Quantitative evaluation for cervical foraminal bony stenosis based on angled sagittal slices along a nerve root on computed tomography

Cervical foraminal stenosis as a risk factor for cervical kyphosis following cervical laminoplasty

BACKGROUND CONTEXT

Cervical laminoplasty (CLP) is an effective spinal cord decompression method for patients with cervical myelopathy. However, cervical kyphosis after CLP may cause insufficient decompression of the spinal cord. Thus, prevention of cervical kyphosis after CLP and identification of its risk factors are essential.

PURPOSE

This study aimed to investigate the relationship between preoperative cervical foraminal stenosis and kyphotic changes after CLP.

STUDY DESIGN

A retrospective study.

PATIENT SAMPLE

We reviewed 108 patients who underwent CLP for cervical myelopathy between May 2014 and May 2019 and who were followed up for at least 24 months.

OUTCOME MEASURES

For clinical assessments, neck pain, arm pain, neck disability index, Japanese Orthopedic Association scores, EuroQol 5-Dimension, and subjective improvement rate reported by the patients were evaluated. For radiologic parameters, C2-7 Cobb lordotic angle (CLA), C2-7 sagittal vertical axis, T1 slope (TS), TS minus CLA (TS-CLA), and cervical range of motion were assessed preoperatively and postoperatively for 24 months. Cervical foraminal stenosis was evaluated by magnetic resonance imaging and computed tomography.

METHODS

The study population was divided into the kyphosis group (n = 25 patients) and the lordosis group (n = 83 patients) according to the CLA at 24 months postoperatively. Preoperative risk factors related to postoperative kyphosis were analyzed. Statistical analyses were performed using independent two-sample t test, Chi-square test, logistic regression analysis, and linear mixed model.

RESULTS

Preoperative foraminal stenosis, CLA, TS, and TS-CLA were significantly different between the kyphosis and lordosis groups. In multivariate logistic regression analysis, foraminal stenosis (odds ratio [OR], 4.471; p = .0242) significantly increased the risk of kyphosis. The probability of developing kyphosis decreased with an increase in the CLA (OR, 0.840; p = .0001), while the probability of developing kyphosis increased with an increase in the TS-CLA (OR, 1.104; p = .0044).

CONCLUSIONS

Preoperative cervical foraminal stenosis is an independent risk factor for cervical kyphosis following CLP. Thus, CLP may not be a suitable surgical option for cervical myelopathy combined with foraminal stenosis.

A systematic review of validated classification systems for cervical and lumbar spinal foraminal stenosis based on magnetic resonance imaging

PURPOSE

Foraminal stenosis is commonly investigated with radiological methods in patients with radiating pain in extremities. However, there is a lack of consensus regarding the methodology to assess compression of the nerve roots. This systematic review was performed to identify validated classification systems for foraminal stenosis in the lumbar and cervical spine based on magnetic resonance imaging (MRI).

METHODS

A systematic search was conducted according to the PRISMA guidelines. The search included Cochrane, Embase, Medline and PubMed databases going back 30 years and up to September 2021. Three categories of words were used in different variations; foraminal stenosis, MRI and scoring. For inclusion, at least one word from each category had to be present. Articles suggesting classification systems or reporting on their validation were selected for inclusion.

RESULTS

A total of 823 articles were identified and all abstracts were reviewed. Subsequently, a full-text review of 64 articles was performed and finally 14 articles were included. A total of three validated classification systems were found for the cervical and lumbar spine. The remaining 11 articles reported on validation or suggested modifications of the classification systems.

CONCLUSION

The three classification systems demonstrated moderate to good reliability and have all been shown feasible in the clinical setting. There is however a need for further studies testing the validity of these classifications in relation to both clinical findings and to surgical outcome data.

Clinical validity of the smallest oblique sagittal area of the neural foramen in patients with suspected cervical spondylotic radiculopathy

OBJECTIVE

To evaluate the smallest oblique sagittal area of the neural foramen in detecting cervical spondylotic radiculopathy (CSR) and to determine its potential significance for treatment decisions.

METHODS

The subjects of the study were patients with CSR who visited the spine surgery from 2016 to 2019. All patients were compared according to the minimum oblique sagittal area and the cut-off point value, and they were divided into positive and negative parameters. The changes in neck disability index (NDI), Japanese Orthopaedic Association score (JOA), and visual analog scale (VAS) during the two treatment groups from baseline to at least 24 months of follow-up were compared.

RESULTS

In the surgery group, there was no significant difference in symptom improvement between patients with positive and negative parameters. In the non-surgical group, for patients with positive parameters, NDI decreased by 2.35, JOA increased by 0.88, and neck VAS score improved by 0.42. For patients with negative parameters, NDI decreased by 10.32, JOA increased by 2.86 on average, and neck VAS score improved by 2.46 points on average (both p<0.01 on t test).

CONCLUSIONS

Patients with both positive and negative parameters showed significant improvement in their symptoms after surgery, and the smallest oblique sagittal area of the neural foramen seems to be unable to predict the outcome of the surgery. However, in non-surgical patients, symptomatic improvement was more limited in patients with positive parameters than in those with negative parameters. This suggests that patients with positive parameters may be more suitable for surgery and those with negative parameters are more suitable for conservative treatment.

A New Parameter, the Smallest Oblique Sagittal Area of the Neural Foramen, as an Index to Diagnose Cervical Neural Foramen Stenosis

OBJECTIVE

The objective was to reconstruct the cervical neural foramen and accurately measure the minimum oblique sagittal area of the neural foramen. Then, a quantitative diagnostic standard for cervical neural foramen stenosis was proposed and its value as an indication for surgery was evaluated.

METHODS

(1) CT data were used to reconstruct the neural foramen using Mimics software, and the minimum area was measured. (2) The optimal cut-off value was determined using a receiver operating characteristic (ROC) curve. (3) Patients who underwent single-segment surgery were divided into 2 groups according to the cut-off value. Then the postoperative neurological function improvement rate was analyzed to identify any significant difference between the 2 groups.

RESULTS

A total of 1056 neural foramens were measured in 132 patients, of which 495 (46.88%) were diagnosed as radiculopathy by clinical neurological examination. The optimal cut-off value determined by the ROC curve was 25.95 mm² (sensitivity 74.1%, specificity 80.9%) and the area under the curve (AUC) was 0.827 (95%CI: 0.803-0.849). There was a significant difference in the neurological function improvement rate between the 2 groups after surgery (P < 0.05). The intraclass correlation coefficient (ICC) was 0.969.

CONCLUSION

Three-dimensional digital simulation reconstruction of CT data is a good measurement method. The optimal cut-off value determined here not only has a certain reference value for the diagnosis of cervical neural foramen bony stenosis, but also helps to select patients suitable for neural foramen decompression and can be used as a reference for surgical indication.