|Year : 2021 | Volume
| Issue : 2 | Page : 226-227
Head Canting – A Motor Adaptation
Kirandeep Kaur, Fredrick Mouttapa, Bharat Gurnani
Department of Paediatric ophthalmology and Strabismus, Aravind Eye Hospital, Puducherry, India
|Date of Submission||13-Aug-2020|
|Date of Acceptance||30-Aug-2020|
|Date of Web Publication||24-Jun-2021|
Dr. Bharat Gurnani
Aravind Eye Hospital, Cuddalore Main Road, Thavalakuppam, Puducherry - 605 007
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kaur K, Mouttapa F, Gurnani B. Head Canting – A Motor Adaptation. TNOA J Ophthalmic Sci Res 2021;59:226-7
A 21-year-old boy presented with the complaints of difficulty in reading for the past 3 months. Snellen's visual acuity was 20/20 in both the eyes. Anterior segment examination was normal, except abnormal eye movements and a V-pattern exotropia [Figure 1]. Fundoscopy revealed an extortion of the macula in the right eye [Figure 2]. The patient had a 10° left-sided head tilt. Binocular single vision was intact, and a stereopsis of 120° was present. Squint evaluation revealed right eye 10 prism diopters (PDs) of exotropia and 12 PDs of hypertropia, and the hypertropia increased on left gaze and right head tilt. Vertical fusional amplitude test revealed 12 PDs of fusional amplitudes.
|Figure 1: Clinical image of the patient showing 9 gaze ocular movements showing an underacting right superior oblique, an overacting left inferior rectus, and right inferior oblique muscle|
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|Figure 2: Fundus image of the right eye showing extortion of the macula and fundus image of the left eye showing normal position of the macula in relation to the optic disc|
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- What is the most probable diagnosis?
- Inferior oblique overaction
- Recent-onset fourth nerve palsy
- Congenital fourth nerve palsy
- Habitual head tilt.
- Choose the correct muscle sequelae in long-standing cases?
- Overaction of ipsilateral inferior rectus muscle (Herring's law)
- Overaction of contralateral inferior rectus muscle (Herring's law)
- Underaction of ipsilateral inferior oblique (Sherington's law)
- Overaction of ipsilateral inferior oblique (Herring's law).
- How will you manage this patient?
- Observation as this condition might resolve over course of time
- Weaken/recess the left inferior oblique muscle
- Strengthen/tuck the yoke contralateral inferior rectus muscle
- Strengthen/tuck the right superior oblique.
- What differentiates bilateral from unilateral palsy?
- Positive Bielschowsky head tilt test on tilting head toward either shoulder
- V pattern of 15 PD
- More obvious head tilt toward one side
- Double Maddox rod revealing an excyclotorsion of 5°.
A. c; B. b; C. d; D. a.
| Discussion|| |
Fourth nerve palsy is the most common congenital cranial nerve palsy. It is physically slender, has the longest intracranial course, and is subject to traumatic damage. Fourth nerve palsy results in characteristic motility patterns including elevation in adduction, V-pattern related to reduced abduction force in downgaze, and excyclotorsion. Patients often acquire a contralateral head tilt for unilateral palsy and chin down head posture for bilateral palsy. The common muscle sequelae following long-standing cases include overaction of the contralateral inferior rectus (Herring's law), overaction of the ipsilateral inferior oblique (Sherrington's law), and secondary inhibitional palsy of the contralateral superior rectus.
The characteristic findings of a decompensated congenital fourth nerve palsy include a long-standing head tilt, overaction of the ipsilateral inferior oblique in adduction, and a large vertical fusional amplitude of 10–15 PDs (normal vertical fusional amplitude is between 2 and 3 PDs). Because in this patient there is only a mild head tilt, and no diplopia in primary and downgaze, observation can be planned. If needed, the surgical options include strengthening the affected superior oblique muscle, weakening the antagonist ipsilateral inferior oblique muscle, or weakening the yoke contralateral inferior rectus muscle. Bilateral fourth nerve palsy presents with a crossed hypertropia, excyclotorsion of 10° or greater, and a large (≥25 PD) V-pattern of strabismus.
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.
| References|| |
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Knapp P. Classification and treatment of superior oblique palsy. Am Orthopt J 1974;24:18-22.
[Figure 1], [Figure 2]