Spinal Cord Arteriovenous Malformations (AVMs)
(See also Overview of Spinal Cord Disorders.)
Arteriovenous malformations are the most common spinal vascular malformations. Most are thoracolumbar, posterior, and outside the cord (extramedullary). The rest are cervical or upper thoracic and often inside the cord (intramedullary). AVMs may be small and localized or may affect up to half the cord. They may compress or even replace normal spinal cord parenchyma, or they may rupture, causing focal or generalized hemorrhage.
A cutaneous angioma sometimes overlies a spinal AVM. AVMs commonly compress the following:
Combined lower and upper motor neuron deficits are common. AVMs may rupture into the spinal cord parenchyma, causing sudden, severe back pain and sudden segmental neurologic deficits. Rarely, high cervical AVMs rupture into the subarachnoid space, causing subarachnoid hemorrhage with sudden and severe headache, nuchal rigidity, and impaired consciousness.
Spinal cord arteriovenous malformations may be detected incidentally during imaging. They are suspected clinically in patients with unexplained segmental neurologic deficits or subarachnoid hemorrhage, particularly those who have sudden, severe back pain or cutaneous midline angiomas.
Diagnosis of AVMs is by MRI (usually done first), then magnetic resonance angiography, and then selective arteriography. Occasionally, myelography plus CT is used.
Surgery is indicated if spinal cord function is threatened, but expertise in specialized microtechniques is required. Stereotactic radiosurgery is helpful if the AVM is small and located in a surgically inaccessible location.
Angiographic embolization occludes feeder arteries and often precedes surgical removal or stereotactic radiosurgery.
Arteriovenous malformations may be small and localized or may affect up to half the cord.
AVMs may compress nerve roots (causing pain down the distribution of a nerve root) or the spinal cord (causing segmental neurologic deficits that gradually progress or that wax and wane); they may rupture (causing sudden, severe back pain and sudden segmental neurologic deficits).
Diagnose using MRI, followed by magnetic resonance angiography, then selective arteriography.
If spinal cord function is threatened, treat surgically.