What is the reason for the vertical diplopia in a 45-year-old man?

How to diagnose and differentially diagnose patients facing vertical diplopia in both eyes? How to distinguish trochlear nerve palsy from ocular deviation? Recently, the clinical reasoning series of Neurology magazine reported a case of a male patient with acute vertical diplopia
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Let's take a look at the clinical reasoning process .

Translation: Compiled and compiled by Reflection Wuhen Yimaitong, please do not reprint without authorization
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Case brief introduction The patient is a 45-year-old male with a previous history of hypertension and presented to the doctor for "diplopia for several weeks"
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The patient reported double vision in both eyes, but disappeared in one eye; in addition, the patient reported intermittent numbness on the left side of the tongue
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Denies any diurnal changes in symptoms and any related limb weakness; denies dysphagia and dysarthria; denies history of thyroid disease
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Physical examination showed adduction numbness in the left eye during right vision, and dissociative nystagmus in abduction of the right eye
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When gazing in situ, the left eye is slightly higher than the right eye; when gazing to the left, the vertical dislocation is not obvious; due to the adduction of the left eye, the right gaze assessment cannot be performed
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When the head is tilted to the left, the upward tilt of the left eye increases, and it improves when the head is tilted to the right
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There was no significant change in the vertical dislocation of the eyeball when lying on his back or standing upright
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There was no obvious abnormality in the convergent reflection
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There was no eyelid retraction, ptosis, exophthalmos, or periorbital swelling
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The rest of the nervous system examination showed no obvious abnormalities
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 Questions to ponder: 1.
What are the differential diagnoses of vertical diplopia? 2.
Where is the adduction palsy of the left eye located when conjugate stares to the right? 3.
What is the Parks-Bielschowksy test? What differential diagnosis is required? This patient had acute vertical diplopia in both eyes
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Binocular diplopia is the result of misalignment of the visual axis.
It is usually caused by dyskinesia of extraocular muscles.
It may be the result of various lesions involving the extraocular muscles or neuromuscular junction (NMJ) or any part of the cranial nerve in this pathway
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In addition, the deflection caused by brain stem disease can also cause vertical double vision in both eyes
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Monocular diplopia is usually caused by ophthalmological diseases, such as refractive errors, astigmatism, and corneal diseases; it can also be caused by retinopathy
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When gazing to the right, the left eye is incompletely adducted, and the right eye abduction shows dissociative nystagmus, suggesting that the left medial longitudinal fascia (MLF) is involved, leading to left internuclear ophthalmoplegia (INO)
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MLF lesions will not affect the convergent reflex unless the lesion involves the convergent reflex pathway of the midbrain
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For vertical diplopia, the muscles that may be affected include the superior rectus (SR) or inferior oblique (IO) of the inferior oblique eye or the inferior rectus (IR) or superior oblique (SO) of the superior oblique eye
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The Parks-Bielschowsky three-step test helps to locate the affected muscle (Figure 1A-C)
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Step 1: Which eye is oblique up in situ? This patient has the left eye
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Step 2: Does a certain level of fixation aggravate dislocation? When the patient looked to the left, the left eye was not obliquely upward, indicating that the left side IR was normal
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Therefore, dysfunction may be related to left SO or right SR
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Due to the left INO, the degree of upward tilt of the left eye cannot be assessed for gazing to the right
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Step 3: Will head tilt aggravate misalignment? The dislocation was more obvious when the patient's head was tilted to the left, and it was positioned on the left SO
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Another cause of the vertical misalignment of the eyes is the deviation of the eyes
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Usually, the results of the Parks-Bielschowksy test can distinguish between ocular deviation and trochlear nerve palsy
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However, this patient was partially limited in the trial due to the left INO
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 Figure 1 Parks-Bielschowsky test and upright-supine test
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A.
Left eye oblique in situ; B.
Adduction of the left eye is obstructed when gazing to the right, and left eye oblique improvement when gazing to the left; C.
The head is tilted to the right and the left eye is obliquely improved, and the head is tilted to the left.
Supratropia increased; D.
There was no change in vertical and torsional diplopia during the upright and supine test using double Maddox rods
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Questions to ponder: 1.
How to distinguish trochlear nerve palsy and ocular deviation? How to distinguish trochlear nerve palsy from ocular deviation? The upright-supine test is a reliable test for distinguishing ocular deviation and trochlear nerve palsy
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For eye deflection, a reduction of more than 50% in vertical and torsional deflection from upright to supine position indicates a positive upright-supine test
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The torsional deflection can be quantified using the double Maddox rod test, and the vertical deflection can be quantified by alternate coverage testing and prism inspection
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The position change from upright to supine will cause the direction of the utricle relative to gravity to change, resulting in an overall decrease in the projection activity of the bilateral utricle
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There was no significant difference in the degree of vertical dislocation between the patient's upright and supine positions (Figure 1D)
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The patient can reliably describe the degree of subjective diplopia in the two positions
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 Questions to ponder: 1.
How to locate the above test results? 2.
What are the differential diagnoses? How to locate? A single lesion involving the MLF and the trochlear nucleus or pre-crossing fibers will manifest as INO and contralateral SO palsy
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However, this patient may have two lesions, one involving the left MLF, leading to the left INO; the second lesion involving the trochlear nerve fibers originating from the trochlear nucleus on the right and crossing to the dorsal side of the left midbrain, causing SO on the left Paralysis (Figure 2A)
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Multiple lesions involving MLF and trochlear nerve fibers indicate multifocal central nervous system disease, such as multiple sclerosis or brainstem multiple infarction
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Diseases involving NMJ (such as myasthenia gravis) and diseases affecting extraocular muscles (such as thyroid ophthalmopathy) need to be distinguished
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The patient's head MRI showed a lesion on the dorsal side of the left midbrain, multiple lesions on the supratentorial white matter and subtentorial white matter (Figure 2B)
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The dorsal lesion in the left midbrain is enhanced, confirming the diagnosis of multiple sclerosis
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After corticosteroid treatment, the patient's symptoms improved, and finally switched to ocrelizumab treatment without recurrence
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 Figure 2 Neuroanatomical positioning and head MRI
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A.
Illustration of the midbrain at the level of the inferior colliculus.
The two red crosses show the left MLF and the left trochlear nerve fiber from the cross of the trochlear nucleus on the right, innervating the left SO muscle; B.
(a) The midbrain at the level of the tail MRI FlAIR shows hyperintensity lesions on the dorsal side of the left midbrain (blue circle); (b) MRI at the level of the lateral ventricles FLAIR shows multiple white matter hyperintensity lesions in both hemispheres (blue arrows); (c) MRI at the level of the cerebellum FLAIR shows hyperintense lesions in the left cerebellar hemisphere (blue circle)
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(D) MRI T1 enhanced display enhancement
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Discussion For INO patients, a more common cause of vertical misalignment is ocular deviation, which is caused by interruption of the central otolith pathway
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The vestibular signals from the utricle (such as during head tilt) are mainly projected to the medial vestibular nucleus of the back and the ventrolateral superior vestibular nucleus
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In turn, these nuclei project to the eye motor neurons that control vertical and torsional eye movements
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The projection fiber crosses and rises in the brain stem through the MLF, and is a pathway for the vestibular eye reflection in the rolling plane
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Part of this projection fiber also reaches the interstitial nucleus of Cajal, which plays an important role in coordinating the movement of the eyes and head in the rolling plane
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Lesions involving these pathways below the pons-midbrain junction can cause ipsilateral hypotropia, while lesions above the pons-midbrain junction can cause ipsilateral eye elevation
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Since MLF is shared by the horizontal conjugate gaze and the central otolith pathway, in lesions involving MLF, ocular deviation with INO is usually seen
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The misalignment in ocular deflection is usually corotational strabismus (that is, it remains the same in all gaze directions), which is similar to the non-corotational strabismus observed in patients with SO palsy during the Parks-Bielschowsky test (with different gaze directions).
Different degrees of misalignment) are different
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The patient's examination results are inconsistent with ocular deviation
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In addition, the upright-supine test does not support ocular deflection
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It is rarely reported in the literature that INO and trochlear nerve palsy occur simultaneously
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The typical manifestation is INO with contralateral superior oblique palsy, caused by a single lesion involving the MLF and the trochlear nucleus or the trochlear nerve fibers before the cross of the dorsal midbrain
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What is unusual in this patient is that INO and ipsilateral SO palsy occurred at the same time
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This combination can only be explained by two separate lesions: one involving the MLF and the other involving the trochlear nerve fibers after the crossover (Figure 2A)
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This manifestation is more likely to be caused by multifocal lesions, such as multiple sclerosis or posterior circulation infarction that affects different parts of the brainstem
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The patient was diagnosed with multiple sclerosis
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Original index: Neel Fotedar, Junling Dong, Alexander Lewis, et al.
Clinical Reasoning: A 45-Year-Old Man With Vertical Diplopia.
Neurology published online October 21, 2021.
DOI 10.
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