A middle-aged woman is found wandering the streets with an abnormal gait. She is brought to the hospital by police officers. When asked for identification, the patient mumbles incoherently. She is not oriented to time or place. Her temperature is 36.2 C (97.3 F), blood pressure is 160/100 mm Hg, pulse is 100/min, and respirations are 18/min. BMI is 17 kg/m2. Head and neck examination shows bitemporal wasting and dry mucous membranes. The pupils are 3 mm bilaterally and react slowly to light. Her neck is supple, and she moves all extremities equally. Deep-tendon reflexes are symmetrical bilaterally. Which of the following is the best initial treatment for this patient?
Causes of altered mental status | |
Drugs/toxins |
|
Infections |
|
Metabolic |
|
Central nervous system |
|
Altered mental status (AMS), as in this patient, suggests widespread dysfunction of the cerebral cortex and/or reticular activating system. AMS can be due to a broad spectrum of disorders, including psychiatric illness, substance intoxication/withdrawal, infection, metabolic derangements (eg, hypoglycemia, hypernatremia), primary central nervous system disorders (eg, seizures), trauma, or organ dysfunction (respiratory, liver, or renal failure).
Chronic malnutrition, especially in the setting of alcoholism, can lead to thiamine (vitamin B1) deficiency with progression to Wernicke encephalopathy (WE). WE typically presents with the classic triad of encephalopathy, ocular dysfunction, and gait ataxia. Giving thiamine promptly in suspected WE may prevent further complications. Thiamine is a cofactor in many enzymes required for energy metabolism, and giving intravenous fluids containing glucose prior to thiamine can precipitate or worsen WE. Therefore, thiamine should be given along with or before glucose. When the cause of AMS is not apparent after initial assessment, empiric treatment for likely causes (eg, WE) is often appropriate.
(Choice A) Flumazenil is a competitive antagonist of the GABA/benzodiazepine receptor and is used to treat benzodiazepine overdose. Patients typically have slurred speech, ataxia, hypotension, and depressed mental status. This patient's hypertension makes this unlikely.
(Choice B) Haloperidol is an antipsychotic medication used to treat schizophrenia and acute psychotic states. However, this patient should have medical causes of altered mental status excluded before receiving haloperidol.
(Choice C) Labetalol can treat hypertensive encephalopathy, which usually presents with blood pressure >180/120 mm Hg, headache, nausea, vomiting, and confusion. This patient's moderate blood pressure elevation is more likely due to the underlying condition and will likely resolve after appropriate treatment.
(Choice D) Naloxone is an opioid antagonist used to treat opioid overdose, which typically presents with pinpoint pupils and respiratory depression (respirations usually <12/min).
Educational objective:
Wernicke encephalopathy is due to thiamine (vitamin B1) deficiency and is most commonly seen in malnourished patients with underlying alcoholism. Features include encephalopathy, ocular dysfunction, and gait ataxia. Patients should be treated empirically with thiamine prior to or along with glucose administration.