Association of Radiological Parameters (X-ray, CT, MRI) with Difficult Video-Laryngoscopy Guided Intubation in Patients Posted for Upper Cervical Spine (C1-C4) Surgery: A Prospective Observational Study

This is a prospective observational cohort study evaluating the association between radiological parameters derived from routine preoperative imaging (cervical X-ray, CT, and MRI) and difficult video-laryngoscopy guided intubation in patients with upper cervical spine (C1-C4) disease undergoing elective surgery.

Background: Patients with upper cervical spine disease demonstrate significantly higher incidence of difficult laryngoscopy (14.9-25%) compared to the general surgical population (4.5-9.7%). Traditional bedside clinical airway assessment tests (Modified Mallampati Test, thyromental distance, inter-incisor gap, upper lip bite test) show limited sensitivity (0.38-0.52) and specificity (0.83-0.86) for predicting difficult intubation. These patients routinely undergo comprehensive imaging (X-ray, CT, MRI) for surgical planning, which can be leveraged for objective airway assessment without additional procedures or costs.

Study Hypothesis: Specific radiological parameters from routine preoperative imaging will significantly associate with difficult video-laryngoscopy guided intubation in upper cervical spine patients.

Methods: At least 55 patients aged 18-65 years with ASA I-III status scheduled for elective upper cervical spine (C1-C4) surgery will be enrolled after IEC approval. Radiological parameters will be measured by an experienced radiologist blinded to clinical assessment: (1) X-ray parameters - LMHT, atlantooccipital distance (O-C1), C1-C2 distance, cervical angles; (2) CT parameters - radiological thyromental distance, retropharyngeal space dimensions; (3) MRI parameters - tongue thickness, oral cavity area, tongue area, TA/OCA ratio, retropharyngeal space dimensions. Traditional clinical airway assessment (MMT, TMD, IIG, ULBT) will be performed preoperatively. Standardized video-laryngoscopy (C-MAC) with manual in-line stabilization will be performed by experienced anaesthesiologist (>3 years) blinded to radiological measurements.

Primary Outcome: Incidence of difficult video-guided intubation defined as >1 intubation attempt OR intubation time >60 seconds.

Secondary Outcomes: (1) Incidence of difficult video-laryngoscopy (Cormack-Lehane Grade III-IV or POGO score <25%); (2) Quantification of radiological measurements; (3) Comparison of sensitivity, specificity, PPV, and NPV of radiological parameters versus traditional clinical tests.

Statistical Analysis: Categorical variables will be compared using chi-square or Fisher’s exact test; continuous variables using Student’s t-test or Mann-Whitney test. Univariate and multivariate logistic regression, ROC curve analysis will determine predictive accuracy. Statistical significance set at p<0.05.

Clinical Significance: This study will establish objective, validated radiological predictors for difficult video-laryngoscopy in high-risk cervical spine patients using existing standard-of-care imaging, potentially improving preoperative planning, reducing naesthesia-related complications, and enhancing patient safety without additional healthcare costs.