A 76-year-old woman is brought to the emergency department due to altered mental status. Before admission, she had lived independently and had no contact with her family or primary care physician for several months. Past medical history includes type 2 diabetes mellitus, hypertension, and osteoporosis, but she has no history of dementia or alcohol or illicit drug use. The patient's medications include metoprolol, glipizide, hydrochlorothiazide, and alendronate; she has been on these for several years. Her temperature is 36.7 C (98 F), blood pressure is 130/70 mm Hg, pulse is 105/min, and respirations are 16/min. Pulse oximetry is 97% on room air. Examination shows a drowsy woman in no acute distress who is disoriented to time and place. The neck is supple without thyroid enlargement. Cardiopulmonary examination is normal. Pupillary reflexes are intact, but the patient is otherwise not cooperative with neurologic examination. Laboratory studies show normal complete blood count, basic metabolic panel, and urinalysis. Chest x-ray is normal. CT scan of the head shows generalized cerebral atrophy. Lumbar puncture with cerebrospinal fluid analysis is normal. What is the most appropriate next step in evaluation of this patient?

Question

A 76-year-old woman is brought to the emergency department due to altered mental status.  Before admission, she had lived independently and had no contact with her family or primary care physician for several months.  Past medical history includes type 2 diabetes mellitus, hypertension, and osteoporosis, but she has no history of dementia or alcohol or illicit drug use.  The patient's medications include metoprolol, glipizide, hydrochlorothiazide, and alendronate; she has been on these for several years.  Her temperature is 36.7 C (98 F), blood pressure is 130/70 mm Hg, pulse is 105/min, and respirations are 16/min.  Pulse oximetry is 97% on room air.  Examination shows a drowsy woman in no acute distress who is disoriented to time and place.  The neck is supple without thyroid enlargement.  Cardiopulmonary examination is normal.  Pupillary reflexes are intact, but the patient is otherwise not cooperative with neurologic examination.  Laboratory studies show normal complete blood count, basic metabolic panel, and urinalysis.  Chest x-ray is normal.  CT scan of the head shows generalized cerebral atrophy.  Lumbar puncture with cerebrospinal fluid analysis is normal.  What is the most appropriate next step in evaluation of this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c132_4435_8f63_9baf744683be_MD0005_00 The most common causes of mental status change in elderly patients are medications, infections (eg, urinary tract infection, pneumonia), and metabolic abnormalities. Thyroid dysfunction, both hypothyroidism and thyrotoxicosis, also frequently causes mental status change in the elderly, but it may present with nonspecific or atypical symptoms. Thyroid disorders are most likely in patients with a subacute or chronic decline in mental function. Apathetic thyrotoxicosis is an atypical presentation of hyperthyroidism in older patients characterized by lethargy, confusion, and depression. It is often misdiagnosed as dementia, which may be present as well. A high index of suspicion is required for making a diagnosis of apathetic thyrotoxicosis as elderly patients may not have classic manifestations of hyperthyroidism. In this patient, thyroid function tests may quickly and noninvasively provide an etiology for her symptoms. (Choice A) Abnormal findings on arterial blood gas, such as respiratory alkalosis (eg, early sepsis, hepatic encephalopathy, salicylate intoxication) or anion gap acidosis (eg, intoxication, uremia, ketoacidosis), may provide a clue to the etiology of mental status change in some patients. However, it is less likely that this patient has a significant acid-base disorder in light of her normal respiratory rate and metabolic profile. (Choice B) Electroencephalogram (EEG) can be useful in the diagnosis of nonconvulsive status epilepticus, especially in patients showing subtle signs of a convulsive disorder such as nystagmus, hippus (spontaneous episodic pupillary contractions), or automatism (eg, facial twitching). EEG would be considered for this patient if the etiology cannot be determined by simpler tests. (Choice C) Liver function tests are often performed in the evaluation of abnormal mental status but are unlikely to be diagnostic in the absence of other historical (eg, alcohol or intravenous drug abuse) or examination (eg, jaundice) features. (Choice D) The role of brain MRI in evaluation of acute mental status change is not entirely clear. MRI is more sensitive than CT in diagnosis of acute stroke, posterior fossa lesions, and encephalitis. In this patient, an MRI may be considered later if other evaluations are not diagnostic. Educational objective: Elderly patients with thyrotoxicosis may not have classic manifestations. Apathetic thyrotoxicosis is an atypical presentation of hyperthyroidism in older patients that is characterized by lethargy, confusion, and depression. It is often misdiagnosed as dementia. References: Apathetic thyrotoxicosis secondary to atypical subacute thyroiditis. (http://www.ncbi.nlm.nih.gov/pubmed/22548945)

A 76-Year-Old Woman Is Brought to the Emergency Department Due