A 58-year-old man presented with vertical diplopia for 10 days which was sudden in onset. Extraocular movement examination revealed findings suggestive of internuclear ophthalmoplegia. Investigations were suggestive of diabetes mellitus, and reverse transcription-PCR for SARS-CoV-2 was positive. At 3 weeks of follow-up, his diplopia had resolved. Neuro-ophthalmic manifestations in COVID-19 are increasingly being recognised around the world. Ophthalmoplegia due to cranial nerve palsy and cerebrovascular accident in COVID-19 has been reported. We report a case of internuclear ophthalmoplegia in a patient with COVID-19.
- drugs: infectious diseases
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The novel coronavirus has engulfed the globe in a pandemic. One year after it was first detected,1 SARS-CoV-2 continues to surprise clinicians with newer manifestations. Ophthalmic manifestations were initially reported to be limited to conjunctivitis.2 3 Now there are increasing instances of other ophthalmic manifestations of COVID-19, such as uveitis4 and occlusive vascular diseases.5 The possibility of SARS-CoV-2 being a neurotropic virus is increasingly being reported, and neuro-ophthalmological manifestations are being reported. Neuro-ophthalmological manifestations range from isolated cranial nerve palsy6–8 to supranuclear gaze palsy,9 optic neuritis,10 vision loss11 and Miller Fisher syndrome.12
We present a case of COVID-19 presenting with internuclear ophthalmoplegia (INO).
A 58-year-old man presented to a rural eye care centre with complaints of binocular diplopia for 10 days which was sudden in onset. He had no known comorbidities of diabetes, hypertension or thyroid disorder and gave no history of trauma. There was no headache or diurnal variation. Examination revealed a vertical diplopia, enhanced in downgaze and levoversion. There were left eye exotropia and hypotropia of 15°. There was a −1 limitation of adduction in the right eye (figure 1) and his vertical saccades were partially impaired. He had a left-beating nystagmus in the left eye noted only on abduction. Pupillary reaction was normal. Best corrected visual acuity was 6/6p and 6/12 in the right and left eye, respectively. Colour vision was normal. Anterior segment evaluation revealed bilateral nasal pterygium and posterior polar cataract in the left eye, while posterior segment examination was unremarkable. His vitals at the time of screening were 94% saturation of peripheral oxygen (SpO2), temperature of 35.8°C and pulse rate of 91 per minute. His overall systemic status was stable, with no respiratory symptoms noted.
Extraocular motility examination, the abducting nystagmus in the left eye and the saccades were indicative of INO. Fatigue and ice pack test were negative. Initial blood investigations of complete blood count, lipid profile and 24-hour urine protein were within normal range. Fasting and postprandial blood sugar levels were 121 mg/dL and 205 mg/dL, respectively, and haemoglobin A1c (HbA1c) was 7.5%, suggestive of diabetes mellitus. At the same time, he also underwent SARS-CoV-2 reverse transcription-PCR as part of the community screening at his village which was positive. The sample submitted for this test was a nasopharyngeal swab. He later revealed positive contact history with his brother and family who stayed close to his house.
Ischaemic nerve palsy secondary to impaired blood glucose, myasthenia gravis, thyroid eye disease and INO were considered. The absence of clinical features suggesting an isolated nerve palsy on clinical examination ruled out ischaemic nerve palsy secondary to diabetes mellitus, although HbA1c was 7.5 gm%. The rapid resolution of diplopia over a period of 2–3 weeks is unlikely in diabetes mellitus.
The absence of eyelid signs and the normal thyroid function test ruled out the possibility of thyroid eye disease. The absence of diurnal variation, negative ice pack test and absent Cogan twitch clinically ruled out ocular myasthenia. The patient was diagnosed with right-sided INO based on adduction limitation in the right eye and the abducting nystagmus in the left eye.
Prior to sending the patient for investigations, we started him on vitamin B12 supplements once daily. The local physician treated the patient with oral doxycycline two times per day, ivermectin once daily and vitamin C supplementation for 10 days; this was an off-label treatment started by his general physician. He was also started on tablet metformin 500 mg once daily.
Outcome and follow-up
The patient presented to our eye clinic after 3 weeks of first presentation and 1 week of a repeat nasopharyngeal swab for SARS-CoV-2 PCR test which was negative. He was relieved of his diplopia. However, the adduction limitation of −1 persisted in the right eye (figure 2). His general demeanour was better. On retrospective probing, he had no anosmia, headache or any other COVID-19 symptoms apart from diplopia. At 1-month follow-up, his vertical saccades were normal and he was free of diplopia.
Neurological symptoms in COVID-19 are well established, ranging from headache, dizziness, anosmia or hyposmia, and hypogeusia, to Guillain-Barre syndrome, ischaemic and haemorrhagic strokes, and so on.12 Reports of neuro-ophthalmic findings such as cranial nerve paresis, optic neuritis, gaze palsy, vision loss and so on are being increasingly described in the literature.6–16
Multiple mechanisms in the aetiopathogenesis of neuro-ophthalmic manifestations in COVID-19 have been proposed, and these include postviral inflammatory syndrome, sequelae of a proinflammatory state and as a consequence of systemic conditions, such as cardiovascular disease or uncontrolled hypertension.14 Haematological spread and direct viral invasion have also been suggested.12
There are increasing reports of cerebrovascular accidents (CVA) with neuro-ophthalmological manifestations ranging from gaze palsy8 to devastating vision loss11 in COVID-19. Vision loss has been reported due to occipital infarcts and central retinal artery occlusion as well.9 11 Along with severe COVID-19, all patients reported had additional cardiovascular and other systemic comorbidities, increasing their susceptibility to thrombotic events.9 11
Apart from being newly diagnosed with diabetes mellitus, our patient had no other predisposition to thrombotic events and no other signs or symptoms indicative of CVA.
Clinical signs seen in INO can be caused by ocular myasthenia and hence it needs to be ruled out. Clinical tests in ocular myasthenia include fatigue test, a positive ice pack test, peak sign, saccadic fatigue and Cogan twitch sign.17 Cogan twitch sign has a sensitivity of up to 75% and a specificity approaching 99%.18 Ice pack test has sensitivity and specificity of 80% and 100%, respectively.17 Ocular myasthenia was clinically ruled out in our patient based on normal pupillary reaction, negative ice pack test and absent Cogan twitch sign.
Our patient presented with ophthalmoplegia not conforming to any pattern of cranial palsy. He was free from diplopia within 4 weeks of onset. In the absence of neuroimaging and with the patient being recently diagnosed with diabetes, it is difficult to be absolutely certain about INO being caused by COVID-19. A review by Brouwer19 and associates reported the possible aetiology of stroke in COVID-19. They suggest that there is coagulation system activation and an inflammatory response that can lead to embolism and cerebral infarction. Our patient being diabetic possibly put him at an additional risk of stroke due to COVID-19.19
Damage in the medial longitudinal fasciculus causes INO.20 The aetiology includes demyelinating disorders, infarcts, infections, vasculitis, trauma and iatrogenic injury.20 In a series of 410 patients, Keane21 reported infarction in 38% of INO, followed by multiple sclerosis in 34%. Unusual causes were reported in a quarter (28%) of the patients in the series, out of which only 17 cases had an infectious aetiology. Six cases had AIDS, four cysticercosis, two had each of syphilis, meningitis and sepsis, and one had brucellosis.
INO secondary to infection is rare.21 Few reports of herpes zoster infection propose demyelination and vasculopathy in the aetiopathogenesis of INO.22–24 The possible pathophysiology in our case may have been demyelination or related to stroke.19
Lack of neuroimaging for this patient due to the rural set-up and lack of serological investigations to rule out ocular myasthenia due to the patient’s financial constraints are limitations.
With the community spread of SARS-CoV-2 in villages and areas with fewer healthcare facilities, a thorough clinical examination by an ophthalmologist can play an important role in the identification and ensuring adequate referral. This report highlights a case of mild COVID-19 with no respiratory symptoms and having primarily neuro-ophthalmic manifestations.
I was suffering with double vision since a few days and was facing difficulty with walking. I was hitting into the furniture at my house and had a fall breaking my phone. I decided to visit the eye hospital close to my village where the Doctor checked by eye sight. I was told that there is something wrong with my eye movements and needed some blood tests. My doctor gave me a capsule saying it is a vitamin capsule which I needed to take till my blood reports come. During the same time, the government COVID testing van came to my village and took samples from my family members. Around 2 weeks back, my brother and his family had tested positive for the virus. After giving my swab, I got blood tests done from a laboratory near my house. The health authorities informed me that I have COVID. I called my eye hospital and I was advised to visit the Physician. The Physician started my treatment and gave me some tablets for COVID. He also told me that I have Diabetes. I am taking tablets for Diabetes since then. I was at home for about 2 weeks. The government van came again to my village and repeated my COVID test which was negative now. I then visited my eye doctor after another 1 week. After checking the doctor said that there is still some problem with my eye movements but I had no double vision. I was able to comfortably walk now and go about my daily chores. I have visited my eye doctor twice now since recovering from COVID. I have been told that the cataract in my left eye will be operated later.
Neuro-ophthalmic symptoms can be the only manifestation of COVID-19.
SARS-CoV-2 can cause internuclear ophthalmoplegia possibly by demyelination or stroke.
A meticulous clinical examination can help arrive at the diagnosis.
A thorough systemic work-up aids in the diagnosis.
Correction notice This article has been corrected since it was published Online First. The spelling of author's name is corrected to "Varshitha Hemanth Vasanthpuram".
Contributors VHV was involved in the care of the patient, along with expert advice from AB. VHV wrote the first draft and collected the images. AB helped refine the draft and was involved in responding to reviewer comments.
Funding The case report was funded by Hyderabad Eye Research Foundation.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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