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Understanding Dementia: Creutzfeldt-Jakob Disease - DementiaGuide.com
   
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Understanding Dementia

Creutzfeldt-Jakob Disease

This is an excerpt from the book Understanding Dementia, which is meant to be a practical manual for primary care physicians and other health care professionals. Dementia exists when impairment with cognition (e.g. memory , language, calculation) is severe enough to interfere with function. Chapter Three notes that there are many cause of dementia, however, and the point is made that many can be distinguished from Alzheimer's disease by features such as their onset and rate of progression . Creutzfeldt-Jakob Disease illustrates this.



Thankfully rare, Creutzfeldt-Jakob Disease (CJD) is a truly horrifying illness. This rapidly progressive dementia can strike at any age, but usually presents in the 5th and 6th decades. Patients typically have memory complaints and language abnormalities. Myoclonus commonly occurs after only a few months, and heralds typical EEG abnormalities and rapid progression (within another few months) to complete disability and death. A small proportion of cases are inherited, some are caused by exposure to infectious tissue (such as dura mater grafts or human growth hormone ), but the majority of cases are sporadic . A small outbreak of a new form of Creutzfeldt-Jakob disease in Great Britain and Europe seems to be related to bovine spongiform encephalopathy. Although, this disease remains very rare, the recent outbreak of variant CJD in England, and fears regarding the blood supply, have made this disease the focus of much public attention.

Chapter 3: Case 1
Mrs C, a 62-year-old woman, presented with functional decline, memory loss and disorientation of one month's duration. According to a close family member (who had been away for a month) the patient had been a capable, active member of her community. Now, after the family member's return, the situation was dramatically different. She could no longer run her household; her finances were in disarray. She had difficulty dressing, and on more than one occasion had put clothing on inside out or backwards. Her memory was poor. She had become lost while driving and driven through red lights. Her appetite had diminished, and she had lost twenty pounds.

She had a history of elevated cholesterol and was taking pravastatin and enteric-coated aspirin. There was no family history of dementia.

General physical and neurological examinations were remarkable only for their unremarkability. She was disinhibited, often laughing or giggling inappropriately. The MMSE score was 19/30. She mis-remembered the number of her siblings and could not remember all of their names. She could not count backwards from 10 to 1.

Commentary
The rate of decline is not typical of Alzheimer's disease. If her family member had been absent for a year and noticed a change Alzheimer's disease would be a possibility; the excellent history of a change occurring over the space of a month makes Alzheimer's disease highly unlikely. The cognitive exam revealed severe concentration defects with a moderately impaired memory; in general, Alzheimer's disease manifests as globally consistent cognitive impairment , not patchy deficits.

One diagnosis carefully to consider is vascular dementia. We would expect, in a patient with this degree of cognitive impairment, at least some non-specific neurologic or vascular signs, if not obvious focal findings. Although elevated cholesterol puts her at risk and vascular dementia is, on a population basis, the most common cause of sudden cognitive _decline, it is a remote possibility in this case. Other focal intracerebral pathology, such as a tumour or arterio-venous malformation, is unlikely for the same reasons.

Another remote possibility is depression . A death had occurred in the family several months earlier, and impairment of concentration is prominent in depression. Although depressed patients may let their homes run down and have less concern for themselves, they would rarely become genuinely lost while driving and do not put their clothes on inside-out.

Delirium needs to be considered in any patient with rapid cognitive decline. The normal level of consciousness and consistency (as opposed to fluctuation) of her symptoms argue against delirium. In most cases of delirium a standard history and physical will identify an underlying illness, none of which were identified in this case. She is taking no drugs which could be implicated.

The condition most consistent with a global cognitive defect progressing rapidly, manifesting a patchy pattern and associated with marked functional decline, is Creutzfeldt-Jakob disease. Because of the rapid decline this is an appropriate case for urgent referral to a specialist .

Mrs C was admitted to hospital where laboratory investigations, a lumbar puncture, CT scan and EEG were done. Everything other than the EEG was normal. The EEG, though showing abnormal sharp wave activity, did not demonstrate the characteristic periodic complexes of Creutzfeldt-Jakob disease.

Commentary
With normal laboratory tests delirium is very unlikely. The normal CT scan virtually excludes vascular dementia. Creutzfeldt-Jakob disease seems to be the only reasonable explanation, and the EEG, while not diagnostic, is supportive.
It is not our practice to obtain an EEG routinely. We find it useful in two situations: when the dementia is very unusual, and a specific pattern may be helpful diagnostically (as in the current case), or when we are uncertain if someone truly has important cognitive impairment, and the presence of non-specific slowing of the EEG would increase our confidence.

She declined rapidly in hospital, progressing through incessant wandering to muteness to a bedbound state. Late in the disease course startle myoclonus evolved, and at this point the EEG did demonstrate the characteristic findings. She stopped eating or drinking and died one month after presentation. Creutzfeldt-Jakob disease was confirmed pathologically.

Commentary
Some may argue that an accurate diagnosis in this case is not necessary, as no effective treatment is available. On the contrary, patients with Creutzfeldt-Jakob disease are excluded from organ donation (even corneas) and the autopsy suite needs to take special precautions, requiring advance notice. There is currently an interest in the potential effects on the blood supply of Creutzfeldt-Jakob disease, and local blood authorities should be notified if the patient had been a donor.



Taken from Understanding Dementia: A Primer of Diagnosis and Management
Kenneth Rockwood & Chris MacKnight, 2001
Chapter 3, pp 37-39

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About Dementia > Types of Dementia > Creutzfeldt-Jakob Disease
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Last updated June 21, 2017
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