Cause of Duane Retraction Syndrome in Patients with ADHD
Duane Retraction Syndrome (DRS) and ADHD are separate conditions with distinct etiologies, and there is no established causal relationship between them. While they may coexist in some patients, one does not cause the other.
Etiology of Duane Retraction Syndrome
Duane Retraction Syndrome is primarily a congenital neurological disorder characterized by:
- Abnormal development of the abducens nucleus (cranial nerve VI) 1, 2
- Miswiring of the lateral and medial recti muscles 2
- Erroneous innervation of the lateral rectus muscle by branches from the oculomotor nerve (cranial nerve III) 1, 2
The condition is now classified as a congenital cranial dysinnervation disorder 3. Key features include:
- Deficient horizontal eye movements
- Eyelid retraction
- Palpebral fissure narrowing
- Abnormal vertical eye movements 1
Most cases of DRS are:
- Sporadic (not inherited)
- Unilateral (usually affecting the left eye)
- Showing slight female predominance 1
Etiology of ADHD
ADHD is a neurodevelopmental disorder with a different pathophysiology:
- Primarily characterized by dysfunction in the prefrontal cortex and connected brain networks 4
- Dysregulation of dopamine and norepinephrine neurotransmission is the central neurobiological mechanism 4
- Executive dysfunction is a core feature, affecting working memory, inhibition, cognitive flexibility, planning, and self-monitoring 4
Clinical Presentation and Classification
Duane Retraction Syndrome
DRS is classified into three types based on ocular motility patterns:
- Type I (most common): Limited abduction with normal or mildly limited adduction
- Type II (least common): Limited adduction with normal or mildly limited abduction
- Type III: Limitation of both abduction and adduction 5, 2
From a management perspective, DRS is more practically classified based on primary position deviation as:
- Esotropic
- Exotropic
- Orthotropic 5
ADHD
ADHD presents with:
- Inattentive symptoms (poor attention to detail, difficulty concentrating, disorganization)
- Hyperactive-impulsive symptoms (fidgeting, restlessness, excessive talking)
- Combined presentation (both inattentive and hyperactive-impulsive symptoms) 6
Management Considerations
When both conditions coexist:
For DRS:
- Surgical intervention may be considered for:
- Abnormal head posture
- Deviations in primary position
- Significant retraction and narrowing of palpebral aperture
- Pronounced up- or downshoots during adduction 3
- Surgical techniques include lateral rectus recession, periosteal fixation, and vertical rectus transposition 3
- Surgical intervention may be considered for:
For ADHD:
- Pharmacological treatment with stimulants (methylphenidate, amphetamines) that target dopamine and norepinephrine systems 4
- Cognitive behavioral therapy and other non-pharmacological interventions 4
- Careful monitoring during pregnancy if applicable, as discontinuing psychostimulant treatment during pregnancy can lead to worse mental health outcomes 6
Important Clinical Considerations
Comorbidities: Approximately 46% of DRS patients have associated congenital abnormalities 7, making comprehensive evaluation important when DRS and ADHD coexist.
Visual Function: About 20% of DRS cases have absent binocular stereoacuity and 16.9% have amblyopia 7, which could potentially compound attention difficulties in patients with ADHD.
Treatment Prioritization: When both conditions coexist, treatment decisions should address the condition causing the greatest functional impairment to morbidity, mortality, and quality of life.
Monitoring: Regular follow-up is essential to assess treatment efficacy and adjust management strategies as needed.
While these conditions may coexist in some patients, current medical evidence does not support a causal relationship between DRS and ADHD. Each condition requires its own specific diagnostic workup and management approach.