Association between Postoperative Neck Pain and Intraoperative Transcranial Motor-Evoked Potential Waveforms of the Trapezius Muscles in Patients with Cervical Myelopathy Who Underwent Cervical Laminoplasty

Methods@#A total of 79 patients with cervical myelopathy who underwent cervical laminoplasty at our facility between June 2010 and March 2013 were included in this study. Intraoperative control and final waveform were evaluated based on the trapezius muscle MEPs by measuring the latency and amplitude. A neck pain group comprised patients with higher neck pain Visual Analog Scale scores from preoperative value to 1 year postoperatively. The cross-sectional areas of the trapezius muscles and the MEP latencies and amplitudes were compared between patients with and without neck pain. @*Results@#The latency and amplitude of the control waveforms were not significantly different between groups. The neck pain group had a significantly shorter final waveform latency (neck pain: 23.6±2.5, no neck pain: 25.8±4.5; p =0.019) and significantly larger amplitude (neck pain: 2,125±1,077, no neck pain: 1,630±966; p =0.041) than the no neck pain group. @*Conclusions@#Postoperative neck pain was associated with the final waveform latency and amplitude of the trapezius muscle MEPs during cervical laminoplasty. Intraoperative electrophysiological trapezius muscle abnormalities could cause postoperative neck pain.

Evaluation of the Association between Neck Pain and the Trapezius Muscles in Patients with Cervical Myelopathy Using Motor Evoked Potential: A Retrospective Study

Methods@#The study included 100 patients with cervical myelopathy who underwent surgery at the National Center for Geriatrics and Gerontology in Obu, Japan from June 2010 to March 2013. Before the surgery, neck pain was evaluated using a Visual Analog Scale (a score ≥50 indicated neck pain and a score <50 indicated no neck pain). The preoperative cross-sectional areas of the trapezius muscles were measured with cervical magnetic resonance imaging sagittal T2-weighted images. Cranial stimulation under general anesthesia was used to derive the MEPs, enabling the measurement of latency and amplitude, using preoperative MEPs of the trapezius muscles. @*Results@#The MEP of the trapezius muscle in patients with neck pain had significantly shorter latencies than those in patients who did not have neck pain. However, there was no significant difference in the amplitude between patients with and without neck pain. However, this tended to be greater in patients with neck pain as compared to that in those without neck pain. The cross-sectional area of the trapezius muscle in patients with neck pain was significantly smaller than that in those who did not have neck pain. @*Conclusions@#MEPs revealed electrophysiological abnormalities of the trapezius muscles in patients with neck pain, supporting a relationship of neck pain with the trapezius muscles.

Scoliosis Caused by Limb-Length Discrepancy in Children

Methods@#The subjects were 23 children with LLD ≥20 mm (range, 27–65 mm) treated at Nagoya University Hospital between 2007 and 2017. Whole spine posteroanterior standing radiographs and whole lower limb radiographs in a supine position were recorded. Data were collected for demographics, LLD, Cobb angle, pelvic obliquity, and Nash/Moe index. Scoliosis was defined as a Cobb angle ≥10°. Leg length was measured from the top of the femoral head to the middle of the tibial plafond, and LLD was defined as the difference between the left and right leg lengths. @*Results@#The patients (nine males and 14 females) had a mean age of 14.0 years (range, 5–18 years). The average LLD was 44.3±17.2 mm, with LLDs of 20 to 39 mm, 40 to 59 mm, and ≥60 mm in 13, five, and five subjects, respectively. The average Cobb angle was 13.0°±7.0°, and 15 subjects (65%) had scoliosis. Convexity of the scoliosis was to the short leg side in all cases. The Cobb angle was significantly related to the severity of the LLD (R=0.736, p<0.01), pelvic obliquity (R=0.966, p<0.01), and Nash/Moe index (p<0.05). @*Conclusions@#LLD is a common pediatric condition that can cause scoliosis of the spine. Severe scoliosis may develop if the LLD is ≥30 mm. Long-term studies are needed to examine the effect of LLD resolution on the elimination of scoliosis.

Scoliosis Caused by Limb-Length Discrepancy in Children

Methods@#The subjects were 23 children with LLD ≥20 mm (range, 27–65 mm) treated at Nagoya University Hospital between 2007 and 2017. Whole spine posteroanterior standing radiographs and whole lower limb radiographs in a supine position were recorded. Data were collected for demographics, LLD, Cobb angle, pelvic obliquity, and Nash/Moe index. Scoliosis was defined as a Cobb angle ≥10°. Leg length was measured from the top of the femoral head to the middle of the tibial plafond, and LLD was defined as the difference between the left and right leg lengths. @*Results@#The patients (nine males and 14 females) had a mean age of 14.0 years (range, 5–18 years). The average LLD was 44.3±17.2 mm, with LLDs of 20 to 39 mm, 40 to 59 mm, and ≥60 mm in 13, five, and five subjects, respectively. The average Cobb angle was 13.0°±7.0°, and 15 subjects (65%) had scoliosis. Convexity of the scoliosis was to the short leg side in all cases. The Cobb angle was significantly related to the severity of the LLD (R=0.736, p<0.01), pelvic obliquity (R=0.966, p<0.01), and Nash/Moe index (p<0.05). @*Conclusions@#LLD is a common pediatric condition that can cause scoliosis of the spine. Severe scoliosis may develop if the LLD is ≥30 mm. Long-term studies are needed to examine the effect of LLD resolution on the elimination of scoliosis.

Changes in Sagittal Alignment Following Short-Level Lumbar Interbody Fusion: Comparison between Posterior and Lateral Lumbar Interbody Fusions

STUDY DESIGN: Retrospective case-control study.PURPOSE: We aimed to compare radiologic outcomes between posterior (PLIF) and lateral lumbar interbody fusion (LLIF) in short-level spinal fusion surgeries.OVERVIEW OF LITERATURE: Although LLIF enables surgeons to insert large lordotic cages, it is unknown whether LLIF more effectively corrects local and global sagittal alignments compared with PLIF in short-level spinal fusion surgeries.METHODS: Radiographic data acquired from patients with lumbar interbody fusion (≤3 levels) using PLIF or LLIF for degenerative lumbar diseases were analyzed. The following radiographic parameters were evaluated preoperatively and at 2 years postoperatively: segmental lordotic angle, disk height, lumbar lordosis (LL), pelvic tilt (PT), C7 sagittal vertical axis, and thoracic kyphosis (TK).RESULTS: In total, 144 patients with PLIF (193 fused levels) and 101 with LLIF (159 fused levels) were included. Patients’ backgrounds and preoperative radiographic parameters for any level of fusion did not differ significantly between PLIF and LLIF procedures. The LLIF group exhibited significantly greater changes at 1-level fusion compared to the PLIF group in the parameters of segmental lordotic angle (5.1°±5.8° vs. 2.1°±5.0°, p<0.001), disk height (4.2±2.3 mm vs. 2.2±2.0 mm, p<0.001), LL (7.8°±7.6° vs. 3.9°±8.6°, p=0.004), and PI–LL (−6.9°±6.8° vs. −3.6°±10.1°, p=0.03). While, a similar trend was observed regarding 2-level fusion, significantly greater changes were only observed in LL (12.1°±11.1° vs. 4.2°±9.1°, p=0.047) and PI–LL (−11.2°±11.3° vs. −3.0°±9.3°, p=0.043), PT (−6.4°±4.9° vs. −2.5°±5.3°, p=0.049) and TK (7.8°±11.8° vs. −0.3°±9.7°, p=0.047) in the LLIF group at 3-level fusion.CONCLUSIONS: LLIF provides significantly better local sagittal alignment than PLIF in 1- or 2-level fusion cases and improves spinopelvic alignment and local alignment for 3-level fusion cases. Thus, LLIF was demonstrated to be a useful lumbar interbody fusion technique, constituting a powerful tool for achieving sagittal realignment with minimal surgical invasiveness.

Factors Affecting Postoperative Sagittal Alignment after Lateral Lumbar Interbody Fusion in Adult Spinal Deformity: Posterior Osteotomy, Anterior Longitudinal Ligament Rupture, and Endplate Injury

STUDY DESIGN: Prospective cohort study. PURPOSE: To identify factors that affect sagittal alignment correction in lateral lumbar interbody fusion (LIF) surgery for adult spinal deformity (ASD) and to investigate the degree of correction in each condition. OVERVIEW OF LITERATURE: LIF is a useful procedure for ASD, but the degree of correction can be affected by posterior osteotomy, intraoperative endplate injury, or anterior longitudinal ligament (ALL) rupture. METHODS: Radiographical data for 30 patients who underwent LIF for ASD were examined prospectively. All underwent two-stage surgery (LIF followed by posterior fixation). Radiographical parameters were measured preoperatively, after LIF, and after posterior fixation; these included the segmental lordotic angle, lumbar lordosis (LL), and other sagittal alignment factors. RESULTS: LL was corrected from 16.5°±16.7° preoperatively to 33.4°±13.8° after LIF (p<0.001) and then to 52.1°±7.9° following posterior fixation (p<0.001). At levels where Schwab grade 2 osteotomy was performed, the acquired segmental lordotic angles from the preoperative value to after posterior fixation and from after LIF to after posterior fixation were 19.5°±9.2° and 9.9°±3.9°, respectively. On average, 12.4° more was added than in cases without osteotomy. Endplate injury was identified at 21 levels (19.4%) after LIF, with a mean loss of 3.4° in the acquired segmental lordotic angle (5.3°±8.4° and 1.9°±5.9° without and with endplate injury, respectively). ALL rupture was identified at seven levels (6.5%), and on average 19.3° more was added in these cases between the preoperative and postoperative values than in cases without ALL rupture. CONCLUSIONS: LIF provides adequate sagittal alignment restoration for ASD, but the degree of correction is affected by grade 2 osteotomy, intraoperative endplate injury, and ALL rupture.

Unplanned Second-Stage Decompression for Neurological Deterioration Caused by Central Canal Stenosis after Indirect Lumbar Decompression Surgery

STUDY DESIGN: Prospective cohort study. PURPOSE: This study aimed to identify risk factors for unplanned second-stage decompression for postoperative neurological deficit after indirect decompression using lateral lumbar interbody fusion (LLIF) with posterior fixation. OVERVIEW OF LITERATURE: Indirect lumbar decompression with LLIF has been used as a minimally invasive alternative to direct decompression to treat degenerative lumbar diseases requiring neural decompression. However, evidence on the prevalence of neurological deficits caused by spinal canal stenosis after indirect decompression is limited. METHODS: This study included 158 patients (mean age, 71.13±7.98 years; male/female ratio, 67/91) who underwent indirect decompression with LLIF and posterior fixation. Indirect decompression was performed at 271 levels (mean level, 1.71±0.97). Logistic regression analysis was used to identify the risk factors for postoperative neurological deficits. The variables included were age, sex, body mass index, presence of primary diseases, diabetes mellitus, preoperative motor deficit, levels operated on, preoperative severity of lumbar stenosis, and preoperative Japanese Orthopedic Association (JOA) score. RESULTS: Postoperative neurological deficit due to spinal canal stenosis occurred in three patients (1.9%). Spinal stenosis due to hemodialysis (p<0.001), ligament ossification (p<0.001), presence of preoperative motor paralysis (p<0.001), low JOA score (p=0.004), and severe canal stenosis (p=0.02) were significantly more frequent in the paralysis group. CONCLUSIONS: Severe preoperative canal stenosis and neurological deficit were identified as risk factors for postoperative neurological deterioration caused by spinal canal stenosis. Additionally, uncommon diseases, such as spinal stenosis due to hemodialysis and ligament ossification, increased the risk of postoperative neurological deficit; therefore, in such cases, indirect decompression is contraindicated.

Comparative Radiographic Outcomes of Lateral and Posterior Lumbar Interbody Fusion in the Treatment of Degenerative Lumbar Kyphosis

STUDY DESIGN: Retrospective case–control study. PURPOSE: To compare surgical invasiveness and radiological outcomes between posterior lumbar interbody fusion (PLIF) and lateral lumbar interbody fusion (LLIF) for degenerative lumbar kyphosis. OVERVIEW OF LITERATURE: LLIF is a minimally invasive interbody fusion technique; however, few reports compared the clinical outcomes of conventional PLIF and LLIF for degenerative lumbar kyphosis. METHODS: Radiographic data for patients who have undergone lumbar interbody fusion (≥3 levels) using PLIF or LLIF for degenerative lumbar kyphosis (lumbar lordosis [LL] <20°) were retrospectively examined. The following radiographic parameters were retrospectively evaluated preoperatively and 2 years postoperatively: segmental lordotic angle, LL, pelvic tilt (PT), pelvic incidence (PI), C7 sagittal vertical axis, and T1 pelvic angle. RESULTS: Nineteen consecutive cases with PLIF and 27 cases with LLIF were included. There were no significant differences in patients' backgrounds or preoperative radiographic parameters between the PLIF and the LLIF groups. The mean fusion level was 5.5±2.5 levels and 5.8±2.5 levels in the PLIF and LLIF groups, respectively (p=0.69). Although there was no significant difference in surgical times (p=0.58), the estimated blood loss was significantly greater in the PLIF group (p<0.001). Two years postoperatively, comparing the PLIF and LLIF groups, the segmental lordotic angle achieved (7.4°±7.6° and 10.6°±9.4°, respectively; p=0.03), LL (27.8°±13.9° and 39.2°±12.7°, respectively; p=0.006), PI–LL (19.8°±14.8° and 3.1°±17.5°, respectively; p=0.002), and PT (22.6°±7.1° and 14.2°±13.9°, respectively; p=0.02) were significantly better in the LLIF group. CONCLUSIONS: LLIF provided significantly better sagittal alignment restoration in the context of degenerative lumbar kyphosis, with less blood loss.

Utility of a Computed Tomography-Based Navigation System (O-Arm) for En Bloc Partial Vertebrectomy for Lung Cancer Adjacent to the Thoracic Spine: Technical Case Report

We describe successful vertebrectomy from a posterior approach using a computed tomography (CT)-based navigation system (O-arm) in a 53-year-old man with adenocarcinoma of the posterior apex of the right lung with invasion of the adjacent rib, thoracic wall, and T2 and T3 vertebral bodies. En bloc partial vertebrectomy for lung cancer adjacent to the thoracic spine was planned using O-arm. First, laminectomy was performed from right T2 to T3, and pedicles and transverse processes of T2 to T3 were resected. O-arm was used to confirm the location of the cutting edge in the T2 to 3 right vertebral internal body, and osteotomy to the anterior cortex was performed with a chisel. Next, the patient was placed in a left decubitus position. The surgical specimen was extracted en bloc. This case shows that O-arm can be used reliably and easily in vertebrectomy from a posterior approach and can facilitate en bloc resection.

Postoperative Severe Headache Following Cervical Posterior Surgical Fixation from C2 Distally

STUDY DESIGN: Retrospective study. PURPOSE: To identify the prevalence of severe headache occurring after cervical posterior surgical fixation (PSF) and to evaluate the clinical and radiological findings associated with severe headache after surgery. OVERVIEW OF LITERATURE: Several studies have reported on the axial pain after cervical surgery. However, to our knowledge, the incidence of severe headache after cervical PSF has not been elucidated. METHODS: The medical records and radiological assessment of patients who underwent surgical treatment from August 2002 to May 2012 were reviewed to identify the prevalence and risk factors for severe headaches occurring following PSF from C2 distally. Neck disability index scores (NDI) (the item for neck pain), the type of C2 screw, number of cervical fused levels (1–6), and smoking habit were calculated preoperatively and postoperatively. In addition, radiological parameters (T1 slope angle, C1/2 angle, C2–7 Cobb angle, C2–7 sagittal vertical axis and C1-implant distance) were assessed for all patients. Severe headache was defined as a high NDI headache score (>4 out of 5). RESULTS: Eighty-two patients met the inclusion criteria. The mean age was 59.2 years (range, 21–78 years), and the mean number of fused levels was 5.1. The mean follow-up period was 2.9 years (range, 1–10.9 years). While only one severe headache occurred de novo postoperatively in a patient in the C3 or C4 distally group (total 30 patients, average age of 50.2 years), 11 patients in the C2 distally group (p=0.04) had severe headache occur postoperatively. The radiological parameters were not significantly different between the postoperative milder headache and severe headache (SH) groups. The SH group had a significantly higher preoperative NDI score (neck pain) (p<0.01). CONCLUSIONS: Newly occurring severe headaches can occur in 18% of patients after PSF from C2 distally. The patients with newly occurring severe headaches had significantly higher preoperative NDI score (neck pain).

Spinal Metastasis from Struma Ovarii: Case Report and Review of the Literature

Struma ovarii is a rare tumor that is defined as an ovarian teratoma with a thyroid tissue component exceeding 50%. Most of these tumors are benign, with malignant struma ovarii occurring in <1% of patients. Here, we describe the case of a 49-year-old female patient with malignant struma ovarii who developed thoracic spine metastasis. She had undergone an oophorectomy and was diagnosed with struma ovarii 10 years previously. She had remained recurrence-free thereafter. At 49 years of age, she developed low back pain and was admitted to our hospital for evaluation of a spinal tumor at the Th7 level. An emergency bone biopsy led to a diagnosis of metastasis from malignant struma ovarii. External beam radiotherapy inhibited further tumor growth and there was no resulting muscle weakness. This is the first report of spinal metastasis occurring 10 years after resection of struma ovarii, indicating the need for long-term follow-up.

Outpatient Myelography: A Prospective Trial Comparing Complications after Myelography between Outpatients and Inpatients in Japan

STUDY DESIGN: Prospective comparative study. PURPOSE: To compare the incidence and severity of adverse reactions associated with myelography performed in outpatients vs. in inpatients and report the safety and usefulness of outpatient myelography in Japanese patients. OVERVIEW OF LITERATURE: Myelography is normally performed as an inpatient procedure in most hospitals in Japan. No studies have reported the usefulness and adverse effects of outpatient myelography in Japanese patients. METHODS: We performed 221 myelography procedures. Eighty-five of the 221 patients underwent outpatient myelography using our new protocol. The incidence and severity of adverse reactions were compared with the other 136 patients, who underwent conventional inpatient myelography. We further compared the cost of outpatient and inpatient myelography. RESULTS: The overall rate of adverse effects was 9.4% in outpatients, as compared with 7.4% in inpatients. Overall, 1.2% of outpatients and 0.74% inpatients experienced "severe" adverse effects (requiring hospitalization). There were no significant differences between the 2 groups in either the overall rate of adverse effects or the rate of "severe" adverse effects. Moreover, the average outpatient procedure cost was only one-third to one-half that of the inpatient procedure. CONCLUSIONS: This was the first study to address the safety and usefulness of outpatient myelography in Japanese patients. If selected according to proper inclusion criteria for outpatient procedure, no significant differences were observed in the adverse effects between inpatients and outpatients. The outpatient procedure is more economical and has the added benefit of being more convenient and time-efficient for the patient.

Variety of the Wave Change in Compound Muscle Action Potential in an Animal Model

STUDY DESIGN: Animal study. PURPOSE: To review the present warning point criteria of the compound muscle action potential (CMAP) and investigate new criteria for spinal surgery safety using an animal model. OVERVIEW OF LITERATURE: Little is known about correlation palesis and amplitude of spinal cord monitoring. METHODS: After laminectomy of the tenth thoracic spinal lamina, 2-140 g force was delivered to the spinal cord with a tension gage to create a bilateral contusion injury. The study morphology change of the CMAP wave and locomotor scale were evaluated for one month. RESULTS: Four different types of wave morphology changes were observed: no change, amplitude decrease only, morphology change only, and amplitude and morphology change. Amplitude and morphology changed simultaneously and significantly as the injury force increased (p<0.05) Locomotor scale in the amplitude and morphology group worsened more than the other groups. CONCLUSIONS: Amplitude and morphology change of the CMAP wave exists and could be the key of the alarm point in CMAP.

Progressive Relapse of Ligamentum Flavum Ossification Following Decompressive Surgery

Thoracic ossification of the ligamentum flavum (T-OLF) is a relatively rare spinal disorder that generally requires surgical intervention, due to its progressive nature and the poor response to conservative therapy. The prevalence of OLF has been reported at 3.8%-26%, which is similar to that of cervical ossification of the posterior longitudinal ligament (OPLL). The progression of OPLL after cervical laminoplasty for the treatment of OPLL is often shown in long-term follow-up. However, there have been no reports on the progression of OLF following surgery. We report a case of thoracic myelopathy secondary to the progressive relapse of OLF following laminectomy.

Single-Stage Removal of Thoracic Dumbbell Tumors from a Posterior Approach Only with Costotransversectomy

PURPOSE: Thoracic dumbbell tumors are relatively rare, usually arising from neurogenic elements. Methods for surgical removal thereof remain controversial. The purpose of this study was to evaluate the surgical results of a single-stage posterior approach with laminectomy and costotransversectomy only for the management of thoracic dumbbell tumors. MATERIALS AND METHODS: Eight cases of thoracic large dumbbell tumor were analyzed retrospectively: seven men and one woman (mean age, 49 years). Pathologic findings included schwannoma in five patients, neurofibroma in two patients (Recklinghausen in one patient), and ganglioneuroma in one patient. All patients underwent single-stage removal of dumbbell tumors by a posterior approach followed by laminectomy and costotransversectomy combined with instrumentation. Clinical and radiologic outcomes were reviewed, thereafter. RESULTS: Operative time ranged from 185 to 420 minutes (mean, 313 minutes), with estimated blood loss ranging from 71 to 1830 mL (mean, 658 mL). Postoperative complications included atelectasis in one case. All patients had tumors successfully removed with no neurological deterioration. Spinal deformities were not observed in any patients at the last follow-up (mean, 52 months), with instrumentation. CONCLUSION: Single-stage surgery with laminectomy and costotransversectomy may be useful for removing thoracic dumbbell tumors without a combined anterior approach.