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Objectives: Conventional and quantitative MRI was performed in patients with chronic progressive external ophthalmoplegia (CPEO), a common manifestation of mitochondrial disease, to characterise MRI findings in the extra-ocular muscles (EOMs) and investigate whether quantitative MRI provides clinically relevant measures of disease.Methods: Patients with CPEO due to single mitochondrial DNA deletions were compared with controls. Range of eye movement (ROEM) measurements, peri-orbital 3 T MRI T1-weighted (T1w) and short-tau-inversion-recovery (STIR) images, and T2 relaxation time maps were obtained. Blinded observers graded muscle atrophy and T1w/STIR hyperintensity. Cross-sectional areas and EOM mean T2s were recorded and correlated with clinical parameters.Results: Nine patients and nine healthy controls were examined. Patients had reduced ROEM (patients 13.3°, controls 49.3°, p < 0.001), greater mean atrophy score and increased T1w hyperintensities. EOM mean cross-sectional area was 43 % of controls and mean T2s were prolonged (patients 75.6 ± 7.0 ms, controls 55.2 ± 4.1 ms, p < 0.001). ROEM correlated negatively with EOM T2 (rho = -0.89, p < 0.01), whilst cross-sectional area failed to correlate with any clinical measures.Conclusions: MRI demonstrates EOM atrophy, characteristic signal changes and prolonged T2 in CPEO. Correlation between elevated EOM T2 and ROEM impairment represents a potential measure of disease severity that warrants further evaluation.Key Points: Chronic progressive external ophthalmoplegia is a common clinical manifestation of mitochondrial disease. • Existing extra-ocular muscle MRI data in CPEO reports variable radiological findings. MRI confirmed EOM atrophy and characteristic signal changes in CPEO. EOM T2 was significantly elevated in CPEO and correlated negatively with ocular movements. EOM T2 represents a potential quantitative measure of disease severity in CPEO. [ABSTRACT FROM AUTHOR]

Optic neuritis is an inflammatory optic neuropathy that affects many patients with multiple sclerosis (MS) at some point during their disease course. Differentiation of acute episodes of MS-associated optic neuritis from other autoimmune and inflammatory optic neuropathies is vital for treatment choice and further patient management, but is not always straightforward. Over the past decade, a number of new imaging, laboratory and electrophysiological techniques have entered the clinical arena. To date, however, no consensus guidelines have been devised to specify how and when these techniques can be most rationally applied for the diagnostic work-up of patients with acute optic neuritis. In this article, we review the literature and attempt to formulate a consensus for the investigation of patients with acute optic neuritis, both in standard care and in research with relevance to clinical treatment trials. [ABSTRACT FROM AUTHOR]

The afferent visual pathway is commonly affected in MS. Assessment of the afferent visual pathway using clinical, imaging and electrophysiological methods not only provides insights into the pathophysiology of MS, but also provides a method of investigating potential therapeutic measures in MS. This review summarises the various assessment methods, in particular imaging techniques of the visual pathway. Retinal nerve fibre layer (RNFL) thickness is usually reduced following an episode of optic neuritis. Techniques such as optical coherence tomography, scanning laser polarimetry, and confocal scanning laser ophthalmoscopy are used to quantify RNFL thickness. MRI of the optic nerve is not routinely used in the diagnosis of MS or optic neuritis, but is valuable in atypical cases and in research. T2- weighted images of the optic nerve usually show the hyperintense lesion in optic neuritis and gadolinium enhancement is seen in the acute attack. Quantifying atrophy of the optic nerve using MRI gives an indication of the degree of axonal loss. Magnetization transfer ratio (MTR) of the optic nerve provides an indication of myelination. Diffusion tensor imaging (DTI) of the optic nerve and optic radiation provide information about the integrity of the visual white matter tracts. Functional MRI following visual stimulation is used to assess the contribution of cortical reorganisation to functional recovery following optic neuritis. Investigations including logMAR visual acuity, Sloan contrast acuity, Farnsworth- Munsell 100-hue colour vision tests and Humphrey perimetry provide detailed quantitative information on different aspects of visual function. Visual evoked potentials identify conduction block or delay reflecting demyelination. These collective investigative methods have advanced knowledge of pathophysiological mechanisms in MS and optic neuritis. Relevant ongoing studies and future directions are discussed. [ABSTRACT FROM AUTHOR]

This study reports the prospective follow–up of a cohort of patients with acute optic neuritis examined with serial visual tests, visual evoked potentials (VEPs), conventional and triple–dose gadolinium (Gd)–enhanced magnetic resonance imaging (MRI) to examine which factors are important in visual recovery. Thirty–three patients were recruited with acute unilateral optic neuritis. A clinical and VEP assessment was performed on each. Optic nerve MRI was performed using fast spin echo (FSE) (on all) and triple-dose Gdenhanced T1–weighted sequences (n = 28). Optic nerve lesion lengths were measured. Serial assessments were performed on 22 of the patients up to one–year. Serial Gd–enhanced optic nerve imaging was performed on 15 of the patients until enhancement ceased. The final 30–2 Humphrey visual field mean deviation (MD) was 2.55 dB higher in patients in the lowest quartile of initial Gd–enhanced lesion length compared with the other quartiles (p < 0.01) but recovery was not related to the duration of enhancement. The initial recovery of Humphrey MD was 4.60 dB units per day in patients with good eventual recoveries (MD > –6.0 dB) and 0.99 dB per day in poor-recovery patients (p = 0.02).Good–recovery patients had mean central field VEP amplitudes 2.29 µV higher during recovery than poor-recovery patients (p = 0.047). The results suggest that factors which are associated with a better prognosis are: having a short acute lesion on triple–dose gadolinium enhanced imaging, higher VEP amplitudes during recovery and a steep gradient of the initial improvement in vision. [ABSTRACT FROM AUTHOR]