Turkish Neurosurgery 8: 36 - 38, 1998

CASE REPORTS

Jplikçioglu: Mixed Vascular Malformatioii of the Braiii

MIxed Venous and Cavemous MalfonnatIons of the BraIn

Beyinde Birlesik Venöz ve Kavernöz Malformasyon

A. CELAL IPLIKÇIOGLU, A.ÖZCAN BINATU, VAsFi YARADANAKUL

SSK Tepecik Haspital Department af Neurasurgery, Izmir, Turkey

Abstract: Vascular ma1formations with histopatholagicalfeatures of more than a single type of ma1formation presentwithin the same lesion have been previously described.These lesions are very rare and named as mixed vascularmalformations.In this report, we presented a case of mixedvascular ma1farmation with radiological features ofcavernous and venous malformations.Key Words: Arteriovenous ma1formation, capillaryma1formation, cavernous ma1farmation, mixedma1formation, vascular ma1formation, venausma1formatian

INTRODUCTION

Vascular malforma tions of the brain are

classically divided into four groups, each withdifferent pathological and radiological properties.This widely accepted classificalion includes venous,ca vernous, arteriovenous and capillarymalformations (4,5,6). However, some authorsrecently reported cases of vascular maHormationsexhibiting pathological features of more than onediscrete maHormation type within the same lesion(1,3,9,10). These lesions are rare and are named as"mixed vascular maHormations".In this report, wepresent a case of vascular maHormation which hascharacteristic magnetic resonance (MR) andangiographic features of cavernous and venousmalformations.

CASE REPORT

A 34-year-old woman was admitted to thehospital because of recurrent headaches. Her medical

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Özet: Ayni malformasyonda birden fazla histolojik tipiçeren damarsal ma1formasyonlar daha öncetanimlanmistir. Nadir görülen bu lezyonlar birlesikdamarsal ma1farmasyanlar alarak adlandirilir. Bumakalede kavernöz ve venöz ma1formasyonlarinradyolojik özelliklerini gösteren bir birlesik damarsalmalformasyan sunuldu.

Anahtar Sözcükler: Arteriyo venöz ma1formasyan,damarsal ma1farmasyon, kapiller ma1formasyon,kavernöz malformasyon, venöz malfarmasyon

history was insignificant. Neurological and physicalexaminations were entirely normaL. A computedtomography (CT) sean showed a hyperdense lesionon the roof of the fourth ventricle (Figure 1).The lesionwas enhancing and typical appearance of caputmedusa adjacent to the lesi on was also seen (Figure2a). An MR sean revealed both the venous structureand the lesi on characterized by a core of mixedincreased and decreased signal intensities, typical ofcavernous maHormation (Figure 2b). Angiographydemonstrated abnormal venous drainage of thepontomedullary venous circulation (Figure 3). Thepatient did not receive any surgical treatment.

At follow-up examination, three months later,the patient was neurogically intact.

DISCUSSION

Histopathological criteria for the classificationof vascular maHormations of the brain have been welldescribed (4,5). An arteriovenous maHormation

Turkish Neurosurgerj 8: 36 - 38, 1998

Figure 1: Postcontrast CT sean showing a hyperdensecontrast enhancing mass on the left wall of thefourth ventride and a vascular structure havingcaput-like appearance.

lplikçioglu: Mixed Vascular Malformatian of the Brain

parenchyma. These veins converge into a largecentrally located vein making the feature of caputmedusa. A capillary maHormation consists of acompilation of dilated capillaries with interveningnormal brain tissue. The category of mixed vascularmaHormation has recently been added to thisc1assification 0,9). However, the real prevalence ofmixed vascular maHormations is not known.

A1though almost all cases have been reported in theMR era, most of the reports have emphasized therarity of such lesions. According to Awad et aL.5 %of the all vascular maHormations are mixed lesionsO). However, increasing availability of moderndiagnostic techniques will allow better recognitionof such lesions.

Mixed vascular maHormations consist of threemajor subgroups including mixed cavernous andvenous maHormations,mixed arteriovenous andvenous maHormations and mixed cavernous andarteriovenous or capillary maHormations. Most of themixed vascular maHormations are mixed cavernousand venous maHormations, and can be easily

Figure2 a, and b:Tl-weighted MR images revealed the lesion characterized by a core of mixed signal intensity and a rimof decreased signal intensity. This apperance is highly characteristic for cavernous malformations. Thelinear signal void adjacent to the lesion outlines the venous strocture.

inc1udes c1usters of abnormal arteries and veins with

typically thickened vessel walls and minimalintervening gliotic brain tissue. A cavernousmaHormation is com po sed of large sinusoidalvascular spaces without intervening brainparenchyma, while a venous maHormation entirelyconsists of veins interspersed in neural

diagnosed on imaging studies be cause MR featuresof cavernous maHormations are well known a1thoughtheyare usually occu1t on angiography (8).

A mixed arteriovenous and venous

maHormation is more difficult to recognize. MR andCT studies are usually insufficent for diagnosis. Only

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Turkish Neiirosiirgery 8: 36 - 38, 1998

Figure 3: Angiography showing venous angioma in theposterior fossa.

comprehensive angiographic studies can visualizethe arteriovenous and venous components of thelesion.

Cavernous malformations with mixed

arteriovenous or capillary maHormation are mostdifficu1t to recognize on diagnostic radiologicalstudies. Only careful histopathological examinationof the lesi on and the surraunding brain can be helpfulin establishing the correct diagnosis.

Most vascular malformations have been

thought of as developmental anomalies orhamartomas, while enlargement of a cavernousmaHormation following repetitive hemorrhages andthrombosis has been shown (7). Therefore,

micrahemorrhages within an occult maHormationcause reactive angiogenesis with new vesselformation.This process is named as hemorrhagicangiogenic proliferation and explains the occurenceof mixed vascular maHormations (1).

Patients with mixed vascular maHormations

may present with seizures,recurrent hemorrhages orprogressive neurological deficits (4). These clinicalmanifestations are not different from those

encountered in patients with a single-type vascularmaHormation. However, venous angioma is the mostcommon form of intracranial vascular maHormation

and has a risk of hemorrhage of only 0.22 % per year(2). Thus, venous angiomas are considered to be

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lplikçioglii: Mixed Vasciilar Malformatian of the Brain

relatively benign lesions and clinical findings areusually related to the other component of the mixedvascular maHormation.

Management of mixed vascular

malformations is difficu1t and complicated, especiallyif the lesion has a venous component. Since thevenous maHormation is frequently the only venousdrainage pathway for the surrounding brain tissue,preserving the venous maHormation during surgeryis essential (10). However, if venous hypertensioncauses recurrent hemorrhages which subsequentlystimulate the growth of new vascular maHormations,only total removal of the mixed vascularmaHormation will be curative.

Correspondence: A.Celal IplikçiogluSSK Tepecik HastanesiBeyin Cerrahisi Klinigi,Tepecik, Izmir, TurkeyPhone: (232) 433 0810/1301

REFERENCES

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