An 18-year-old man is brought to the emergency department following a generalized tonic-clonic seizure. He developed full body jerking at home this morning, which lasted approximately 1 minute. The episode occurred just before the patient was about to visit the clinic for evaluation of a worsening headache for the past 2 days. His parents say that he has also seemed clumsy over the same period, including tripping a few times yesterday. He has no history of seizures and was previously healthy except for seasonal allergies managed with over-the-counter medications. Temperature is 38.9 C (102 F), blood pressure is 130/80 mm Hg, and pulse is 92/min. The patient is awake but oriented only to person. Pupillary examination is unremarkable. The patient has bilateral hyperreflexia in the upper and lower extremities. MRI of the brain is shown below: Which of the following is the most likely diagnosis for this patient?

Question

An 18-year-old man is brought to the emergency department following a generalized tonic-clonic seizure.  He developed full body jerking at home this morning, which lasted approximately 1 minute.  The episode occurred just before the patient was about to visit the clinic for evaluation of a worsening headache for the past 2 days.  His parents say that he has also seemed clumsy over the same period, including tripping a few times yesterday.  He has no history of seizures and was previously healthy except for seasonal allergies managed with over-the-counter medications.  Temperature is 38.9 C (102 F), blood pressure is 130/80 mm Hg, and pulse is 92/min.  The patient is awake but oriented only to person.  Pupillary examination is unremarkable.  The patient has bilateral hyperreflexia in the upper and lower extremities.  MRI of the brain is shown below:  Which of the following is the most likely diagnosis for this patient?

Quizplus · Accepted Answer

11ec25c8_d58d_ced5_bc81_29fce69f2f5c_MD0003_00 This patient has fever, headache, seizure, and altered mental status suggestive of viral encephalitis, a life-threatening inflammation of the brain parenchyma. Symptoms develop acutely (over <1 week), and seizure with fever is a common presentation. All patients have altered mental status (eg, disorientation, somnolence), and focal neurologic findings (eg, ataxia, hyperreflexia, cranial nerve palsies) may be present on examination. A common cause of viral encephalitis is herpes simplex virus (HSV), arising from either primary or reactivated infection. Spread of primary infection likely occurs via the olfactory bulb to the olfactory cortex (within the temporal lobe) whereas reactivated HSV spreads from the trigeminal ganglion (where HSV typically remains dormant) to the adjacent temporal lobe. Therefore, temporal lobe abnormalities on imaging, such as hemorrhage or edema, are highly suggestive of HSV. Cerebrospinal fluid analysis in HSV encephalitis usually reveals elevated white blood cells, red blood cells, and protein with normal glucose; HSV DNA on PCR is diagnostic. temporal lobe abnormalities While awaiting confirmatory testing, empiric intravenous acyclovir should be started for suspected HSV encephalitis due to significant morbidity and mortality of untreated disease. (Choice A) Drug-induced encephalopathy due to excessive anticholinergic medication (eg, first-generation antihistamine) can cause delirium and seizures. However, additional symptoms such as urinary retention and pupillary dilation would be expected. In addition, temporal lobe abnormalities would not be seen. (Choice C) Medulloblastoma is a malignant brain tumor arising from the cerebellum. Signs of increased intracranial pressure (eg, morning headache, vomiting), ataxia, and cranial nerve deficits are typical. A cerebellar mass (not temporal lobe abnormalities) would be seen on MRI. (Choice D) Reye syndrome is characterized by encephalopathy with liver dysfunction and can present in children with altered mental status and generalized seizures after a viral illness. However, hepatomegaly and generalized cerebral edema without focal findings would be expected. (Choice E) Subacute sclerosing panencephalitis is a fatal complication of measles that progresses from personality changes to dementia and death over months to years. This patient has acute neurologic findings and no history of measles. Educational objective: Viral encephalitis typically presents with altered mental status in addition to fever, headache, seizure, and focal neurologic findings. Temporal lobe abnormalities and edema are highly suggestive of herpes simplex virus encephalitis. References: Herpes simplex virus-1 encephalitis in adults: pathophysiology, diagnosis, and management. (http://www.ncbi.nlm.nih.gov/pubmed/27106239) Acute encephalitis - diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/29626021)

An 18-Year-Old Man Is Brought to the Emergency Department Following