# Incomitant Strabismus/Module 2: A/V Patterns & Neurogenic Palsies/Introduction

This section will provide an overview of the causes of acquired cranial nerve palsies and the principles for differential diagnosis and management of neurogenic palsie. These principles can be applied across this enquiry.

## 1.1 Aeitiology

This topic will provide an overview of the aetiology of acquired cranial nerve palsies
Instructions
* Read the Ansons & Davis (2014) reference related to aeitiology of acquired palsies
* Watch the Tim Root video titled Cranial Nerve Palsies available below
* Watch the video by Westmead Neurological Centre titled Eye movements and their dirorders. You need only watch the video from 58:15 to 82:35 (00.57:46 to 01:22:01 as per the video time stamp) which relates directly to the causes of cranial nerve palsies. The screenshot below depicts where you need to commence the video (commence at 'Disorders of cranial nerves III, IV and VI' and stop at 'Lesions of the third nerve nuclear complex') and will link you to the library resource. A powerpoint related to this video is provided to assist you to take notes throughout the video.This includes diagrams of the cranial nerves and key notes from the video.
Supplementary Optional Reading
Read the Rush & Younge (1981), Richards et al (1992) and Tiffin et al (1996) regarding causes of neurogenic palsies.
Videos
Aeitiology of Neurogenic Palsies
Eye Movements & Their Disorders
View the above 'Eye Movements & Their Disorders' video from 58:15 to 82:35 (00.57:46 to 01:22:01) with the below handout
References
Ansons AM, Davis H. (2014) Diagnosis and Management of Ocular Motility Disorders. 4th ed. London: Blackwell. pp 463-468 (3rd ed. 353-358).
Rush JA, Younge BR. (1981) Paralysis of cranial nerves III, IV, and VI: cause and prognosis in 1,000 cases. Arch Ophthalmol 99(1): 76-79.
Richards et al (1992). Causes and Prognosis in 4,278 Cases of Paralysis. American Journal of Ophthalmology. 113: 489-496
Tiffin et al (1996). Acquired Palsy of the III, IV & VI Nerves. Eye 10: 377-384

## 1.2 Differential Diagnosis

This topic will provide an introductory overview of key characteristics of paralytic strabismus and how to distinguish (i) a congenital palsy from an acquired palsy and (ii) a neurogenic palsy from limited movement due to a mechanical restriction.
Instructions
* Read Ansons & Davis (2014), von Noorden & Campos (2002a), von Noorden & Campos (2002b) and von Noorden & Helveston (1995) Part A (Innervational vs Restrictive) and Part B (Old vs Recent)
* Watch the below video on 'Introduction Differential Diagnosis" in Incomitant Strabismus.
Videos
Cranial Nerve Palsies
References
Ansons AM, Davis H. (2014) Diagnosis and Management of Ocular Motility Disorders. 4th ed. London: Blackwell. pp.458 (Differential diagnosis of congenital and acquired palsies), 459 (Differential diagnosis between neurogenic palsies and mechanical restriction) (3rd ed. pp. 347, 349).
von Noorden GK, Campos E. (2002a) Binocular Vision and Ocular Motility. Theory and Management of Strabismus. 5th ed. St. Louis: Mosby. 427-428 (Paralytic vs Non-paralytic Strabismus & Congenital vs Acquired Paralysis).
von Noorden GK, Campos E. (2002b) Binocular Vision and Ocular Motility. Theory and Management of Strabismus. 5th ed. St. Louis: Mosby. 421-422 (Past-pointing)
von Noorden GK & Helveston EM. (1995) Strabismus: A Decision Making Approach. St. Louis: Mosby. Sections 1.30, 1.31

## 1.3 Management Principles

This topic will provide an overview of principles of managing neurogenic palsies. Both non-surgical and surgical intervention will be discussed.
Instructions
* Read Ansons & Davis (2014), von Noorden & Campos (2002), von Noorden & Helveston (1995) and Strabismus Minute: Adjustable Sutures
* Watch the below videos in the playlist 'Principles of Management'.
Optional Supplementary Reading
* Read Mills et al (2004) regarding effectiveness and safety of surgical intervention, Siatkowski (2004) regarding the principles of surgical management for various cranial nerve palsies and Keech (2006) on adjustable sutures.
Videos
Principles of Managing Neurogenic Palsies
References
Ansons AM, Davis H. (2014) Diagnosis and Management of Ocular Motility Disorders. 4th ed. London: Blackwell. 458-461 (Principles of management), 176-178 (Prisms), 187-194 (Botulinum Toxin) (3rd ed: 392-393, 146-147, 155-159).
The Strabismus Minute: Adjustable Sutures. (n.d) Section 24. Retrieved from: http://www.cybersight.org/bins/volume_page.asp?cid=1-600-3-38
von Noorden GK & Campos E (2002). Binocular Vision and Ocular Motility. Theory and Management of Strabismus. 6th ed. St. Louis: Mosby. 444-445
von Noorden GK, Helveston EM. (1995) Strabismus: A Decision Making Approach. St. Louis: Mosby. Section 2.49
Keech RV (2006) Adjustable Suture Strabismus Surgery. In W Tasman & EA Jaegar (Eds) Duane's Opthalmology. Philadelphoa: Lippincott, Williams & Wilkins
Mills et al (2004) Strabismus Surgery for Adults. Ophthalmology 111:1255-1262
Siatkowski (2004) Principles of Surgical Management for Cranial Nerve Palsies. American Orthoptic Journal 54:62-69