International Journal of Ophthalmic PathologyISSN: 2324-8599

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Commentary, Int J Ophthalmic Pathol Vol: 10 Issue: 3

Diagnosis and Management of Fourth Cranial Nerve Palsy

Anuhya Sabbineni
Department of Pharmacy, Malla Reddy collage of pharmacy, Hyderabad, India
Corresponding Author: Anuhya Sabbineni
Department of Pharmacy, Malla Reddy collage of pharmacy, Hyderabad, India
E-mail: [email protected]
Received: March 03, 2021 Accepted: March 17, 2021 Published: March 24, 2020

Abstract

Trochlear nerve palsy can be divided into acute or congenital. Congenital trochlear nerve palsy is generally noted in childhood with development of abnormal head posture. Various pathologies can lead to acute IV nerve palsy, most commonly trauma. Other causes include vascular, inflammatory, neoplastic and aneurysms.

Keywords: Trochlear nerve palsy, Trauma

Introduction

Trochlear nerve palsy can be divided into acute or congenital. Congenital trochlear nerve palsy is generally noted in childhood with development of abnormal head posture. Various pathologies can lead to acute IV nerve palsy, most commonly trauma. Other causes include vascular, inflammatory, neoplastic and aneurysms.

Signs and symptoms

It is necessary to differentiate acute IV cranial nerve (CN) palsy from longstanding but decompensating one. Patients normally present with sudden onset, intermittent or constant vertical diplopia. Full orthoptic assessment is essential to confirm the condition. The assessment will show that the affected eye is hypertropic and this hypertropia increases on contralateral gaze and on ipsilateral head tilt. It is also necessary to obtain a Hess chart as well as assessing the patient on the synoptophor looking for subjective torsion. Fundus photography taking at the position of the fovea relative to the optic nerve head is a way of detecting objective torsion.“It is important to have a period of stable measurements of at least six months before surgery.”

Common features of longstanding Fourth nerve palsy

• Extended vertical fusion range

• Lack of subjective torsion

• Development of muscle sequelae on Hess chart

• Longstanding head tilt to the contralateral side.

Common features of bilateral Fourth cranial nerve palsy

• Reversal of vertical deviation on side gazes

• Torsion of more than 10 prism diopters in primary gaze

• V pattern

• Chin up position instead of head tilt.

Investigations

Once confirmed as acute onset, several investigations are recommended including neuro imaging (MRI), blood tests such as ESR, CRP, FBC, glucose, lipids, U&Es. Other tests for autoimmune antibodies, ACh-R antibodies are done if felt necessary.

Non-surgical options

These include patching one eye or using Fresnel prisms in order to avoid diplopia, it is also important to tell patients to avoid driving and inform the DVLA about their diplopia.

Surgical options

It is important to have a period of stable measurements of at least six months before embarking on surgery. The surgical option depends on the angle of deviation in primary position, area of maximum deviation and presence of torsion. Torsion can be corrected by the Harada Ito procedure, Knapp class I can be addressed by ipsilateral IO recession, class II can be addressed by ipsilateral SO tuck, class III can benefit from either options and class IV and V might need also a contralateral inferior rectus recession. It is important to counsel the patient about the possibility of unmasking a bilateral IV palsy following surgery on one eye then needing further surgical intervention. Adjustable sutures could be utilised in adults’ surgery.

Complications

It is important to avoid over corrections by staging the surgery or using adjustable sutures. Other specific complications include inducing a Brown syndrome following SO tuck and it is important to counsel patients regarding this possibility. IR muscle surgery can induce lower lid malposition.

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