(a) The pathological mechanism of spinal arteriovenous disease.
1, intravertebral venous hypertension: arterial blood enters the vein through a low resistance fistula, the pressure within the venous return system is increased, the normal spinal venous return is blocked, the spinal cord swells, neuronal degeneration and necrosis cause clinical symptoms.
2, hemorrhage: Although rare, it often causes acute injury to spinal cord function, such as craniocervical junctional area DAVF can cause SHA, SCA and SAVM can both lead to spinal cord hemorrhage. Chen Gong, Department of Neurosurgery, Huashan Hospital, Fudan University
3, “blood theft”: due to the appearance of low resistance vessels such as arteriovenous short circuit (A-V Shunt) or malformed vascular mass (Nidus), blood supplying spinal cord tissues directly from the artery through the lesioned low resistance area into the reflux vein, resulting in ischemia of spinal cord tissues causing clinical symptoms.
4.Occupancy effect: SCAVLs itself has no obvious occupancy effect, but in most cases it is caused by hematoma due to hemorrhage of the lesion, or accompanied by aneurysm, enlarged draining vein or venous aneurysm or ball.
(b) Clinical manifestations of spinal arteriovenous type disease.
1. There are three modes of onset.
(1) Slow onset with progressive exacerbation.
(2) intermittent onset, with periods of remission in the course of the disease, but the overall trend is chronic exacerbation.
(3) Sudden onset, with complete paraplegia in some cases, mostly related to spinal cord hemorrhage or SAH.
2. The main clinical symptoms are: pain, sensory disorders, motor disorders, autonomic disorders, etc. Most of these symptoms are mixed, and a few can appear alone.
3. Clinical features.
Compared with other diseases of the spinal cord (such as tumors), there are major differences.
(1) Diversity of pathogenesis and symptoms.
(2) The planes of sensory and motor impairment are not fixed, usually relatively diffuse in the early stages and relatively fixed in the later stages, with some lesions showing multi-segmental spinal cord nerve dysfunction.
(3) The plane of sensory and motor impairment does not necessarily reflect the site of SCAVLs, but the plane of spinal cord injury caused by SCAVLs, and the localized symptoms and signs do not correspond to the site of the lesion.
(4) Most of them have a bilateral lower extremity sensory (more common) and motor impairment onset, followed by an upward progression. The sphincter function is often involved at admission, usually with constipation first, followed by loss of urinary control.
5. Assessment of spinal cord neurological function.
The Aminoff-Logue scale (Table 3-9-3) is usually used for preoperative and postoperative spinal cord function.
(1) Excellent: normal or basically normal, gait 0 to 1, urination 0, stool 0 to 1
(2) Good: mild dysfunction, total score <6 for all three combined.
(3) Moderate: moderate dysfunction, total score 6 to 8
(4) Poor: severe dysfunction, with a total score of 9 to 11.
The specific criteria for evaluating the surgical results were
(1) Cure: complete resection of the lesion and excellent functional score at follow-up.
(2) Improvement: The follow-up score was reduced by 3 points or more compared with the preoperative score. (2) Improvement: The follow-up score decreased by 3 or more points compared with the preoperative score, but did not meet the criteria of excellent or the patient’s follow-up functional score was excellent, but the SCAVLs were not completely eliminated.
(3) No change: The score changed less than 3 points before and after treatment and during the follow-up.
(4) Worsening or poor: score increased by 3 points or more. Or the score continued >9 points before and after treatment and during follow-up.
(iii) Diagnosis of spinal arteriovenous disease.
1. Radiographs: Plain radiographs are the basis of imaging methods, including orthogonal, lateral and oblique films and functional films. It can observe the pathological changes such as scoliosis, congenital variation, osteophytes, fracture and bone destruction of vertebral body and accessories, and also observe the changes such as narrowing of vertebral space.
2, myelography (spinal canal imaging): rarely used at present.
3. Lumbar puncture of cerebrospinal fluid (CFS): non-conventional examination. In general, CSF is normal; when SCAVLs are accompanied by hemorrhage, CSF can be bloody.
4, CT and CTA: plain and enhanced scans, especially horizontal and coronal scans, can show more clearly the specific location of the lesion in the spinal canal and the relationship with the spinal cord, and can also see local bone destruction to help determine whether the lesion involves the spinal canal or conus. The enlarged spinal canal suggests a possible dilated draining vein, and CTA can visualize dilated draining veins and/or vascular malformations (Figure 3-9-8).
5. MRI.
MRI has great reference value for the diagnosis of SCVD, especially T2-weighted sagittal imaging, enhancement and MRA. it can also show the combination of SCVD with hemorrhage, thrombosis, spinal cord cavity or spinal cord atrophy. For details, see the following knot for each disease.
The sensitivity, specificity and accuracy of MRI plain scan are 85% to 90%, 82% to 100% and 87% to 90%, respectively. The sensitivity, specificity, and accuracy of the enhanced MRI scan were 80%-100%, 82%, and 81%-94%, respectively, for the enhancement of tortuous vessels on the spinal cord surface.
MRV has a unique role in showing venous lesions (such as venous sinus occlusion); high-quality enhanced magnetic resonance angiography (CEMRA) can clearly show SCAVLs.
6.Whole spinal cord angiography (DSA)
is the gold standard for diagnosing SCAVLs, confirming the diagnosis and providing the main reference basis for selecting treatment methods and strategies.
Special emphasis is placed on.
(1) SCAVLs angiography is a whole spinal cord angiography including bilateral vertebral arteries, thyrocervical trunk and cribriocervical trunk to bilateral internal iliac arteries, not a selective angiography.
(2) In the craniocervical junction area and upper cervical lesions, bilateral internal and external carotid angiograms should be added to avoid omission.
If there is a high clinical suspicion of a vascular lesion in the spinal cord and a negative spinal arteriogram is selected, further examination should not be easily abandoned.
(1) Selective left renal arteriogram – to understand whether there is spinal venous hypertension caused by renal vein stenosis or occlusion.
(2) Femoral vein cannulation selective odd, semi-oval, para-oval, lumbar and iliac vein angiography to understand whether there is stenosis or occlusion of these veins causing venous hypertension due to obstruction of inferior vena cava return. For example: paravertebral vein anomaly, left renal vein stenosis.
7.Diagnostic flow chart of SCAVLs
8.Leakage and misdiagnosis
Spinal cord vascular DSA examination is not commonly carried out because of its high price and certain pain to patients, coupled with different imaging manifestations and clinicians are not familiar with it, so the diagnosis is often delayed.
In 2004, the neurosurgery department of Huashan Hospital of Fudan University recorded 66 cases of SCVD, and the misdiagnosis rate of MRI was 51.5%, with 19 cases (the majority) being misdiagnosed as intraspinal tumors, 6 cases of spinal hydrocele, 5 cases of disc herniation, 5 cases of acute myelitis, and 2 cases of arachnoiditis, which shows that SCVD has not yet attracted the general attention of clinicians.