Enlargement of the tensor intermuscularis muscle in Graves' ophthalmopathy. A computed tomographic and magnetic resonance imaging study.

OBJECTIVE: To determine whether the tensor intermuscularis muscle (TIM), which consists of muscle fibers in the superolateral intermuscular orbital septum, is involved in Graves' ophthalmopathy (GO). DESIGN: The computed tomographic (n = 24) and magnetic resonance imaging (n = 10) appearances of the TIM were retrospectively examined in 34 patients with known GO. The severity of GO was assessed by applying a scoring system from 0 to 3 (ie, normal [0], mild [1], moderate [2], and severe [3]) to each of the rectus muscles and superior oblique muscle. The severity of exophthalmos, enlargement of the superior ophthalmic vein, and displacement of the lacrimal gland were also recorded. RESULTS: The TIM appeared as thickening of the septum immediately behind the globe, and it was best seen on coronal magnetic resonance images. There was enlargement of the TIM in 19 of the 34 patients, and it was bilateral in 17. Enlargement was present only in patients with moderate or severe involvement of other muscles (muscle index, > 7/15), and it was significantly correlated with the muscle index (P < .05), exophthalmos (P < .05), enlargement of the superior ophthalmic vein (P < .005), and anterior displacement of the lacrimal gland (P < .01). Severe enlargement of the TIM was seen in only five of the 34 patients, and it showed a close correlation with the muscle index (P < .005), exophthalmos (P < .001), enlargement of the superior ophthalmic vein (P < .001), and anterior displacement of the lacrimal gland (P < .001). CONCLUSIONS: Enlargement of the TIM in GO can be identified on computed tomographic and magnetic resonance imaging scans. It is invariably associated with moderate or severe involvement of other extraocular muscles, and it correlates closely with other well-recognized imaging features of severe GO.

Lateral canthotomy and inferior cantholysis: an effective method of urgent orbital decompression for sight threatening acute retrobulbar haemorrhage.

Retrobulbar haemorrhage (RBH) occurs in a variety of situations. It can complicate facial fractures, orbital surgery and retrobulbar injections and can occur spontaneously. It is relatively uncommon and sight-threatening RBH is even less common. If not detected early enough it can lead to devastating loss of vision. We have collected five cases of acute RBH, following trauma, associated with a profound reduction in vision. In each case a permanent loss of vision was avoided using a lateral canthotomy and inferior cantholysis approach to obtain urgent orbital decompression.

Graves ophthalmopathy: intracranial fat prolapse on CT images as an indicator of optic nerve compression.

PURPOSE: To determine the usefulness of a number of imaging features in the differentiation of patients with Graves ophthalmopathy who had optic neuropathy from those who did not. Intracranial herniation of orbital fat through the superior ophthalmic fissure and its clinical importance was also assessed. MATERIALS AND METHODS: The computed tomographic (CT) appearance of the orbital apex was examined in 50 patients without and in 50 patients with Graves ophthalmopathy. The clinical diagnosis of optic neuropathy was made by an ophthalmologist who was unaware of the imaging appearances and was based on clinical features and abnormalities of visual evoked potentials or changes at automated perimetry. RESULTS: Intracranial fat prolapse (P < .001) and optic nerve crowding (P < .05) were the only imaging features that were independently related to optic neuropathy. The presence of intracranial fat prolapse or optic nerve crowding on CT scans helped identify 16 of 17 patients with optic neuropathy. Sensitivity was 94%, specificity was 91%, positive predictive value was 69%, and negative predictive value was 98%. CONCLUSION: Intracranial fat prolapse correlates closely to the presence of optic neuropathy in Graves ophthalmopathy. This sign, in combination with optic nerve crowding, demonstrates a closer correlation to optic neuropathy than previously described imaging features.