Differential Diagnosis for the Patient's Condition

The patient's symptoms suggest a complex neurological condition. Here's a breakdown of the differential diagnosis:

• Single most likely diagnosis

  • Brainstem stroke (specifically, a lesion in the midbrain or pons): The combination of vertical double vision, weakness, and decreased coordination on one side of the body, along with the specific eye deviation and improvement with head tilt, points towards a brainstem lesion. The brainstem's compact structure means that even small lesions can cause multiple, seemingly unrelated symptoms.

• Other Likely diagnoses

  • Cranial nerve III (oculomotor nerve) palsy: This could explain the eye deviation and double vision, especially if it's a pupil-sparing palsy, which is more common in diabetic or hypertensive patients. However, it wouldn't fully account for the weakness and coordination issues on one side of the body.
  • Cerebellar stroke: While this could cause coordination issues and weakness, it's less likely to cause the specific eye findings described.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • Posterior communicating artery aneurysm: Although less likely, an aneurysm pressing on the third cranial nerve could cause similar eye symptoms. Missing this diagnosis could be catastrophic if the aneurysm ruptures.
  • Basilar artery occlusion: This is a medical emergency that can present with a variety of neurological deficits, including those described. Prompt recognition and treatment are crucial to prevent severe brainstem injury or death.

• Rare diagnoses

  • Wernicke's encephalopathy: This condition, often associated with alcohol abuse and thiamine deficiency, can cause ophthalmoplegia, ataxia, and confusion. However, the specific pattern of weakness and the improvement with head tilt are not typical.
  • Tolosa-Hunt syndrome: This rare condition involves non-specific inflammation of the cavernous sinus or superior orbital fissure and can cause ophthalmoplegia and pain. It's less likely given the additional neurological findings.