Differential Diagnosis for the Presented Case

The patient, a 48-year-old lady, presents with a 1-day history of giddiness, 2 days of blurred vision (BOV), and associated symptoms such as nausea, polydipsia, polyuria, and nocturia, without significant neurological deficits or systemic symptoms. Her past medical history includes hypertension, which she had defaulted on follow-up. The examination findings include impaired horizontal gaze, multidirectional nystagmus, impaired accommodation, and normal pupil size and reactivity. The key findings and history guide the differential diagnosis into the following categories:

• Single Most Likely Diagnosis
  • Hypertensive Emergency with Posterior Circulation Infarct: The patient's extremely high blood pressure (256/121 mmHg) and symptoms such as giddiness, blurred vision, and nystagmus point towards a hypertensive emergency. The posterior circulation (which includes the brainstem, cerebellum, and parts of the temporal and occipital lobes) is often affected in such cases, leading to visual disturbances and balance issues.
• Other Likely Diagnoses
  • Demyelinating Disease (e.g., Multiple Sclerosis): Although less likely given the acute presentation and the presence of hypertension, demyelinating diseases can cause similar neurological symptoms, including vision problems and nystagmus.
  • Ischemic Stroke: Given the patient's history of hypertension and the acute onset of neurological symptoms, an ischemic stroke in the posterior circulation is a plausible diagnosis.
  • Neoplastic Lesions: Tumors in the brainstem or posterior fossa could cause similar symptoms, including cranial nerve palsies and visual disturbances.
• Do Not Miss Diagnoses
  • Pituitary Apoplexy: Although rare, pituitary apoplexy can present with sudden visual loss, headache, and altered mental status. It's a medical emergency requiring prompt intervention.
  • Diabetic Ketoacidosis or Hyperosmolar Hyperglycemic State: Given the patient's symptoms of polydipsia, polyuria, and weight loss, a metabolic emergency such as DKA or HHS should be considered, especially if there's a suspicion of undiagnosed diabetes.
  • Wernicke's Encephalopathy: This condition, caused by thiamine deficiency, can present with nystagmus, ophthalmoplegia, and confusion. It's a medical emergency that requires immediate treatment.
• Rare Diagnoses
  • Inflammatory or Autoimmune Conditions (e.g., Lupus, Sarcoidosis): These conditions can cause a wide range of neurological and systemic symptoms but are less likely given the patient's presentation and lack of other systemic symptoms.
  • Endocrine Disorders (e.g., Thyroid Storm, Adrenal Insufficiency): While endocrine disorders can cause significant systemic and neurological symptoms, they are less likely in this case without other supporting symptoms or history.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and laboratory findings to determine the most appropriate course of action.