Q8 Infectious Diseases St George 2002

Q8 Infectious Diseases St George 2002 Which is the least likely symptom associated with CJD? a) myoclonus b) dementia c) areflexia d) visual field abnormalities e) ………..

Rapidly progressive mental deterioration and myoclonus are the two cardinal clinical manifestations of sCJD. However, a number of variants or subtypes of disease have been defined based upon focal neurologic findings reflecting predominant involvement of one region of the brain. Examples of these include forms with mainly visual, cerebellar, thalamic, and striatal features. Mental deterioration may be manifest as dementia, behavioral abnormalities and deficits involving higher cortical function. Concentration, memory and judgment difficulties are frequent early signs. Mood changes such as apathy and depression are common; euphoria, emotional lability, and anxiety occur less frequently. With disease progression, dementia becomes dominant in most patients and can advance rapidly. Death usually occurs within one year.

Myoclonus, especially provoked by startle, is present in more than 90 percent of patients. sCJD should always be considered in a patient with the combination of a rapidly progressive dementia and myoclonus. Extrapyramidal signs such as hypokinesia and cerebellar manifestations including nystagmus and ataxia occur in approximately two- thirds of patients. Signs of corticospinal tract involvement develop in 40 to 80 percent of patients, which include such findings as hyperreflexia, extensor plantar responses (Babinski sign), and spasticity.

Variant CJD:

These patients were distinguished from cases of typical sCJD by:

• A considerably younger age at the onset of symptoms • Less rapid progression of illness • Differences in clinical presentation • Differences in neuropathology

The mean age at onset of vCJD in the initial report was 29 years (range 16 to 48 years) compared to 65 years for sCJD. However, a patient presenting with vCJD at age 74 has subsequently been described. The mean duration of illness for vCJD is longer than for sCJD (14 versus 4 to 5 months) although both diseases are uniformly fatal. Patients with vCJD in contrast to sCJD frequently displayed prominent sensory disturbances and psychiatric symptoms. Sensory abnormalities included dysesthesias and paresthesias of the face, hands, feet, legs or even the hemibody. Unlike sCJD, the 14-3-3 is not a sensitive marker for vCJD. PRNP gene mutations are not present in vCJD, but all patients have been homozygous for methionine at codon 129. Type 4 PrPSc, which is not characteristic of other human prion diseases, has also been found in patients with vCJD