What is Nonspecific Orbital Inflammation (NSOI)?
Nonspecific orbital inflammation (NSOI), also known as psuedotumor, is disease of the eye that not uncommonly presents to the emergency room or ophthalmologist. Typically, its onset is acute and manifests with severe orbital pain, swelling around the eyes, limitation and pain with eye movements, and even loss of vision. It is easily confused with infection (pre-septal or post-septal eyelid cellulitis) and may be treated initially –and unsuccessfully– with antibiotics.
Computed tomography of the orbits may reveal thickening of the extraocular muscles, stranding of the orbital fat, a poorly defined mass (hence the name “pseudotumor”), thickening of the sclera, soft tissue inflammation in the eyelids, or even nothing at all. NSOI can affect children as well as adults. Typically, it responds very quickly to high dose corticosteroids. In fact, this rapid response usually confirms the diagnosis. Atypical presentations warrant further testing, including blood tests and tissue biopsy.
NSOI is so named because of the way a biopsy of affected tissue appears microscopically. There is a scattering of plasma cells, lymphocytes, neutrophils, and histiocytes with no particular pattern. The differential diagnosis for pseudotumor includes the following: thyroid-associated orbitopathy (Graves’ disease), non-infectious granulomatous inflammation (specific orbital inflammation such as Wegener’s granulomatosis and sarcoidosis), infectious orbital inflammation (bacterial, fungal, and parasitic), lymphocytic inflammation (Sjogren’s syndrome and Kimura’s disease), xanthogranulomatous and histiocytic inflammations (non-Langerhans cell histiocytosis and Langerhans cell histiocytosis), fibrotic inflammation (idiopathic sclerosing orbital inflammation and chronic dacryocystitis), and amyloid deposition.
The treatment for NSOI is immunosuppression. Typically, high dose oral prednisone at 60-80 mg a day is tapered over a long period of months. Occasionally, patients may become steroid dependent and unable to be weaned from the prednisone without relapses. Alternative treatments include other forms of immunosuppression, such as methotrexate and immunomodulators such as infliximab. Irradiation of the orbit is also an option, although a tissue diagnosis should be obtained before pursuing radiation treatment. Irradiation is contraindicated in patients with diabetes, due to potential worsening of diabetic retinopathy.
Injuries to the globe, eyelid, lacrimal system, and orbit should considered when dealing with facial trauma. Careful ocular and adnexal exams are necessary to diagnose hidden ocular injuries. Furthermore, it is easy to focus on an obvious or serious ocular injury and lose sight of concomitant injuries. Expect the unexpected.
To begin with, obtain a careful history. The nature of the injury, timing, associated injuries are documented as best as circumstances will allow. Is there loss of vision, pain, double vision, or trismus? Is there a retained foreign body within the globe, eyelid, or orbit? Prior ocular history is also important. Previous surgeries, injuries, medical problems such as glaucoma, refractive error, amblyopia use of glasses and contacts are documented. Life threatening injuries obviously take precedence over globe or orbit injuries.
Examination includes as thorough an eye exam as possible, including visual acuity, ocular motility, confrontational visual fields, intraocular pressure, color vision. Next, an overview of the ocular adnexa, slit lamp exam, dilated fundoscopic exam. Consider B-scan ultrasonography computed tomography (CT scan), and/or magnetic resonance imaging (MRI) to rule out foreign bodies, fractures, and neuro-ophthalmic injuries.
Eyelid injuries can involve retained organic or inorganic foreign bodies. Organic matter, such as vegetable matter should always be removed. Inorganic bodies, such as glass and bullet fragments are removed. Though typically inert and usually not function-impairing, inorganic foreign bodies can prevent future or immediate MRI scans due to their magnetic properties.
Eyelid injuries can include partial and full thickness lacerations. Do not disgard even remotely viable tissue during repair, as the eyelids heal well due to their rich blood supply. If eyelid tissue is lost, reconstruction with flaps, allografts, or skin grafts is necessary. Immediate protection of the globe is always the priority. Eyelid lacerations often involve the lacrimal apparatus, such as canalicular lacerations. Repair canalicular lacerations with silicone stents. Lacerations involving the medial canthal tendon are particularly challenging. One must reattach the posterior limb of the medial canthal tendon to the posterior lacrimal crest to restore anatomic positioning of the lower eyelid to the globe. Lateral canthal tendon repair is simpler to repair, but just as important to proper eyelid orientation. If lateral eyelid tissue is lost, a periosteal flap with a myocutaneous advancement flap is necessary for repair.
Orbital injuries can vary and imaging is usually necessary. CT scan is the first line imaging modality due to speed, bony anatomy, possibility of metallic foreign body. Obtain an MRI for more soft tissue detail, particularly if the optic nerve, chasm, tract and cavernous sinus are involved.
Orbital Injuries can result in subperiosteal hematomas, intra- or extraconal hematomas, wall and orbital buttress fractures, foreign bodies, and extra ocular muscle contusions, lacerations, and hematomas. Orbital hematomas can often be watched if stable and not causing an orbital compartment syndrome. Otherwise, they are immediately evacuated. Repair orbital wall fractures in one to two weeks if there is persistent diplopia due to extra ocular muscle involvement or enophthalmos. Perform urgent repair ( within 24 hours) for pediatric patients with “green stick” trap-door fractures, or obvious muscle entrapment in adults. Zygomaticomaxillary facial complex fractures with significant zygomatic displacement or trismus should also be repaired in one to two weeks. The reason for waiting is to allow bruising and swelling to subside and allow easier repair. Preoperative antibiotics and corticosteroids are typically given.
Management of retained orbital foreign bodies depends on several variables. If possible, remove organic foreign bodies, particularly vegetable matter. Otherwise, chronic bacterial and fungal infections may develop. Organic foreign bodies are notoriously difficult to detect on both CT and MRI, even with contrast dye. Explorative orbital surgery is necessary if a high suspicion for foreign body exists even with negative imaging.
Remove retained inorganic orbital foreign bodies if they indent the globe, interfere with extra ocular muscle function, or are causing a direct optic neuropathy. Otherwise, they may be observed. Copper and iron foreign bodies may produce a chemical orbital cellulitis, and their removal is weighed against possible surgical iatrogenic trauma.
Globe injuries can range from mild to severe. A thorough ocular exam at the slit lamp or hand light is key. Examine corneal epithelial defects with a Seidel test if one suspects a full-thickness laceration. A shallow anterior chamber with an irregular pupil suggests a corneal, scleral or globe perforation until proven otherwise. Explore conjunctival lacerations for scleral perforations. Intraocular foreign bodies may be detected on CT or MRI, as well as B-scan ultrasonography.Look for traumatic iritis and hyphema. Retinal tears and detachments as well as intraocular foreign body warrant retinal consultation as soon as possible.
Head trauma can cause damage anywhere along the visual pathway: optic nerves, chiasm, tracts, and radiations. Traumatic indirect or direct optic neuropathy is common with oculofacial trauma. Decreased visual acuity, color vision, and abnormal pupillary reflex raises suspicion for neurological damage and ruled out if possible.
In summary, oculofacial trauma can present in a myriad of ways. It is important to keep an open mind when evaluating these patients and obtain the most expedient and thorough exam as possible.