Investigating Cervical Foraminal Stenosis Using Imaging Techniques

Background
Cervical foraminal stenosis is a common cause of radiculopathy, but its radiological assessment remains inconsistent. Multiple grading systems have been proposed and this thesis aimed to evaluate the existing systems, assess their consistency and determine whether radiological severity or morphology predicts functional outcomes after surgery. It also explored the potential role of diffusion tensor imaging in quantifying cervical nerve microstructure.

Methods
A published systematic review identified and appraised 59 published grading systems for cervical foraminal stenosis. A published retrospective cohort study analysed pre-operative magnetic resonance imaging of 50 surgical patients, with six independent raters applying Kim and modified Kim methods to assess inter-rater and intra-rater reliability. A subsequent published retrospective study correlated radiological features with pre-operative and post-operative neck disability index scores following anterior cervical discectomy or posterior cervical foraminotomy. An unpublished prospective diffusion tensor imaging pilot study then investigated diffusion metrics of the cervical nerve roots in relation to pre-operative and post-operative neck disability index scores.

Results
The systematic review highlighted wide methodological variation and limited clinical validation of existing grading systems. Inter-rater agreement for Kim (κ=0.01) and modified Kim (κ=0.08) was poor, though intra-rater reliability was good (κ=0.69–0.81). There was no significant correlation between radiological grades or morphological features and pre-operative or post-operative neck disability index. Surgery significantly improved mean neck disability index but outcomes did not differ between anterior cervical discectomy and posterior cervical foraminotomy. The diffusion tensor imaging pilot demonstrated quantitative assessment of the cervical nerve roots was technically feasible.

Conclusions
Current radiological grading systems for cervical foraminal stenosis demonstrate poor inter-rater reliability and lack predictive value for surgical outcomes. While surgery improved NDI, the existing magnetic resonance imaging-based grading systems used in isolation cannot determine prognosis or surgical approach. Future research should explore 3D imaging and diffusion tensor imaging to provide quantitative measures of nerve integrity that may enhance diagnostic precision, prognostication and personalised surgical decision-making.