1. Clinical data
Inclusion criteria: Preoperative MRI examination to make clear that:
ⅰ The paravertebral tumor is located outside of the spinal canal, behind the peritoneum, and there is no space-occupying tissue (tumor) in the intervertebral foramen.
ⅱ The location of the tumor corresponds to the lumbar spine segments.
ⅲ Complete follow-up data.
ⅰ Tumors in the lumbar intervertebral foramen or in the spinal canal.
ⅱ The location of the tumor corresponds to higher or lower spine segments such as thoracic spine or sacral spine.
ⅲ Existence of systemic diseases that cannot tolerate surgical treatment, such as coagulation dysfunction.
1.2 Radiological imaging data
All patients in this group underwent X-Ray, CT and enhanced MRI examinations. General X-Ray examination confirmed that there was no enlargement of intervertebral foramen, and no spinal deformity or other manifestations. CT examination utilized thin-layer slices scanning and three-dimensional reconstruction was conducted to clarify the relationship between the tumor and the bony structures, whether there was expression of bony structure erosion or other manifestations, at the same time, CT examination provided imaging evidence for the evaluation of spine stability. Enhanced magnetic resonance imaging examination revealed that localized para-lumbar spine mass was located outside the spinal canal and behind the peritoneum. T1-weighted image showed equal or lower inhomogeneous signal (Fig 1A), T2-weighted image showed equal or slightly higher inhomogeneous signal (Fig 1B), gad-enhanced image showed mild inhomogeneous enhancement, clear boundary and no tumor in the intervertebral foramen (Fig 1C, D). Corresponding segments for paravertebral tumors were located para T12-L1 in 1 case, L1-L2 in 1 case, L1-L3 in 2 cases, and L5-S1 in 2 cases. There were 4 cases on the left side and 2 cases on the right side.
1.3 Surgical methods
This group of cases are operated all by the same surgeon. After general anesthesia tracheal intubation, take the lateral position (the affected side facing upward), operating table was adjusted to jackknife position, and the iliac crest and intercostal space on the affected side are fully extended. The projection of lumbar intervertebral space in interest on the lateral side of the skin is acquired and located with the C-arm imaging system. A straight incision on the skin started from the projection of anterior edge of the vertebral body that went anteriorly parallel to the external oblique muscle was made (Fig 1G), the skin and subcutaneous tissue was cut open (cut off the ribs or spread the intercostal space with spreaders if necessary), muscles of the abdominal wall was separated layer by layer along the muscle bundle direction of external oblique muscle, internal oblique muscle, and transversus abdominis muscles, blunt dissection with fingers was made to separate retroperitoneum, under the condition where kidney, ureter, peritoneum, intestine and other abdominal structures were fully protected, peritoneum was retracted to the ventral side with retractors, exposing the retroperitoneal space (Fig 1E). The deep retroperitoneal paravertebral space was gradually separated by the dissector, fully exposing the tumor. The relationship between the tumor and surrounding tissues, especially with blood vessels and nerves were distinguished and analyzed. If the tumor was encapsulated, the capsule was cut open with scalpel, the tumor was separated along the inner wall of the capsule, the proximal and distal nerve connections were cut off and the tumor was completely removed (Fig 1F). If the tumor is relatively large in size, it can be removed in pieces. Bleeding was completely stopped in the residual cavity, the retractors were removed, and the transversus abdominis, internal oblique muscle, external oblique muscle, subcutaneous tissue and skin was sutured layer by layer.
1.4 Observation and evaluation indicators and statistical methods
In this study, the operation time (the time from the start of skin incision to the end of skin suturing), the amount of blood loss, the length of the surgical incision, and the length of the hospital stay (the time from admission to discharge) were selected as the observation indicators; the effectiveness of tumor resection was evaluated by comparing preoperative and postoperative enhanced MRI; At follow-up, the scoring method of Barthel Index was used to score the patient's ability of daily living activities. At the same time, follow-ups also include the level of patient's clinical symptom relief, whether there is abdominal infection, incisional infection, incisional hernia, or death. The mean standard deviation was used as the statistical method.