Abstract
Inter-nuclear ophthalmoplegia (INO) may not always have overt or obvious clinical signs during bedside examination. In patients presenting with mild/subtle INO with no focal neurological deficits or cerebellar signs, an unremarkable radiographic imaging and blood work, diagnosis will be challenging. Results of bedside head thrust tests will also be confounded and difficult to interpret, leading to discordant impressions among physicians of different specialties. Patients with mild INO will still require active surveillance to watch for any progression and development of clinical signs and should be managed by neuro-ophthalmology specialty. Video-oculography can assist with the interpretation of bedside head thrust and reveal slowing of adduction that is otherwise not obvious bedside. This has downstream implications on the management of patients with mild INO as they may be “volleyed” among different medical specialties if covert bedside signs are overlooked. Greater caution is needed on interpreting positive head thrust/video head impulse test as a peripheral vestibular sign in the presence of disconjugate oculomotor movements. Patients with mild INO may be relatively asymptomatic but may still have some functional impairments that should be addressed appropriately.
5. Clinical PEARL
1) Interpret bedside head thrust with caution as a peripheral sign when nystagmus or eye movements are disconjugate.
2) Subtle clinical signs may require video-oculography to assist in the diagnosis and management of INO patients especially in the absence of other neurological signs.
3) Multi-disciplinary team of health professionals needed with good conceptual and procedural knowledge of INO needed to minimize “patient volleying” among departments.
4) Mild/subtle INO requires active surveillance and should be treated similarly to patients with overt INO.
