A Veteran With Acute Progressive Encephalopathy of Unknown Etiology

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Case Presentation. A 70-year-old US Marine Corps veteran of the Vietnam War with no significant past medical history was brought by ambulance to VA Boston Healthcare System (VABHS) after being found on the floor at home by his wife, awake, but with minimally coherent speech. He was moving all extremities, and there was no loss of bowel or bladder continence. He had last been seen well by his wife 30 minutes prior. When emergency medical services arrived, his finger stick blood glucose and vital signs were within normal range. In the emergency department, he was able to state his first name but then continuously repeated “7/11” to other questions. A neurologic examination revealed intact cranial nerves, full strength in all extremities, and normal reflexes. A National Institute of Health Stroke Scale (NIHSS) was 3, and a code stroke was activated. At the time of presentation, the patient was an active smoker of 15 cigarettes per day for 50 years and did not use alcohol or recreational drugs.

Jonathan Li, MD, Chief Medical Resident, VABHS and Beth Israel Deaconess Medical Center (BIDMC). Dr. Fehnel, the patient’s medical team was most worried about a transient ischemic attack (TIA) or cerebrovascular accident (CVA). Is his presentation consistent with these diagnoses, and what else is on your differential diagnosis?

►Corey R. Fehnel, MD, Neuro-Intensivist, BIDMC, and Assistant Professor of Neurology, Harvard Medical School. This patient is presenting with what appears to be an acute encephalopathy—a sudden onset of global alteration in mental status. The most worrisome underlying etiology for this presentation would be acute stroke, but this is an uncommon cause of acute encephalopathy. The differential diagnosis at this stage remains broad, but a careful neurologic examination can help narrow the possibilities. In particular, I would aim to differentiate an apparent language deficit (ie, aphasia) from a deficit of attention. A key finding that may help is the ability to name high- or low-frequency objects. If the patient can successfully name objects, aphasia is less likely. Based on the limited examination at present, the patient produces some normal speech, but perseverates; therefore, the finding remains nonspecific. My leading diagnoses are complex partial seizure and toxic/metabolic encephalopathy.

►Dr. Li. This patient’s NIHSS score is 3. How do you use this score in your management decisions for the patient?

►Dr. Fehnel. The NIHSS is a useful tool for gauging severity of ischemic and hemorrhagic stroke. However the score is not specific for establishing the diagnosis of stroke. Many common and chronic neurologic problems will score on the NIHSS, so it can never be interpreted in isolation. If the clinical history and complete neurologic examination support the diagnosis of stroke, then the NIHSS can be used with the understanding that it is biased toward anterior circulation strokes, and posterior circulation strokes will score lower even though they are potentially more life threatening.1 In this case, even though a complex partial seizure appears more likely, it is difficult to rule out the possibility of an acute stroke affecting the thalamus or, less likely, a distal middle cerebral artery occlusion. I would consider IV thrombolysis pending further history and neuroimaging results.

►Dr. Li. Initial laboratory data include a hemoglobin of 12.8 mg/dL. The white cell count, platelet count, chemistry panel, liver function tests, thyroid-stimulating hormone, and troponin were within normal range (Table 1).

Serum and urine toxicology screening was negative. Computed tomography (CT) of the head and CT angiogram of the head and neck were negative for acute intracranial abnormality or vessel occlusion. The patient’s mental status improved shortly after, and he was able to recall going to a 7-Eleven convenience store with friends in the morning but had no recollection of subsequent events. He reported no fevers, headache, weakness, vision problems, paresthesia, dysphagia, or gait imbalance. A decision was made to admit the patient for monitoring and workup.


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