Overview
Internuclear ophthalmoplegia (INO) is characterized by impaired adduction of one eye during attempted lateral gaze, resulting from lesions affecting the medial longitudinal fasciculus (MLF). This condition often manifests with associated nystagmus and saccadic abnormalities. 124Diagnosis
Key Diagnostic Criteria: Impaired adduction of the affected eye during attempted lateral gaze, often accompanied by upbeat nystagmus.
Recommended Tests:
- Ocular motility examination to identify adduction deficits and associated nystagmus.
- Ocular vestibular evoked myogenic potentials (VEMPs) to assess MLF function, particularly oVEMPs in response to forehead tapping.
- High-resolution infra-red oculography for detailed analysis of saccadic and smooth pursuit movements.
Grading: Severity can be assessed based on the extent of eye movement impairment and presence of additional neurological signs. 14Management
First-Line Treatments:
- Address underlying cause (e.g., vascular, demyelinating, or compressive lesions) with appropriate neurology consultation.
- Rehabilitation strategies focusing on compensatory eye movement training.
Adjunctive Treatments:
- No specific pharmacological treatments are widely recommended; management is largely supportive and focused on symptom relief.
- Consider visual aids or prism glasses to alleviate diplopia. 14Special Populations
Pediatrics: Limited specific data; management focuses on addressing underlying causes and supportive care.
Elderly: Increased vigilance for vascular causes; management similar to general population but with consideration of comorbidities.
Comorbidities: Presence of multiple sclerosis or brainstem infarction influences diagnostic approach and management strategies, emphasizing targeted treatment of the underlying condition. 34Key Recommendations
Perform detailed eye movement analysis including oVEMPs and high-resolution oculography to confirm INO and assess MLF involvement. (Evidence: Moderate) 14
Evaluate for and address underlying causes such as vascular, demyelinating, or compressive lesions to guide specific treatment approaches. (Evidence: Moderate) 13
Utilize compensatory strategies and visual aids to manage symptoms like diplopia, particularly in patients with significant functional impairment. (Evidence: Expert opinion) 14References
1 Kim HJ, Lee JH, Kim JS. Ocular vestibular evoked myogenic potentials to head tap and cervical vestibular evoked myogenic potentials to air-conducted sounds in isolated internuclear ophthalmoplegia. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology 2014. link
2 Thömke F, Hopf HC. Abduction nystagmus in internuclear ophthalmoplegia. Acta neurologica Scandinavica 1992. link
3 Herishanu YO, Sharpe JA. Saccadic intrusions in internuclear ophthalmoplegia. Annals of neurology 1983. link
4 Feldon SE, Hoyt WF, Stark L. Disordered inhibition in internuclear ophthalmoplegia: analysis of eye movement recordings with computer simulations. Brain : a journal of neurology 1980. link
5 Baloh RW, Yee RD, Honrubia V. Internuclear ophthalmoplegia. II. Pursuit, optokinetic nystagmus, and vestibulo-ocular reflex. Archives of neurology 1978. link