1. Overview.
The earliest depiction began in the late 19th century when it was thought to be a vascular fistula of the spinal soft spinal membrane. It was generally considered rare, but with the advent of MRI, and especially with the development of spinal angiography, the number of cases reported is increasing.
The natural history of SCVM remains unclear, and large-scale studies are lacking. A significant proportion of SCVMs have no associated symptoms (exact percentage is unknown) and are detected for other disease examinations, and many small SCMs are found incidentally. Chen Gong, Department of Neurosurgery, Huashan Hospital, Fudan University
There is a lack of sound epidemiological data. The common one is spinal cavernous hemangioma, whose incidence is about 20 cases per million people, followed by spinal dural arteriovenous fistula, perimedullary arteriovenous fistula and spinal arteriovenous malformation (total incidence is about 5-10 cases per million people/year). Most of these diseases belong to the neurosurgical category and will be discussed in this section.
2. The clinical pathogenesis of
(1) Spinal venous hypertension: It is the most common mechanism of injury in SCVM. Arterial blood passes through the lesion into the low-pressure veins and increases the pressure in the venous return system, resulting in swelling of the spinal cord, neuronal degeneration and necrosis.
(2) “Blood theft”: Due to the presence of low-resistance vascular constructs such as arteriovenous short circuit (A-V Shunt) or malformed vascular mass (Nidus), blood supplying spinal cord tissue passes directly from the artery through the low resistance area of the lesion into the returning vein, resulting in ischemia of spinal cord tissue.
(3) Occupancy effect: The occupancy effect of SCVM itself is not obvious, but in most cases is caused by a hematoma due to hemorrhage from the lesion, or by an accompanying aneurysm, enlarged draining vein or venous aneurysm or ball. Larger SCM, AN and SAVM can cause occupying effects and spinal cord compression symptoms
(4) Hemorrhage: uncommon, but often causes acute injury to the spinal cord, e.g., both SAVM and SCM with AN can cause spinal cord hemorrhage, and DAVF in the craniocervical junction can also cause SHA.
(5) Thrombosis: lesioned vessels can cause thrombosis, which can occur in arteries (such as ASA syndrome), but is particularly prone to occur in long, twisted and narrowed draining veins, which then produce symptoms of spinal cord ischemia and necrosis.
3. Clinical symptoms of SCVM.
(1) There are three modes of onset.
(1) Slow onset with progressive exacerbation: the most common, with sensory impairment, motor impairment, and sphincter dysfunction below the plane of the lesion. Most of these symptoms are mixed, and a few can occur separately. Painful symptoms are less common.
② Intermittent onset: There are periods of symptomatic remission during the course of the disease, but the overall trend is toward chronic exacerbation. It occurs mainly in cases of intermittent small amounts of bleeding (e.g., SCM) and thrombosis.
(③) Sudden onset: some present with complete paraplegia, mostly associated with acute bleeding, SAH or acute thrombosis (e.g. Foix-Alajouanine syndrome).
(2) Foix-Alajouanine syndrome.
It was described by Foix and Alajouanine in 1926 as “subacute necrotizing myelitis”. It occurs in adults and rarely in children, with a male to female ratio of about 3 to 4:1.
① Definition: Ischemic necrosis of the spinal cord parenchyma due to venous hypertension in the spinal cord when spinal venous return is impaired.
② Vascular constructs that predispose to it: long, twisted draining veins, hypertrophy of the vessel wall and narrowing of the inner lumen, and gravity-resistant drainage.
③ Clinical manifestations:as rapidly progressive spinal cord sensory, motor, and sphincter dysfunction.
④ Signs: spastic paraplegia in the early stage and flaccid paraplegia in the late stage, with hyperactive tendon reflexes in the early stage and absent in the late stage.
⑤ Imaging: there may be irregular dotted patchy enhancement areas within the T1 low signal area after enhancement suggesting that the lesion is ischemic necrosis.
(3) Clinical characteristics: Compared with other diseases of the spinal cord (such as tumors), there are major differences.
(1) Long duration of disease, diversity of pathogenesis and symptoms.
(2) Similar degree of injury in the left and right sides under the plane of lesion (except for SCM on one side), less radicular radiological pain, significant sphincter dysfunction, and high acute morbidity.
③ The planes of sensory and motor impairment are not fixed, usually relatively diffuse in the early stages and relatively fixed in the later stages; some lesions show multi-segmental spinal cord nerve dysfunction.
④ The plane of sensory and motor impairment does not necessarily reflect the site of the lesion, but rather the plane of spinal cord injury caused by the lesion, and the localized symptoms and signs do not correspond to the site of the lesion.
⑤ The majority of cases have a bilateral onset of sensory (more common) and motor deficits in the lower extremities, followed by an upward progression. Often sphincter function is involved, usually with constipation first, followed by loss of urinary control.
4. Diagnosis of SCVM.
(1) Clinical symptoms: compared with other spinal cord lesions, there is no obvious specificity, although there are differences, and imaging is the main diagnostic method.
(2) Imaging: is the main diagnostic method
① Plain x-ray radiography, vertebral myelography (rarely used nowadays), lumbar puncture cerebrospinal fluid (CFS) examination (unconventional), CFS mainly examines proteins, cells and bacteria to screen for bleeding, infection and tumor, etc.
② CT and CTA: plain and enhanced scans, especially horizontal and coronal scans, can show more clearly the exact location of the lesion in the spinal canal and its relationship to the spinal cord. local bone destruction helps to determine whether the lesion involves the spinal canal or conus. CTA can visualize dilated draining veins and or vascular malformations.
MRI can show the signal of worm-like vascular flow in the spinal cord of SCVM lesions (Figure 5-98-1 A) and other information such as edema, hemorrhage, thrombus, spinal cord cavity or spinal cord atrophy, etc. MRA and enhanced magnetic resonance angiography (CEMRA) can provide more information about SCVM
④ Total spinal angiography (DSA) is the gold standard for the diagnosis of most SCVM and provides the main basis for the choice of treatment.
Special emphasis is placed on the following.
(1) total myelography is a total spinal angiogram including bilateral vertebral arteries, metacervical trunk, cribriform trunk and bilateral internal iliac arteries (including median sacral artery), and is not a selective angiogram.
(2) In the craniocervical junction area and upper cervical segment lesions, bilateral internal and external carotid artery angiograms should be added to avoid omission.
(3) When SCVM is highly suspected clinically and total spinal arteriogram is negative, further investigations are required.
(4) Selective left renal arteriogram – to understand the presence of spinal venous hypertension caused by renal vein stenosis or occlusion.
(5) 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.
(6) If the first total myelogram is negative, but the clinical suspicion of SCVM is still high, repeat the total myelogram after the condition has stabilized, if necessary.
5. Diagnosis and differential diagnosis of SCVM.
Because of the lack of obvious specificity of its symptoms and the lack of understanding of its imaging by clinicians, it often results in a high rate of underdiagnosis and misdiagnosis, and is often misdiagnosed as lumbar spinal stenosis, disc herniation, demyelinating disease, myelitis or spinal cord tumor. Even if the diagnosis of SCVM is made, SAVM, SDAVF and PMAVF are often confused with each other.
In 2004, the neurosurgery department of Huashan Hospital of Fudan University recorded 66 cases of SCVM, 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, respectively. It is evident that SCVM has not yet attracted sufficient attention from clinicians.
6. Spinal cord neurological function assessment.
(1) The Aminoff-Logue table (referred to as the AL table) is usually used to assess preoperative and postoperative spinal cord function (Table 5-98-3).
① Excellent: normal or basically normal, gait 0 to 1, urine 0, stool 0 to 1
② good: mild dysfunction, the total score of the three summed < 6 points
③ medium: moderate dysfunction, total score of 6 to 8 points
④ Poor: severe dysfunction, total score of 9 to 11
(2) Evaluation of surgical results.
① Cure: complete resection of the lesion and excellent functional score at follow-up.
② Improvement: the follow-up score is 3 or more points less than the preoperative score. However, the standard of superiority has not yet been reached or the patient’s functional score at follow-up is superior, but the lesion is not completely eliminated.
③ No change: The score changed less than 3 points before and after treatment and during follow-up.
④ Deterioration or poor: The score increased by 3 points or more. or score >9 points consistently before, after and during follow-up.