Samra and Ramtahal Journal of Medical Case Reports 2012, 6:15 http://www.jmedicalcasereports.com/content/6/1/15 examination suggestive of connective tissue disease or sarcoidosis. Initial blood tests showed a normal full blood count, normal urea and electrolytes (U&Es), nor- mal liver function tests, a normal C-reactive protein (CRP; < 1) and plasma viscosity and a raised glycated haemoglobin (HbA1c) of 7.3% (normal 4 to 6.1). Chest X-ray was normal. A lumbar puncture was performed which yielded cerebrospinal fluid (CSF) with normal white and red blood cells, a normal angiotension con- verting enzyme (ACE) level, no oligoclonal bands and a marginally elevated protein level of 467.7 mg/L (normal 150 to 450 mg/L). A magnetic resonance imaging (MRI) scan of her brain and spinal cord was normal. A provisional diagnosis of acute ischaemic optic neu- ropathy was made by the general medical team and the patient was started on aspirin with omeprazole cover. On review by the neurology team a day later the cause was thought to be inflammatory rather than ischemic. She received a three day course of intravenous methyl prednisolone. Vision improved to 6/6 in both eyes within two days with full restoration of color vision and visual field defects. Ten days later however, vision dete- riorated again in the right eye to 6/36 with a temporal peripheral field loss. The relative afferent papillary defect had now switched to the right eye. The patient received 500 mg oral methyl prednisolone for five days. Her visual acuity and visual fields returned to normal within two days. A subsequent auto-immunity screen including aqua- porin-4 antibodies was negative. Visual evoked poten- tials performed twelve days after the onset of the second episode of visual loss were delayed bilaterally (left > right) indicating bilateral optic nerve dysfunction. Her pattern electroretinograms, brainstem evoked potentials, median nerve and posterior tibial somatosensory evoked potentials were normal bilaterally. There was no evidence of Leber’s hereditary optic neuropathy on genetic molecular analysis. The m.11778G > A, m.3460G > A, m.14484T > C mitochon- drial mutations were tested for and not detected in our patient. A chest computed tomography (CT) was normal and did not show any hilar adenopathy or any other features of sarcoidosis. Serial MRIs over the next four months were normal without any inflammatory lesions and oligoclonal bands were negative which excluded multiple sclerosis. Discussion Our patient presented with subacute visual loss, the general medical team made a provisional diagnosis of acute ischemic optic neuropathy. When reviewed by the neurology team the pathology was deemed to be optic neuritis, however there was no evidence for any Page 2 of 2 demeyelinating or autoimmune process. Sarcoidosis was also ruled out. There was an excellent and prompt response to corti- costeroids and a dramatic deterioration of vision follow- ing steroid withdrawal consistent with CRION. Our case report highlights the importance of the prompt recogni- tion of CRION. The condition is an extremely rare cause of visual loss caused by optic neuropathy and if missed it can have sinister consequences such as perma- nent visual loss. Conclusion The clinical picture of the patient was similar to those described by Kidd et al. in terms of subacute onset of visual deficit, significant pain, excellent response to ster- oids and visual deterioration following steroid withdra- wal [1]. The importance of identifying these patients has considerable clinical implications as the condition is highly responsive to steroids. CRION requires careful consideration and differentiation from demyelinating optic neuritis and ischemic optic neuropathy since the treatment is entirely different and the outcome without treatment is likely to be poor. A complete work up for demyelination, autoimmune disease and sarcoidosis must be made before considering CRION. At present there are no systemic studies evaluating the duration and intensity of immunosuppression required in patients with CRION [2]. Consent Written informed consent was obtained from the patient for publication of this case report and any accompany- ing images. A copy of the written consent is available for review by the Editor-in-Chief of this journal. Authors’ contributions JR examined the patient, analyzed and interpreted investigative data. AS examined the patient, performed a literature review and contributed in writing the manuscript. Both authors read and approved the final manuscript. Competing interests The authors declare that they have no competing interests. Received: 5 July 2011 Accepted: 16 January 2012 Published: 16 January 2012 References 1. Kidd D, Burton B, Plant GT, Graham EM: Chronic Inflammatory Optic Neuropathy. Brain 2003, 126:276-284. 2. Saini M, Khurana D: Chronic Inflammatory Optic Neuropathy. Ann Indian Acad Neurol 2010, 13:61-63. doi:10.1186/1752-1947-6-15 Cite this article as: Samra and Ramtahal: Recurrent subacute visual loss presenting in a 52-year-old Caucasian woman with chronic relapsing inflammatory optic neuropathy: a case report. Journal of Medical Case Reports 2012 6:15.