|Year : 2021 | Volume
| Issue : 2 | Page : 354-356
Congenital abducens-oculomotor dysinnervation: A novel congenital cranial dysinnervation disorder phenotype
Pramod K Pandey, Neha Sachdeva, Priya Saraf, Rupak B Choudhury, Vidula Yadav, Divya Kishore
Department of Ophthalmology, Guru Nanak Eye Center and Maulana Azad Medical College, New Delhi, India
|Date of Submission||13-Jul-2020|
|Date of Acceptance||11-Dec-2020|
|Date of Web Publication||01-Apr-2021|
Dr. Neha Sachdeva
Guru Nanak Eye Centre, Maharaja Ranjit Singh Marg, New Delhi - 110 002
Source of Support: None, Conflict of Interest: None
In a boy aged 6 years left unilateral congenital ptosis with medial rectus-levator palpebrae superioris (MR-LPS) synkinesis; the coexisting hitherto unreported likely lateral rectus-superior rectus (LR-SR) dysinnervation is reported. Ocular movements were full and cover test did not reveal any ocular misalignment. Such a presentation can only arise from two concurrent dysinnervations: first one between inferior and superior divisions of third nerve and second one between third and sixth cranial nerve. The dysinnervation may conform to a forme-fruste TUBB3 (Tubulin, Beta 3 Class III Gene) pathogenic variant phenotype and may be classed as a novel congenital cranial dysinnervation disorder (CCDD).
Keywords: Congenital abducens-oculomotor synkinesis, congenital cranial dysinnervation disorder, lateral rectus-superior rectus dysinnervation, Levator-medial rectus synkinesis, tortuosity of retinal vessels
|How to cite this article:|
Pandey PK, Sachdeva N, Saraf P, Choudhury RB, Yadav V, Kishore D. Congenital abducens-oculomotor dysinnervation: A novel congenital cranial dysinnervation disorder phenotype. Indian J Ophthalmol Case Rep 2021;1:354-6
|How to cite this URL:|
Pandey PK, Sachdeva N, Saraf P, Choudhury RB, Yadav V, Kishore D. Congenital abducens-oculomotor dysinnervation: A novel congenital cranial dysinnervation disorder phenotype. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2022 Dec 5];1:354-6. Available from: https://www.ijoreports.in/text.asp?2021/1/2/354/312367
Medial rectus-levator palpebrae superioris (MR-LPS) dysinnervation is seen as aberrant regeneration in congenital/acquired third cranial nerve palsies (3NP). Beyond 3NP, MR-LPS synkinesis has also been reported anecdotally with/without congenital ptosis.,, Lateral rectus (LR)-LPS dysinnervation has also been reported. Congenital monocular elevation deficiency (MED) as a variant of CFEOM3 phenotype arising from a TUBB3 mutation has been documented and screening for TUBB3 mutations recommended in congenital MEDs. A novel LR-SR synkinesis with unilateral congenital ptosis and MR-LPS synkinesis is reported.
| Case Report|| |
A boy aged 6 years presented in January 2020 with complaints of drooping of left eye lid and bizarre movements in left eye since birth. Visual acuity was 20/20 both eyes with a mild hypermetropic refractive error. He had moderate ptosis left eye and cover tests did not reveal any ocular misalignment. Ocular movements were full; head tilt test results were unremarkable. On levo-version, left eye showed gaze evoked upshoot with worsening of ptosis and no accompanying globe retraction. On upgaze ptosis remained same without any accompanying limitation of elevation or globe retraction. On adduction, elevation/depression in adduction, left eye ptosis resolved with maximum aperture height in depression and adduction. No pattern strabismus or other signs of 3 NP/miswiring were present including Marcus Gunn Jaw winking phenomena. Pupils and fellow eye examination were unremarkable [Figure 1]. Tortuous retinal vessels left eye >right eye, were noted with normal torsion documented on fundus photography [Figure 2]. The boy's mother did not consent for genetic testing, neuroimaging or surgery and the child was lost to follow up after a few visits.
|Figure 1: (a) Nine gaze montage showing no limitation on versions, left eye moderate ptosis in primary position, upshoot and worsening of ptosis in abduction with absent globe retraction and improvement in ptosis in adduction. (b): Head tilt test results were unremarkable|
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|Figure 2: (a) No duction limitations in left eye. (b) Fundus photographs OU showing normal fundus torsion and tortuosity of retinal vessels, left eye >right eye|
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| Discussion|| |
The dysinnervation in this boy has two components, an anecdotally reported MR-LPS synkinesis and a novel LR-SR dysinnervation. Pang and colleagues described two sisters with inherited MR-LPS synkinesis, one of the sisters also had 1 mm ptosis. Lid retraction increased in adduction and depression. No additional features were noted pointing towards 3rd cranial nerve palsy. Tawfik et al. reported a similar case with mild ptosis that resolved on adduction with aperture surpassing that of the fellow normal eye by 1 mm. Martorina et al. in a case of congenital ptosis described maximum lid elevation in adduction and depression in the field of superior oblique muscle and speculated synkinesis between 3rd and 4th cranial nerves presumably from obstetric trauma.
The second component of dysinnervation in this child is elevation of the left eye on abduction translating to LR-SR synkinesis. Such an oculomotor-abducens dysinnervation does not find mention in the literature. With full abduction, elevation and depression of left eye any component of vertical/inverse Duane's retraction syndrome, congenital 3NP is excluded.
The reverse, SR-LR miswiring giving rise to Y/V pattern strabismus however finds mention in literature and is also known as pseudo inferior oblique overaction (IOOA) as it simulates IOOA. It is usually an isolated finding with limited abduction with activation of LR on SR activation, there is no excyclotorsion as seen in inferior oblique overaction and no superior oblique under-action. No association is usually seen with ptosis.
Chalvatzis et al. reported just opposite, LR-LPS -SR miswiring in a young male with isolated ptosis with no limitation of ocular movements. Resolution of ptosis occurred in upgaze and abduction and worsened in adduction. There was no LR-SR synkinesis on abduction. The authors noted that no such miswiring has been reported, no explanation for the miswiring was advanced and presentation was speculated as an addition to CCDDs.
Congenital isolated hereditary ptosis both unilateral and bilateral has been classed as a CCDD. Ptosis or change in palpebral aperture with horizontal gaze is often seen with congenital 3NPs, Duane's retraction syndrome, congenital (MEDs), congenital Brown's syndrome, Marcus Gunn jaw winking phenomena, entities that stand classed as CCDDs.
In this child there is likely novel primary dysinnervation of the left superior division of the 3rd nerve, secondary dysinnervation being routed to LPS via branch to medial rectus in the inferior division and to SR through abducens nerve respectively. As the innervation to LPS pierces through SR, the SR may have drawn required innervation with full elevation from superior division of 3rd nerve and a twig from 6th nerve accounting for elevation in abduction. The LPS had deficient innervation accounting for ptosis, aberrant innervation being routed through inferior division of third nerve through branch to MR. All three nerves are in close proximity in the oculomotor foramen in the superior orbital fissure making the cross-talk tenable.
The LPS enjoys complex anatomy, rendering it prone for dysinnervation. In peripheral course is known to divide into two parts, a bigger superior (for LPS aponeurosis) and a smaller inferior (for Mueller's muscle origin). The LPS muscle unlike SR has no proprioceptive structures like muscle spindles/palisade endings. Mueller's muscles acts like a serial kind of muscle spindle for LPS and is doubly innervated by unmyelinated efferent sympathetic nerves and myelinated trigeminal proprioceptive efferents. Tortuosity of retinal vessels seen in this boy has also been described in a case with Moebius syndrome.
Thomas et al. described congenital MED arising from a TUBB3 variant and suggested that congenital MED can be considered as a limited form of CFEOM3. Ptosis is almost constant accompaniment of CFEOMs.
| Conclusion|| |
The novel presentation congenital abducens-oculomotor dysinnervation in our patient could be conflated as a forme-fruste variant of unilateral CFEOM3 phenotype sans fibrosis from a de novo TUBB3 mutation harboring novel dysinnervation.
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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[Figure 1], [Figure 2]