ACUTE ORBITAL MYOSITIS C. M. MOORMAN and J. S. ELSTON Oxford SUMMARY clinical picture and confirmed by CT scan. Specific We examined 9 consecutive cases of unilateral orbital MRI appearances have been described enabling a myositis (7 women and 2 men; age range 15-46 years) precise diagnosis to be made and the differentiation presenting to Casualty. Only 3 were correctly diagnosed of myositis from orbital neoplasia (e.g. lymphoma) on the first visit. Eight patients exhibited globe and pseudo tumours? ·retraction in the acute stages and, after treatment Tissue biopsy is rarely indicated in 'typical' cases. with systemic steroids, all made a full recovery. None of Open muscle biopsy or fine needle aspiration the patients had associated systemic disease and all biopsies have shown non-granulomatous inflamma­ remain well over a 6-12 month follow-up period. tory changes with marked lymphocytic infiltration.8,9 Orbital myositis may be a more common condition The aetiology of orbital myositis is not clear than previously thought; it can present with a variety of although it has been reported in association with clinical signs, and may be difficult to diagnose in the many conditions, including respiratory tract infec­ early stages. The presence of globe retraction on tion, myocarditis, Lyme disease, herpes zoster and 0- movement of a painful, injected eye is a useful Whipple's disease. 1 1 4 Weinstein et al. 9 reported 12 diagnostic sign which indicates inflammation of extra­ patients with orbital myositis 4 of whom had histories ocular muscles and is present in the acute stages of the of ocular or systemic autoimmune disease. disease; we explain how to elicit globe retraction and Treatment of acute orbital myositis with high-dose. suggest a management protocol for these patients. systemic corticosteroids usually results in prompt clinical improvement; non-steroidal anti-inflamma­ Orbital myositis can be defined as a non-specific, tory agents such as indomethacin are also effective.15 localised orbital inflammatory process in which any Subacute or chronic cases which prove refractory to one or more of the extraocular muscles may be this regime have been shown to respond to second­ involved. The condition may be acute, subacute or line anti-inflammatory agents such as low-dose recurrent. In the acute form patients complain of a methotrexate or radiation treatment.9,16 painful eye and may notice diplopia; clinical We report 9 consecutive cases of acute orbital examination may show a variety of features ranging myositis presenting to the Eye Casualty Department from minimal conjunctival injection over the at the Oxford Eye Hospital over a 21 month period. involved muscle to extensive conjunctival chemosis, This study shows that the condition may present proptosis, eyelid swelling and blepharoptosis. There more commonly to Casualty than previously thought may be extraocular muscle limitation. The condition and that with appropriate treatment there is a good may be unilateral or bilateral and the rectus muscles long-term prognosis. We present a protocol for the may be involved alone or in association with the management of these patients. oblique muscles.1,2 Recurrences may involve the same orbit or the contralateral side? PATIENTS AND METHODS Orbital myositis can mimic a variety of other The patients presented over a 21 month period to the ocular conditions such as thyroid eye disease, orbital Oxford Eye Hospital Accident & Emergency pseudotumour, orbital cellulitis or any condition Department with the symptoms indicated in Table which causes enlargement of the extraocular mus­ I, which also shows the initial diagnosis. A provi­ cles?,4 Differential diagnosis depends on blood tests sional clinical diagnosis of orbital myositis was made and specific radiological investigations.5,6 In practice after re-examination by the authors, when globe the diagnosis of orbital myositis is made on the retraction was specifically looked for. The sign was Correspondence to: Ms C. M.Moorman, Oxford Ey e Hospital, elicited by first performing horizontal and vertical The Radcliffe Infirmary, Woodstock Road, Oxford 0X2 6H, UK. eye movements with the patient facing the examiner Eye (1995) 9, 96-101 © 1995 Royal College of Ophthalmologists ACUTE ORBITAL MYOSITIS 97 Table I. Presenting symptoms and initial diagnosis in patients with orbital myositis (n=9) Presentation Duration of Patient no., age (yr) and sex PMH Redness Pain Diplopia Headache symptoms (days) Initial diagnosis 1.18 F No ++ ++ + 5 Conjunctivitis + + 2 + 4 2.30 F No + + + 14 Episcleritis 3.46 F Crohn's disease + + + 21 Episcleritis 4.25 M No ++ + + 30 Orbital myositis 5.36 M No + + + 7 Allergy; orbital cellulitis 6.36 F No + + + 5 Orbital myositis 7.15 F Migraine + + 1 Episcleritis 8.26 F No ++ 3 Orbital myositis 9.31 F No ++ + ++ 35 Thyroid eye disease PMH, past medical history. and checking for narrowing of the palpebral fissure, myositis. Five of the patients were eventually and then repeating eye movements with the patient admitted to hospital once the diagnosis of orbital in profile and looking for retraction of the globe, myositis had been made. which usually occurs when the eye is looking in a All the patients underwent full physical examina­ direction opposite to the direction of action of the tion including neurological examination and were involved muscle. Eight patients then had orbital CT found to be healthy; blood tests for full blood count scanning to confirm the diagnosis; 1 patient had an and blood film, urea, electrolytes, blood sugar, liver orbital ultrasound scan. Systemic investigations were function tests, erythrocyte sedimentation rate, C­ undertaken as shown in Results. Treatment was reactive protein, thyroid function tests, VDRL and initiated as indicated in Table II. an auto-antibody screen showed no abnormality. N one of the patients has developed systemic disease RESULTS over a 6-24 month follow-up period. The mean age of the patients at presentation was 29 Hess charts were performed on 7 patients; the 2 years (range 15-46 years). Eight of the patients had a who did not have orthoptic follow-up had no diplopia history of acute onset, persistent ocular discomfort despite slight restriction in adduction of the affected beginning 1-35 days earlier. eye. All patients were in good general health with no A CT scan was performed on 8 patients as a relevant family history. Ocular examination revealed diagnostic procedure and in all cases showed swelling normal visual acuity, pupil responses, colour vision of the insertion and the belly of the extraocular testing, intraocular pressure and dilated fundal muscle involved (Fig. 2) which was consistent with appearance in all patients. There was no sign of orbital myositis. Dysthroid eye disease has a similar intraocular inflammation. Eight patients had globe appearance on CT scan but the muscle insertion is retraction with narrowing of the palpebral fissure in usually spared and several muscles in both orbits the acute stages (see Fig. 1). normally show some change. One patient had an The patients with presumed conjunctivitis and ultrasound scan (orbital B-scan) which showed episcleritis were all reviewed within 2-4 days and enlargement of the belly of the involved muscle on subsequent examination were found to have an with reduced reflectivity on the A scan (Fig. 3). These orbital condition. The patient with orbital cellulitis are typical features of orbital myositis, in contrast to was admitted with this diagnosis and treated as such thyroid eye disease which would show normal or until a CT scan revealed the typical features of increased reflectivity on scanning. Table II. Clinical features and treatment of patients with orbital myositis (n=9) Patient Diagnostic no. delay (days) Proptosis Globe retraction Muscle affected Steroid treatment Recurrent attacks 1. 5 No Yes Left MR, right LR, left 20 mg b.d. 2 LR 2. 3 No Yes Left LR 20 mg b.d. 0 3. 16 Yes Yes Right LR 30 mg b.d. 0 4. No Yes Left Mr None 0 5. 4 Yes Yes Left LR 40 mg b.d. 0 6. No Yes Right LR 20 mg b.d. 1 7. 11 No Yes Left LR None 0 8. No Yes Right LR 20 mg o.d. 0 9. 8 No No Left SO 30 mg o.d. 0 MR, medial rectus; LR, lateral rectus; SO, superior oblique. 98 C. M. MOORMAN AND 1. S. ELSTON Fig. 1. Patient 3. Lateral view of the riKht orhit with the Fig. 2. Patient I. CT scan of the orhits showing marked patient in primary Kazc (ahove) and in addltction (helow) enlargement of the left medical rectlls from the insertion demonstrating narrowing of the palpehral fissltre. Glohe to the orhital apex. retraction was present, hut dlte to the dynlllnic nature of this sign it is difficltlt to demonstrate in print. Fig. 3. Patient R. A- and B-nwde echography of the riKht lateral rectus. The A scans show marked redltction of internal reflectivity (sinKle arrows). The B-mode echoKraph shows enlarKement of the mllscle helly in the horizontal (A) and the vertical (B) plane (douhle arrows). The CT scan can be difficult to interpret in cases DISCUSSION involving the oblique muscles and patient 9 was All our patients had acute orbital myositis confirmed initially thought to have enlargement of the left by either CT or ultrasound scan appearances of the medial rectus; careful examination of the patient's involved muscles and the response to treatment. eye movements and an ultrasound scan showed that Neither open nor fine needle biopsies were consid­ the superior oblique alone was affected? It was ered necessary. However. only 3 of the 9 patients interesting that despite clinically normal-looking eyes were correctly diagnosed at the first casualty visit due patients 6 and 8 both demonstrated globe retraction to a combination of low awareness of the condition and had diagnostic CT and ultrasound scans.