A 9-year-old girl is brought to the emergency department following a 3-minute generalized seizure. She has had a fever with a worsening headache for 3 days. The girl has no medical problems and is not taking any medications. She lives with her parents and pet cat and has traveled to Canada and England. On physical examination, she is disoriented and has difficulty staying awake. Her speech is difficult to understand due to inappropriate word choice. She is admitted to the intensive care unit for further workup. The patient becomes unresponsive the following day and dies overnight. Autopsy reveals bilateral, hemorrhagic necrosis of the inferior and medial temporal lobes. This patient's condition was most likely caused by infection with which of the following?

Question

A 9-year-old girl is brought to the emergency department following a 3-minute generalized seizure.  She has had a fever with a worsening headache for 3 days.  The girl has no medical problems and is not taking any medications.  She lives with her parents and pet cat and has traveled to Canada and England.  On physical examination, she is disoriented and has difficulty staying awake.  Her speech is difficult to understand due to inappropriate word choice.  She is admitted to the intensive care unit for further workup.  The patient becomes unresponsive the following day and dies overnight.  Autopsy reveals bilateral, hemorrhagic necrosis of the inferior and medial temporal lobes.  This patient's condition was most likely caused by infection with which of the following?

Quizplus · Accepted Answer

11ec160b_387e_387f_9249_83f7eb74f96f_MD0001_00 Herpes simplex virus type 1 (HSV-1) encephalitis is the most common cause of fatal sporadic encephalitis, or inflammation of the brain parenchyma. HSV-1 encephalitis results from primary oropharyngeal infection that travels via the olfactory tract or from the reactivation of latent virus in the trigeminal ganglion with subsequent spread into the cerebral vault. CT, MRI (red arrow), and post-mortem macroscopic brain examination reveal edema and hemorrhagic necrosis of the temporal lobe. Unilateral involvement is most common, but bilateral necrosis can also occur. Definitive diagnosis is made by polymerase chain reaction testing of cerebrospinal fluid. Symptoms of acute encephalitis include acute onset of headache, fever, mental status changes (eg, lethargy, disorientation), cranial nerve deficits (eg, Bell's palsy), and seizures. Temporal lobe damage can result in receptive aphasia and personality changes (eg, hypersexuality, aggression). (Choice A) Enterovirus, particularly group B coxsackievirus, is the most common cause of viral meningitis in children. Less commonly, enterovirus causes encephalitis and acute flaccid paralysis, but temporal lobe involvement is not typical. (Choice C) Naegleria fowleri is a free-living, protozoan parasite that causes rapid meningoencephalitis with a high mortality rate. N fowleri is found in fresh water, and transmission occurs through nasal inhalation during recreational activities (eg, swimming, diving). After spread through the cribriform plate to the olfactory cortex, infection leads to symptoms of encephalitis, as described above, in addition to smell and taste abnormalities. Inflammation can be seen in the frontal and temporal lobes, brainstem, and meninges. (Choices D and E) Neisseria meningitidis and Streptococcus pneumoniae are the 2 most common causes of bacterial meningitis. Unlike encephalitis, meningitis does not affect the brain parenchyma; rather, infection of the connective tissue layers of the brain leads to classic symptoms of fever, nuchal rigidity, and altered mental status. (Choice F) Immunocompromised hosts (eg, patients with HIV) are predisposed to opportunistic pathogens (eg, Toxoplasma gondii, cytomegalovirus [CMV]) that can cause encephalitis. Toxoplasma encephalitis is classically associated with ring-enhancing lesions (white arrows) in the parietal or frontal lobes after ingestion of oocysts from soil or cat litter. CMV encephalitis can lead to parenchymal micro-nodules and ventricular enlargement. Educational objective: Herpes simplex virus type 1 encephalitis is a potentially fatal complication from primary infection or reactivation of latent disease. Nervous system invasion leads to necrosis of the temporal lobe, which can result in aphasia and personality changes in addition to classic features of encephalitis (eg, headache, fever, altered mental status, seizure). __________ References: Herpes simplex encephalitis: adolescents and adults. (http://www.ncbi.nlm.nih.gov/pubmed/16675036) Herpes simplex encephalitis: from virus to therapy. (http://www.ncbi.nlm.nih.gov/pubmed/21488834)

A 9-Year-Old Girl Is Brought to the Emergency Department Following