Differential Diagnosis

The patient's symptoms of persistent horizontal diplopia and dizziness, worsened after a severe head cold, and the lack of improvement after multiple eye muscle surgeries, suggest a complex underlying condition. The following differential diagnoses are considered:

• Single most likely diagnosis
  • Myasthenia Gravis: This autoimmune disorder can cause fluctuating muscle weakness, including eye muscles, leading to diplopia. The worsening of symptoms in the morning and after a viral illness, such as a head cold, is consistent with Myasthenia Gravis. The positive results for Sjogren's syndrome also suggest an underlying autoimmune component.
• Other Likely diagnoses
  • Thyroid Eye Disease: This condition can cause diplopia, dizziness, and balance issues, especially if there is a significant inflammatory component. The patient's symptoms and history of multiple eye muscle surgeries make this a plausible diagnosis.
  • Cranial Nerve Palsy (e.g., sixth nerve palsy): A head cold or viral illness can cause or exacerbate a cranial nerve palsy, leading to horizontal diplopia. The persistence of symptoms despite eye muscle surgeries suggests a possible underlying cranial nerve issue.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Brainstem or Cerebellar Stroke: Although less likely, a stroke in the brainstem or cerebellum can cause diplopia, dizziness, and balance issues. Given the patient's severe and persistent symptoms, it is essential to rule out a cerebrovascular event.
  • Multiple Sclerosis: This demyelinating disease can cause a wide range of symptoms, including diplopia, dizziness, and balance issues. The patient's history of a severe head cold and positive results for Sjogren's syndrome make this a possible, albeit less likely, diagnosis.
• Rare diagnoses
  • Superior Oblique Myokymia: This rare condition causes intermittent, involuntary contractions of the superior oblique muscle, leading to diplopia and other eye movement abnormalities.
  • Whiplash-associated Disorder: Although the patient's symptoms started after a head cold, it is possible that an underlying whiplash injury or other trauma contributed to her condition. This diagnosis would require further investigation into the patient's history and physical examination.