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Guidelines for Diagnosing Duane’s Retraction Syndrome in Infants and Young Children
Rudolph S. Wagner, MD · Anthony R. Caputo, MD · Suqin Guo, MD · Alvina Pauline Santiago, MD
The diagnosis of Duane’s Retraction syndrome (DRS) is not difficult when patients present with the classic features: abduction and adduction deficiency, retraction of the globe, and narrowing of the palpebral fissure on attempted adduction. The findings of upshoots or downshoots of the affected eye in adduction and convergence insufficiency support the clinical diagnosis.1 The plethora of literature that followed Duane’s original publication supports the observation that patients may present with a variety, or a constellation, of signs and symptoms, which has led to multiple attempts at classification2-8 of which Huber’s4 remains the most commonly used to date.
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Type I DRS in Huber’s classification consists of marked abduction deficiency, minimally defective or normal adduction, globe retraction, and palpebral fissure narrowing on adduction and widening on abduction.
The recognition of DRS in infants and young children may be difficult.9 Many infants present only with an abduction deficit, which can be easily mistaken for a sixth cranial nerve (abducens) palsy in the absence of the diagnostic signs of DRS, such as adduction deficit, palpebral fissure narrowing, and globe retraction (Slide 1, Slide 2, Slide 3, Slide 4).10
Differentiation of DRS from an abducens nerve palsy is important because the surgical management of each condition is different and misdiagnosis can have serious consequences.
This tutorial reviews the results of our study of a series of patients who presented with an abduction deficiency during infancy in whom the diagnosis of DRS type I, sixth nerve palsy, or both was entertained.
The records of all patients presenting with abduction deficits prior to age 36 months in our private practice were reviewed. Twenty-four patients (13 boys; 11 girls) were identified for inclusion.
Each patient had been initially examined before age 36 months (range: 3-36 months). Extraocular muscle motility was evaluated by ductions and versions. Abduction deficiency was confirmed by careful duction testing. Patching of the contralateral eye was undertaken to force the affected eye to maximize horizontal ductions and to determine the existence of a true deficiency of abduction.11 Stabilizing the child and rotating the head of the child in the horizontal plane to induce nystagmus and to elicit full ductions were also done. For purposes of this study, particular attention to the following parameters was made once an abduction deficiency was suspected: the binocular misalignment (deviation) in primary gaze position; globe retraction; lid fissure narrowing; face turn and/or head tilt; and upshoot or downshoot of the globe on ductions and versions.
All patients had received a complete ophthalmological examination including vision testing, dilated fundus examination, and cycloplegic retinoscopy. Strabismus deviations were measured, whenever possible, at 10 feet using the prism alternate cover test. Otherwise, measurements were obtained using the Hirschberg corneal light reflection test or the modified Krimsky method. All measurements used for analysis in this study are in the (forced) primary position.
Of the 24 patients younger than 2 years that were studied, 13 patients (54%) were diagnosed with DRS, while one patient (4%) was diagnosed with abducens (sixth) nerve palsy. In 10 patients (42%), the diagnosis was uncertain.
By age 35 months, eight out of 10 patients who initially did not clearly show the diagnostic signs of DRS had later developed narrowing of the palpebral fissure, retraction of the globe, and upshoots or downshoots on adduction (Slide 5, Slide 6, Slide 7). The percentage of patients diagnosed with DRS, therefore, increased to 87.5%. At the conclusion of this study, the diagnosis of two patients still remained uncertain.
It is important to note that the average esotropia in DRS was 18 Δ D, which was much less than the 80 Δ D of esotropia in the one patient in whom a sixth nerve palsy was diagnosed.
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DRS is frequently difficult to confirm in infants. Many patients present initially only with an abduction deficit and manifest other diagnostic signs of the syndrome later. The signs and symptoms may develop as the lateral rectus muscle, over time, becomes more inelastic or fibrotic.1,12-14 Aside from this mechanical explanation, innervational and central nervous system anomalies have also been proposed to explain globe retraction and vertical upshoots or downshoots.15-18 In addition, a leash or tethering phenomenon from the lateral rectus muscle slipping on the globe has been proposed to explain the latter finding.19-26
While several studies have reported on the association of DRS with other ocular anomalies, congenital anomalies and systemic syndromes, such cases continue to be rare. (The interested reader is referred to a previously published review article9 which has a more extensive discussion of this association.) The prognosis for DRS is usually benign.9
On the other hand, an abducens (sixth) nerve palsy may carry a more ominous prognosis.9 In contrast to patients with DRS, patients with abducens palsy have normal adduction and preservation of convergence. The associated esotropia is usually large, in contrast to the smaller esotropia typical of DRS and also found in our series, and is not associated with globe retraction and vertical upshoots or downshoots. It is, however, important not to confuse true oblique overaction with the leash phenomenon. Nevertheless, in infancy, the difficulty in distinguishing this entity from DRS is a distinct challenge even for experienced pediatric ophthalmologists.10 Souza-Dias10 believes that a strong association of infantile abduction deficit exists with DRS compared to the relatively rare congenital sixth nerve palsy.
Differential diagnosis include Moebius Syndrome, congenital oculomotor apraxia, and infantile esotropia.9 The details of these diagnoses are beyond the scope of this tutorial. Briefly, as outlined by previous authors,9 Moebius is associated with seventh nerve palsy, and frequently associated with limb, chest, and tongue deformity. In congenital oculomotor apraxia, a characteristic head thrust is observed. Infantile esotropia will frequently show reasonable abduction following monocular occlusion. None of these conditions show globe retraction or lid fissure narrowing on adduction.
The importance of identifying the etiology of the abduction deficit lies in the clinical implications. Recession of a rectus muscle is more effective and less traumatic than a resection in treating DRS.1,19,27-31 Surgical transposition of the vertical rectus muscles to the insertion of the lateral rectus should be avoided in infants until abducens nerve palsy is proven. Transposition procedures and resection of lateral rectus muscles may worsen the upshoots and downshoots and the globe retraction, and may also produce marked adduction deficiency in DRS.16,32-37 Theoretically, this is due to an increase in restriction in adduction and a worsening of the co-contraction.38 A vertical tropia can also be so induced in at least 10% to 15% of cases.36,39,40
The vertical rectus muscles have also been demonstrated to co-contract with the medial rectus muscle10,17 leading to an increased resting tonus and a greater abducting force in adduction.10 Hence, exotropia is a frequent complication especially if surgery includes a medial rectus recession.10 Furthermore, surgery on three rectus muscles also increases the risk of anterior segment ischemia.41
Clearly, infants with abduction deficits may not manifest the diagnostic findings of DRS until after 2 1/2 years of age. The earliest finding following abduction deficits is lid fissure narrowing on adduction presenting at a mean age of 14 months, followed by retraction on adduction by mean age 18 months, and upshoots and downshoots by mean age 25 months.42
Infantile abduction deficits always need to be evaluated to determine the etiology. The majority of infants presenting with abduction deficit alone, after careful follow-up, turn out to have DRS. Other findings suggestive of DRS include a smaller angle of esotropia and adduction deficits manifesting as exotropia in contralateral gaze and convergence insufficiency.
