Spinal dural arteriovenous fistulas: a congestive myelopathy that initially mimics a peripheral nerve disorder

Abstract

Spinal dural arteriovenous fistula (SDAVF) is a rare and enigmatic disease entity. The clinical features and structural changes have been recognized since 1926, and the pathophysiology and the essentials of treatment since 1974, but up to the present day it is unknown why these fistulas develop. The fistula between a radicular artery and the corresponding radicular vein within the dural root sleeve leads to congestion of the venous outflow of the spinal cord and eventually ischaemia. Patients, who are mostly middle-aged men, develop a progressive myelopathy, which at the early stages of the disease often mimics a polyradiculopathy or anterior horn cell disorder. By the time involvement of upper motoneurons or sacral segments makes the diagnosis of SDAVF inescapable, patients suffer from considerable neurological deficits. The diagnosis relies on MRI, which shows swelling of the spinal cord, with a centrally located hyperintense signal on T2-weighted images, and with hypointense 'flow void' phenomena dorsal to the cord, representing enlarged and tortuous veins. Catheter angiography is required to determine the exact location of the fistula as well as the angio-architecture, on which the mode of treatment depends. If the arterial feeder of the fistula is a tributary of the anterior spinal artery, embolization is not possible. After embolization recanalization may occur, but this is rarely seen after filling of the draining vein with glue. Alternatively, operation is a safe and permanent mode of treatment. No prognostic factors have been reliably established. Muscle strength and gait disturbances respond better to treatment than pain and symptoms related to damage of sacral segments. In any middle aged male patient with ascending motor or sensory deficits in the legs, SDAVF should be considered in order to prevent irreversible handicap.

Endovascular management of spinal dural arteriovenous fistulas

“…The time between the onset of symptoms and diagnosis has been reported to be between 12 and 44 months, with a mean duration of 22.9 months. 32,48 This delay in diagnosis is likely (in part) due to a frequently nonspecific clinical presentation. Presenting symptoms of motor weakness, gait disturbances, and paresthesias commonly lead clinicians to consider and rule out many other disorders before considering spinal DAVFs.…”

“…Common misdiagnoses include degenerative disc disease, spinal cord tumors, peripheral vascular disease, neuromuscular diseases, or neuropathy. 8,32,48 The long-term clinical significance of the delay in diagnosis has yet to be fully elucidated. 14,20,50,57 It is likely that many patients would benefit from more prompt diagnosis and intervention.…”

“…12,30,36,59,63 Although a gradual progression in clinical symptoms has been reported in the majority of patients with spinal DAVFs, a more punctuated, stepwise deterioration has been reported in some patients. 32,61 At the time of diagnosis, many patients have already experienced a considerable progression in the severity of symptoms, and approximately half of all patients report motor disturbances, including weakness and gait abnormalities.…”

“…32 Other initial complaints include sensory disturbances (paresthesias, lower extremity sensory loss, back/radicular pain) and urinary symptoms. A significant proportion of patients present with bowel and bladder deficits or sexual dysfunction.…”

Spinal Dural Arteriovenous Fistulas: Clinical and Radiological outcome of Endovascular Treatment

“…This is because of the nonspecific clinical presentation. 16,24 Patients may present with gait disturbances, difficulty climbing stairs, sensory symptoms, and even radicular pain that may affect 1 or both extremities. The neurologic symptoms show progression with time.…”