Spinal dural arteriovenous fistulae (SDAVF) are acquired spinal vascular malformations, in which a small connection between a radicular artery and radicular vein causes venous hypertension, congestive myelopathy and infarction of the spinal cord. Here the case of a 47-year-old man is presented who had pain in his back irradiating to his right leg, numbness of his right leg as well as weakness of both legs. Urination was disturbed with detection of residual urine. Six weeks later he developed a progressive paraparesis of the legs. A T2 weighted MRI of the lower back showed intramedullary hyperintensity. A myelitis was assumed and treatment with acyclovir and dexamethasone was started. Nevertheless, he developed total paralysis of his legs. Six years later, re-evaluation of the initial MRI and a new MRI showed abnormal blood vessels on the dorsal side of the spinal cord, which had been overlooked at the first MRI examination. Spinal angiography demonstrated an arteriovenous fistula. Fistula obliteration was performed. Six months later he was able to stand with canes for 2 min and showed improvement in sensibility. The remarkable aspect of this case of SDAVF is the relevant improvement of complete paraplegia by surgical obliteration 78 months after onset of symptoms. The delay of more than 6 years between onset of first symptoms and final diagnosis underlines the difficulties in making a correct diagnosis of SDAVF. However, even after delayed diagnosis, surgical obliteration should be done, as improvement of neurological function can still be achieved.
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Spinal dural arteriovenous fistulae (SDAVF) are acquired spinal vascular malformations1 2 in which a small connection between a radicular artery and radicular vein causes venous hypertension3 and subsequently congestive myelopathy with infarction of the spinal cord. Patients present with a progressive myelopathy with gait difficulties, motor disturbances, sensory disturbances, pain, micturation and defecation problems.
Treatment of first choice is surgical ligation of the fistula, which should be done as early as possible.
A 47-year-old man was seen by his general practitioner and complained of pain in his back radiating to his right leg, numbness of his right leg, bottom and testicles on both sides, as well as weakness of both legs. Urination was disturbed with detection of residual urine by ultrasound examination.
Six weeks later the patient showed an initially mild, but progressive, paraparesis of the legs and was admitted to hospital. A myelopathy was diagnosed. A T2 weighted MRI of the lower back showed intramedullary hyperintensity and a moderate swelling of the lumbar spine (fig 1). CSF was normal; herpes simplex virus antibody and herpes simplex virus PCR in CSF were negative.
Because he had blisters on his back, myelitis caused by herpes simplex type 2 was assumed and treatment with acyclovir and dexamethasone was started. Nevertheless, he continued to deteriorate and developed total paralysis of his legs and bladder dysfunction within a couple of weeks after hospital admission. Aminoff Score of Disability with classification of gait disturbance was grade 5 (requires wheelchair).
Six years later, he was seen for the first time in our department. Neurological examination revealed a flaccid paraplegia with pes equines on both sides, a positive Babinski sign on the left and hypaesthesia beginning from the inguinal region and anaesthesia from the knees downwards. Re-evaluation of the initial MRI and a new MRI showed abnormal blood vessels on the dorsal side of the spinal cord, which had been overlooked at the first assessment.
Spinal angiography demonstrated a perimedullary arteriovenous fistula fed by the right L2 radicular artery. Right L2 hemilaminectomy and fistula obliteration were performed. Postoperative spinal angiography confirmed occlusion of the fistula. Six months later he was able to lift his legs when lying in bed, was able to stand with sticks for 2 min and noted improvement in the numbness of his legs so that he was able to feel touch and pain in his legs. Follow-up 12 months after surgery showed further improvement with paraparesis grade 3–4/5, hip flexor grade 3/5 left, 0/5 right, knee extension 3–4/5 on both sides, knee flexion 2/5 on both sides, foot extension 3/5 left, 0/5 right, lower limb reflexes were depressed and sensory disturbance with hypaesthesia at the L3 level.
The remarkable aspect of this case of SDAVF is the relevant improvement of complete paraplegia by surgical obliteration 78 months after onset of symptoms. Many reports show that a long duration of symptoms (longer than 30 months) before surgical obliteration of SDAVF adversely affects long term outcome4: 50% of untreated patients become wheelchair bound within 3 years. Several case reports confirm the fact that a long duration of symptoms leads to a poor outcome: Tacconi et al described three patients with a duration of symptoms of 96 months before operation. None improved postoperatively, two were stable and one deteriorated.4 In another study, two patients with long term symptoms were studied (45 and 40 months); one improved and the other remained unchanged after surgery. In contrast, there is only one study involving 37 patients showing that the duration of symptoms before treatment had no relation to outcome after treatment.
In most of the cases, outcome of surgery is worse in patients with severe preoperative neurological deficits than in those with mild deficits. The majority of studies demonstrated an improvement of 1 point on the Aminoff and Logue scale regarding gait difficulties. In our patient, the improvement in symptoms was evident but not reflected by the Aminoff scale.
The delay of more than 6 years between onset of first symptoms and final diagnosis underlines the difficulties in make the correct diagnosis. In the present case, the delay was caused mainly by misinterpretation of the initial spinal cord MRI. A recent study reported an average delay of 2 years before SDAVF is correctly diagnosed.5
However, even after delayed diagnosis, surgical obliteration should be done, as improvement of neurological function can be still achieved. On the other hand, it should be pointed out that this case is exceptional and postoperative improvement after long-lasting symptoms should not be expected in general.
Competing interests: None.