Neurosurgery notes/Extradural-intradural AVMs

Extradural-intradural AVMs

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Spinal AVM
RAG
RAG
MCQ
MCQ
Last edited time
Jul 13, 2026 07:06 PM GMT+0

General

  • Aka
    • Juvenile (Metameric) type III lesions
    • Spinal Metameric AVM
      • The “metameric” part refers to the fact that our bodies are, fundamentally, made in segments or blocks.
        • For example, each pair of ribs, the vertebral bone they are attached to, adjacent muscle, fat, skin, and a piece of spinal cord at that level are built from one segment of embryonic tissues.
        • Another word for segment is “metamere”, and from that comes the term “metameric”.
  • Exceedingly difficult to treat because of the large area of anatomy and eloquent structures they can encompass.

Location

  • Extensive AVMs that can encompass an entire somite of the spine and involve bone, muscle, skin, and nerve tissue
    • Reside in the extradural and intradural space and even extend beyond the spine
    • When these lesions are so extensive as to encompass an entire somite (metamere), they are referred to as Cobb’s syndrome

Clinical features

  • Though
    • Mass effect
    • Venous congestion within the spinal cord
    • Arterial steal phenomenon
  • Causing progressive myelopathy and neurological deficit.

Radiology

A close-up of a model of the human body AI-generated content may be incorrect.
A close-up of a person's neck AI-generated content may be incorrect.
(A) The back of the neck shows scattered port-wine–stained nevi (orange star). (B) Sagittal T2-weighted image showing extraspinal involvement in a large spinal AVM (orange arrows). The AVM's pial component is demonstrated as a flow void behind the cord (red arrow), with evident hematomyelia (blue arrow). (C) A catheter angiographic image clearly depicts the AVM lesion and affected areas.
A close-up of an x-ray of a spine AI-generated content may be incorrect.

Treatment

  • Similar to Intramedullary AVM

Reference