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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_2745_Библиотеки_им_академика_М_И_Перельмана
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but it is uncommon in adults and should generate a broader
differential diagnosis.
6
Case 1
Idiopathic demyelinating optic neuritis
with no prior established ms diagnosis
A 36-year-old man presented with a “white spot” in the
vision of his left eye, and left eye pain increased with
movement. Upon further questioning, he reported numbness
over his left cheek that occurred when he was out in the
heat.
Examination revealed visual acuity of 20/20 in the right eye
and 20/15 in the left eye and normal color vision in each eye
on Ishihara color plate testing. The left pupil was sluggishly
reactive to light, and a left afferent pupillary defect was
present. Optic discs appeared normal without swelling or
obvious pallor; however, optical coherence tomography
(OCT) revealed elevation of the retinal nerve fiber layer in
the left eye (Figure 8.1A), suggesting subclinical disc edema
and strongly suggesting acute optic neuritis. No objective
sensory deficit was noted. Automated visual field testing
revealed a very subtle temporal visual field defect in the left
eye.
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FIGURE 8.1 Retinal nerve fiber layer (RNFL) optical
coherence tomography. A. Average RNFL thickness of 90 is
normal in the right eye and elevated to 114 µm in the left
eye in Case 1 at initial presentation with acute vision loss in
the left eye, suggesting mild optic nerve swelling in the left
eye. B. Average RNFL thickness remains 90 and normal in
the right eye and has declined to 76, now thin, in the left
eye, as expected several months after acute optic neuritis.
See eBook for color figure.
Magnetic resonance imaging (MRI) of the orbits and brain
with gadolinium demonstrated left optic nerve T2
hyperintensity and enhancement (Figure 8.2A and B), thus
confirming acute demyelinating optic neuritis. There were
periventricular, deep white matter, juxtacortical, and left
pontine T2-hyperintense lesions compatible with
demyelination (Figure 8.2C). He was diagnosed with optic
neuritis and MS. Corticosteroids were discussed for
immediate treatment of optic neuritis, and a decision was
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made between the doctor and the patient not to administer
corticosteroid treatment. He was given peginterferon beta1a. At follow-up, his vision improved in the absence of
steroid treatment and retinal nerve fiber layer thinning had
developed in the left eye (Figure 8.1B).
FIGURE 8.2 MRI orbits and brain with gadolinium. A.
Coronal T2-weighted image through the orbits shows
increased T2 signal in the left optic nerve (arrow). B.
Coronal T1-weighted image with gadolinium through the
orbits shows left optic nerve enhancement (arrow). C. Axial
T2-weighted FLAIR image shows multiple demyelinating
lesions (arrows).
Commentary: Our patient had visual symptoms suggestive
of optic neuritis; however, his visual acuity, color vision, and
low contrast vision were normal. Nonetheless, an afferent
pupillary defect and mild visual field defect are two of the
most characteristic features of an optic neuropathy. OCT
confirmed mild subclinical disc swelling supporting the
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diagnosis of an acute optic neuropathy. The visual
symptoms, presence of subclinical optic nerve swelling in
the left eye, and the orbital MRI findings established the
diagnosis of acute optic neuritis in our patient. The transient
numbness of his face likely reflected a prior demyelinating
event exacerbated by a small rise in body temperature.
Visual acuity, color vision, low contrast vision, pupils, visual
fields, and funduscopic examination are the key elements of
the examination to perform in the patient with suspected optic
neuritis. Optic neuritis is a clinical diagnosis, and it is
important to keep in mind a list of red flags (Table 8.1) that
would be atypical for idiopathic demyelinating optic neuritis
and may suggest an alternative cause of optic neuropathy. The
degree of vision loss is highly variable in optic neuritis and
can range from mild to severe, with initial visual acuity
typically between 20/25 and 20/200. 4 However, the presence
of no light perception vision is a red flag and should suggest
other potential causes of an acute optic neuropathy, including
ischemic and systemic causes. The patient’s best visual acuity
should always be assessed using corrective lenses or pinhole
correction. Color vision is typically formally tested with
Ishihara or Hardy Rand Rittler (HRR) color plates that display
differentially colored numbers or geometric shapes. The
advantage of the HRR plates is that they contain blue and
purple shapes, which can sometimes be more affected than the
red-green plates contained in the Ishihara series. A simple
beside assessment of color vision can be performed by
comparing the brightness of a red object between the affected
and unaffected eyes, seeking “red desaturation” in the affected
eye. Other color tops can also be tried. Detection of an afferent
pupillary defect is critical in determining that the vision loss is
attributable to an optic nerve process. The afferent pupillary
defect may be detected by moving a light back and forth
rhythmically between the two pupils. With an optic
neuropathy, there will be an asymmetric response and the
affected pupil will often paradoxically dilate to the light
stimulus. 7 Central visual field loss, called a central scotoma,
can often be found on confrontation or automated visual field
examination. On ophthalmoscopy, most adults with optic
neuritis will have a normal-appearing fundus, suggesting that
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most of the swelling is retrobulbar or behind the optic nerve
head. 4 However, OCT may reveal subclinical optic disc
swelling in some of these patients (Case 1). The optic disc will
demonstrate mild swelling on ophthalmoscopy in about onethird of patients. Terms to describe this optic nerve head
swelling include anterior optic neuritis or papillitis. Children
are more likely than adults to have anterior optic neuritis.
8
The presence of severe optic disc swelling in an adult with
vision loss in one eye is unlikely to be idiopathic
demyelinating optic neuritis, and other etiologies should be
considered. Bilateral optic neuropathy is also unusual for
typical optic neuritis, and other causes, such as sarcoid,
syphilis, vasculitis, and viral processes, should be sought. It
should be remembered that papilledema, which is the term
used to describe optic nerve head swelling from raised
intracranial pressure, usually does not affect the visual acuity
like a case of optic neuritis.
Table 8.1
Features Suggesting Atypical Optic Neuritis
No pain
No light perception vision
Retinal hemorrhages
Macula exudates
Severe optic nerve swelling
Bilateral visual loss
No visual recovery
Visual loss progresses beyond 2 wk
Visual improvement in optic neuritis typically occurs over
several weeks independent of whether or not corticosteroid
treatment is administered, with 90% of patients recovering
visual acuity to 20/40 or better. 9 Nonetheless, patients with
good high contrast acuity recovery often report reduced visual
quality of life and have residual visual dysfunction,
particularly for low contrast vision. 10 In the ensuing weeks to
months after a bout of optic neuritis, retinal nerve fiber layer
thinning can be documented by OCT (Case 1) and optic
atrophy occurs. Uhthoff phenomenon, or transient blurring of
vision when overheated from exercise or a hot shower, is a
common complaint following optic neuritis.
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Ancillary testing in the clinic includes formal automated visual
field testing and OCT, which is a retinal and optic nerve
imaging tool that uses light waves to take cross-sectional
images and has wide application in interrogation of optic nerve
health in optic neuritis and MS.
11
Initiated over 20 years ago, the Optic Neuritis Treatment Trial
(ONTT) is a landmark clinical trial in which patients were
followed for 15 years following an initial clinically isolated
idiopathic demyelinating optic neuritis. Participants were
randomized to three acute treatment arms: intravenous
corticosteroids for 3 days followed by an oral corticosteroid
tapered for 11 days, oral corticosteroids in 1 mg/kg/d dosing
tapered over 14 days, or oral placebo. At 6 months, the
intravenously treated cohort experienced faster recovery of
vision 12 ; however, there was no difference in final visual
outcome at 1 year among the groups. 9 The oral corticosteroid
cohort had an increased risk of recurrent optic neuritis,
resulting in a recommendation not to treat patients with optic
neuritis solely with oral corticosteroids in standard 1 mg/kg/d
dosing.
Given that optic neuritis can be the harbinger of a diagnosis of
MS, much attention has been given to assessment of factors
that may shed light on prognosis. It is clear that the presence
of brain lesions on MRI at the time of the initial demyelinating
event has the highest predictive value.
13,14
Fifteen years after
the bout of optic neuritis diagnosis, the risk of MS was 25% in
the patients with no MRI brain lesions, whereas 72% of
patients with one or more brain lesions had developed MS in
the ONTT study.
13
Other Afferent Disorders in MS
Many patients with MS have reduced visual quality or visual
symptoms in the absence of acute optic neuritis, and referral of
any patient with MS for visual and OCT assessment can be
helpful in establishing a baseline and to follow the disease
course. Subclinical visual system involvement may also occur
and deficits of low contrast vision and structural optic nerve
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injury with retinal nerve fiber layer thinning on OCT are well
documented in the absence of acute optic neuritis (Case 2).
15-17
Case 2
Subclinical optic neuropathy
A 58-year-old man with past medical history of
hypertension, asthma, and recently diagnosed MS presented
with pressure and discomfort of his right eye for several
weeks. He described the discomfort as a feeling that
something was in his eye. There was no change with eye
movements and no vision change in his right eye. He had no
history of vision loss.
On examination, vision was 20/15 in the right eye and 20/20
in the left eye. He perceived all Ishihara color plates
correctly with each eye. Formal automated visual fields were
normal. Low contrast vision was slightly reduced in each
eye. Pupils were equal and briskly reactive to light without
an afferent pupillary defect. Eye movements were normal.
Optic discs were normal without swelling or pallor. Retinal
nerve fiber layer OCT was thin in the right eye and slightly
thin in the left eye (Figure 8.3). Slit lamp examination
showed an impaired right eye tear film.
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FIGURE 8.3 Retinal nerve fiber layer (RNFL) optical
coherence tomography for Case 2, showing thinning in the
right eye and a borderline low average thickness in the left
eye. See eBook for color figure.
Commentary:Although this patient had a diagnosis of MS
and a symptom of eye pain, his eye pain was more
suggestive of an irritative process affecting the cornea rather
than an optic neuritis. Although asymptomatic of any visual
deficit, he was found to have slightly reduced low contrast
vision in each eye and retinal nerve fiber layer thinning on
OCT, findings likely suggesting subclinical demyelinating
optic neuropathy. The presence of a thin retinal nerve fiber
layer is not consistent with acute optic neuritis, as it often
takes weeks to months for retinal thinning to occur after a
bout of acute visual loss.
Not all vision loss in MS is due to optic nerve involvement.
Other conditions to be aware of that may require
ophthalmology consultation include steroid-induced cataracts
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and serous retinopathy from repetitive steroid treatment of
demyelinating exaccerbations 18 and macular edema (Figure
8.4). The latter may occur as the result of the MS medication
fingolimod.
19
FIGURE 8.4 Optical coherence tomography through the
macula showing fingolimod-induced macular edema.
Courtesy of Ari Green, MD. See eBook for color figure.
Efferent Visual Disturbances
Visual symptoms attributable to abnormalities of eye
movements, such as unstable fixation, impaired range of eye
movements, or misalignment of the eyes are common in MS
20-
23
and often reflect acute or chronic demyelinating lesions in
the brainstem or cerebellum. Symptoms can be quite
debilitating and are associated with worse functional and
quality of life outcomes in patients with MS.
23,24
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With regard to symptoms, diplopia that is only present with
both eyes open and resolves with closure of either eye, socalled binocular diplopia, is due to a misalignment of the two
eyes due to demyelination of an ocular motor cranial nerve or
connecting pathways that govern ocular motility. In contrast, if
double vision persists with one eye covered, MS is not likely
the cause, and suspicion should be high for refractive error or
ocular problem.
A second eye symptom strongly suspect for abnormal eye
movements is oscillopsia, which is a perception that the world
is jumping or bouncing. This most often results from
nystagmus, or oscillations of the eyes. A common cause in MS
is a type of slow shaking of the eyes called acquired pendular
nystagmus (APN) (Case 3). Because of persistent movement
of the eyes with APN, there is also sometimes decreased
central visual acuity.
Case 3
Acquired pendular nystagmus
A 34-year-old woman with a 10-year history of MS with
substantial gait impairment and chronically poor vision was
evaluated for oscillopsia, as she reported constant visual
motion. On examination, visual acuity was 20/40 in the right
eye and 20/80 in the left eye, color vision was reduced in
each eye, and both optic nerves appeared pale. When asked
to hold her eyes steady and look straight ahead, small
horizontal oscillations of the eyes were seen (Video 8.1 in
eBook) consistent with APN. She walked with a walker.
MRI brain revealed several chronic demyelinating lesions in
the brain, including in the brainstem. She was started on
gabapentin to treat her nystagmus and resultant oscillopsia.
The dose was gradually increased over several months from
a starting dose of 300 mg once a day to 900 mg three times a
day, at which point, her oscillopsia was substantially reduced
and the nystagmus was less visible on examination.
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