Hounsfield units of vertebrae as a predictor of cervical deep paraspinal muscles atrophy and neck pain in degenerative cervical myelopathy.

Objective: This study investigated the correlation between Hounsfield units (HU) of the cervical vertebrae and atrophy of the cervical deep paraspinal muscles, namely the multifidus and semispinalis cervicis (SCer), in patients diagnosed with degenerative cervical myelopathy (DCM).

Methods: The authors retrospectively analyzed data from 136 patients aged 50-79 years (81 males and 55 females) who underwent surgical intervention for DCM. HU measurements of the cancellous bone in the C4 vertebra were acquired through standardized techniques. The authors evaluated fatty infiltration (FI); analyzed functional and vertebral cross-sectional area (CSA) of the multifidus and SCer at the C4-5, C5-6, and C6-7 levels; and analyzed the presence of Modic changes (MCs) and the incidence of axial neck pain.

Results: Patients were categorized into group A (n = 56) with mean ± SD HU of 293.3 ± 15.6 and group B (n = 80) with mean ± SD HU of 389.5 ± 10.6. Both groups demonstrated significant improvements in postoperative clinical outcomes (p < 0.05); however, no statistically significant difference was observed (p > 0.05). Significant disparities in HU measurements and visual analog scale (VAS) scores for neck pain were observed between the groups (p < 0.05). The highest VAS score correlated with MCs-1 type (i.e., low signal on T1-weighted images and high signal on T2-weighted images). The functional CSA to vertebral CSA ratios of the multifidus and SCer in group A were markedly reduced compared to those of group B (p < 0.05). No significant difference was noted in functional CSA asymmetry between the groups for both muscles (p > 0.05). Lower HU measurements directly correlated with increased FI in the multifidus (p = 0.002) and SCer (p = 0.035). Furthermore, a strong positive association was found between the functional CSA to vertebral CSA ratio of the multifidus and HU values (p = 0.003), whereas HU measurements and VAS scores exhibited a negative correlation (p = 0.020).

Conclusions: Among those patients older than 50 years with DCM, those with decreased HU values demonstrated elevated FI levels in the multifidus and SCer muscles. Moreover, these patients presented with pronounced muscle atrophy, which correlated with axial neck pain. A significant relationship was also identified between MCs and diminished HU values.