Effectiveness of multiple-level decompression in laminoplasty and simultaneous C1 laminectomy for patients with cervical myelopathy.

A retrospective study to investigate the relationship between the surgical levels and decompression effects was performed in patients with cervical myelopathy who had undergone Tension-band laminoplasty (TBL) with/without simultaneous C1 laminectomy. One hundred and sixty-eight patients (115 males, 53 females; age: 31-80 years, average 58.9 years; follow-up period: 12-120 months, average 20 months) were divided into three groups according to the range of the surgical levels: seventy-two patients in group A underwent TBL at the C2-C7 levels with C1 laminectomy; 60 patients in group B underwent TBL at the C2-C7 levels; 36 patients in group C underwent TBL at the C3-C7 levels. Neurological evaluation was performed by using the Japanese Orthopedic Association (JOA) scoring system. The alignment changes of the spinal column and the spinal cord were analyzed using pre- and post-operative roentgenograms and MRIs. The differences in the pre- and post-operative anterior subarachnoid spaces (D-ASAS), the spinal cord diameters (D-CORD), and the dural sleeve diameters (D-DURA) at the C1-C7 levels were also analyzed by using MRIs. The JOA scores improved in all groups. As for the spinal alignment, neither significant changes between pre- and post-operation in any group nor significant differences among the three groups were found. The lordosis of the cervical spinal cord was decreased in all groups. D-ASAS of group A was larger than that of group B at the C1-C5 levels (P<0.05), as were those of D-CORD and D-DURA at the C1-C2 and C4-C5 levels (P<0.05). D-ASAS of group A was larger than that of group C at the C1-C4 levels (P<0.05), as were those of D-CORD and D-DURA at the C1-C5 levels (P<0.05). In conclusion, laminoplasty including the C2-C7 levels with simultaneous C1 laminectomy was proven to allow the most posterior shift of the spinal cord within the widened dural sleeve at C5 or higher levels without significantly changing the spinal alignment.