Short-term disc herniation change after posterior laminoplasty in multilevel cervical spondylotic myelopathy patients

English Keywords:Cervical spondylotic myelopathy  Laminoplasty  Disc herniation

English Abstract:

  【Abstract】 Objectives: To observe the size changes of disc herniation at 3 months after posterior cervical laminoplasty in patients with multilevel cervical spondylotic myelopathy(CSM). Methods: Clinical data of patients with multilevel CSM who underwent posterior laminoplasty in our hospital from January 2017 to September 2019 were collected and patients with posterior longitudinal ligament ossification were excluded. A total of 67 patients were included, consisting of 44 males and 23 females, and the age ranged from 31 to 78 years(56.5±9.9 years). The sizes of cervical disc herniation at each level were measured on sagittal MRI T1-weighted images before surgery and at 3 months after surgery, and the disc herniation≥2.0mm before surgery was defined as a large disc herniation. The herniation size change between postoperative 3 months and preoperation≤0.5mm was defined as no significant change, and >0.5mm was defined as regression or progression. The incidence of regression, no significant change or progression was calculated. Paired sample t test and nonparametric test were used to compare the size changes of large disc herniation before and after surgery. Results: A total of 314 intervertebral discs were herniated before surgery among the 335 measured, which fell into 57 at C2/3, 64 at C3/4, 66 at C4/5, 65 at C5/6, and 62 at C6/7, and the median herniation size was 2.09(1.43, 2.69)mm. Among them, 163 herniation≥2.0mm, including 9 at C2/3, 42 at C3/4, 38 at C4/5, 41 at C5/6 and 33 at C6/7. At 3 months after surgery, there were 313 herniations with median size of 1.97(1.35, 2.76)mm. Among the 314 discs with preoperative herniation, 83(26.4%) herniations regressed, 175(55.7%) had no significant change, and 56(17.8%) progressed. Among the 163 discs with preoperative herniation≥2.0mm, 54(33.1%) regressed, 86(52.8%) had no significant change, and 23(14.1%) progressed at postoperative 3 months. Of the large disc herniations at C2/3, C3/4, C4/5, C5/6 and C6/7, the numbers were 2, 5, 14, 19 and 14 of regression, 5, 28, 20, 19 and 14 of no significant change, and 2, 9, 4, 3 and 5 of progression, respectively. The postoperative disc herniation sizes at C2/3 and C3/4 were not significantly different from those before operation(P>0.05), while the herniation sizes regressed significantly at C4/5, C5/6 and C6/7(P<0.05). Three patients(4.5%) underwent secondary anterior cervical surgery due to large disc herniation or herniation progression after surgery with no obvious relief of symptoms. Conclusions: The size of large disc herniation could change at 3 months after posterior cervical laminoplasty in multilevel CSM patients. About 1/3 of the herniated discs may regress, mostly at C4/5, C5/6, and C6/7 segments, while the incidence of disc progression is low.