Neuropathic Pain Components in Patients with Lumbar Spinal Stenosis

PURPOSE: To determine the prevalence and characteristics of neuropathic pain (NP) in patients with lumbar spinal stenosis (LSS) according to subgroup analysis of symptoms. MATERIALS AND METHODS: We prospectively enrolled subjects with LSS (n=86) who were scheduled to undergo spinal surgery. The patients were divided into two groups according to a chief complaint of radicular pain or neurogenic claudication. We measured patient's pain score using the visual analog scale (VAS), Oswestry Disability Index (ODI) and Leads Assessment of Neuropathic Symptoms and Signs (LANSS). According to LANSS value, the prevalence of NP component pain in patients with LSS was assessed. Statistical analysis was performed to find the relationship between LANSS scores and the other scores. RESULTS: From our sample of 86 patients, 31 (36.0%) had a NP component, with 24 (63.4%) in the radicular pain group having NP. However, only seven patients (15.6%) in the neurogenic claudication group had NP. The LANSS pain score was not significantly correlated with VAS scores for back pain, but did correlate with VAS scores for leg pain (R=0.73, p<0.001) and with ODI back pain scores (R=0.54, p<0.01). CONCLUSION: One-third of the patients with LSS had a NP component. The presence of radicular pain correlated strongly with NP. The severity of leg pain and ODI score were also closely related to a NP component. This data may prove useful to understanding the pain characteristics of LSS and in better designing clinical trials for NP treatment in patients with LSS.

A Biomechanical Comparison of Intralaminar C7 Screw Constructs with and without Offset Connector Used for C6-7 Cervical Spine Immobilization : A Finite Element Study

OBJECTIVE: The offset connector can allow medial and lateral variability and facilitate intralaminar screw incorporation into the construct. The aim of this study was to compare the biomechanical characteristics of C7 intralaminar screw constructs with and without offset connector using a three dimensional finite element model of a C6-7 cervical spine segment. METHODS: Finite element models representing C7 intralaminar screw constructs with and without the offset connector were developed. Range of motion (ROM) and maximum von Mises stresses in the vertebra for the two techniques were compared under pure moments in flexion, extension, lateral bending and axial rotation. RESULTS: ROM for intralaminar screw construct with offset connector was less than the construct without the offset connector in the three principal directions. The maximum von Misses stress was observed in the C7 vertebra around the pedicle in both constructs. Maximum von Mises stress in the construct without offset connector was found to be 12-30% higher than the corresponding stresses in the construct with offset connector in the three principal directions. CONCLUSION: This study demonstrated that the intralaminar screw fixation with offset connector is better than the construct without offset connector in terms of biomechanical stability. Construct with the offset connector reduces the ROM of C6-7 segment more significantly compared to the construct without the offset connector and causes lower stresses around the C7 pedicle-vertebral body complex.

Microsurgery for degenerative conditions of the cervical spine

Although the operating microscope has been used for spine surgery for more than 20 years, its use is still not widely accepted by the orthopedic spine surgeons. Nevertheless, surgeons who have used the operating microscope are well aware of its many advantages in performing spine surgery. The superior visualization allows for faster, safer and more extensive decompressions. The reluctance of many surgeons to use the operating microscope often has to do with trepidation regarding new technology. The use of the operating microscope when performing anterior and posterior cervical spine surgery makes these procedures easier to carry out and decreases the risk of complications during decompression of the spinal cord

Effect of Bone Mineral Density and Endplate Thickness on the Compressive Strength in the Cervical Spine / 대한척추외과학회지

STUDY DESIGN: This is a biomechanical study to evaluate the subsidence at the cervical endplate from seven fresh cadavers. The study performed after evaluating a bone mineral density(BMD) and a thickness of the endplate. OBJECTIVES: To evaluate the effect of BMD and endplate thickness on the biomechanical strength in an anterior cervical interbody fusion model. MATERIAL AND METHODS: A total of 7 cervical spines(C3-C7) were obtained from fresh cadavers and dissected through the intervertebral disc to obtain the isolated vertebrae. BMD of each vertebral body was measured using a dual-energy x-ray absorptiometry(DEXA) and thickness of endplates was measured by CT images. Each vertebral body was cut into halves through the horizontal plane and prepared specimens were assigned one of the following 3 groups so that group mean BMDs became similar. In group 1, the endplates were preserved intact. The endplates in group 2 were burred into approximately 1/2 of the intact thickness. In group 3, the endplates were totally removed. Each specimen underwent the destructive compression test by using an Instron material test system(MTS). RESULTS: There was significant linea relationship between BMD and load to failure. The load to failure of group 1 was significantly greater than group 3. CONCLUSION: Preoperative consideration of BMD would be important for patient selection and the choice of a surgical technique. And it may be important to preserve the endplate as much as possible to reduced the incidence of subsidence when performing the cervical interbody fusion.

Biomechanical Motion Characteristics of Lumbar Motion Segments : Effects of Radial Tear of the Annulus Fibrosus / 대한척추외과학회지

STUDY DESIGN: Lumbar disc degeneration and segmental instability of the lumbar spine are causes of low back pain. Disc degeneration causes specific changes of the intervertebral disc, and could affect anatomic variations of end plate and vetebral body. However, the exact relationship between degenerative changes of the intervertebral disc and segmental motion characteristics is not known. It is known that radial tears of the annulus fibrosus initiate or accompany degenerative process of nucleus pulposus and the motion segment. It is hypothesis of this study that the existence of radial tear in the annulus fibrosis affects 3 dimension motion characteristics of motion segment. For the purpose, the degree of intervertebral disc degeneration is newly classified by existence of radial tear. Then, the resulting biomechanical motions are investigated. OBJECTIVES: To investigate effects of disc degeneration by the classification on kinematic motions of the motion segment from human lumbar spine and to suggest a quantified method to determine spinal instability in vivo. MATERIALS AND METHODS: A total of 60 spinal motion segments from human lumbar spine was used for this study. To measure 3 dimensioal motion of the motion segments, Vicon system(Oxford, England) with 3 cameras reflective markers and VAX station was used. 6 kinds of pure moments(flexion, extension, right and left axial rotation, and right and left lateral bending) were applied to the motion segments using dead weight for each loading step. At the end of test(maximum loading), motion segments were frozen for anatomical study. For making clear the degree of the degeneration of the disc, a new classification based on MRI results was used: Grade 1 is a normal young disc without tear; Grade 2 is a normal aging disc without radial tear; Grade 3 is a degenerative disc with radial tear; and Grade 4 is a severely degenerative disc with radial tear and other degeneration such as showing decreased disc height. RESULTS: The upper lumbar specimens with radial tears has increased flexion motions as compared to the normal group. Also, the right and left axial rotation in radial tear group increased as compared to the normal group. However, there were no statistical differences in other motions. For the lower lumbar specimens, there were no significant differences in measured motions in all directions between the normal and radial tear groups CONCLUSIONS: These results suggests that the segmental motions are affected by radial tear in the intervertebral disc. Thus, the radial tear in the annulus fibrosus of lumbar intervertebral disc could cause the instability of lumbar spine. Further research is required to determine the relationship between other structural changes and biomechanical characteristics, and future studies should include in vivo investigations to correlate these findings to patients'symptoms.