Cushing and Bailey (1928) were the first to separate two groups:
I. Angioblastoma (true neoplasm),
II. Angiomatous malformation.
They did not consider cavernous angioma as a separate entity and listed it under angioblastoma. Their venous angiomas would be called AVMs today.
Bergstrand et al. (1936) added to the neoplastic group the angioglioma of Roussy and Oberling. These are to a large degree still not accepted, yet appear to have been occasionally identified (Bonnin et al. 1983). Bergstrand doubted the existence of a true arterial aneurysm as described and illustrated by Simmonds (1905) (Figs 3.5, 3.6).
Fig 3.6 Coloured artistic drawing of Simmonds (1905) unique case of a pure arterial malformation in a 53 year old man who died of an acute intracerebral hematoma. At autopsy a medium-sized arterial convolution was found. It was histologically verified to be purely arterial.
Historical review shows that 4 or 5 different vascular diseases (angioblastoma, telangiectasia, venous, cavernous and arteriovenous angiomas) were recognized in the very earliest studies and then gradually identified as being separate entities.
McCormick’s classification (Table 3.6b) is similar to earlier works and he no longer appears to regard “varix” as a special entity. His contribution was important in that he provided statistics regarding the numbers of different types of malformation and reopened the discussion on the relationship of transitional types of angiomas to vascular tumors as originally mentioned by Virchow.
Huang et al. (1984) noted the wide acceptance of Russel and Rubinstein’s (1963) classification. However, they pointed out the disadvantages of attempting to differentiate histologically between many cavernous venous malformations and venous angiomas and showed that some areas within venous angiomas may be similar to capillary malformations or even an AVM. The classification of Huang et al. has put forward new and important elements for consideration.
We include the classification of Merland et al. (1983) as a very stimulating view of the external angiomas, seen from the perspective of the interventional neuroradiologist.
The classification of Kaplan (1983), Spira (1983) show up the similar problems experienced by plastic surgeons in describing cutaneous malformations.
The Author’s Classification
Our own classification is based on the relative preponderance and contribution of the various vascular elements, arteries, veins, capillaries, and abnormal channels (Table 3.6c). There may run a spectrum from theoretically completely arterial lesions to completely venous lesions and from large fistulae to extensive convoluted vessels. While the lesions can conveniently be grouped into four primary headings, there are at each level examples of transitional lesions, e. g. AVMs with slow flow or venous malformations with increased flow. Part of the definition of the lesion must rest with dynamic properties related to flow and shunting, which cannot be examined by the pathologist in the resected specimen or at autopsy. We propose the following classification more for practical use in neuroradiology, neurology and neurosurgery but hope that neuropathologists will be stimulated to undertake further investigation of these lesions.
Table 3.6c Authors classification
| I. Vascular neoplasms 1. Hemangioblastoma a. Cystic b. Solid 2. Angioglioma (mixed hemangioblastoma and glioma) 3. Angioblastic meningioma 4. Hemangiopericytic meningioma (hemangiopericytoma of the meninges) 5. Angiosarcoma II. Malformations 1. Telangiectasia 2. Cavernous malformation a. Intrinsic b. Extrinsic 3. Venous malformation a. Cortical b. Subcortical (medullary) α superficial β deep 4. Arteriovenous malformation a. Plexiform (dilated, tortuous pathological vessels with thickened or thinned (or combined) walls, arteriectasia, aneurysms, phlebectasia, varices; they can be cryptic, occult, micro, moderate, large or giant in size.They may be uni- or multilocular.They may have a mono-nidus with mono- or multi-compartments) b. A-V Fistula (direct communication between arteries and venous channels (veins and sinuses) without the interposition of a convolue. α simple: – carotid = cavernous, carotid = jugular, – MCA = v. Labbé or v. Trolard or Sylvii, – ACA = inferior sagittal sinus, – pericallosal artery = v. Galen, – PCA = v. Galen, PCA – transverse or sigm. sinus, – vertebra = vertebral, vertebra = jugular, – AICA = lateral rec. vein or petrosal sinus, – SCA = transverse sinus, – basilar artery = galenic vein β complex: – pericallosal + PCA + MCA = v. Galeni, – MCA + dural branches = hero-philic sinus or SSS, – PCA + dural branches = hero-philic sinus or transverse sinus. c. Transitional type between a–c α more fistula > less plexiform (network) β more network > less fistula 5. Transitional malformations Combinations 1+2, 1+3, 2+3, 1+2+3, 3+4 (Huang) 1+3+4 (Huang) III. Vascular malformation and vascular tumor associated with phacomatosis (Phacomatotic angiomatous diseases) Neurocutaneous syndromes 1. Angioblastoma (angioreticuloma) (von Hippel-Lindau)(angioblastomatosis) 2. Encephalofacial angiomatosis = neuro-oculo-cutaneous(Sturge-Weber-Krabbe-Dimitri) 3. a. Hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber) (cutaneous, mucosal and visceral capillary malformation) b. Ataxia telangiectasia (Louis-Bar) facial naevus, cerebellar angioma, angioma of the choroid of the eye, defective immune globulin system of the IgA class 4. Encephaloretinofacial angiomatosis } (Wyburn – Mason)(Bonnet–Dechaume-–Blanc) 5. Orbitothalamoencephalic angiomatosis (Brégeat syndrome) 6. Diffuse corticomeningeal capillovenous familial angiomatosis (non calcifying) (Divry-Van Bogaert) 7. Cutaneomeningospinal angiomatosis (Cobb) 8. Congenital venous dysplasia (extremities, spinal) (Klippel-Trénaunay-Weber syndrome) 9. Glomangiomatosis (glomus tumor) (Bailey) 10. Dyschondroplasic hemangioma (Maffucci-Kost) 11. Angiokeratosis naeviformis (?) 12. Extensive cavernous hemangioma + thrombocytopenia and purpura (Kasabach-Merritt syndrome) 13. Blue Rubber Bleb syndrome 14. Malignant hemangioma |
Location of AVMs
As the disorder occurs quite early in development, it would be anticipated that a vascular malformation may be present in any tissue layer from skin to ependyma. The primitive vascular plexus forms from cephalad to caudad with the meninges forming in the 30 to 60 mm period cleaving the vascular plexus into vessels destined to supply the dura and skull and those destined to supply the brain and choroid plexuses. As pointed out by Padget, the superficial vascular plexus supplying the scalp does not appear until after the membranous skull is complete. Nevertheless, the vascular plexus supplying the face is in continuity with the brain and at times connections exist with the scalp through the skull especially in the venous system. It would follow that association of scalp and brain vascular malformations would be rare, association of facial, retinal, and brain malformations more common, and dural and brain malformations even more frequent.
If the vascular malformations do indeed represent the result of an early deep fistula with remote effects, it is surprising that the lesions are not multiple more often, as many areas of the vasculature would be at risk.
Garretson (1985) has categorized cerebral AVMs (which, incidentally are seen most frequently involving branches from the MCA, less often the ACA, and least frequently the PCA) as those involving the epicerebral, transcerebral and subependymal circulations (see also section on microcirculation). He notes that AVMs involving only the transcerebral (long perforating) arteries are not visible on the surface of the hemisphere yet arterialized veins may frequently be seen owing to the anastomoses between the transcerebral and