|Year : 2020 | Volume
| Issue : 1 | Page : 70-72
Optic nerve hypoplasia with sixth nerve palsy
C Vidhya, Kanika Gupta
Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Bengaluru, Karnataka, India
|Date of Submission||01-Jul-2019|
|Date of Acceptance||13-Dec-2019|
|Date of Web Publication||17-Apr-2020|
Dr. C Vidhya
Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Optic nerve hypoplasia (ONH) can occur as an isolated anomaly or in association with various ocular abnormalities, cranial abnormalities (agenesis of septum pellucidum, anencephaly, and midline abnormalities of brain), or facial anomalies. Here, we present a case report of ONH with sixth cranial nerve palsy, which has never been reported in literature.
Keywords: Abducens nerve palsy, optic nerve hypoplasia, septo-optic dysplasia
|How to cite this article:|
Vidhya C, Gupta K. Optic nerve hypoplasia with sixth nerve palsy. Kerala J Ophthalmol 2020;32:70-2
| Introduction|| |
Optic nerve hypoplasia (ONH) can occur as an isolated anomaly or in association with various ocular abnormalities, cranial abnormalities (agenesis of septum pellucidum, anencephaly, and midline abnormalities of brain), or facial anomalies. It may occur as a component of syndrome of septo-optic dysplasia (De Morsier's syndrome).
Characteristically, the disc is small with a peripapillary double-ring sign, vascular tortuosity, and thinning of the nerve fiber layer. A patient with ONH should be assessed for the presence of neurologic, radiologic, and endocrine associations. Here, we present a case report of ONH with sixth cranial nerve palsy, which has never been reported in literature.
| Case Report|| |
A 4-month-old female child was referred to our hospital in view of face turn at the age of 4 months. The child had full-term birth through normal delivery with a birth weight of 2.75 kg. Head control was attained at 4 months. The parents noticed the face turn since 3 months of age.
On examination, the child was following light and toys. There was no resistance to occlusion of either eye. The child had left face turn with esotropia. There was a horizontal jerky nystagmus with vertical and latent components with no null zone. Extraocular movement assessment showed limitation of abduction of −2 in the left eye [Figure 1] both during versions and duction. Doll's eye maneuver and patch test were done, which confirmed the limited abduction of the left eye. No palpebral fissure changes were seen in adduction. Pupils in both eyes were 3 mm in size and were reacting to light. Cycloplegic refraction showed simple myopic astigmatism of −2.00 D cyl in the right eye and −1.50 D cyl in the left eye. On fundus examination, small, hypoplastic optic disc was observed in both eyes, with the left more hypoplastic than the right [Figure 2]. The ratio of center of disc to macula to mean disc diameter (DD) (DD + horizontal disc diameter divided by two) in the right eye was 4 and in the left eye was 5.
|Figure 1: The esotropia in primary gaze with limitation of abduction in the left eye|
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|Figure 2: Fundus picture taken with smartphone showing optic nerve hypoplasia|
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Clinical impression was OU asymmetric ONH with left-eye sixth nerve palsy.
The child was sent for magnetic resonance imaging brain for further evaluation. The report came to be absent septum pellucidum with hypoplastic pituitary stalk. The child was sent to a pediatric endocrinologist for further management. She was found to have central cortisol insufficiency and hypothyroidism and was started on thyroxine and cortisol for the same.
| Discussion|| |
This case shows the rare association of sixth nerve palsy with ONH described nowhere in literature.
The congenital ONH is a unilateral or bilateral nonprogressive underdevelopment, accounting for 15%–25% of infants with serious vision loss. Over the years, the incidence seems to be rising.
ONH is recognized as a common cause of congenital blindness. In 2007, the Babies Count registry reported ONH as the third most prevalent cause (behind cortical visual impairment and retinopathy of prematurity) of any vision impairment, which is most likely to cause legal blindness in children 3 years or younger in the United States.
ONH is a sporadic condition, although genetic and maternal risk factors (primiparity, young age, and fetal alcohol syndrome) have been documented.
Absence of corpus callosum is the common radiographic finding and has been associated with developmental delay. It can be associated with treatable conditions such as hydrocephalus.
Nystagmus develops between the age of 1 and 3 months followed by strabismus, usually esotropia (comitant). Approximately 80% are bilaterally affected, with two-third being asymmetrical. Eighty percent of bilateral cases are legally blind. Visual improvement occurs in initial years but less common in patients with low thyroid levels.
Endocrinopathy affects the majority of children with ONH regardless of laterality or neuroradiographic abnormalities of septum pellucidum or corpus callosum.
In our case, there was no antenatal risk factor elicited from the history. The child presented with nystagmus and left-eye sixth nerve palsy with asymmetric ONH. PubMed search showed no previous association of ONH with sixth nerve palsy.
In addition, imaging in sixth nerve palsy helped in diagnosing the associated neurological and endocrinological abnormalities.
| Conclusion|| |
Congenital sixth nerve palsy is a diagnosis of exclusion. Detailed eye examination is warranted in these cases to look for ONH, which requires imaging and further management for the systemic associations.
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]