A 52-year-old man is evaluated for ongoing cognitive difficulties. For the past 2 months, he has been sleeping 12-16 hours daily, much more than he usually does. When he is awake, he is withdrawn and less socially engaged than normal. During this time, the patient has had trouble driving, sideswiping cars on the right side of the road more than once. He also has had several falls, which he attributes to feeling off-balance. Vital signs are normal. The patient scores 22/30 (normal: ≥26) on the Montreal Cognitive Assessment. A partial right homonymous hemianopsia is noted. Motor and reflex examinations are normal with intact vibratory sensation. He exhibits dysdiadochokinesia and dysmetria on testing of his upper and lower extremities along with a wide-based gait. CT scan of the head is normal. Real-time quaking-induced conversion testing of his cerebrospinal fluid is positive. This patient will most likely develop which of the following?

Question

A 52-year-old man is evaluated for ongoing cognitive difficulties.  For the past 2 months, he has been sleeping 12-16 hours daily, much more than he usually does.  When he is awake, he is withdrawn and less socially engaged than normal.  During this time, the patient has had trouble driving, sideswiping cars on the right side of the road more than once.  He also has had several falls, which he attributes to feeling off-balance.  Vital signs are normal.  The patient scores 22/30 (normal: ≥26) on the Montreal Cognitive Assessment.  A partial right homonymous hemianopsia is noted.  Motor and reflex examinations are normal with intact vibratory sensation.  He exhibits dysdiadochokinesia and dysmetria on testing of his upper and lower extremities along with a wide-based gait.  CT scan of the head is normal.  Real-time quaking-induced conversion testing of his cerebrospinal fluid is positive.  This patient will most likely develop which of the following?

Quizplus · Accepted Answer

11ec25c8_d580_6141_bc81_8d5bd01f085e_MD0003_00 This patient has rapidly progressive cognitive decline, personality changes, hypersomnia, visual field defects (eg, sideswiping cars), and cerebellar dysfunction (eg, falls, dysdiadochokinesia, dysmetria). A positive CSF real-time quaking-induced conversion test (RT-QuIC) confirms a diagnosis of Creutzfeldt-Jakob disease, a rapidly fatal transmissible spongiform encephalopathy caused by an abnormally folded protein (ie, prion). In addition to these clinical features, patients usually develop myoclonus, which is classically provoked by a startle. CJD causes widespread, noninflammatory neurodegeneration affecting both the cerebrum and cerebellum. Because CJD is noninflammatory, standard CSF findings are often unremarkable (ie, no white blood cells, normal glucose, normal or mildly elevated protein) or nonspecific (eg, elevated 14-3-3 protein, elevated tau protein). An RT-QuIC test can also be performed which has significantly greater sensitivity and specificity for CJD. Abnormally folded proteins are isolated, amplified, and then incubated with normally folded proteins. A prion-induced conformational change in the normal proteins can be observed in real time via fluorescence detection. (Choice A) Cogwheel rigidity is classically associated with Parkinson disease. Although Parkinson disease can also present with behavior changes and cognitive impairment, its cardinal features include bradykinesia and resting tremor. It would not explain this patient's visual field deficits, cerebellar dysfunction, and rapidly deteriorating course. (Choice B) Flaccid paralysis can occur with Guillain-Barré syndrome and some neurologic infections (eg, West Nile virus, polio). However, CJD affects the upper motor neurons, so patients classically develop hyperreflexia, increased tone, and myoclonus rather than flaccidity. (Choice C) Damage to cranial nerves can result in vision defects. However, homonymous hemianopsia occurs with lesions distal to the optic chiasm; in CJD, this is due to neurodegeneration of the visual cortex in the occipital lobe. Deficits due to CJD follow cortical patterns and do not typically affect the cranial nerves. homonymous hemianopsia (Choice E) Peripheral neuropathy can lead to gait disturbances and falls. However, a wide-based gait, dysdiadochokinesia, and dysmetria suggest cerebellar dysfunction rather than peripheral neuropathy. Educational objective: Creutzfeldt-Jakob disease is a fatal prion disease that presents with rapidly progressive dementia, often accompanied by personality changes, visual cortex dysfunction, hypersomnia, and myoclonus. A positive real-time quaking-induced conversion test demonstrating prion-induced conformational changes in fluorescent-labeled proteins is the most sensitive and specific diagnostic test. References: RT-QuIC: a new test for sporadic CJD. (http://www.ncbi.nlm.nih.gov/pubmed/30282760) Creutzfeldt-Jakob disease. (http://www.ncbi.nlm.nih.gov/pubmed/28028861)

A 52-Year-Old Man Is Evaluated for Ongoing Cognitive Difficulties