Spinal Cord Arteriovenous Malformations

Indications

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Spinal cord arteriovenous malformations (AVMs) causing neurologic symptoms, such as pain, neurogenic claudication, myelopathy, radiculopathy, and progressive motor and sensory dysfunction
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Spinal cord AVMs causing venous hypertension
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Spinal cord AVMs diagnosed in patients presenting with subarachnoid or intramedullary hemorrhage

Contraindications

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Patients with relative contraindications to surgery include patients with serious medical comorbidities, short life expectancies, severe debilitation, and very complex, challenging intramedullary lesions (ventrally located, type 3).
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Stereotactic radiosurgery and endovascular embolization are alternatives and should be considered.

Planning and positioning

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A thorough history and physical examination should be performed on every patient. Screening studies such as spinal magnetic resonance imaging (MRI) (more commonly) or computed tomography (CT) myelography are initially performed. A diagnostic spinal arteriogram is performed to help determine the type of AVM, locate the fistula or nidus, allow interpretation as to the arterial supply of the malformation and spinal cord, and assess regional vascular anatomy.
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Continuous neurophysiologic monitoring, including somatosensory evoked potentials, is performed to provide feedback during surgery. A long femoral sheath is placed and attached to the lateral aspect of the patient’s right thigh and draped in a sterile fashion at the beginning of the case for intraoperative spinal arteriography.
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The patient receives preoperative antibiotics and dexamethasone (Decadron).
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The patient is positioned prone, on a radiolucent operating table comprising a Wilson frame mounted onto a Jackson table permitting easy C-arm fluoroscopy access. Fluoroscopy is used at the beginning of the case for localization of the skin incision and laminectomy.

Figure 87-1:

MRI of the spine is a useful screening tool and helpful in the management of spinal AVMs. On sagittal T2-weighted MRI, multiple flow voids are visualized posterior to cervicothoracic cord.

Figure 87-2:

Preoperative spinal arteriography is crucial for precise localization of the AVM. On anteroposterior view, a type 1 AVM is shown, localized to the left T12 region.

Figure 87-3:

Patient positioning on a radiolucent operating table comprising a Wilson frame mounted onto a Jackson table permitting easy C-arm fluoroscopy access. The long right femoral sheath is placed before positioning to permit intraoperative spinal arteriography.