Patients
Patients with intraspinal tumors of the upper cervical spine were screened at presentation for eligibility and willingness to undergo tumor surgery via the new surgical approach under study. All patients underwent a clinical examination and local imaging for tumor resection planning. MRI confirming extramedullary intraspinal tumors posteriorly located at C1-2 level and CT angiography (CTA) confirming the tumor was not adhesive to the vertebral artery were further analyzed for supero-inferior extent and tumors not exceeding the upper edge of C1 and/or lower edge of C2 lamina were considered for resection using the atlantoaxial lamina space approach. The lateral limiting factor was the C1-C2 lateral joint margin. The tumor was preliminarily judged as benign by MRI and CT showed no bony destruction.
Between January 1, 2016, and January 1, 2018, 10 patients were included for the study to undergo one-stage posterior resection operation and were included in the final analysis. At intial clinical examination, the most common presentation was neck pain (80%, 8/10), followed by numbness (40%, 8/10), limb weakness (20%, 2/10), hypoesthesial (10%, 1/10), and dizziness (10%, 1/10). The study was approved by the ethics committee of General Hospital of Southern Theatre Command of PLA and this study was conducted in conformity with human principles of research..
Preoperative Evaluation
Local imaging included radiographs of cervical spine (standard and dynamic views), CT and contrast enhanced MRI. The stereoscopic images were depicted by three dimensional CT reconstructions. Vertebral artery angiography was used to assess the proximity of the tumor to the vertebral artery. The diameter of the tumor measured by MRI ranged from 1.8 to 3.2cm in these ten patients (Table 1).
Table 1.Clinical Characteristics of the 10 patients with C1-2 intraspinal tumors
Case
|
Gender
|
Age
(years)
|
MRI tumor diameter (cm)
|
Tumor type
|
Symptoms
|
Follow-up
(months)
|
1
|
Male
|
17
|
3.2
|
Neurofibroma
|
Neck pain; numbness
|
24
|
2
|
Female
|
29
|
2.8
|
Neurofibroma
|
Neck pain
|
36
|
3
|
Female
|
32
|
2.4
|
Meningioma
|
Neck pain; hypoesthesia
|
30
|
4
|
Male
|
46
|
2.0
|
Schwannoma
|
Upper limb weakness
|
24
|
5
|
Female
|
50
|
2.6
|
Neurofibroma
|
Neck pain; numbness
|
36
|
6
|
Male
|
42
|
3.0
|
Schwannoma
|
Neck pain; dizziness
|
36
|
7
|
Male
|
34
|
2.1
|
Meningioma
|
Neck pain; numbness
|
30
|
8
|
Female
|
36
|
2.2
|
Meningioma
|
Lower limb weakness
|
24
|
9
|
Male
|
48
|
1.8
|
Neurofibroma
|
Neck pain
|
36
|
10
|
Male
|
26
|
2.8
|
Schwannoma
|
Neck pain; numbness
|
36
|
Surgical Procedures
General anesthesia was performed with tracheal intubation. After the patient was positioned prone, the skull traction weighing 3-4 kg was applied to maintain neck in moderate flexion position to enlarge the lamina space of C1-C2. Then, the skin was longitudinally incised along the posterior midline of the neck from the occipital to the C2 spinous process. Subperiosteal dissection in both directions was performed to expose the occipital bone, the posterior arch of C1, the lower edge of C2 lamina and the lateral mass joint of C1- C2 without damaging the joint capsule to fully expose the lamina space of C1-C2. The posterior cervical muscular attachment points were not damaged, and extensor muscle insertion on the C2 spinous process and the C1 arch was preserved. If the tumor was intradural, the dura mater should be cut open and pulled to two sides using surgical suture. After the tumor was sutured and suspended gradually, the tumor capsule was carefully separated followed by removal of the tumor (Fig. 1). The spinal cord and nerve root were protected carefully. Then, the dura mater was sutured tightly and covered with repair material to prevent cerebrospinal fluid leakage. If the tumor was extradural, it was sutured and suspended gradually to separate tumor capsule microscopically followed by removal of the tumor. If the tumor was closely adhered to the nerve root, the proximal nerve root which was connected to the tumor was cut before complete removal of the tumor. After a drainage tube was placed, the incision was sutured in layers. The tumor was sent to pathological examination. All patients’ pathological types were all verified by pathological examination after operation.
Postoperative management and follow-up
The vital signs were closely monitored after operation. Prophylactic use of antibiotics, appropriate use of glucocorticoids and neurotrophic drugs were administered as necessary. Postoperative scores were analysed at 1month,1year and 2years following surgery. The neural function was evaluated by JOA [6] score (17 points method) and neck disability index (NDI) [8]. The level of neck pain was evaluated by VAS [7] score. The cervical X-ray was reexamined to measure the cervical curvature and activity after operation. MRI was also retested to understand the tumor removal. The neck bracket was used for 4 weeks. Post operative rehabilitation protocol included at postoperative 1 month and followed by full range of activity at 24 months. The follow-up was in the form of outpatient reexamination at 1 month, 1 year and 2 years after operation included clinical examination and local imaging.
Statistical Analysis
Data was entered into a spreadsheet and SPSS Version 22.0 (IBM, Chicago IL, USA) statistical software package was used for statistical analysis. The Kolmogorov-Smirnov test (P > 0.10) was used for testing normality distribution of quantitative variables. The mean and standard deviation (SD) was used for expressing normally distributed data. The repeated measure ANOVA was used investigate changes in mean VAS score, JOA score and NDI, as well as physiological curvature and activity of cervical spine at different following up time. The post HOC statistical analysis was used for multiple comparisons. A two tailed P value < 0.05 was considered statistically significant.