C3-6 laminoplasty takes over C3-7 laminoplasty with significantly lower incidence of axial neck pain

Abstract

Five-lamina (C3-7) procedure is the most popular cervical laminoplasty and there have been no studies on the most appropriate number of laminae to be opened. We prospectively reduced the range of laminoplasty from C3-7 to C3-6 in 2002 and compared the outcome of C3-6 laminoplasty (n=37) to that of C3-7 laminoplasty (n=28). In both groups, neurological gain was satisfactory, radiographic changes were minimal, and postoperative MRI indicated sufficient expansion of the dura and the spinal cord. Average operating period was significantly shorter, and length of the operative wound was significantly less in the C3-6 group than in the C3-7 group. Postoperative axial neck pain was significantly rarer after C3-6 laminoplasty than after C3-7 laminoplasty (5.4% vs. 29%, P=0.015). Due to its simplicity and various benefits, C3-6 laminoplasty is a promising alternative to conventional C3-7 laminoplasty for treatment of multisegmental compression myelopathy.

Fig. 1

Criteria for deciding between anterior surgery and laminoplasty for compression myelopathy. Patients with cervical kyphosis>15° or solitary anterior lesion are treated by anterior surgery, and all other patients are treated with laminoplasty. When cord compression is restricted to levels above C5/6, C3-6 laminoplasty is used. When cord compression includes C6/7 or lower levels, C3-7 or longer laminoplasty is performed

Fig. 2

Incidence of early and late axial pain after laminoplasty. Axial neck pain was significantly rarer after C3-6 laminoplasty than after C3-7 procedure both in the early postoperative period (<1 month) and late postoperative period (>1 month)

Fig. 3

Anteroposterior diameter of the dura and spinal cord at each disc level. There was no significant difference in antero-posterior diameter of the spinal cord between the two groups. The only significant difference in antero-posterior diameter of the dura occurred at the C6/7, where it was significantly smaller in the C3-6 group. However, there was sufficient subarachnoid space for the spinal cord at C6/7

Fig. 4

Two patterns of MRI after C3-6 laminoplasty. a Antero-posterior diameter of the dura is uniform throughout the entire cervical spine. b Extreme expansion of the dura over the decompression area causes relative impingement at C6/7 (arrow), although the spinal cord is fully released at the same level