Differential Diagnosis for Bilateral Esotropia with INO (Internuclear Ophthalmoplegia)

• Single most likely diagnosis:
  • Multiple Sclerosis: This is a common cause of INO, especially in young adults, due to demyelination in the medial longitudinal fasciculus (MLF) of the brainstem.
• Other Likely diagnoses:
  • Stroke or Brainstem Infarct: A vascular event affecting the MLF can lead to INO. This is more common in older adults or those with vascular risk factors.
  • Traumatic Brain Injury: Head trauma can cause damage to the MLF, resulting in INO.
  • Progressive Supranuclear Palsy: A neurodegenerative disorder that can affect the brainstem and cause INO among other symptoms.
• Do Not Miss diagnoses:
  • Wernicke's Encephalopathy: Although rare, this condition is potentially reversible with thiamine treatment and can cause ophthalmoplegia, including INO, along with other neurological symptoms.
  • Brainstem Tumor: Tumors in the brainstem can compress the MLF, leading to INO. Early diagnosis is crucial for treatment.
  • Myasthenia Gravis: An autoimmune disorder that can cause fluctuating muscle weakness, including eye muscles, potentially mimicking INO.
• Rare diagnoses:
  • Neuromyelitis Optica Spectrum Disorder (NMOSD): An autoimmune condition that primarily affects the optic nerve and spinal cord but can also involve the brainstem, leading to INO.
  • Lyme Disease: Neuroborreliosis, the neurological manifestation of Lyme disease, can rarely cause INO.
  • Sjögren's Syndrome: An autoimmune disorder that can have neurological manifestations, including INO, though this is exceedingly rare.