Differential Diagnosis

• Single most likely diagnosis
  • Vitamin B1 (thiamine) deficiency: The patient's symptoms, including sixth cranial nerve palsy, horizontal diplopia, strabismus, asymmetric horizontal-gaze evoked nystagmus, and a broad-based, uncertain gait, are consistent with Wernicke's encephalopathy, a condition caused by thiamine deficiency. The patient's history of chronic alcoholism and recent increased confusion also support this diagnosis.
• Other Likely diagnoses
  • Magnesium deficiency: Magnesium deficiency can cause neurological symptoms, including confusion, weakness, and gait disturbances. However, the specific eye movement abnormalities and gait pattern described are more characteristic of thiamine deficiency.
  • Folic acid deficiency: Folic acid deficiency can cause neurological symptoms, including confusion and weakness, but it is less likely to cause the specific eye movement abnormalities and gait pattern described.
• Do Not Miss diagnoses
  • Vitamin B12 (cyanocobalamin) deficiency: While less likely, vitamin B12 deficiency can cause neurological symptoms, including weakness, gait disturbances, and confusion. Missing this diagnosis could lead to irreversible neurological damage.
  • Hypoglycemia: Hypoglycemia can cause confusion, weakness, and gait disturbances, and is a common complication of alcoholism. Missing this diagnosis could be life-threatening.
• Rare diagnoses
  • Zinc deficiency: Zinc deficiency can cause neurological symptoms, including confusion and weakness, but it is a rare cause of the specific symptoms described.
  • Other nutritional deficiencies: Other nutritional deficiencies, such as niacin or pyridoxine deficiency, can cause neurological symptoms, but are less likely to cause the specific symptoms described.