Comparison of Cervical Paraspinal Muscles and Fat Infiltration Rates between Laminoplasty and Laminectomy with Fusion for Cervical Spondylotic Myelopathy.

Abstract

To compare postoperative degeneration of cervical paraspinal muscles (CPMs) between laminoplasty (LP) and laminectomy with fusion (LF) in patients with cervical spondylotic myelopathy. We retrospective analyzed 68 patients (LP, n=34; LF, n=34) who underwent C3-C6 surgery. Pre- and postoperative MRI measured cross-sectional area (CSA) and fatty infiltration (FI) of five CPMs (longus coli, multifidus, semispinalis cervicis, semispinalis capitis, splenius capitis) from C3 to C7. Changes in CSA and FI on left and right sides were compared between groups before and after surgery. Atrophy rate of CSA and increase rate of FI were calculated, and postoperative changes were analyzed for each muscle at each vertebral level. Both groups had significant postoperative CSA atrophy and FI increase versus preoperative values (P<0.05), but degeneration was greater in the LF group. Combined muscle CSA atrophy rate was higher in the LF group at C3-C6 (P<0.05), as was FI increase rate at all levels (C3-C7, P<0.05). In the LF group, longus colli showed the most severe atrophy, particularly at C3-4. The magnitude of FI increase substantially exceeded CSA reduction in both groups. Both LP and LF were associated with postoperative CPM degeneration, with greater MRI-defined changes observed after LF. Severe longus colli atrophy after LF suggests that disuse atrophy from loss of cervical mobility may be more impactful than direct surgical injury. The disproportionate FI increase versus CSA reduction suggests that postoperative muscle quality changes may be more radiographically apparent than quantitative muscle loss.