Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 27-year-old man is evaluated for concerns noted by his wife of a marked change in overall behavior over the past 6 months, including deterioration in his general hygiene and episodes of talking to imaginary people. His employer has also raised concerns about his work performance. The patient has also noted intermittent tingling in the hands and feet. Most recent travel includes 2 years in Oxford, England, between 1995 and 1997. Family history is unremarkable.
On physical examination, vital signs are normal. The patient is fully alert, but oriented only to place and person. His gait is ataxic. He scores 14 of 30 (normal >24/30) on the Mini-Mental State Examination. The remainder of the examination is normal.
Routine laboratory studies are normal. Results of urine drug screen, HIV antibody testing, and the rapid plasma reagin test for syphilis are negative. No abnormalities are noted on CT scan of the head, and electroencephalography shows only nonspecific slowing.
Which of the following is the most appropriate next step in management?
A) Brain biopsy
B) Corneal biopsy
C) Intravenous acyclovir
D) Intravenous dexamethasone
E) Tonsillar biopsy
MKSAP Answer and Critique
The correct answer is E) Tonsillar biopsy. This item is available to MKSAP 15 subscribers as item 60 in the Infectious Diseases section. More information about MKSAP 15 is available online.
Variant Creutzfeldt-Jakob disease (vCJD) was first reported in England in 1995 and is caused by bovine-to-human transmission of bovine spongiform encephalopathy. There are many features that distinguish vCJD from CJD, including presentation at a younger age; disease onset marked by psychiatric symptoms, which can lead to a mistaken diagnosis of depression; a slower disease progression; and the presence of PrPSc (an abnormal form of prion protein) in tonsillar biopsies. A brain biopsy is required to confirm a diagnosis of CJD and will also establish the diagnosis of vCJD, but it is more invasive than a tonsillar biopsy, which will provide the presumptive diagnosis in this patient.
Corneal biopsy is one way to establish the diagnosis of rabies. Rabies encephalitis is much more rapidly progressive than is vCJD and is characterized by hydrophobia, aerophobia, pharyngeal spasms, and hyperactivity followed by coma, respiratory and vascular collapse, and death within 2 weeks after coma onset. This patient’s chronic symptoms are not compatible with rabies.
Intravenous acyclovir is appropriate in patients with herpes simplex encephalitis. Clinical features of herpes simplex encephalitis include fever, hemicranial headache, language and behavioral abnormalities, memory impairment, cranial nerve deficits, and seizures as well as MRI findings characterized by edema and hemorrhage in the temporal lobes and hypodense areas and nonhomogeneous contrast enhancement. However, this patient’s clinical tempo and findings are not consistent with herpes encephalitis, and acyclovir has no therapeutic role for vCJD. In fact, there is no effective treatment for vCJD, including corticosteroids.
Key Point
- Variant Creutzfeldt-Jakob disease (vCJD) is characterized by early-onset psychiatric symptoms suggestive of depression, an earlier age of onset than CJD, an absence of periodic sharp waves on electroencephalogram, and presumptive diagnosis by tonsillar biopsy.
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