Differential diagnoses to MS: experiences from an optic neuritis clinic

Abstract

Optic neuritis (ON) is closely linked to multiple sclerosis (MS). It may, however, also be associated to a range of autoimmune or infectious diseases. The purpose of this study was to assess the differential diagnoses in patients with suspected ON. In this retrospective study, we reviewed the files of all patients referred to the Clinic of Optic Neuritis, Glostrup Hospital, University of Copenhagen, Denmark, between January 2000 and November 2011. All patients were referred by ophthalmologists with possible ON. Patients diagnosed with MS prior to referral were excluded from the study. A total of 643 patients were included in the study. Apart from ON, the most frequent diagnoses were tumors (n = 15), ischemic or hypertensive neuropathies (n = 13), and retinal or choroid disorders (n = 9). Six patients were diagnosed with neuromyelitis optica. Rarer causes of visual loss were infections (n = 5), giant cell arteritis (n = 4), sarcoidosis (n = 3), thyrotoxicosis (n = 2), and hereditary or toxic neuropathies (n = 2). Nine percent of patients referred to the Clinic of Optic Neuritis had symptoms caused by medical, neurosurgical or ophthalmic disorders, and 0.9 % of our patients had NMO. Though most of these conditions are rare, it is of importance to keep them in mind upon encountering patients with symptoms of ON.

Mimics and chameleons of optic neuritis

“…Most neurologists will correctly diagnose most cases of optic neuritis but may have difficulty in perhaps 10% of cases 3. We believe that there are two underlying issues contributing to this.…”

“…A mild lymphocytic pleocytosis of up to 30 cells/mm3 develops in about a third of patients 20. Similarly, oligoclonal bands restricted to the cerebrospinal fluid (CSF) occur in 30–70% of patients: their presence significantly correlates with the presence of abnormalities on brain MRI scans.…”

“…NMO is much less common than MS (perhaps 1% of optic neuritis is due to NMO)3 but their pathophysiology is significantly different 21. Unlike MS, NMO requires immunosuppressive therapy.…”

“…The problem is that it can be overdiagnosed. A recent study found that 10% of patients referred to a dedicated optic neuritis clinic had other diagnoses 3. Conversely, it can present in some unusual ways that may cause confusion.…”

“…Nevertheless, the conditions have the potential to cause apparently isolated involvement of the optic nerve(s) which could result in diagnostic difficulty. The list has been compiled from a number of published sources 3 32 67 68. Highlighted items in dark red are discussed in detail in the text.…”