Multiple Sclerosis
Optical Coherence Tomography – A New Monitoring Tool for Multiple Sclerosis?
Patrick Vermersch,1 Olivier Outteryck2 and Axel Petzold3
1. Professor, and Head, Department of Neurology, University of Lille; 2. Neurologist, Department of Neurology, University of Lille; 3. Consultant Neurologist, Free University Medical Centre, Amsterdam, and Honorary Senior Lecturer, Department of Clinical Neurosciences, University College London Institute of Neurology
Abstract
Optical coherence tomography (OCT) is a simple office-based measure that can be used to quantify changes in the retina in patients with multiple sclerosis (MS). Such retinal changes in some MS patient subgroups, as assessed by OCT, are associated with brain atrophy as detected by magnetic resonance imaging (MRI). There is also some evidence that changes detected by OCT are correlated with increasing levels of cognitive impairment. OCT in MS patients introduces a new tool to characterise the disease process and could prove beneficial in the assessment of new therapies. It may provide information additional to that produced by MRI. For example, the use of OCT to quantify the retinal nerve fibre layer may offer some advantages by detecting neural degeneration in the MS disease process more quickly, cheaply and specifically than MRI. The latest OCT equipment and software offer high reproducibility and improve accuracy due to eye-tracking and follow- up scan capabilities.
Keywords Optical coherence tomography, retinal nerve fibre layer, multiple sclerosis, axonal loss, optic neuritis
Disclosure: The authors have no conflicts of interest to declare. Received: 25 May 2010 Accepted: 21 June 2010 Citation: European Neurological Review, 2010;5(1):73–7 Correspondence: Patrick Vermersch, Pôle de Neurologie, Hôpital R Salengro, Université de Lille Nord de France, 59037 Lille cedex, France. E:
patrick.vermersch@
chru-lille.fr
Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS) with inflammatory demyelinating lesions and neuronal loss that is clinically characterised by unpredictable clinical relapses, remissions and progression of disability over time.1–3
Damage
occurs to the myelin sheath that surrounds and protects nerve cells; this slows down or blocks messages between the brain and the body, leading to the symptoms of MS. The disease usually begins with one or more clinically isolated syndrome (CIS) leading to a relapsing– remitting phase (RRMS) that is accompanied by a varying degree of impairment.2
Approximately 10–15% of MS
Acute idiopathic demyelinating optic neuritis (ON) is a frequent early manifestation of MS that is often indicative of early disease and can be predictive of later progressive stages.16
Optical coherence
tomography (OCT) is an evolving technique that has the potential not only to diagnose ON but also to provide a valuable assessment of MS.17
This review will consider the evidence for using OCT in patients with ON and its potential role as a tool for routinely monitoring MS.
After 10–15 years, approximately 50% of these patients advance to the secondary progressive form of the disease, which is characterised by a slow but progressive decline in performance with or without superimposed relapses.4,5
Symptoms are highly heterogeneous from one patient to another. More recently, our attention has been focused on the non- physical symptoms such as fatigue and cognitive symptoms.8–11
patients show progression from the onset (primary progressive MS [PPMS]).6,7
Despite significant advances in treatment, MS remains a highly disabling disease, and in many cases significantly reduces life expectancy.12 Recent studies have shown that initiating treatment early with a disease-modifying drug, possibly during CIS, can provide significant advantages over delaying it until symptoms are more apparent. This has generated much interest and has modified treatment practices in MS.13,14 However, some neurologists have questioned the long-term benefit of treating everyone with CIS, suggesting that in some cases the disease will not progress and that greater investigation of patients is warranted before starting more appropriately tailored therapies.15
© TOUCH BRIEFINGS 2010
The Role of Magnetic Resonance Imaging in Multiple Sclerosis
Magnetic resonance imaging (MRI) has revolutionised the diagnosis of MS and greatly facilitated our understanding of MS. Diagnostic criteria based on both clinical and MRI findings have been proposed and have been adopted by many treatment centres.18
The presence of MRI lesions at symptom onset was found to be correlated with the development of
clinically definite MS (CDMS). In patients with one or more T2-weighted lesion at baseline, 56% developed MS within 10 years.19
Neurological
damage starts before symptoms become apparent. The presence of gadolinium (Gd)-enhancing lesions generally indicates current disease activity and is used as one of the key criteria for the assessment of the
effectiveness of a new drug. Other key MRI variables include T2 lesion load, indicating the global burden of the disease, and T1 lesion load (black holes). The Gd-enhancing lesions and T2 lesion load are considered to be related to the degree of inflammation and provide an
approximation of the demyelinating component of the disease, whereas the black holes and brain and spinal cord atrophy are more related to the degenerative component of MS.20
However, MRI is an imperfect tool that measures the results of many types of tissue loss rather than 73
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