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John L. Doppman and Mary Girton

✓ Autologous blood (0.3 to 5.0 ml) was introduced into the lumbar subarachnoid space of nine monkeys. Serial spinal cord arteriography was performed at frequent intervals over a 24-hour period. Magnification techniques permitted direct measurement of the anterior spinal artery and posterior spinal vein. Neither immediate nor delayed spasm was observed in any animal. Similar techniques have routinely produced spasm of intracranial arteries in our laboratory.

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John L. Doppman and Mary Girton

✓ Laminectomies were performed in 16 monkeys to decompress simulated acute epidural masses in front of the spinal cord. When decompression restored normal arterial and venous hemodynamics, the monkeys were neurologically intact in spite of considerable mechanical distortion of the cord. When either the anterior spinal artery or the posterior spinal vein remained obstructed following laminectomy, the monkeys were paraplegic. Acute anterior epidural masses larger than 4 mm in diameter could not be adequately decompressed via the posterior approach. Only minor posterior displacement of the cord is observed following laminectomy in the presence of large anterior masses.

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John K. B. Afshar, John L. Doppman and Edward H. Oldfield

✓ To establish if interruption of the intradural draining spinal vein or surgical excision are curative treatments for spinal dural arteriovenous fistulas (AVFs), the medical records and radiographic studies of 19 patients with spinal dural AVFs and progressive myelopathy were reviewed. Spinal arteriograms were obtained before and within 2 weeks after surgery in 19 patients, and after a delay of 4 months or more in 11 patients. The mean clinical and arteriographic follow up was at 37 and 35 months, respectively. In the 11 patients who underwent excision of the dural AVF there was no evidence of a residual lesion upon immediate or delayed postoperative arteriography. Surgery in eight patients consisted of simple interruption of the intradural draining vein as it entered the subarachnoid space. In six of these patients the vein draining the AVF intrathecally provided the only venous drainage of the AVF. In these six patients there was no immediate (six of six) or delayed (four of six) arteriographic evidence of residual or recurrent flow through the AVF. Two patients had an AVF with both intra- and extradural venous drainage; after intradural division of the draining vein there was residual flow through the AVF into the extradural venous system. In one of these two patients intrathecal venous drainage was reestablished, which required additional therapy. In the other patient the extradural AVF spontaneously thrombosed and was not evident on delayed follow-up arteriography.

In patients with spinal dural AVFs with only intrathecal medullary venous drainage, which includes most patients with these lesions, surgical interruption of the intradural draining vein provides lasting and curative treatment. In patients with both intra- and extradural drainage of the AVF, complete excision of the fistula or interruption of the intra- and extradural venous drainage of the fistula is indicated. In patients in whom a common vessel supplies the spinal cord and the dural AVF, simple surgical interruption of the vein draining the AVF is the treatment of choice, as it provides lasting obliteration of the fistula and it is the only treatment that does not risk arterial occlusion and cord infarction. Simple interruption of the venous drainage of a spinal dural AVF provides lasting occlusion of the fistula, as it does for cranial dural AVFs, if all pathways of venous drainage are interrupted. This result provides further evidence that the venous approach to the treatment of dural AVFs can be used successfully.

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John L. Doppman, Giovanni Di Chiro and Ayub K. Ommaya

✓ A technique is described for embolically occluding the feeding arteries of spinal cord arteriovenous malformations by non-operative means. Following the identification of each feeder by selective arteriography, a system of coaxial catheters is introduced percutaneously and each feeding artery is occluded within the spinal canal using metallic pellets, gelfoam, and muscle fragments. Technical details of the procedure are described and the choice of embolic material discussed. Embolization has been successfully accomplished in five patients. None were made worse, and three have shown progressive neurological improvement. The simplicity of the procedure and the absence of morbidity are stressed. Percutaneous embolization should be considered as an alternative to operative ligation of feeding arteries.

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Gregory R. Criscuolo, Edward H. Oldfield and John L. Doppman

✓ Acute or subacute neurological deterioration without evidence of hemorrhage in a patient with a spinal arteriovenous (AV) malformation has been referred to as “Foix-Alajouanine syndrome.” This clinical entity has been considered to be the result of progressive vascular thrombosis resulting in a necrotic myelopathy; it has therefore been thought to be largely irreversible and hence untreatable. The authors report five patients with dural AV fistulas who presented in this manner, and who improved substantially after embolic and surgical therapy. The outcome of these patients indicates that acute and subacute progression of myelopathy in cases of spinal dural AV fistulas may be caused by venous congestion and not necessarily by thrombosis. Therefore, a clinical diagnosis of Foix-Alajouanine syndrome is of little practical use, as spinal cord dysfunction from venous congestion is a potentially reversible process whereas thrombotic infarction is not. This diagnosis may result in suboptimal management. The recognition of nonhemorrhagic acute or subacute myelopathy as a complication of a spinal dural AV fistula is important since what appears to be irreversible cord injury is often treatable by standard surgical techniques.

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Walter A. Hall, Edward H. Oldfield and John L. Doppman

✓ Recently, therapeutic embolization has been advocated as the treatment of choice for arteriovenous malformations (AVM's) of the spine. However, no study has established lasting benefit from this procedure or determined the incidence of recanalization, as occurs with cerebral AVM's. In this study, six patients were followed periodically after complete obliteration of their AVM's by particulate embolization was shown by immediate arteriography. The study group included three men (aged 59 to 72 years) with spinal dural arteriovenous (AV) fistulas and three women (aged 27 to 38 years) with intramedullary glomus-type spinal cord AVM's. The patients were treated by embolization with 100- to 1000-µm diameter polyvinyl alcohol particles. Clinical improvement, most commonly manifesting as increased lower-extremity strength, occurred in all patients after embolization. However, recurrent symptoms, including weakness, numbness, and urinary incontinence, occurred within 2 and 8 months in two of the three patients with dural AV fistulas and within 2 months in two of the three patients with glomus AVM's, prompting radiological reevaluation. Spinal arteriography revealed recanalization of the AV fistulas and spinal AVM's in five patients. Magnetic resonance (MR) imaging demonstrated a signal-void area caused by intramedullary AVM's. This area disappeared after embolic occlusion, but recurred after delayed recanalization, indicating restored flow through the AVM.

Embolization provides only temporary treatment for many spinal AVM's. After embolic occlusion, delayed reassessment with arteriography and/or MR imaging is indicated, particularly if the symptoms persist or recur. Surgical excision of spinal AVM's provides the only therapeutic means to eliminate flow through the AVM permanently in most patients, and should be considered the treatment of choice when feasible.

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John L. Doppman, Roy Ramsey and Raymond J. Thies II

✓ The authors describe a percutaneous technique for producing extra- and intramedullary mass lesions in the dog and monkey. Small balloon catheters introduced through needles into the spinal canal can be positioned under fluoroscopic control to simulate epidural masses or masses within the cord. Selective spinal cord arteriography and silicone perfusion studies demonstrate the effect of such masses on spinal cord blood flow.

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Larry C. Fried, John L. Doppman and Giovanni Di Chiro

✓ The direction of blood flow in the cervical spinal cord of monkeys was studied by direct cinematic observation of the results of dye injections, plus separate angiographic studies. The studies indicated that in monkeys blood enters the cervical spinal cord mainly from radicular arteries that are usually derived from branches of the costo-cervical trunk. Although some blood entering at the low cervical level flows toward the thoracic cord, the major component flows up to the C-2 level. The findings cast doubt on the established assumption that the vertebral arteries provide the main blood supply of the cervical cord.

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Larry C. Fried, Giovanni Di Chiro and John L. Doppman

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Acute occlusion of the posterior spinal vein

Experimental study in monkeys

John L. Doppman, Mary Girton and Mark A. Popovsky

✓ The posterior spinal vein was occluded with silicone in seven rhesus monkeys, and locally resected in one. There were no neurological findings associated with acute venous obstruction of the cord. Follow-up arteriography revealed diversion of venous outflow into the anterior spinal venous system. Histology revealed gliosis associated with demyelinization confined to the posterior columns.