Journal ofNeurology, Neurosurgery, and Psychiatry 1993;56:929-931

SHORT REPORT

Dementia with leucoaraiosis and duralarteriovenous malformation: clinical and PETcase study

Patrizia Nencini, Domenico Inzitari, Jeremy Gibbs, Salvatore Mangiafico

AbstractA case of rapidly progressive dementiawith diffuse leucoaraiosis on CT wasattributable to a supratentorial duralarteriovenous malformation. Positronemission tomography (PET) showed lowcerebral blood flow and high oxygenextraction ratio throughout the cerebralhemispheres indicating a state of chronichaemodynamic compromise which couldpredispose to the development of a vas-cular dementia. CT images of dilatedintracerebral veins suggested that avenous drainage overload rather than avascular steal phenomenon might beinvolved in the pathophysiology of thedementia ofvascular origin.

(3 Neurol Neurosurg Psychiatry 1993;56:929-931)

Dural arteriovenous malformations (AVM)represent 10% to 15% of all intracranialAVM.' The most common clinical presenta-tions of dural AVM are vascular bruit,headache, and, less often, increased intracra-nial pressure or intracranial haemorrhage.2'Dementia in relation to dural AVM, as in ourcase, is rare.'-3

Department ofNeurological andPsychiatric Sciences,University ofFlorence, Florence,ItalyP NenciniD InzitariNeuroradiologyService, CareggiHospital, Florence,ItalyS MangiaficoMRC Cyclotron Unit,HamnmersmithHospital, London, UKJ GibbsCorrespondence to:Dr Patrizia Nencini,Dipartimento di ScienzeNeurologiche ePsichiatriche, vialeMorgagni 85, 50134Firenze, Italy.Received 27 August 1992and in revised form20 November 1992Accepted 27 November 1992

Case reportFour months before admission, a 44 year oldtrain conductor began to show little interestin his environment, to have memory prob-lems, and difficulties in driving and dressing.His mood was labile, with episodes ofpseudobulbar laughter and crying. He had toleave his job. His family and personal histo-ries were otherwise unremarkable.The patient presented with marked psy-

chomotor retardation. He was disorientatedin time and space; short term memory was

impaired and long term memory was rela-tively spared. Abstract thinking and judgmentwere severely compromised. There was inat-tention, perseveration in carrying out com-

mands, and apraxia in dressing. His ability tocopy figures was reduced. Writing was limitedto his signature. Only simple calculation was

possible. Neurological examination showedno focal motor deficit. Tendon reflexes andplantar responses were normal bilaterally.

Index to nose and heel to knee tests were per-formed correctly. Sucking and bilateral graspreflexes were present. The patient had urinaryincontinence. General medical examinationwas normal. No bruit was heard in the supra-clavicular fossa, neck, or head. Optic fundiwas normal.

Routine blood tests, CSF, and ECG wereall normal. EEG showed diffuse slowing ofbrain electrical activity and no high voltageperiodic waves. A non-enhanced brain CTrevealed mild ventricular enlargement with-out cortical atrophy, and bilateral markedhypodensity of the subcortical white matter,especially in frontal regions. The infusion ofcontrast medium was followed by vermiformperiventricular and subcortical enhancement(fig). Selective cerebral angiography showedmultiple hypertrophic branches of both exter-nal carotid arteries (that is, left middlemeningeal, accessory meningeal, and super-ficial temporal arteries; and right superficialtemporal and middle meningeal arteries).These branches fed a dural AVM at the ver-tex which drained into an enlarged superiorsagittal sinus (fig).The patient progressively worsened and 2

months after admission, he appeared severelydemented, aphasic, and ataxic while walking.At this time, a positron emission tomographic(PET) study was carried out on an ECAT II(EG and G Ortec, Oak Ridge, TN, USA)scanner, with a transaxial resolution of 16 x16 mm full width half maximum (FWHM) atthe MRC Cyclotron Unit, HammersmithHospital, London. Data were collected fromthree transaxial planes, parallel to the orbito-meatal line (OM + 4-6 cm; OM + 6-6 cm;OM + 8-6 cm). Cerebral blood flow (CBF),cerebral metabolic rate of oxygen (CMRO2),and oxygen extraction ratio (OER) were mea-sured by the steady state technique with con-tinuous inhalation of C'502 and '502.4 In viewof the patient's vascular malformation,CMRO, and OER data were corrected forcerebral blood volume by means of a "COstudy.5 Flow and metabolic data wereanalysed by hemispheric means of corticaland white matter regions at different levels.CBF was low in both cerebral cortex anddeep structures; only occipital cortex seemedto be spared. There was also a symmetricalreduction of CMRO2, but this reduction was

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Nencini, Inzitari, Gibbs, Mangiafico

Figure Contrast enhanced CT scan: (A) congestion of cortical veins (arrows); (B)congestion of cortical veins and choroid plexuses (arrows), and marked hypodensity(leucoaraiosis) ofsubcortical white matter; (C) congestion of cortical veins (arrow); (D)congestion of basal veins (arrow). Left external carotid arteriogram: (E) lateral view,showing enlarged and tortuous middle meningeal, accessory meningeal, and superficialtemporal arteries; (F) anteroposterior view, showing early filling ofsagittal sinus (arrow).

less marked than that of CBF, and OER wasconsequently high. This pattern of very lowperfusion, moderately reduced CMRO2 andhigh OER is indicative of impaired haemo-dynamic and oxygen carriage reserves6 and itwas most severe in the top plane (table).

Table Haemodynamic and metabolic parameters (mean) in grey and white matter(OM + 8-6 cm slice)

Grey matter White matter

CBF CMRO, OER CBF CMRO, OER

Case 15-4 30 09 77 1-5 09Controls* 59-4 5-3 0-5 21-2 1-8 0-5

range 41-5-92-5 4-2-7-1 04-0-6 175-24-5 1-5-2-1 0-1-06

*12 controls, age 30-74 years. CBF (ml/100 ml/min) = cerebral blood flow; CMRO, (ml02/100 ml/min) = cerebral metabolism rate of oxygen; OER = oxygen extraction ratio.

Ten days after the PET study, the patientsuddenly developed a right hemiparesis. Aligation of left external carotid and rightsuperficial temporal arteries was performedbut no clinical improvement was obtained.Four months after the admission, the patientdied from bronchopneumonia. Necropsy wasnot performed.

DiscussionWe suggest that the rapidly progressivedementia observed in our case was due to thedural AVM. Other causes of subacutedementia have been ruled out, in particularwe excluded Creutzfeldt-Jacob disease on thebasis of the clinical and EEG findings.Although rare, mental deterioration can occurwith dural AVM. It has been reported mainlyin dural AVM located in the posterior fossaand draining into the transverse sigmoidsinus. 1-3 However, a case of progressivedementia associated with direct drainage ofextracranial arteries into the superior sagittalsinus has been reported by Friede andSchubiger.7 Angiographic findings in this casewere remarkably similar to those observed inour case. Pathological study showed arteriali-sation of the wall of the sinus and excessivelydistended veins in the leptomeninges andcerebral white matter with thickened fibroticwalls. Widespread patches of myelin lossaround these abnormal vessels were alsoobserved.

Areas of leucoaraiosis on CT scan havebeen reported in three patients with duralAVM and mental deterioration.' In thesepatients, intravenous contrast infusionshowed areas of vermiform or patchyenhancement. Diffuse CT hypodensityindicating subcortical white matterdisease may be present in other dementingdisorders, including cerebromeningoangio-matosis described by Divry and van Bogaert8,and Binswanger's subcortical encephalopa-thy. Chronic hypoperfusion is postulatedamong the possible causes of white matterlesions in Binswanger's encephalopathy9 and,in leucoaraiosis.'0

In our case, the PET findings of low CBFand high OER are consistent with a state ofdiffuse, chronic vascular insufficiency. Littlequantitative information on haemodynamicor metabolic effects ofAVM is available and,to our knowledge, this is the first PET studyof a dural AVM. Recently, Tyler and co-workers" studied 17 patients with intra-cerebral AVM by PET and observedwidespread metabolic and haemodynamicabnormalities both in ipsilateral regionsremote from the lesion and in the cantralat-eral hemisphere. De Reuck et al"2 studied twocases of cerebral AVM, finding areas ofdecreased blood flow and oxygen metabolismat a distance from the malformation. There-fore, AVM can modify cerebral haemo-dynamics in adjacent or distant regions. Thevalidity of the oxygen-15 steady state modelin the presence of AVM has been demon-strated by Lammertsma et al."I

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Dementia with leucoaraiosis and dural arteriovenous malformation: clinical and PET case study

Concerning the pathogenesis of cerebralhypoperfusion in dural AVM, two mainmechanisms can be hypothesised: (i) "steal"by the malformed vessels at the expense ofthe cerebral parenchyma and (ii) increase ofthe dural venous sinus pressure due to shunt-ing from the arterial to the venous system.14Diaschisis has never been described to occurin AVM. In our case, it is difficult to attributethe symptoms to a steal mechanism becauseall the enlarged feeding arteries rose from theexternal carotid arteries, and the angiogramsshowed no definite evidence of shunting fromthe internal to the external carotid circula-tion. Contrast CT scans displayed a vermi-form enhancement owing to dilatation of theintraparenchymal venous system. These find-ings are compatible with an overload ofvenous drainage which may produce achronic and critical reduction of cerebralperfusion pressure, particularly in the morevulnerable deep tissues.

Although not all the clinical criteria of vas-cular dementia (DSM-III-R) were fulfilled,the dementia presented by our case is consis-tent with the diagnosis of vascular dementia:there was evidence of vascular disease of thebrain, the course was punctuated by stroke-like episodes, and the features of dementiawere those characteristic of subcorticaldementia, proposed as typical of vasculardementia.'5 Chronic ischaemia has beenquestioned as a cause of vascular dementia.'6However, modern imaging techniques fre-quently reveal abnormalities in the deep whitematter which is particularly vulnerable totransient perfusion failure and infarction,indicating that multiple cortical infarcts can-not be considered the only cause of dementiaof vascular origin.17 This report confirms that,at least in certain cases, chronic haemo-dynamic compromise caused by increasedvenou4s back pressure may cause vasculardementia.

We thank members of the Clinical Neuroscience, Chemistryand Methods Sections of the MRC Cyclotron Unit for mak-ing this study possible. We are also very grateful to Dr RSJFrackowiack for his helpful comments during the preparationof this article.

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