first described by gleason in 1903 , orbital myositis ( om ) or orbital pseudotumor is a benign idiopathic inflammatory disease that may affect any structure in the orbit .
ocular myositis is now seen as a subgroup within the entity of idiopathic orbital inflammatory syndrome ( iois )   and it just represent 8% of all idiopathic orbital inflammations .
ocular myositis affects mostly females ( 2:1 females to males ratio ) around 32 years old but iois has been reported at any age .while
orbital myositis is an inflammation of any orbital structure , ocular myositis describes a rare inflammatory disorder of extraocular eye muscles   but the two have a lot of over lapses and so are hard to distinguish .
most cases of om have subacute orbital painful diplopia witch is caused by handicapped contraction and distraction of affected eye muscles not by neurogenic associated affections .
pain can be exacerbated by eye movement . in most of the patients , beyond orbital discomfort ,
two major forms of ocular myositis have been described , one with few ocular symptoms and with an additional conjunctival injections called limited oligosymptomatic ocular myositis ( loom ) and a second form with a severe exophthalmic ocular involvement with additional ptosis , chemosis , and proptosis , called severe exophthalmic ocular myositis ( seom ) . also signs and symptoms of other subgroups of iois such as dacryoadentitis , periscleritis and perineuritis
many inflammatory , vascular , neoplastic or infectious disease can affect the extra - ocular muscles and mimic orbital myositis .
muscle biopsies of eoms have reporting mixed infiltrates of plasma cells , lymphocytes , macrophages and polymorphonuclear cells while chronic forms of idiopathic ocular myositis are associated with fibrosis of the affected muscles .
specific myositis either by bacterial or viral infections can be associated to orbital myositis while others can be a local manifestation of a systemic immunomediated disease .   while specific forms of ocular myositis will be resolved with specific systemic treatment , idiopathic ocular mysositis is treated with corticosteroids or with radiotherapy .
  we present the case of a 43 years old caucasian male , ex - smoker ( 15pa ) , stopped 6 years ago , was admitted in our hospital in september 2012 for a history of recurrent palsy of left abductor nerve with left gaze diplopia .
these symptoms began in march 2012 were treated first by his general practitioner with non - steroidal anti - inflammatory drug and b complex vitamins for 10 days with no results .
the patient had a history of arterial hypertension , ischemic cardiomiopathy , dyslipidemia , rhinitis , maxilar sinusistis and he was treated with calcium blocker channels , indapamidum and statin .
physical examination revealed a overweight patient ( mc=26 kg / m2 ) , horizontal gaze diplopia , left nerve vi paresis , mild left retroorbital pain , no dizziness , no nystagmus , no motor deficite , no difficult in swalloing liquids or solids , normal osteotendinous reflexes , bilateral plantar flexion , normal language .
blood pressure was 120/60mmhg , pulse was 74 bpm , respiratory rate was 18 breaths / minute , oxygen saturation was 99% while breathing ambient air ; the rest of the examination were in normal limits . at this point
several diagnoses were taken into consideration , such as thyroid disease , ocular myasthenia gravis , infection , ocular - faringial syndrome and ocular myositis .  
results of laboratory tests revealed a moderate hypercholesterolemia ( 237mg / dl ) and hypertryglideridemia ( 147mg / dl ) ; the rest of the results were in normal limits .
the patient was tested for different pathologies in parallel as following : tsh=0,4mclu / ml , ft4=10,6pmol / l , t3=1,01ng / ml , igm antibodys for lymme were 2.3au / ml , igg for borellia were less than 5 au / ml , anti musk antibodys were less than 5 nmol / l , anti - acetylcholine receptor ( achr ) antibody less than 0,1 nmol / l , , hba1c=5% , anca , anticardiolipin , anti - dsdna , hiv were all negative .
the chest x - ray showed no active pulmonary lesions , so it did nt raised the suspicion of sarcoidosis or malignancy .
the otorhinolaryngology exam revealed signs of maxillar chronic sinusitis , chronic amigdalistis , deviated nasal septum and chronic rhinitis .
the ophthalmology consult observed just edema in the left orbit , with no other modifications .
the orbital mri also did nt offer new information : mild external edema on the left eye , with normal tendon aspect , no thickening or enhancement of the muscle belly and also normal aspect of the bony orbit ( fig.1 ) .
cerebral angiography : normal aspect at injection in both internal and external carotid artery ( fig.2 ) .
also functional testing through visual evoked potentials using a patter - reversal stimuli was normal ( fig.3 ) .  
orbital mri showed for both t2 ( a ) and t1 ( b ) mild external edema on the left eye , with normal tendon aspect , no thickening or enhancement of the muscle belly and also normal aspect of the bony orbit ( c ) .
normal left eye visual evoked potential according with the standard of the lab .    given these results a diagnose of ocular myositis was made without having the biopsy confirmation .
corticosteroid treatment was reinitiated with high doses as 80mg / day of methylprednisolonum for 1 month with a slow decrease in dosage .
all the fallow - up evaluation found the patient struggling between asymptomatic periods and diplopia with left nerve vi paresis periods , according to the corticosteroid dosage .
  it is not precisely known why extraocular muscles ( eoms ) are preferentially affected by inflammation in iois .
eoms have a unique myofibrillar protein isoform composition reflecting their structural and functional properties . compared with skeletal muscle ,
eoms have smaller motor unit sizes , higher motor neuron discharge rates , higher blood flow with higher mitochondrial volume fractions which can suggest that the energy requests and susceptibility to mitochondrial dysfunction are higher as compared with skeletal muscle . due to the high blood flow and vascularisation
, inflammatory blood cells can access more easily this specialized body compartment [ 2 , 10 ] .  
thyroid orbitopathy is the most common cause of orbital disease with a insidious onset is rather than acute leading to lid lag and lid retraction in down - gaze which is characteristic for this disorder .
usually patients will have bilateral eye involvement with signs of inflammation like edema leading to secondary fibrosis and in a few cases to optic neuropathy .   because 50%80% of myasthenia gravis initial manifestation can be an isolated eye muscle weakness with blepharoptosis or ophthalmoparesis this diagnostic has to be taken in consideration in all patients presenting with diplopia .
usually asymmetric ptosis is frequent associated with myasthenia gravis and up to 60% of the patients have acetylcholine receptor antibodies present .  
other pathologies can be taken in consideration in this patient , some can be excluded by carful conducted history interview like tolosa - hunt syndrome , while others need specific tests to confirm ( oculopharyngeal muscular dystrophy , myotonic dystrophy type 1 , congenital cranial dysinnervation disorders and congenital fibrosis of extraocular muscles and mitochondrial myopathies ) .   although not an often pathology , when dealing with a patient with recurrent palsy of eoms , ocular myositis must be always be taken in consideration .
 we report the case of a 43 year old man who presented recurrent left abducens palsy . his medical history included arterial hypertension , ischemic cardiomiopathy , dyslipidemia , rhinitis , maxillary sinusitis . 
 physical examination revealed a overweight patient , horizontal gaze diplopia , left nerve vi paresis , mild left retro - orbital pain . 
 the orbital mri also did nt offer new information : mild external edema on the left eye , with normal tendon aspect , no thickening or enhancement of the muscle belly and also normal aspect of the bony orbit . 
 recurrent palsy of eoms can be caused in rare cases by ocular myositis . 
Introduction
Case Report
Discussion