Chronic venous congestion following embolization of spinal dural arteriovenous fistula

Transcription

1 J Neurosurg Spine 9: , 2008 Chronic venous congestion following embolization of spinal dural arteriovenous fistula Case report TSUYOSHI OHTA, M.D., PH.D., 1 MASANORI GOMI, M.D., 2 HISAYUKI OOWAKI, M.D., PH.D., 3 AND MASATSUNE ISHIKAWA, M.D., PH.D. 1 1 Department of Neurosurgery, Kitano Hospital, Osaka; 2 Department of Neurosurgery, Kyoto University Graduate School of Medicine; and 3 Department of Neurosurgery, Kyoto Katsura Hospital, Kyoto, Japan The authors present a case of spinal dural arteriovenous fistula with fluctuations in symptoms following embolization. Superselective injection of 33% N-butyl cyanoacrylate into the feeding vessel resulted in the complete occlusion of the fistula with traversal of the nidus. The subsequent venous congestion was progressive and treatable with antithrombin therapy. Extended medication with dual antiplatelet therapy was required because dose reduction to aspirin monotherapy worsened symptoms. In this case, it took 2 months for the patient s symptoms to stabilize. The duration of progressive venous thrombosis after embolization of a spinal dural arteriovenous fistula is not well known, nor is the most adequate treatment. Although it is presumed that prevention of venous thrombosis is best achieved with anticoagulation, dual antiplatelet therapy can be a substitute for patients with poor compliance. (DOI: /SPI/2008/9/8/186) KEY WORDS embolization endovascular therapy N-butyl cyanoacrylate progressive venous thrombosis spinal dural arteriovenous fistula S PINAL DAVF is an uncommon acquired disease found primarily in men 50 years of age. Although microsurgical shunt interruption is both secure and reliable, endovascular closure of the spinal DAVF has gained the leading role recently. We report the case of a patient with spinal DAVF in whom embolization was undertaken, after which fluctuations in symptoms emerged in the chronic phase. Case Report History and Examination. This 72-year-old man presented with gait disturbance after having fallen 3 years earlier and later developed urinary retention and paresthesia in both lower limbs. After a long period in which various Abbreviations used in this paper: DAVF = dural arteriovenous fistula; MMT = manual muscle testing; NBCA = N-butyl cyanoacrylate. health care professionals were unable to diagnose his disease, MR imaging performed in our department identified a spinal DAVF. On neurological examination, we noted abnormalities in reflexes (exaggerated bilateral Achilles tendon reflexes and right ankle clonus), as well as in motor (weakness in MMT of 4/5 in the bilateral tibialis anterior muscles and atrophy of the right lower limb), sense (dysesthesia especially in the lateral side of the right lower limb and diminished proprioception in the right knee and ankle), and urinary function (retention of 1 L). The patient could walk only indoors with crutches. The findings on MR images showed an increased T2 signal in the spinal cord from T-7 to L-1 and marked flow voids on both T1- and T2-weighted imaging (Fig. 1A and B). A selective injection to the common trunk of the right T6-8 radicular arteries showed a spinal DAVF at the level of T-6, draining into the dilated perimedullary vein (Fig. 2A). 186 J. Neurosurg.: Spine / Volume 9 / August 2008

2 Chronic venous congestion following embolization FIG. 1. Axial (upper) and sagittal (lower) T2-weighted images of the spinal cord in chronological order. A and B: Images obtained before treatment. Flow voids behind the cord and a hyperintensity area in the cord are visible. C and D: Images obtained on exacerbation. Reduction of the flow voids and shrinkage of the hyperintensity area are shown. E and F: Images obtained 1 year after the embolization procedure. Complete disappearance of the flow voids and the hyperintensity area are noted. Treatment. Complete closure of the spinal DAVF was accomplished by the superselective injection of 33% NBCA through a coaxial assembly system (Tempo4 and Prowler 14, Cordis). Deposition of the NBCA beyond the nidalvenous junction and into the perimedullary venous system of the spinal cord was suspected (Fig. 2B and C). The p- atient did not experience any changes in his symptoms immediately following the procedure. To prevent unexpected thrombosis of the spinal cord venous system, an antithrombin agent (Argatroban) was administered for 2 days prophylactically. On the day following the procedure, the patient showed some improvement in his motor system. After discontinuation of the antithrombin agent, aspirin at a dose of 100 mg per day was given and the patient underwent rehabilitation to improve his activities of daily living. On the 8th day, he was able to walk ~ 30 m with a cane. His hyperreflexia and urinary retention improved slightly; however, the other disturbances remained constant. Abasia without local pain began suddenly on the 9th day. Weakness of the right tibialis anterior muscle (MMT 3/5) and sensory disturbance, especially proprioception, deteriorated on neurological examination. Emergency MR imaging showed a marked reduction of the flow voids along the spinal cord, shrinkage of the increased T2 signal area in the cord, and no signs of hematomyelia (Fig. 1C and D). Recurrence of the spinal DAVF or progressive venous thrombosis was suspected. The patient refused our recommendation that he undergo repeated spinal angiography for confirmation, but reinstitution of the antithrombin therapy rapidly restored his symptoms to the level before worsening. Although anticoagulation with warfarin was considered to be the best treatment to prevent this deterioration, the patient was reluctant to accept the necessary dietary restrictions and instead chose to be treated with dual antiplatelets (aspirin 100 mg and cilostazol 200 mg per day). His symptoms showed gradual improvement until the 27th day, when he stopped taking the cilostazol due to pal- J. Neurosurg.: Spine / Volume 9 / August

3 T. Ohta et al. FIG. 2. Angiograms showing embolization of the spinal DAVF with NBCA. A: Pretreatment image showing the nidus (straight arrow) and the draining vein (angled arrow) of the spinal DAVF at the level of T-6. B: Superselective injection of 33% NBCA. Deposition of the NBCA into the perimedullary venous system (open arrow) was suspected. C: Image obtained just after the embolization procedure. pitations. Three days later, his gait disturbance again worsened. On the 45th day, he was admitted to our hospital with abasia and complete urinary retention. He also showed weakness of the right tibialis anterior muscle (MMT 4/5), an exaggerated right Achilles tendon reflex, right ankle clonus, urinary retention of 500 ml, and loss of proprioception in his right lower limb. The findings on repeated MR imaging remained the same as before. A venous thrombosis that had again become progressive due to the unexpected reduction to a single antiplatelet agent was diagnosed in the patient. His treatment was changed to dual antiplatelets with aspirin 100 mg and ticlopidine 200 mg per day, which gradually improved his symptoms. At 1 year after the embolization, the patient is able to walk ~ 1 km without a cane and the weakness of the tibialis anterior muscles has recovered completely (MMT 5/5). The atrophy of the right lower limb continues as before, and the right Achilles tendon reflex is only slightly exaggerated. Clinical improvement in the dysesthesia, diminished proprioception, and urinary retention ( 200 ml) is evident but less satisfactory. On MR imaging, the flow voids behind the cord and the increased T2 signal in the cord are no longer visible (Fig. 1E and F). The patient s clinical course is illustrated in Fig. 3 according to the Aminoff Logue grading scheme (Table 1). 1,17 Discussion Spinal DAVF is a rare disease entity and primarily afflicts middle-aged men. Most spinal DAVFs are located in the thoracolumbar region. Their exact cause remains unknown, but physiological arteriovenous shunts are likely to become symptomatic due to congenital or environmental factors that lead to impairment of the venous outflow. 10 The choice of treatment is endovascular embolization or surgical ligation of the fistula. Embolization with liquid polymers is advocated over particles such as polyvinyl alcohol, because the use of particles leads to a recurrence rate as high as 30 93%. 12 Recanalization occurs rarely when the draining vein is filled with glue, 9 but the inadvertent deposition of embolic material beyond the nidal-venous junction and into the perimedullary venous system might cause thrombosis of the spinal cord venous system. 3 The most common MR imaging finding of spinal DAVF is an increased T2 signal in the cord. 11 Perimedullary vessels are seen on T2-weighted images as a serpentine or punctate area of signal void in 45 70% of patients. 6,11 After treatment, the perimedullary vessels are no longer appreciable, but serpentine structures of intermediate signal intensity may be observed. Reopening of the fistula is associated with enlargement of cord hyperintensity and contrast-enhanced perimedullary vessels. 11 Niimi et al. 13 have reported that 2 of their 49 patients treated with embolization suffered progressive venous thrombosis. Their subsequent symptomatic aggravation developed within 1 month of the treatment and improved after heparinization. These authors used heparinization for selected patients who showed significantly compromised venous drainage of the spinal cord for 3 days to maintain the activated partial thromboplastin time at times normal. 13 Acute neurological deterioration without evidence of hemorrhage in a patient with a spinal arteriovenous malformation has been referred to as Foix Alajouanine syndrome. 4 Although it has been suggested that this clinical entity might include spinal cord dysfunction due to venous congestion, which is a potentially reversible process, necrotic myelopathy due to progressive venous thrombosis is thought to be irreversible and untreatable. 4 The best treatment of progressive venous thrombosis in the chronic phase is not clear. Because the most obvious method of arresting the thrombotic process is anticoagulation, 16 the use of heparin or warfarin may be the best therapeutic option. The optimal duration of oral anticoagulant treatment after the acute phase is also unknown. In the case of cerebral venous thrombosis, vitamin K antagonists are given with a target international normalized ratio of Warfarinization may be an adequate treatment for spinal venous thrombosis. From a pathophysiological point of view, inhibition of platelet aggregation has been associated with impaired thrombus formation both in an experimental model of venous thrombosis and in vivo. 8 It has been reported that antiplatelet therapy significantly reduces the risk of fatal or nonfatal pulmonary embolism by 25%. 2 Given that anticoagulation therapy has shown a superior efficacy and safety profile, the most recent guidelines advise against aspirin monotherapy for thromboprophylaxis in the surgical pa- 188 J. Neurosurg.: Spine / Volume 9 / August 2008

4 Chronic venous congestion following embolization FIG. 3. Graph showing the clinical course according to the Aminoff Logue grading scheme. tient. 5 A lower risk of major bleeding in patients on longterm low-dose aspirin therapy (annual risk of major bleeding 1% 14 ) compared with vitamin K antagonist therapy (2.7% in 6 months 15 ) might support a supplementary role in prolonged use. With respect to the medication period, vitamin K antagonists for cerebral venous thrombosis are given for 6 months after a first episode of sinus thrombosis unless predisposing factors exist. 16 In the present case, dual antiplatelet therapy was continued for 1 year, because multiple clinical worsening and deposition of NBCA into the venous system were thought to be predisposing factors. In spinal DAVF, extraspinal injection can reflux into the spinal veins, testifying to an impaired venous protective system. 18 Venous flow for the thoracolumbosacral cord is thought to return with the respiratory cycle. 7 It is unclear in the present case why the patient suffered acute deterioration in a period of 9 days rather than a slow and steady decline. Maneuvers that changed intraabdominal or intrathoracic pressure such as active rehabilitation may have suddenly aggravated his unstable venous outflow. In the present case, symptomatic aggravation developed Grade TABLE 1 Functional status determined by the modified Aminoff Logue grading scheme Definition gait 1 leg weakness, abnormal gait or stance, but no restriction of activity 2 restricted activity 3 requiring 1 stick for walking 4 requiring 2 sticks, crutches, or walker 5 confined to wheelchair micturition 0 normal 1 hesitancy, frequency, urgency 2 occasional urinary incontinence or retention 3 total incontinence or persistent retention on the 9th day and reappeared on the 30th day, and it was determined to be the result of progressive venous thrombosis based on the findings on repeated MR images. We were able to treat the patient successfully with antithrombin/dual antiplatelet therapy even after his symptoms worsened due to the unexpected reduction to aspirin monotherapy; recovery could be achieved only by reinstituting dual antiplatelet therapy. Although it would have been better to perform spinal angiography to confirm the cause of delayed deterioration of symptoms, the present MR imaging findings and the patient s later course support our diagnosis of progressive venous thrombosis rather than recurrence of spinal DAVF. Conclusions Progressive venous thrombosis following embolization of spinal DAVF can develop in the chronic phase and can be treated with dual antiplatelet therapy. It should be kept in mind that delayed deterioration is not necessarily caused by the recurrence of spinal DAVF. Disclaimer The authors do not report any conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. References 1. Aminoff MJ, Logue V: The prognosis of patients with spinal vascular malformations. Brain 97: , Antithrombotic Trialists Collaboration: Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 324:71 86, Berenstein A, Lasjaunias P, ter Brugge KG (eds): Surgical Neuroangiography. Berlin: Springer, 2004, Vol 2.2, p Criscuolo GR, Oldfield EH, Doppman JL: Reversible acute and subacute myelopathy in patients with dural arteriovenous fistulas. Foix-Alajouanine syndrome reconsidered. J Neurosurg 70: , 1989 J. Neurosurg.: Spine / Volume 9 / August

5 T. Ohta et al. 5. Geerts WH, Pineo GF, Heit JA, Bergqvist D, Lassen MR, Colwell CW, et al: Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 126 (3 Suppl):338S 400S, Gilbertson JR, Miller GM, Goldman MS, Marsh WR: Spinal dural arteriovenous fistulas: MR and myelographic findings. AJNR Am J Neuroradiol 16: , Gillot C: The infrarenal vena cava. Anat Clin 2: , Hovens MM, Snoep JD, Tamsma JT, Huisman MV: Aspirin in the prevention and treatment of venous thromboembolism. J Thromb Haemost 4: , Jellema K, Sluzewski M, van Rooij WJ, Tijssen CC, Beute GN: Embolization of spinal dural arteriovenous fistulas: importance of occlusion of the draining vein. J Neurosurg Spine 2: , Jellema K, Tijssen CC, van Gijn J: Spinal dural arteriovenous fistulas: a congestive myelopathy that initially mimics a peripheral nerve disorder. Brain 129: , Mascalchi M, Ferrito G, Quilici N, Mangiafico S, Cosottini M, Cellerini M, et al: Spinal vascular malformations: MR angiography after treatment. Radiology 219: , Nichols DA, Rufenacht DA, Jack CR Jr, Forbes GS: Embolization of spinal dural arteriovenous fistula with polyvinyl alcohol particles: experience in 14 patients. AJNR Am J Neuroradiol 13: , Niimi Y, Berenstein A, Setton A, Neophytides A: Embolization of spinal dural arteriovenous fistulae: results and follow-up. Neurosurgery 40: , Patrono C, Coller B, FitzGerald GA, Hirsh J, Roth G: Plateletactive drugs: the relationships among dose, effectiveness, and side effects: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 126 (3 Suppl):234S 264S, Schulman S, Granqvist S, Holmström M, Carlsson A, Lindmarker P, Nicol P, et al: The duration of oral anticoagulant therapy after a second episode of venous thromboembolism. The Duration of Anticoagulation Trial Study Group. N Engl J Med 336: , Stam J: Thrombosis of the cerebral veins and sinuses. N Engl J Med 352: , Steinmetz MP, Chow MM, Krishnaney AA, Andrews-Hinders D, Benzel EC, Masaryk TJ, et al: Outcome after the treatment of spinal dural arteriovenous fistulae: a contemporary single-institution series and meta-analysis. Neurosurgery 55:77 87, Tadié M, Hemet J, Freger P, Clavier E, Creissard P: Morphological and functional anatomy of spinal cord veins. J Neuroradiol 12:3 20, 1985 Manuscript submitted December 26, Accepted May 6, Sources of support: none reported. Address correspondence to: Tsuyoshi Ohta, M.D., Ph.D., , Ohgimachi, Kita-ku, Osaka, Japan, t-oota@kitanohp.or.jp. 190 J. Neurosurg.: Spine / Volume 9 / August 2008