Published on 03/03/2015 by admin
Filed under Neurology
Last modified 03/03/2015
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19 Transmissible Spongiform Encephalopathy (Creutzfeldt–Jakob Disease)
Yuval Zabar
A 56-year-old man noted increasing clumsiness while writing. A tremor developed in his right hand, and he soon noted slurred speech over 2–3 weeks. Initial neurologic evaluation demonstrated an action tremor in the right hand and some reduction in fine dexterity. Brain magnetic resonance imaging (MRI) and electroencephalography (EEG) results were normal. During the next 2 months, the patient’s wife believed that her husband became increasingly confused, as illustrated by his calling her by his sister’s name. He had trouble initiating and maintaining sleep. His driving became erratic and dangerous. He was pulled over for driving too slowly and his license was revoked. On follow-up examination, 4 months later, he was disoriented. He spoke slowly and gave inappropriate responses. His dysarthria was more pronounced.
The results of repeated MRI and EEG were normal, as were cerebrospinal fluid (CSF) study results, including protein 14-3-3. Over the next 6 months, the patient’s cognitive and motor function declined precipitously. His gait became progressively ataxic, and he fell numerous times. He lost proper use of his hands and legs, requiring assistance with eating, dressing, and bathing. Occasionally, his limbs would jerk suddenly, and he appeared startled and anxious. Speech output became largely unintelligible and palilalic. He would shout occasionally but mostly stayed quiet and passive.
Repeated EEG showed generalized slowing and intermittent periodic sharp waves, approximately 1 per second. Another MRI now demonstrated bright lesions on T2-weighted and flair imaging. Right frontal lobe biopsy showed vacuolar encephalopathy consistent with a transmissible spongiform encephalopathy (TSE). The final stages were characterized by increasing stupor and aspiration pneumonia. The patient died 14 months after onset. Autopsy confirmed the diagnosis.
Transmissible spongiform encephalopathy includes rare, subacute, universally fatal neurodegenerative diseases affecting humans and animals. Clinical presentation and distribution of pathologic lesions vary widely, complicating classification of these diseases. Classification focuses on pathogenic mechanisms rather than clinical and pathologic features. Currently, human TSE is classified into three categories: sporadic, familial, and infectious. Most animal TSE cases fall into the infectious category, including scrapie (sheep); bovine spongiform encephalopathy (BSE), also known as mad cow disease (cattle); and chronic wasting disease (deer and elk). The sporadic form of human TSE, Creutzfeldt–Jakob disease (CJD), accounts for 85% of cases of this disorder. Sporadic fatal insomnia cases are also described. The inherited form of human TSE, accounting for 15% of cases, includes familial CJD, fatal familial insomnia, Gerstmann–Straussler–Scheinker disease, and other less well defined clinical syndromes.
The human epidemic forms of TSE, comprising less than 1% of cases, include iatrogenic cases of CJD (exposure via dural grafts, infected surgical instruments, and growth hormone injections), kuru (cannibalism), and variant CJD (vCJD; via ingestion of beef contaminated with BSE). In theory, transfusion of any blood product from an affected patient may pose a risk. To date, only a handful of vCJD cases are attributed to transmission from blood transfusion, much fewer than might be expected given the number of blood transfusions worldwide. There seems to be increased risk of CJD among venison eaters, although this is difficult to confirm. The incidence of human TSE is approximately 1.5/1 million people per year. This rate has remained stable over several decades.
The appearance of symptoms after exposure to “infected” tissue varies widely, and incubation periods lasting several decades are described. One hundred sixty-three vCJD cases have been reported in Europe since 1996. These occurred predominantly in the United Kingdom, where most cases of BSE occurred. No instances of vCJD originated in the United States. Given the potentially long incubation period (several years) of vCJD, all cases of TSE are reported and monitored by several European surveillance centers. A similar laboratory, the National Prion Diseases Pathology Surveillance Center, operates in the United States.
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