INTRODUCTION
Multiple sclerosis is a chronic inflammatory disease and one of the most
common causes of neurological disability in young adults
globally.1,2 Many genetic and environmental factors,
demyelination, and iron-related abnormalities are the etiological and
pathological causes of the MS.3-5
MS can affect all the anatomical parts of the visual system. The most
often seen presentations are optic neuritis, brainstem, and spinal cord
syndromes.1 Optic neuritis may be the first
manifestation of multiple sclerosis.6 Acute
demyelinating optic neuritis is the presenting symptom in about 20% of
MS patients and affects about half of MS patients at some point in the
disease course.7
Computerized tomography has limited applications in optic nerve
pathologies because of the ionizing radiation and low resolution of soft
tissue. Conventional and non-conventional Magnetic Resonance Imaging
(MRI) such as diffusion tensor imaging, diffusion-weighted imaging
provide high-resolution images. Whereas it is time-consuming, expensive,
less obtainable, and often requires the use of gadolinium contrast. A
more practical method is needed to evaluate the optic nerve for the
initial diagnosis and follow-up of patients.8-10
Sonoelastography is an advanced sonographic technique and a non-invasive
method for evaluating the different elasticity characteristics of
tissues. There are two main sonoelastographic techniques that include
strain elastography (SE), which display the local strain of a given
sample of tissue (relative strain) and compresses the tissues axially,
and shear wave elastography (SWE), which uses waves that are generated
by transducers and interact with the tissue and a less
operator-dependent method. Shear wave elastography can allow
visualization and documentation of absolute stiffness in kilopascals or
meters per second objectively without a maneuver.10,11
Sonoelastography has been used in the evaluation of internal organ
pathology, and more recently, its clinical application to optic nerve
tissue has been a growing area of interest.12 As far
as we know, there is only one reported study about the sonoelastography
of the optic nerve in MS patients in the English medical
literature.13
The main purpose of the study is to assess the elasticity features of
the optic nerve, optic disc, and perineuronal area using SWE in patients
with MS (with or without optic neuritis), compare with healthy
volunteers and describe the contribution of SWE findings for visual
dysfunction in MS.