Oman Journal of Ophthalmology

EDITORIAL COMMENTARY
Year
: 2022  |  Volume : 15  |  Issue : 2  |  Page : 131--132

Duane retraction syndrome: Where and how is the abducens nerve?


Meenakshi Swaminathan 
 The Capstone Clinic, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. Meenakshi Swaminathan
The Capstone Clinic, Chennai, Tamil Nadu
India




How to cite this article:
Swaminathan M. Duane retraction syndrome: Where and how is the abducens nerve?.Oman J Ophthalmol 2022;15:131-132


How to cite this URL:
Swaminathan M. Duane retraction syndrome: Where and how is the abducens nerve?. Oman J Ophthalmol [serial online] 2022 [cited 2022 Oct 7 ];15:131-132
Available from: https://www.ojoonline.org/text.asp?2022/15/2/131/348968


Full Text



The etiology of Stilling-Türk-Duane retraction syndrome has perplexed strabismologists and researchers for many centuries. The scientists whose names the syndrome goes by, had speculated about the etiology of the syndrome.

The initial theories were focused on mechanical anomalies of the lateral rectus as the scientists sought an explanation for the lack of abduction. Turk[1] and Wolff[2] published that the lateral rectus behaved like an inelastic band. One theory postulated that the cause of the syndrome was birth trauma or nuclear aplasia that resulted in a tight lateral rectus.[3] Dual insertion of medial rectus was a theory that was prevalent for a long time until this could not be verified during surgery on Duane's patients.[4]

Focus shifted to the possibility of innervational anomalies, as an explanation for the constellation of clinical findings.[5] Support for anomalous lateral rectus innervation came from electromyography recordings by several researchers.[6] It was established that the medial rectus innervation was normal despite clinically significant anomalies occurring during adduction. It was also noticed that the lateral rectus behaved differently as a possible explanation for a whole spectrum of clinical features. The “why” remained unanswered and elusive.

Studies of saccades revealed that there was a slowing of both lateral rectus and medial rectus saccades.[7] Paradoxical innervation and synergistic innervation were also found between the medial rectus and vertical rectus muscles and oblique muscles.

One pauses to wonder why it is important to pinpoint the exact etiology of any entity. While it may be a matter of scientific curiosity, it often is the first step toward finding a cure.

It eventually became clear that what was lacking was the innervation to the lateral rectus muscle. Whether this lack of innervation was nuclear or supranuclear was not clear at the time. The syndrome was included under the larger umbrella of congenital cranial dysinnervation disorders. The absence of an abducens nucleus or hypoplasia of the nucleus, or anomalies in the cavernous sinus where the abducens and oculomotor nerves are in proximity were postulated as the etiological causes of lateral rectus anomalous innervation, most of the data were gathered from autopsy.[8]

In the late 90s, imaging showed the absence of abducens nerve on high-resolution magnetic resonance imaging (MRI).[9] This finding was demonstrated by other authors too in later years.[10] The article in the current issue looks at MRI in a patient with Duane retraction syndrome and has come up with yet another significant finding, which is the presence of a cisternal segment of the abducens nerve in 20% of patients.[11] This underscores the importance of being aware of the spectrum of both clinical and radiological findings in patients with this fascinating strabismic syndrome, which continues to surprise and baffle us in equal measure.

References

1Turk S. Bemerkungen zu einem Falle von Retraction des Auges. Cbl Pract Augenheilk 1899;23:14.
2Wolff J. The occurrences of retraction movements of the eyeball together with congenital defects in the external ocular muscles. Arch Ophthalmol 1900;29:297.
3Gallus E. Sinddiesog angeborener: Retraktionsberegungen des Auges die Folge einer Gebutsverletzurg. Arch Augenheilkd 1921;87:35-45.
4Bahr K. Vorstellung eines Falles von eigenartiger Muskelanomalie eines Auges Ber Dtsch. Ges Opthalmol 1896;25:334.
5Breinin GM. In discussion of: De Gindersen T, Zeavin B. Observations on the retraction syndrome of Duane. Arch Ophthalmol 1956;55:576.
6Strachan IM, Brown BH. Electromyography of extraocular muscles in Duane's syndrome. Br J Ophthalmol 1972;56:594-9.
7Metz HS. The diagnosis and treatment of abduction deficiencies. Ann Ophthalmol 1976;8:683-93.
8Miller NR, Kiel SM, Green WR, Clark AW. Unilateral Duane's retraction syndrome (Type 1). Arch Ophthalmol 1982;100:1468-72.
9Parsa CF, Grant PE, Dillon WP Jr., du Lac S, Hoyt WF. Absence of the abducens nerve in Duane syndrome verified by magnetic resonance imaging. Am J Ophthalmol 1998;125:399-401.
10Gupta C, Sharma P, Saxena R, Garg A, Sharma S. Clinical correlation of imaging findings in congenital cranial dysinnervation disorders involving abducens nerve. Indian J Ophthalmol 2017;65:155-9.
11Unnikrishnan S, Mohammed F, Valiyaveetil B, Jyothi P. Clinical profile and magnetic resonance imaging characteristics of Duane retraction syndrome. Oman J Ophthalmol 2022;15:147-152.