Orbital Apex Syndrome

Orbital apex syndrome (OAS) is a rarely described disorder that may develop as a complication of various conditions, including trauma of the craniomaxillofacial area, malignant disorders of the orbit (rhabdomyosarcoma and lymphoma being the two most common neoplasias), infections (such as herpes zoster ophthalmicus or fungal invasion), and inflammatory changes, either isolated or systemic (eg. Wegener's granulomatosis, sarcoidosis, and polyarteritis nodosa) [1] [2] [3] [4] [5]. This ailment can be seen in any decade of life, with some studies establishing a mean age of 45-50 years [2]. The typical signs stem from pathological effects of the conditions on the structures that pass through the superior orbital fissure and the orbital apex - cranial nerves supplying the extraocular muscles (trochlear, oculomotor, and abducens nerves) and the surrounding anatomical landmarks (numerous divisions of the trigeminal nerve), as well as the optic nerve and blood vessels [1] [5]. According to certain reports, blurred vision arising from reduced visual acuity and a fixed dilated pupil is the most frequent symptom in OAS [2] [3]. In addition, proptosis (eye protrusion), ptosis, reduced sensation on the forehead (hypoesthesia), hyposecretion from the lacrimal apparatus, and diplopia or even vision loss are other notable features [6] [7].

The diagnosis of orbital apex syndrome can be made early on with a detailed history taking and a proper physical examination. Firstly, the physician should assess the onset of complaints and their progression, whereas a detailed inspection of the orbit and a thorough neurological examination may provide solid evidence to make a presumptive diagnosis. Typical findings encountered during the exam are ophthalmoplegia, decreased corneal reflex (a sign of trigeminal nerve palsy) and a variable degree of visual impairment [1] [7]. Imaging studies must be employed whenever these symptoms are present. Plain radiography, apart from its beneficiary role in delineating skeletal trauma and fractures, possesses a limited capacity to discriminate between different etiologies, which is why computed tomography (CT), particularly helical CT (sometimes with iodine as a contrast agent) is recommended for assessing signs pointing to orbital apex syndrome [1]. Gadolinium-enhanced magnetic resonance imaging (MRI), however, is a superior technique that allows a more detailed evaluation of the soft tissues and the vascular structures that may be further examined through MR or CT angiography [1] [7]. In the absence of a clear underlying cause, a thorough laboratory workup must be carried out, including a complete blood count (CBC), serum electrolytes and inflammatory parameters (C-reactive protein and erythrocyte sedimentation rate), antinuclear and extractable nuclear antibodies (ANA and ENA, respectively), antineutrophilic antibodies (ANCAs), angiotensin-converting enzyme (ACE), and serum protein electrophoresis [1].

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3. Sugamata A. Orbital apex syndrome associated with fractures of the inferomedial orbital wall. Clin Ophthalmol. 2013;7:475-478.
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5. Imaizumi A, Ishida K, Ishikawa Y, Nakayoshi I. Successful Treatment of the Traumatic Orbital Apex Syndrome due to Direct Bone Compression. Craniomaxillofac Trauma Reconstr. 2014;7(4):318-322.
6. Warburton RE, Brookes CC, Golden BA, Turvey TA. Orbital apex disorders: a case series. Int J Oral Maxillofac Surg. 2016;45(4):497-506.
7. Gupta R, Khan YA. Traumatic orbital apex syndrome. Can J Ophthalmol. 2015;50(1):e8-e11.