Fannie Onen

Intracranial fluid dynamics in normal and hydrocephalic states: Systems analysis with phase-contrast magnetic resonance imaging

Objective: To present a novel magnetic resonance (MR) method of analysis of cerebrospinal fluid (CSF) flow dynamics. Methods: Fifty-one subjects were explored with phase-contrast cine MR imaging. There were 36 volunteers, 9 patients with normal pressure hydrocephalus (NPH), and 6 patients with asymptomatic ventricular dilation (VD). The transfer function XFRA/CSF from the arterial pulse waves (APWs) and the CSF pulse waves (CSFPWs) and the transfer function XFRCSF/SS from the CSF pulse waves (CSFPWs) and the sagittal sinus pulse waves (SSPWs) were studied separately. Results: There was a significant difference in the amplitude spectrum of the XFRA/CSF of patients with VD and volunteers (P < 0.05) and in that of patients with NPH and volunteers (P = 0.005). The amplitude of the fundamental frequency was higher in the NPH group than in the VD group (P = 0.02). In patients with NPH, the amplitude spectrum of XFRCSF/SS showed an attenuation of the pulse wave components that significantly differed from the observed amplification in healthy subjects (P = 0.009) and patients with VD (P = 0.012). Conclusion: This systems analysis method could help to detect increased venous compliance in VD and decreased venous compliance in NPH.

Leukoaraiosis and mobility decline: a high resolution magnetic resonance imaging study in older people with mild cognitive impairment.

Patterns of leukoaraiosis were analyzed on both T2-weighted fast fluid-attenuated inversion-recovery and 3D T1-weighted sequences in 23 community-dwelling older subjects with mild cognitive impairment. Mobility assessment had allowed their classification into higher and lower mobility groups (P<0.0001). Lower mobility appeared correlated with frontal subependymal lesions (P=0.0005). The absence of marked ventriculomegaly, any thick caps, deep white matter lesions curved along the ventricles bodies, large deep white matter lesions, deep grey matter leukoaraiosis was an hallmark of the higher mobility group (P<0.0001). High resolution MRI demonstrated regular patterns of the subependymal lesions and detected perivascular distribution in other forms of leukoaraiosis. It suggests that the underlying mechanism of mobility decline in the elderly may be impairment of cerebrospinal fluid dynamics with cerebral small vessel disease.

Classifying late-onset dementia with MRI: Is arteriosclerotic brain degeneration the most common cause of Alzheimer’s syndrome?

Our aim was to use early magnetic resonance imaging (MRI) to investigate the causes of cognitive decline in elderly people with mild cognitive impairment (MCI). Baseline structural and flow quantification MR sequences, and clinical and neuropsychological follow-up for at least two years, were performed on 62 elderly subjects with MCI. Of these subjects, 17 progressed to dementia, and 15 of these progressed to dementia of the Alzheimer type (DAT). Conversion to clinically diagnosed DAT was related to six distinct MR profiles, including one profile suggesting severe AD (20% of these converters) and five profiles suggesting severe cerebrovascular dysfunction. Two profiles suggested arteriosclerotic brain degeneration, one profile suggested severe venous windkessel dysfunction, and two suggested marked cerebral hypoperfusion associated with very low craniospinal compliance or marked brain atrophy. As compared with vascular MR type converters, AD MR type converters showed high executive and mobility predementia performances. Severe whole anteromesial temporal atrophy and predominantly left brain atrophy on visual MR analysis was only observed in AD MR type converters. In conclusion, these observations enhance the pathogenic complexity of the Alzheimer syndrome, and suggest that the role of arteriosclerotic brain degeneration in late life dementia is underestimated.

Cerebrospinal fluid MR dynamics and risk of falls in the elderly.

RATIONALE AND OBJECTIVES To investigate the relationship between CSF dynamics and risk of falls of unknown origin in the elderly. POPULATION AND METHODS Phase contrast MR studies allowed CSF aqueductal flow quantification on 23 community-dwelling older people initially explored for mild cognitive impairment. Mobility assessment included report of falls, talking walking test, stance test, one leg standing test, up and go test, and measurement of fast gait speed. RESULTS History of falls was associated with larger aqueduct, steeper diastolic slopes higher ratios RDV/SD of diastolic volume/CSF systole duration (p</=0.0006). Amplitude CSF parameters, diastolic slopes and RDV/SD appeared correlated with the aqueduct area (p<0.01). CONCLUSIONS These preliminary data suggest that disturbances of CSF dynamics could play a role in mobility decline with aging especially in falls of unknown origin.

P-39 Dynamique du LCS en IRM et chutes du sujet âgé

Objectifs rechercher par IRM de flux une eventuelle relation entre dynamique du LCS et risque de chutes d’etiologie indeterminee chez le sujet âge. Materiels et methodes une quantification du flux a travers l’aqueduc de Sylvius a ete realisee par cine IRM en contraste de phase chez 23 sujets âges ambulatoires. Ces sujets etaient initialement explores pour Deficit Cognitif Leger, mais n’etaient pas dements et ne presentaient pas de pathologie ou traitement medicamenteux pouvant etre a l’origine de chutes. L’evaluation de la motricite incluait la recherche d’un antecedent de chute(s), le « walking talking » test, le « up and go » test, l’evaluation du polygone de sustentation, de la station debout en appui monopodal, et la mesure de la vitesse de marche rapide. Resultats l’antecedent de chute(s) etait associe a une alteration des courbes de debit du LCS — acceleration diastolique initiale majoree, augmentation du rapport R volume diastolique/duree de la systole du LCS — ainsi qu’un elargissement de l’aqueduc (p Conclusion ces premiers resultats suggerent qu’une alteration de la dynamique du LCS pourrait jouer un role dans la survenue de chutes d’etiologie inconnue chez le sujet âge.

CO-31 Aspects de la leucoaraïose cérébrale en irm haute résolution

Objectifs Analyser, sur une imagerie de resolutions spatiale et en contraste elevees, les caracteristiques morphologiques des lesions dites « Age-Related White Matter Changes ». Materiels et methodes Les lesions de leucoaraiose ont ete etudiees chez 60 sujets âges (73 ± 5 ans) presentant un Deficit Cognitif Leger, par ailleurs sans antecedent neurologique ou maladie generale evolutive. Le protocole d’imagerie incluait des sequences coronales 3D de ponderation T1 (FSPGR) et FLAIR. Resultats Les lesions subependymaires etaient de contours reguliers et ne s’etendaient pas aux regions superficielles sous corticales. Elles n’etaient que rarement de topographie posterieure (13 %) –– avec dans ce cas un caractere tres focal –– et jamais de localisation temporale. Des lesions en « bandes » (20 %) paraventriculaires de grand axe anteroposterieur suivaient la courbure ventriculaire adjacente dans le centre ovale ou en temporoparietal. De fin signaux lineaires, de trajet correspondant a celui des perforantes, etaient detectes au sein des lesions de la substance blanche profonde, superficielle et des noyaux gris centraux. Des anomalies focales de signal du corps calleux etaient frequentes (57 %). Conclusion l’imagerie haute resolution permet de distinguer les lesions strictement periventriculaires, de configuration et distribution specifiques repondant aux caracteristiques hydrodynamiques locoregionales, les bandes paraventriculaires de topographie « jonctionnelle », et les lesions « striees » evocatrices de degenerescence perivasculaire.