FATAL FAMILIAL INSOMNIA

Transcription

1 Azienda ASL 9 TREVISO Presidio Ospedaliero di Treviso Dipartimento di Medicina Unità Operativa di Medicina Interna Seconda Responsabile dr Ignazio Roiter FATAL FAMILIAL INSOMNIA Dr I. ROITER

2 FATAL FAMILIAL INSOMNIA (FFI) FFI is an autosomal dominant prion disease, characterized by Sleep loss Dysautonomia Motor signs Endocrinological disturbances

3 PATHOLOGY FFI is thus a prion disease selectively damaging the talamocortical limbic structures, i.e. The anterior ventral and mediodorsal thalamic nuclei The cingulate gyrus The orbito-frontal cortex

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5 Thalamus

6 THALAMUS - MedioDorsal Nucleus FFI Control

7 GENETIC FFI is linked to a missense mutation at codon 178 of the prion proteine gene (PRNP) The mutation is coupled with the presence of the codon methionine at position 129

8 GENETIC POLYMORPHISM Homozygotes at codon 129 expressing methionine also in the nonmutate allele, have a shorter disease course (often less than 1 year), prominent sleep and autonomic disturbances at disease onset and pathology restricted to the talamus

9 Heterozygotes at codon 129 expressing valine in the nonmutated allele, have a longer disease course (often longer than 1 year), ataxia, dysarthria and lesions widespread to cerebral cortex

10 Two FFI Phenotypes CODON 129 Met/Met Met/Val Clinical course (range)* 7 18months 11-33months Presentation Insomnia, Ataxia, dysautonomia dysarthria PET study** Thalamus Thalamus+cortex (hypometabolic regions) Pathology* Thalamic atrophy Neocortical spongiosis + ++ (*) Based on none subjects, six homozygous, and three heterozygous at codon 129 (**) Based on seven subjects, 4 homozygous

11 Genotypic difference between FFI and CJD 178 FFI Codon 129 Codon 178 Met Asparagine Met/Val Aspartate Mutant allele Normal allele CJD 178 Val Met/Val Asparagine Aspartate Mutant allele Normal allele

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13 A model of prion disease propagation. The correct (helical) form of a protein misfolds to a β-structure in the presence of the stiff misfolded β-structure form.

14 MOTOR SIGNS ATAXIA ASTASIA - ABASIA DYSARTHRIA UNINTELLIGIBLE SPEECH SPONTANEOUS AND EVOKED MYOCLONIAS

15 AUTONOMIC FINDING Increased perspiration and salivation Impotence and constipation Tachycardia Systemic hypertension Mild fever Stimulated sympathetic activity

16 INSOMNIA Progressive loss of sleep Stupor Coma Enacted dreams Hallucinations - Delusions

17 POLYGRAPHIC RECORDING Disappareance of sleep spindles and k complex EEG pattern oscillating between diffuse alpha activity and low amplitude theta activity Brief recurrent episodes of REM sleep Delta sleep abnormally emerging from wakefulness

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19 IMAGING CT and MNR are normal FDG-PET scans documented a marked hypometabolism in the thalamus with milder involvement of cingulate gyrus

20 FFI M/M and FFI M/V PET Scanning

21 HORMONAL FINDINGS 24-hour study assayed at 30 min intervals Elevated catecholamines (adrenalin and noradrenalin) plasma concentrations Elevated Cortisol plasma concentration Normal levels of ACTH and lacks physiological peaks The nocturnal increase in melatonin secretion progressively subsides

22 BLOOD PRESSURE (mmhg) Controls n =6 Month 6 Month 9 TIME (clock hour) MELATONIN (nmol/l) Controls n =6 Month 9 Month 19 TIME (clock hour)

23 Serum somatotropin and prolactin concentrations never exceeded the normal range of variation. The nocturnal elevation of somatotropin disappeared simultaneoulsy with sleep loss. A significant component of variations in serum prolactin levels was present for months after total disruption of the sleep/ wake cycle, with normal nocturnal acrophase.

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26 The 24-hour hypnogram, rectal body temperature, and profiles of plasma hormones (metadrenaline, noradrenaline, cortisol, growth hormone, and melatonin) secretion in an advanced stage of fatal familial insomnia (FFI) with heterozygosity at PRNP codon 129 (FFI patient in black; healthy control subjects in gray)