Case Report of Familial Fatal Insomnia and Diagnostic Challenges
Arlinda Deng1, Bogdana Petko2, William Dalrymple3
1Neurology, University of Virginia Medical Systems, 2Neurology, Emory University Hospital, 3Neurology, University of Virginia Health System
Objective:
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Background:
Fatal familial insomnia (FFI) is a rare inherited neurodegenerative prion disease resulting from a mutation of the prion protein gene. It is characterized by autonomic, motor, and cognitive dysfunction, and progressive insomnia. Diagnosis is mainly based on clinical presentation, and management is largely supportive. Here we present a case of FFI, with consent from the patient’s daughter.
Design/Methods:
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Results:

A 55 year old female presented with 9 months of progressive cognitive decline, with more rapid progression 3 months prior to presentation. Early in the course, she exhibited memory loss and diplopia. Later, she had difficulty performing activities of daily living, weight loss, hallucinations, shortness of breath, and abnormal movements. Neurologic exam demonstrated disorientation, diplopia, low amplitude myoclonus with no startle, and clonus at the ankles.

While admitted, she had several episodes of laryngeal stridor, which was investigated by otolaryngology and demonstrated poor adduction of vocal cords. This improved with BiPAP and racemic epinephrine. Diagnostic workup with MRI of the brain, electroencephalogram (EEG), and lumbar puncture (including prion testing such as 14-3-3 and RTQuIC) were unrevealing, though EEG showed paucity of sleep. Full body imaging with computed tomography were unrevealing for sources of malignancy, and vitamin levels were within normal limits. Given reports of difficulty sleeping, a crude sleep study was conducted inpatient which revealed no oxygen desaturations overnight. She was ultimately discharged with plans for an outpatient DaTScan, as atypical parkinsonian conditions such as corticobasal degeneration remained on the differential. Prior to follow up, the patient was re-hospitalized and died from respiratory arrest secondary to viral infection. Postmortem autopsy revealed neuropathological changes consistent with FFI, and diagnosis was also confirmed in genetic testing.

Conclusions:
This case highlights the difficulties in diagnosis of FFI, especially given the rarity of the disease and that initial chief complaint often does not present with insomnia.
10.1212/WNL.0000000000210754
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