Standardised echography in the differential diagnosis of extraocular muscle enlargement

Measurement of Intra-Orbital Structures in Normal Chinese Adults Based on a Three-Dimensional Coordinate System

PURPOSE OF THE STUDY

This study was to establish a three-dimensional (3D) coordinate system and to study the normal dimensions of intra-orbital structures in Chinese adults.

MATERIALS AND METHODS

One hundred and forty-five adult Chinese were selected from patients who had undergone cranio-facial computed tomography scans with diagnosis other than orbital or ocular abnormality. An orbital 3D coordinate system was built on the basis of the scans. Morphological variables of intra-orbital structures were measured in this coordinate system. Bilateral symmetry, sexual dimorphism, and correlations between variables were investigated.

RESULTS

No evident laterality was found in bilateral intra-orbital structures. The distance from the center of the eyeball to the prechiasmatic groove, the length of the optic nerve, and the thickness of rectus extraocular muscles were larger in males than in females. No sex-related difference was observed in the anteroposterior diameter of the eyeball or the exophthalmometric value. The exophthalmometric value was found to be related to the anteroposterior diameter of the eyeball, whereas the y-coordinate of the center of the eyeball had no correlation with the anteroposterior diameter of the eyeball. The optic nerve length was closely correlated to the distance from the center of the eyeball to the prechiasmatic groove.

CONCLUSIONS

The 3D coordinate system and measurement method established in this study can be applied to the standardization of orbital morphometry. The measurements obtained from normal Chinese adults may provide reference values for the morphology of intra-orbital structures.

Orbital ultrasonography in the diagnosis of neoplastic extraocular muscle enlargement

Neoplastic infiltration of the extraocular muscle (EOM) is a rare condition which can pose a diagnostic dilemma due to its rarity and overlapping ultrasonographic features with orbital myositis. The ultrasonographic features of neoplastic enlargement of EOM have not been systematically studied and previously have been described in only a few case reports. Orbital ultrasonography, in conjunction with the pattern of ocular misalignment, was assessed for its potential role in identifying patients with neoplastic EOM enlargement. Retrospective chart review of patients with neoplasm and myositis. The clinical features of 8 patients with neoplastic infiltration of the EOM were compared to 15 patients with myositis. In the neoplastic group the width of the EOM was (10.5 mm) almost twice the normal width of the muscle with myositis (p < 0.001). All the muscles in the neoplastic category were low to medium reflective. Paretic deviation was seen in 4/8(50%), purely restrictive in 2/8 (25%) and combined pattern in 2/8 (25%) were noted. In the myositis group the average EOM enlargement was 5.8 mm and all muscles showed low reflectivity. Although ultrasonographic features overlapped between the 2 groups paretic deviations were more common in the neoplastic group versus the myositis group (50% versus 7%). Neoplastic muscle enlargement tends to be larger with paretic deviations of ocular motility seen clinically. These findings in a patient with EOM enlargement should raise the suspicion of neoplasm as the etiology and further work up should be considered.

Diagnostic Ophthalmic Ultrasound for Radiologists

Ophthalmic ultrasound is an invaluable tool that provides quick and noninvasive evaluation of the eye and the orbit. It not only allows the clinicians to view structures that may not be visible with routine ophthalmic equipment or neuroimaging techniques but also provides unique diagnostic information in various ophthalmic conditions. In this article, the basic principles of ophthalmic ultrasound and examination techniques are discussed. Its clinical application is illustrated through a variety of ocular pathologic abnormalities (eg, narrow angles, ciliary body tumor, detached retina, choroidal melanoma, and papilledema).

Echographic study of extraocular muscle thickness in normal Indian population

PURPOSE

To establish normative data of extraocular muscle (EOM) dimensions, both vertically and horizontally, using a reproducible echographic method in various age groups.

METHODS

Two hundred eyes of 100 healthy subjects (50 males and rest females) were included in this prospective observational study. All subjects were divided into 5 groups with an interval of 10 years from 10 to 60 years. Each group contained 10 male and 10 female healthy subjects. A single operator took measurements at 4 mm distance from the globe plane after drawing a perpendicular line on the globe to the muscle belly.

RESULTS

The average age of subjects was 37.28 ± 17.14 years. Intraobserver reproducibility was very high (intersession concordance correlation co-efficient = 0.995). Mean horizontal and vertical diameters of recti were 3.0775 and 8.26 mm, respectively. Mean muscle thickness of superior rectus/levator palpebral superioris (LPS) muscle complex and LPS was 4.56 and 1.45 mm, respectively. Extraocular muscle diameter increases up to the middle age, then it starts decreasing. There was no statistically significant correlation between diameter of each EOM, both eye and gender (p ⩾ 0.05). There was a non-significant change in extraocular muscle thickness with age.

CONCLUSION

The study provides normative data for extraocular muscle thickness in both genders of various age groups in Indian population. Muscle dimensions do not change significantly with age, between the eyes and gender.

Magnetic resonance imaging and ultrasound measurements of extraocular muscles in thyroid-associated ophthalmopathy at different stages of the disease

PURPOSE

To assess extraocular muscle (EOM) involvement in thyroid-associated orbitopathy (TAO) of different stages with magnetic resonance imaging (MRI) and ultrasound techniques.

METHODS

A total of 32 patients with TAO were divided into three groups according to whether they had mild active, pronounced active or longstanding inactive disease. Six patients with Graves' disease but no clinical signs of TAO and 10 healthy control subjects were also studied. Muscle volume and cross-sectional area were measured with MRI. A-scan ultrasound was used to measure muscle thickness.

RESULTS

The average MRI volume and maximal cross-sectional area of the EOM were significantly larger in patients with pronounced active and longstanding inactive TAO than in control subjects. Increased average muscle thickness measured by ultrasound was found mainly in patients with longstanding disease. Muscle enlargement was seen with MRI and ultrasound in individual patients in all patient groups, including those with Graves' disease but no TAO. Bilateral muscle enlargement was revealed by MRI in about two-thirds of patients with mild active TAO and in all patients with pronounced active and longstanding inactive TAO. Bilateral involvement estimated with ultrasound was less common in all patient groups. The MRI and ultrasound findings were not well correlated in any patient group.

CONCLUSIONS

Extraocular muscle enlargement was seen in all patient groups with TAO of differing levels of severity. Measurements with MRI of muscle volume or maximal cross-sectional area are considered good indicators of muscle enlargement in TAO.

[Bilateral idiopathic orbital myositis]

INTRODUCTION

Orbital myositis is an idiopathic inflammation of the extraoccular muscles. It is often included under the broad description of orbital pseudotumor. It is commonly a unilateral affection.

CASE REPORT

We report one case of bilateral orbital myositis in a 45-year-old woman. The first symptoms were diplopia and acute bilateral orbital pain exacerbated by eye movements. Physical examination especially neurological was normal. Serum creatine kinase and biological thyroid function were normal. CT scan found a bilateral enlargement of rectus oculi medialis and lateralis. Clinical improvement was obtained a few days after oral corticosteroid treatment with remission of all signs.

CONCLUSION

Orbital myositis is a rare entity. 90-95p.cent of cases are unilateral. Bilateral forms are exceptional and in this case require search for specific etiologies particularly thyroid ophthalmopathy. There is controversy concerning treatment options but corticosteroids are still the most common first choice therapy with good outcome.

Interobserver and intraobserver variability of measurements of uveal melanomas using standardised echography

AIMS

To report on the intraindividual and interindividual variability of tumour size (height and base diameter) measurements using standardised echography in a masked prospective study.

METHODS

20 consecutive eyes of 20 patients were examined on four different visits by three experienced examiners using standardised echography. As common in standardised echography, tumour height was evaluated with A-scan technique, while transverse and longitudinal base diameter were calculated with B-scan.

RESULTS

Tumour height measurements using A-scan were more accurate than base diameter measurements using B-scan. The standard deviation for tumour height over all visits/measurements was 0.18 mm (A-scan), 0.79 mm for transverse, and 0.69 mm for longitudinal base diameters (B-scan). The interclass correlation coefficient (ICC) was much higher for tumour height measurements with A-scan (0.7735 for three examiners on one visit) than for transverse (0.6563) or longitudinal (0.4522) base diameter measurements with B-scan techniques.

CONCLUSIONS

A-scan techniques for tumour height measurements provide very reproducible results with little intraindividual and interobserver variability. As B-scan techniques for tumour base evaluation are less accurate they should be used for topographic and morphological examinations.

Echographic study of extraocular muscle thickness in children and adults

BACKGROUND

Echobiometric evaluation of extraocular muscles in normal subjects has been performed previously, but only in adults. We determined extraocular muscle thickness in normal subjects in three age groups.

METHODS

Extraocular muscle thickness was studied in 75 normal subjects divided into three age groups (5-10, 11-15 and 28-37 years) using a Biovision B-scan-S instrument in standardized A-mode (frequency, 10 MHz; biometry resolution, 0.15 mm; depth, 40-60 mm; points on X axis, 512; levels on Y axis, 256). All measurements were performed by the same operator and repeated five times. The reproducibility of the technique was determined using the coefficient of variation. The one-way ANOVA test was used to compare the three groups, and the two-tailed unpaired t-test was used to compare subjects aged 5-10 years and those aged 11-15 years, and subjects aged 11-15 years with those aged 28-37 years.

RESULTS

The technique showed good reproducibility. In subjects 5-10 years old, the coefficient of variation was 8%; in subjects 11-15 years and 28-37 years old, it was 5%. Increased muscle thickness was observed with age (p < 0.001). A statistically significant difference between the medial and inferior recti muscles in subjects 11-15 years and 28-37 years old was found (p < 0.001).

CONCLUSIONS

The increased thickness of all recti muscles may be influenced by growth (primarily during puberty), and the variations in thickness of the extraocular muscles may be attributable to near-vision stimulus of the inferior and medial recti muscles.

Venous stasis orbitopathy: a clinical and echographic study

AIMS

A variety of acute and chronic orbitopathies may be distinguished by standardised echography. Venous stasis orbitopathy (VSO) often presents with orbital signs when secondary to cavernous sinus and middle cranial fossa disorders. In this study, the aim was to assess whether differentiation between vascular and nonvascular causes of VSO could be made on the basis of clinical and echographic features at the time of presentation.

METHODS

This study comprised 37 patients with echographic features of VSO (17 patients with arteriovenous fistulae, confirmed by computed tomography imaging or angiography, and 20 patients with non-vascular diseases). Excluded were patients with orbital mass lesions detected by echography and muscle enlargement due to other causes (for example, orbital myositis). Patients with a suspected mass involving the orbital apex and echographic features of VSO were included. After full neuro-ophthalmic and ocular examination, both orbits were examined to document maximal thickness and reflectivity of four recti muscles and compared with the normal contralateral orbit with standardised A-scan (Kretz-technik 7200MA or Ophthascan) and contact B-scan (Ultrascan or Ophthascan S).

RESULTS

Cumulative ocular recti muscle thickness was significantly greater in patients with arteriovenous fistulae compared with the non-fistula group (23.3 (SD 3.7) and 17.8 (2) mm, p = 0.001). Clinically, the presence of a bruit and a uniocular rise in intraocular pressure were significantly greater in the fistula group of patients.

CONCLUSIONS

Standardised echography is a safe and non-invasive method of diagnosing VSO in patients presenting with signs of proptosis, ophthalmoplegia, and inflammation of the conjunctiva. Furthermore, using these standard techniques the two major causes of VSO (arteriovenous fistulae and compressive mass lesions) could be differentiated.

Acute orbital myositis

We examined 9 consecutive cases of unilateral orbital myositis (7 women and 2 men; age range 15-46 years) presenting to Casualty. Only 3 were correctly diagnosed on the first visit. Eight patients exhibited globe retraction in the acute stages and, after treatment with systemic steroids, all made a full recovery. None of the patients had associated systemic disease and all remain well over a 6-12 month follow-up period. Orbital myositis may be a more common condition than previously thought; it can present with a variety of clinical signs, and may be difficult to diagnose in the early stages. The presence of globe retraction on movement of a painful, injected eye is a useful diagnostic sign which indicates inflammation of extraocular muscles and is present in the acute stages of the disease; we explain how to elicit globe retraction and suggest a management protocol for these patients.