Reduced hypopharyngeal muscle strength in patients with dysphagia symptoms after anterior cervical discectomy and fusion

Abstract Background Dysphagia symptoms are a common complication following anterior cervical discectomy and fusion (ACDF). The Eating Assessment Tool-10 (EAT-10) is widely used to screen for dysphagia symptoms, particularly in patients with scores ≥ 3. However, the underlying pathophysiological mechanisms and specific swallowing muscle impairments associated with dysphagia symptoms after ACDF remain incompletely understood. Videofluoroscopy is considered the gold standard for evaluating swallowing function. High-resolution impedance manometry (HRIM) enables quantitative assessment of pressure dynamics during swallowing. Therefore, this study aimed to identify alterations in pharyngeal contractile function and pathophysiological changes associated with dysphagia symptoms following ACDF using HRIM and videofluoroscopy. Methods Patients who underwent ACDF within one year postoperatively were enrolled in this cross-sectional study. Dysphagia symptoms were defined as an EAT-10 score ≥ 3. Swallowing function was evaluated using HRIM and videofluoroscopy. Swallowing tests were performed with two food textures, as defined by the International Dysphagia Diet Standardisation Initiative (IDDSI): level 0 (thin liquid) and level 4 (extremely thick liquid). HRIM parameters were compared between patients with and without dysphagia. Aspiration was defined as a Penetration–Aspiration Scale (PAS) score ≥ 6 on videofluoroscopic examination. Results A total of 43 patients were included, comprising 29 with dysphagia symptoms and 14 without. During thin liquid swallowing (IDDSI level 0), patients with dysphagia symptoms had significantly lower hypopharyngeal mean peak pressure (hypoPeakP) and higher Swallow Risk Index (SRI) compared with those without dysphagia symptoms (median 55.79 vs. 104.85 mmHg and 18.60 vs. 4.30, respectively). During extremely thick liquid swallowing (IDDSI level 4), hypoPeakP remained significantly lower in the dysphagia symptoms group (median 86.96 vs. 161.19 mmHg), whereas SRI did not differ significantly between groups. No aspiration events were observed. Conclusions Post-ACDF dysphagia symptoms were associated with reduced hypopharyngeal contractile pressure. These findings offer physiological insights into the association between dysphagia symptoms and swallowing biomechanics and may inform future research on swallowing assessment in this population. Trial registration ClinicalTrials.gov Identifier: NCT04591665; IRB Approval: 202008024RINC.