|Year : 2021 | Volume
| Issue : 3 | Page : 585-587
A rare case of racemose ocular myocysticercosis masquerading as exotropic Duane's retraction syndrome
Sumit Monga1, Puneet Jain2, Geeta Sethi3
1 Department of Pediatric Ophthalmology, Strabismus and Neuro-Ophthalmology Services, Centre for Sight Group of Eye Hospitals, Meerut, Uttar Pradesh, India
2 Department of Oculoplasty and Ocular Oncology Services, Centre for Sight Group of Eye Hospitals, Delhi NCR, India
3 Anterior Segment Service, Centre for Sight Group of Eye Hospitals, Meerut, Uttar Pradesh, India
|Date of Submission||04-Oct-2021|
|Date of Acceptance||12-Jan-2021|
|Date of Web Publication||02-Jul-2021|
Dr. Sumit Monga
Centre for Sight, B5/24, Safdarjang Enclave, Delhi - 110 029
Source of Support: None, Conflict of Interest: None
A 13-year-old girl presented with recent onset diplopia. At presentation, she had an ocular motility deficit resembling left eye exotropic-Duane's retraction syndrome. On imaging, her left eye lateral rectus was grossly swollen, with the presence of an elongated cystic lesion in its belly. The latter was a rare presentation of racemose cysticercosis, an uncommon variant of neurocysticercosis, hitherto unreported in an extraocular muscle. The child was medically managed with oral steroids and albendazole. There was a partial resolution of ocular motility deficit and complete regression of the intramuscular cysticercus lesion.
Keywords: Acquired Duane's retraction syndrome, myocysticercosis, racemose cysticercosis
|How to cite this article:|
Monga S, Jain P, Sethi G. A rare case of racemose ocular myocysticercosis masquerading as exotropic Duane's retraction syndrome. Indian J Ophthalmol Case Rep 2021;1:585-7
|How to cite this URL:|
Monga S, Jain P, Sethi G. A rare case of racemose ocular myocysticercosis masquerading as exotropic Duane's retraction syndrome. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Jul 28];1:585-7. Available from: https://www.ijoreports.in/text.asp?2021/1/3/585/320108
Cysticercosis of extraocular muscles is known to manifest as a cystic lesion, often with scolex. The racemose variety is an unusual form, hitherto reported mostly in neuro-cysticercosis. Herein, we report a unique case of racemose myocysticercosis, masquerading as Duane's retraction syndrome (DRS).
| Case Report|| |
A 13-year-old vegetarian girl presented to us with binocular diplopia, and painful left eye ocular movements, for 1 week. She was otherwise healthy; ophthalmic family history was noncontributory. Her unaided visual acuity was 20/20 in both eyes (OU). Her positive findings included primary exodeviation (20 PD on Prism bar cover test), with left eye adduction deficit (–4), retraction of globe and narrowing of palpebral aperture (pseudo-Exo DRS, sans the abduction deficit-[Figure 1]a and [Figure 1]b). Forced duction test was not possible, owing to limited cooperation of the child. She had no sign of ocular inflammation. The fundus examinations were unremarkable. Given the acute presentation, we kept a clinical differential diagnosis of myocysticercosis, myositis, tumors, muscle abscess or hematoma, and hydatid cyst. MRI imaging was done, which revealed fusiform enlargement of the left lateral rectus muscle belly, with evidence of an elongated and partially septate intramuscular cystic lesion [Figure 1]c. The latter was non-enhancing, with no scolex seen [Figure 1]c. As per literature search, the radiological pattern was suggestive of racemose cysticercosis, unusually seen in cerebral cases. A diagnosis of left lateral rectus racemose myocysticercosis was made, and the patient started on a standard treatment protocol of oral steroids (1 mg/kg/day for 1 month, tapered over subsequent 4 weeks) and oral albendazole (15 mg/kg/day, for 1 month), as described elsewhere, under physician supervision. After 8 weeks, with treatment, there was much improvement in primary exodeviation (6 PD on Prism bar cover test) but only limited improvement in the adduction deficit (–2) [Figure 2]a. The head posture improved significantly [Figure 2]b. A check MRI after 10 weeks showed complete regression of the cystic intramuscular lesion, a partial reduction in lateral rectus muscle swelling, and the decreased pressure effect on adjacent tissues [Figure 2]c. The patient was diplopia-free for most gazes, except for near and right gazes. She preferred to manage with a minimal abnormal head posture and did not accept prisms for diplopia relief. She was stable at her last follow up at 6 months.
|Figure 1: Presentation (a) Primary gaze exodeviation (small arrow); Left eye adduction deficit (-4) with globe retraction, ptosis, and upshoot (long arrow); left eye-full abduction (arrowhead). (b) Contralateral face turn. (c) Axial T2W MRI image showing a multi-lobulated, hyperintense cysticercosis lesion in swollen left LR muscle (broad arrow); Coronal T2W image showing hyperintense intramuscular cystic lesion (broad arrowhead); Non-enhancing, hypointense intramuscular cystic lesion with no scolex (long arrow); hypointense cystic lesion in inflamed LR belly (slender arrowhead)|
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|Figure 2: Post-therapy (a) Improved alignment (small arrow); improved adduction deficit (-2), with persistent globe retraction, ptosis and upshoot (long arrow); full abduction OS (arrowhead). (b) Improved head posture. (c) Partially regressed LR thickening with completely resolution of myo-cysticercus (broad arrow); Improved LR muscle thickness, with no residual cystic pathology (broad arrowhead); Heterogeneous enhancement of residual LR muscle fibers (long arrow); Residual thickening and patchy enhancement of LR muscle fibers (slender arrowhead)|
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| Discussion|| |
Cysticercosis is a well-documented zoonotic disease attributed to the parasite, Taenia species.,, It commonly affects the brain, eyes, heart, striated muscle, etc. In cerebral cases, two morphological variants-parenchymal (the predominant encysted larvae form) and extra-parenchymal (the unusual racemose form) are known., Extraocular muscles are known to be one of the most common lodgment sites of encysted larvae. To the best of our knowledge, this is the first report of racemose cysticercosis of an extraocular muscle.
Commonly, the larvae of Taenia pierce into the human tissues, including the extraocular muscle, forming larval cysts (cysticercus) with scolex, which degenerate over time and may release cytotoxins (classical parenchymal type)., A lesser common variant, racemose cysticercosis, is also known to occur in lesser confined spaces like brain ventricles, meninges, and subarachnoid space., In these sites, in absence of the limiting parenchymal tissue, the larval cysts gradually expand to larger sizes, lose scolex, and often acquire a multi-lobulated cystic appearance resembling a “bunch of grapes” (extra parenchymal type)., The racemose cysticercosis has also been rarely reported in the ocular adnexa-one case involving the anterior orbit and another affecting the lower eyelid., In our case, the occurrence of a racemose variant of cysticercosis in the extraocular muscle parenchyma was perplexing. We hypothesize that the vasogenic edema, as part of intense, induced myositis of the lateral rectus muscle, may have created lax tissue planes, facilitating the proliferation of cysticercus lesions. However, the real reason which prevented the encapsulation of cysticercus cyst, in our case, remains an enigma.
Computerized tomography (CT) scan has been the mainstay of diagnosis of classical myocysticercosis, revealing hypo-dense encysted larvae with hyper-dense scolex., However, for demonstrating lesions of racemose neurocysticercosis, MRI was found to be the preferred modality., On MRI, it appears as a hypointense multi-lobulated cystic mass without a scolex., They do not show calcification, scolex, or enhancement, as was seen in our case also. Notably, in the two reported cases of racemose cysticercus involving the ocular adnexa, the diagnosis could be established only on histopathology.,
Myocysticercosis is known to have varied presentations with inflammation, proptosis, ptosis, and restricted ocular motility., The ocular motility deficit in our case simulated the pattern seen in exotropic-Duane retraction syndrome, akin to a previously reported case. Mohan et al., in a series of extraocular myocysticercosis (n = 32), reported that half of their cases had residual ocular motility deficit, in spite of combining oral steroids with albendazole. In our case, too, the ocular motility deficit improved only partially.
There are reported differences in the management approach of parenchymal versus racemose neuro-cysticercosis, albeit without consensus., However, in absence of similar evidence for ocular cysticercosis, we decided to follow the standard medical management protocol for myocysticercosis, as described elsewhere. Our patient responded favorably to the therapy, with complete radiological regression of the cystic lesion and only partial resolution of the ocular motility deficit.
| Conclusion|| |
Racemose variety of cysticercosis is a possibility, in a case of extraocular myositis. However, the preferred diagnostic and therapeutic protocols for such cases need further research.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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