SDAVF is a type of intraspinal vascular malformation that has been gradually recognized in clinics in the past 20 years. It occurs when the arteries supplying the nerve roots or dura mater communicate with the spinal drainage vein when passing through the dura mater at the intervertebral foramen. Because the incidence of SDAVF is extremely low and the clinical manifestations are not typical , early diagnosis is not easy, and the misdiagnosis rate is high [6, 7]. If diagnosis and treatment are delayed, spinal venous pressure continues to increase and can cause spinal cord ischemia and edema and even irreversible injuries, such as necrosis and demyelination. Therefore, it is necessary to improve the clinical and imaging understanding of this disease to reduce misdiagnosis and missed diagnoses.
Analysis of clinical manifestations
The disease is more common in elderly men, with a male-to-female ratio close to 4:1 . Ten of the 12 patients in this study were men, accounting for 83.3% of all patients. SDAVF usually begins with progressive spinal dysfunction. The most common symptoms include gait abnormality, decreased myodynamia, paresthesia, sphincter dysfunction and sexual dysfunction. Almost half of all patients initially present more than one of these symptoms. In particular, in cases of patients with bladder dysfunction, physicians should be especially vigilant about considering this disease as a possible diagnosis. Within half a year of onset, symptoms of decreased myodynamia, abnormal sensation and bladder/bowel dysfunction can all appear.
The typical imaging findings usually include hypointense T1 or isointense signals, hyperintense T2 signals of spinal cord edema, and bead-like flow void signs in the dorsal and ventral spinal cord. However, some atypical images include local “weed” signs locally in the dorsal or ventral spinal cord. When these weed signs are present, the possibility of this disease should be considered to avoid a missed diagnosis.
Analysis of causes of misdiagnosis
1.This is a rare disease with an annual incidence of 5 to 10 per 1 million ; therefore, it is easily ignored by some specialists. 2. Additionally, the onset of the disease is not typical, and there are no obvious causes. The clinical manifestations may indicate the involvement of multiple health care specialties, including orthopedics, urology, neurology, pain management, and neurosurgery. Most patients seek medical advice from multiple specialists. However, specialists usually make diagnoses based on their own expertise and thus fail to pay adequate attention to this disease. This is an important reason for the misdiagnosis of this disease . 3. Most patients are middle-aged and elderly men with an onset of sensorimotor dysfunction in the lower limbs; therefore, a diagnosis of degenerative changes of the lumbar spine is often the first choice. BPH is considered when patients present with bladder dysfunction or a decline in sexual function. 4. Physical examinations are not detailed enough to provide a conclusive diagnosis. Although the patient may already have increased muscle tone and positive pathological signs of this disease, the diagnosis of lumbar degenerative diseases, such as LDH, is made only based on MRI findings. 5. MRI may not be available in primary hospitals, so only lumbar CT is used for diagnosis. It is also possible that if MRI is used as a screening method and the initial symptoms are relatively mild, spinal cord MRI is not considered immediately because of its high cost. 5. Physicians do not fully understand the manifestations of this disease on spinal cord MRI images and only consider inflammatory changes or secondary edema of the spinal cord caused by LDH compression when mild changes in long T2 signals are observed, especially when atypical flow voids are observed near the spinal cord. 6. The level of the spinal cord scanned by MRI is too high or too low, causing a missed diagnosis.
The median time from the onset of the patient's clinical symptoms to the diagnosis of the disease is 12 to 44 months, which is an important reason for the high disability rate associated with the disease. Therefore, early diagnosis is key to reducing the disability rate . In this study, 1. Patients misdiagnosed with LDH accounted for approximately 50% (16/33) of all misdiagnosed patients. Most patients with LDH present with root pain that is obviously related to the LDH. However, the pathological signs are negative, which is a very important indicator of SDAVF. In addition, some patients with SDAVF may also have LDH, and this is also an important reason for missed diagnosis. 2. Myelitis progresses rapidly, and spinal cord swelling can be seen on spinal cord MRI images, but there is no flow void sign. In patients with atypical flow void signs, spinal angiography can be an option for confirming the diagnosis. 3. Patients with BPH usually do not have specific clinical manifestations or signs of lower extremity abnormality, and the diagnosis is generally not difficult to make. For patients who cannot be diagnosed, further spinal cord MRI or spinal angiography should be performed.
How to prevent misdiagnosis and missed diagnosis
Primary physicians should obtain detailed a medical history from patients and perform comprehensive physical and neurological examinations. The relevant specialists should improve their understanding of the clinical features of this disease. MRI can be used as a preliminary screening method to analyze myeleterosis on longitudinal and axial views. Furthermore, it is necessary to strengthen collaboration among various departments to reduce the occurrence of misdiagnosis and missed diagnosis.