A 59-year-old patient with a history of focal epilepsy and prior strokes, presenting with altered mental status (AMS) and bilateral extremities weakness, has a negative computed tomography (CT) scan for acute stroke, subtherapeutic valproic acid (VPA) levels, and worsening acute on chronic kidney disease, with comorbidities including uncontrolled hypertension (Htn) and diabetes mellitus (DM)?

Differential Diagnosis for 59 y/o with AMS and b/l extremities weakness

• Single most likely diagnosis
  • Valproic Acid (VPA) toxicity: The patient has a low VPA level of 38, which may indicate toxicity due to decreased renal function from worsening acute on chronic kidney disease, despite the level being below the therapeutic range. VPA toxicity can cause altered mental status (AMS), weakness, and seizures.
• Other Likely diagnoses
  • Seizure or status epilepticus: Given the patient's history of focal epilepsy, a seizure or status epilepticus could be causing the AMS and bilateral extremities weakness.
  • Hypertensive emergency: Poorly controlled hypertension (Htn) could lead to a hypertensive emergency, causing AMS, weakness, and worsening kidney disease.
  • Diabetic emergency (e.g., diabetic ketoacidosis or hyperosmolar hyperglycemic state): The patient's diabetes mellitus (DM) could be contributing to the AMS and weakness, especially if the blood glucose levels are not well-controlled.
  • Uremic encephalopathy: Worsening acute on chronic kidney disease could lead to uremic encephalopathy, causing AMS, weakness, and other neurological symptoms.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Cerebral vasculitis: Although less likely, cerebral vasculitis could be causing the patient's symptoms, and missing this diagnosis could be devastating.
  • Infectious causes (e.g., meningitis or encephalitis): Infections could be causing the AMS and weakness, and prompt diagnosis and treatment are crucial to prevent serious complications.
  • Intracranial hemorrhage: Although the CT scan was negative for acute stroke, it's essential to consider the possibility of an intracranial hemorrhage, which could be life-threatening if missed.
• Rare diagnoses
  • Mitochondrial disorders: The patient's history of epilepsy, strokes, and worsening kidney disease could be related to a mitochondrial disorder, although this is a rare possibility.
  • Porphyria: Acute intermittent porphyria could cause AMS, weakness, and seizures, although this is a rare condition.