Episode 118: Wernicke’s Encephalopathy

Episode 118: Wernicke’s Encephalopathy Dr. Malave explains the diagnosis and treatment of Wernicke’s encephalopathy. Editing and comments by Hector Arreaza.  Written by Maria Fernanda Malave, edited by Hector Arreaza, MD.You are listening to Rio Bravo qWeek Podcast, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California, a UCLA-affiliated program sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home. This podcast was created for educational purposes only. Visit your primary care provider for additional medical advice.Definition.As a reminder for everyone, vitamin B1 and thiamine are the same substance with different names. Wernicke’s encephalopathy (WE) is a neurological syndrome secondary to severe, short-term B1 deficiency. In the past, but less frequently nowadays, it was more commonly associated with alcohol use disorder. However, today we know that any condition that decreases dietary intake and increases thiamine use, or its elimination, puts patients at risk of developing this encephalopathy. Causes:Chronic alcoholism is the most important cause of WE. Around 70-80% of the causes are associated with chronic alcohol consumption. Non-alcoholic WE may be caused by Decreased intake: Some types of WE may be caused by a psychiatric illness that decreases the dietary intake of B1, such as anorexia nervosa, schizophrenia, or dementia. Arreaza: Also, prolonged fasting or starvation.Lack of absorption of B1: Other causes might be related to malabsorptive syndromes, bariatric surgeries, or hyperemesis gravidarumIncreased use of B1: Any disease that increases the use of B1 and, therefore, low levels of thiamine, such as cancer, thyrotoxicosis, and systemic illnesses like infections. High-carb diets are associated with high thiamine use. Also, patients who receive IV glucose w/o supplements are at risk of developing Wernicke’s encephalopathy.Increased elimination of B1: Other causes are related to increased elimination of B1, such as dialysis.Immunodeficiencies: Immunodeficiency syndromes and transplantation also cause WE.Why is thiamine important?Thiamine is one of the main cofactors in three key enzymes for energy metabolism: alpha-ketoglutarate dehydrogenase, pyruvate dehydrogenase, and transketolase. If we go back to biochemistry in med school, we can remember these enzymes play a significant role in the Krebs cycle and pentose phosphate pathways. Thiamine uses Mg+2 as a cofactor, so a magnesium deficiency can mimic WE.Pathophysiology.B1 deficiency causes lactic acid accumulation due to anaerobic glycolysis, leading to neuronal cytotoxic edema and vasogenic edema with petechial hemorrhages. MRI of the brain shows symmetrical hyperintensities, most commonly in the thalamus, mammillary bodies, cerebellum, and the periaqueductal area surrounding the third and fourth ventricles. The diagnosis of WE is made clinically, even though the MRI is a useful complementary tool to the clinical diagnosis. Diagnosis.WE presentation has always been described as the classic triad of ophthalmoplegia (or nystagmus), encephalopathy (confusion or memory impairment), and gait ataxia. However, this presentation is present only in less than 20% of patients, and most of the patients present with a neurologic syndrome that includes 2 out of the classic triad plus nonspecific symptoms such as hallucinations, hypothermia, hypotension, indifference or inattentiveness, seizures, behavioral disturbances, and bilateral lower extremity weakness. In 1997, Caine et al. suggested that a diagnosis of WE can be made if 2 out of 4 of these criteria were present in a patient with ophthalmo