CT correlated with clinical palpability and occurred more frequently in patients with optic neuropathy. Severe apical crowding was the most sensitive indication of optic neuropathy at CT.

Quantification of Orbital Apex Crowding for Screening of Dysthyroid Optic Neuropathy Using Multidetector CT

“…10,12,13,18,19 Because of its great importance in DON, apical crowding is quantified with a score first described by Nugent et al 15 and reproduced by many other authors, 1,3,7,9,16 which grades the effacement of the perineural fat as 0 (none), 1 (up to 25%), 2 (25%-50%), or 3 (greater than 50%). 15 Using this method, Nugent et al found severe apical orbital crowding (grade 3) in 12 of 18 orbits with DON but in only 16 of 124 orbits without DON. 15 Neigel et al graded as moderate or severe crowding 79.2% of orbits with DON but only 12.9% of orbits without DON.…”

“…A categoric score of orbital apical crowding, as described by Nugent et al, 15 was also determined at a predetermined coronal section at the midpoint of the intraorbital optic nerve. The score reflects circumferential effacement of perineural fat by the extraocular muscles (0 ϭ none; 1 ϭ mild, 1%-25%; 2 ϭ moderate, 25%-50%; 3 ϭ severe, Ͼ50%).…”

“…The score reflects circumferential effacement of perineural fat by the extraocular muscles (0 ϭ none; 1 ϭ mild, 1%-25%; 2 ϭ moderate, 25%-50%; 3 ϭ severe, Ͼ50%). 15 Finally, we assessed each set of images for the presence of intracranial fat prolapse through the superior orbital fissures (recorded as present or absent) using the method described by Birchall et al…”

“…Most of these studies used axial and direct or reformatted coronal images acquired with conventional CT scanners, and calculations were often performed manually from hard copies of the scans. Subjective assessment of apical crowding based on coronal images described by Nugent et al, 15 and detection of intracranial fat prolapse introduced by Birchall et al, 16 have also been used to evaluate the risk of development of DON.…”

Postural visual obscurations in patients with inactive thyroid eye disease; a variant of ‘hydraulic’ disease

“…Some patients with inactive thyroid eye disease and mild proptosis, however, have a markedly increased orbital pressure that can be associated with deep orbital vascular congestion, persistently raised intraocular pressures and, in some cases, optic neuropathy. 2,6 This congestive variantFtermed 'hydraulic' disease by the writer, to distinguish it from the congestion of the active inflammatory phaseFappears commoner with certain races (particularly Asians 7,8 ), this probably being due to their thicker orbital walls and relatively less compliant orbital septum.…”