Spinal vascular malformations

Spinal vascular malformations are a rare but important group of lesions that range widely in size, flow, and pathophysiology. Some, if undiagnosed and untreated, can lead to serious complications.

Although numerous classification systems exist, from the point of view of routine clinical practice, the main lesions to consider are:

• lesions with arteriovenous shunting

  • spinal arteriovenous fistula

  • spinal arteriovenous malformation

• lesions without shunting

  • cavernous malformation of the spinal cord

  • vertebral haemangioma

  • epidural haemangioma ⁷

  • intradural extramedullary capillary haemangioma ⁸

Terminology

It is worth separating lesions without arteriovenous shunting (i.e. cavernous malformations) from those that do have shunting (i.e. AVM and AVF). Notably, much of the older literature described all arteriovenous shunting lesions as arteriovenous malformations (AVM), but newer classifications have distinguished arteriovenous malformations from arteriovenous fistulas (AVF) ¹³.

Classification

Many classifications for spinal vascular malformations have been proposed without a clear consensus nomenclature.

Spinal arteriovenous shunts ("malformations") have classically been categorised in a numbered system and broadly speaking these have remained similar, although over time the names for each have changed and additional categories and subcategories have been proposed ^9-15.

The two probably most widely used systems are:

• Takai classification of spinal arteriovenous shunts ¹³

• Spetzler classification of spinal cord vascular lesions ³

Takai classification

Published in 2017, the Takai classification built upon numerous prior classifications dating back to the earlier system published by Di chiro et al in 1971 ¹⁶. It limits itself to esions with arteriovenous shunts and divides them into 5 types ¹³:

• type I: dural AVF

• type II: intramedullary glomus AVM

• type III: intramedullary juvenile AVM

• type IV: perimedullary AVF

• type V: extradural AVF

For a detailed description of this classification see: Takai classification of spinal arteriovenous shunts

Spetzler classification

In 2002 Spetzler et al. proposed the following categories of spinal cord vascular malformations ^3,5:

• arteriovenous fistulas (AVF)

• arteriovenous malformations (AVM)

• neoplastic vascular lesions

• spinal aneurysms

For a detailed description of this classification see: Spetzler classification of spinal cord vascular lesions

Other classification systems

The Bicêtre group classified spinal cord arteriovenous shunts into 3 aetiologic categories ⁴:

• genetic hereditary lesions (such as hereditary haemorrhagic telangiectasia)

• genetic nonhereditary lesions (multiple lesions with metameric or myelomeric associations, such as Cobb syndrome, Klippel-Trenaunay syndrome, and Parkes Weber syndrome)

• single lesions (which may reflect incomplete expression of the above two categories but represent the majority of spinal vascular malformations)

Krings et al. noted that spinal vascular malformations can be distinguished by their vascular anatomy into dural and pial arteriovenous shunting lesions and cavernous malformations, analogous to brain vascular malformations ^2,6. The main types are as follows:

• dural arteriovenous fistulae (DAVF; 70% of all spinal arteriovenous shunts)

• arteriovenous malformations (AVM)

  • fistulous (perimedullary fistula type) AVM

  • glomerular (plexiform or nidus-type) AVM

  • juvenile AVM

• cavernous malformation

Patsalides et al. classified spinal vascular lesions topographically ¹:

• arteriovenous lesions

  • arteriovenous fistula (AVF) (direct shunt between artery and vein)

    • pial AVF (type IV, spinal cord AVF, ventral intradural AVF, or perimedullary AVF)

      • small

      • large

      • giant

    • dural AVF (type I, dural intradural AVF)

    • epidural AVF (type V, extradural AVF)

  • arteriovenous malformation (AVM) (nidus between artery and vein)

    • intramedullary AVM (type II, glomus-type AVM)

    • pial AVM

    • epidural AVM

    • intra- and extramedullary AVM (type III, intradural-extradural, juvenile AVM, or metameric AVM)

• lesions without arteriovenous shunting

  • cavernous malformation

  • capillary telangiectasia