3.3 | Early diagnosis procedure for SDAVF
The reason for the delayed diagnosis of SDAVF is that it is easily misdiagnosed as another disease. Spinal degenerative diseases and myelitis are particularly common misdiagnoses.
The initial symptoms of SDAVF are nonspecific motor and sensory deficits in the lower extremities. Symptoms worsen with walking and improve with rest. These symptoms are similar to those of intermittent cauda equina claudication caused by lumbar spinal stenosis, which is a common disease. The first investigation is often a lumbar MRI scan. If spinal stenosis is suggested, it may be misdiagnosed as the cause. To avoid this misdiagnosis, it is important to consider whether the symptoms can actually be explained by lumbar spinal stenosis and to check for abnormal conus medullaris signals on lumbar spine MRI.
SDAVF is worsened not only by walking but also by singing, the Valsalva maneuver, and alcohol consumption 1, 3. Additionally, it is crucial to remain vigilant for symptoms that may be challenging to account for due to lumbar spinal lesions, such as weakness in the iliopsoas muscle, sensory disturbances extending beyond the groin, and the presence of the Babinski sign. Furthermore, SDAVF should be considered if symptoms are slowly worsening. Attention should be paid to the presence or absence of abnormalities in the thoracolumbar junction (intramedullary high signal intensity, abnormal vascular images in the subarachnoid space) on lumbar spine MRI.
SDAVF is easily misdiagnosed as myelitis because long intramedullary hyperintensities are observed on T2-weighted images. When a long intramedullary hyperintensity is observed, one should be aware of the abnormal vascular image in the subarachnoid space that is characteristic of SDAVF. The course of SDAVF is often progress slowly; however, it can worsen rapidly with exercise. SDAVF is often misdiagnosed as myelitis, which has an acute onset 13. SDAVF often has a mild increase in the number of cells in the cerebrospinal fluid. The administration of steroids has been documented to lead to sudden clinical deterioration in individuals with SDAVF. When encountering a patient with myelitis whose symptoms worsen with steroid administration, SDAVF must be differentiated 7, 14.
SDAVF is suspected based on clinical and spinal MRI findings. Next, minimally invasive 3D CT angiography or contrast-enhanced MRA is used to detect abnormal blood vessels. Subsequently, selective spinal angiography is employed to establish a conclusive diagnosis of SDAVF.