Keigo Ito

MR T2 image classification in cervical compression myelopathy: predictor of surgical outcomes.

Study Design. Prospective imaging study of patients undergoing surgery for cervical compressive myelopathy. Objectives. To investigate whether the classification of increased signal intensity (ISI) on magnetic resonance imaging (MRI) in patients with cervical compressive myelopathy reflects the severity of symptoms and surgical outcome. Summary of Background Data. The association between ISI and surgical outcome in cervical myelopathy remains controversial. The degree of ISI has not been well discussed. Methods. A total of 104 patients with cervical compressive myelopathy were prospectively enrolled. All were treated with cervical expansive laminoplasty. MRI was performed in all patients before surgery. ISI of spinal cord was classified into three groups based on sagittal T2-weighted images as follows: Grade 0, none; Grade 1, light (obscure); and Grade 2, intense (bright). The severity of myelopathy was evaluated according to the Japanese Orthopedic Association (JOA) score for cervical myelopathy. Results. Eighty-six patients (83%) showed ISI before surgery. Patients with ISI were significantly older, and had a longer duration of disease, a lower postoperative JOA score, and a worse postoperative recovery rate of JOA score than those without ISI. Preoperative MRI showed 18 patients in Grade 0, 49 patients in Grade 1, and 37 in Grade 2. Duration of disease was the shortest in Grade 0 and longest in Grade 2. Although there was no significant difference in preoperative JOA scores among the three groups, Grade 0 patients had a higher postoperative JOA score and the best postoperative recovery, and Grade 2 had a lower postoperative JOA score and the worst postoperative recovery. Conclusion. Preoperative ISI on T2-weighted sagittal MRI was correlated with patient age, duration of disease, postoperative JOA score, and postoperative recovery rate. Patients with the greatest ISI had the worst postop erative recovery. Classification of ISI can be a predictor of surgical outcome.

Placement and complications of cervical pedicle screws in 144 cervical trauma patients using pedicle axis view techniques by fluoroscope

Cervical pedicle screw fixation is an effective procedure for stabilising an unstable motion segment; however, it has generally been considered too risky due to the potential for injury to neurovascular structures, such as the spinal cord, nerve roots or vertebral arteries. Since 1995, we have treated 144 unstable cervical injury patients with pedicle screws using a fluoroscopy-assisted pedicle axis view technique. The purpose of this study was to investigate the efficacy of this technique in accurately placing pedicle screws to treat unstable cervical injuries, and the ensuing clinical outcomes and complications. The accuracy of pedicle screw placement was postoperatively examined by axial computed tomography scans and oblique radiographs. Solid posterior bony fusion without secondary dislodgement was accomplished in 96% of all cases. Of the 620 cervical pedicle screws inserted, 57 (9.2%) demonstrated screw exposure (<50% of the screw outside the pedicle) and 24 (3.9%) demonstrated pedicle perforation (>50% of the screw outside the pedicle). There was one case in which a probe penetrated a vertebral artery without further complication and one case with transient radiculopathy. Pre- and postoperative tracheotomy was required in 20 (13.9%) of the 144 patients. However, the tracheotomies were easily performed, because those patients underwent posterior surgery alone without postoperative external fixation. The placement of cervical pedicle screws using a fluoroscopy-assisted pedicle axis view technique provided good clinical results and a few complications for unstable cervical injuries, but a careful surgical procedure was needed to safely insert the screws and more improvement in imaging and navigation system is expected.

Laminoplasty and skip laminectomy for cervical compressive myelopathy: range of motion, postoperative neck pain, and surgical outcomes in a randomized prospective study.

Study Design. A prospective randomized clinical trial in surgical treatment for cervical compressive myelopathy. Objective. We prospectively compared modified laminoplasty and skip laminectomy in terms of surgical invasiveness, postoperative range of cervical motion, axial pain, and surgical outcomes. Summary of Background Data. Laminoplasty is an established procedure for the decompression of multisegmental cervical compressive myelopathy. However, it often induces postoperative problems, such as axial pain, restriction of neck motion, and loss of lordotic alignment. Skip laminectomy was recently developed as a minimally invasive procedure. Methods. Forty-one patients with cervical spondylotic myelopathy (CSM), excluding developmental stenosis, were randomized to modified double-door laminoplasty (Lamino group; n = 21) or skip laminectomy (Skip group; n = 20), and followed for more than 1 year (average, 28.1 months). Of these patients, radiographs were taken in neutral, extension, and flexion positions before surgery and after surgery. The cervical alignment of C2–C7 curvature and range of motion (ROM) were calculated. After surgery patients were asked to rate their neck pain, using the visual analogue scale (VAS) periodically. Clinical outcomes were estimated with the Japanese Orthopedic Association scoring system (JOA score). Results. There was no significant difference about operative time and blood loss between Lamino and Skip groups. The C2–C7 lordosis of neutral position in both groups was decreased by a few degrees at final follow-up. The final ROMs were 77.4/88.6% of preoperative ROM, respectively. At all collection times, no significant difference in VAS score of axial pain was seen in either group. There was no significant difference in JOA score between both groups before and after surgery. Conclusion. No significant differences were seen between Lamino and Skip groups, in terms of operative invasiveness, axial neck pain, cervical alignment, and ROM, and clinical results in the patients of CSM without developmental stenosis.

Multivariate analysis of C-5 palsy incidence after cervical posterior fusion with instrumentation

OBJECT Postoperative C-5 palsy is a significant complication resulting from cervical decompression procedures. Moreover, when cervical degenerative diseases are treated with a combination of decompression and posterior instrumented fusion, patients are at increased risk for C-5 palsy. However, the clinical and radiological features of this condition remain unclear. Therefore, the purpose of this study was to clarify the risk factors for developing postoperative C-5 palsy. METHODS Eighty-four patients (mean age 60.1 years) who had undergone posterior instrumented fusion using cervical pedicle screws to treat nontraumatic lesions were independently reviewed. The authors analyzed the medical records of some of these patients who developed postoperative C-5 palsy, paying particular attention to their plain radiographs, MRI studies, and CT scans. Risk factors for postoperative C-5 palsy were assessed using multivariate logistic regression analysis. The cutoff values for the pre- and postoperative width of the intervertebral foramen (C4-5) were determined by receiver operating characteristic curve analysis. RESULTS Ten (11.9%) of 84 patients developed postoperative C-5 palsy. Seven patients recovered fully from the neurological complications. The pre- and postoperative C4-5 angles showed significant kyphosis in the C-5 palsy group. The pre- and postoperative diameters of the C4-5 foramen on the palsy side were significantly smaller than those on the opposite side in the C-5 palsy group and those bilaterally in the non-C5 palsy group. Risk factors identified by multivariate logistic regression analysis were as follows: 1) ossification of the posterior longitudinal ligament (relative risk [RR] 7.22 [95% CI 1.03-50.55]); 2) posterior shift of the spinal cord (C4-5) (RR 1.73 [95% CI 1.00-2.98]); and 3) postoperative width of the C-5 intervertebral foramen (RR 0.33 [95% CI 0.14-0.79]). The cutoff values of the pre- and postoperative widths of the C-5 intervertebral foramen for C-5 palsy were 2.2 and 2.3 mm, respectively. CONCLUSIONS Patients with preoperative foraminal stenosis, posterior shift of the spinal cord, and additional iatrogenic foraminal stenosis due to cervical alignment correction were more likely to develop postoperative C-5 palsy after posterior instrumentation with fusion. Prophylactic foraminotomy at C4-5 might be useful when preoperative foraminal stenosis is present on CT. Furthermore, it might be useful for treating postoperative C-5 palsy. To prevent excessive posterior shift of the spinal cord, the authors recommend that appropriate kyphosis reduction should be considered carefully.

A prospective randomized study of preemptive analgesia for postoperative pain in the patients undergoing posterior lumbar interbody fusion : Continuous subcutaneous morphine, continuous epidural morphine, and diclofenac sodium

Study Design. A prospective randomized clinical trial in preemptive analgesia for postoperative pain was conducted. Objective. To compare the efficacy of three preemptive analgesics combined with local anesthesia: continuous subcutaneous morphine (SC), continuous epidural morphine (ED), and diclofenac sodium (DS). Summary of Background Data. Systemic opioids are known to be effective methods of postoperative pain control. The use of epidural morphine for postoperative analgesia has been a standard treatment in spinal surgery. Only a few studies in the literature have investigated the efficacy of preemptive analgesia using morphine. This is the first prospective randomized clinical trial to assess both subcutaneous and epidural continuous administration of opioids for preemptive analgesia. Methods. For this study, 73 patients were assigned randomly to one of three treatment groups: SC, ED, or DS. All patients underwent posterior lumbar interbody fusion with instrumentation. Pain management was assessed using the visual analogue scale (VAS). Usage of supplemental analgesics, the time to first request of them, and side effects were also investigated. Results. Twenty-two patients were randomized to SC, 23 to ED, and 27 to DS. No baseline variable differences among the three groups were seen. The results showed no significant difference in analgesic effects among those three preemptive analgesics. Only immediately after surgery (at 0 hours), the VAS of the DS group was lowest among three groups. But the DS group took more supplemental analgesic drugs until 72 hours, and the time to first request of this group was shorter than that of the other two groups. High rates of minor side effects were seen in both the ED and DS groups. SC gave moderate analgesic effects as well as the other two groups with few adverse effects. Conclusions. DS provided a favorable effect immediately after surgery, but the effective time was short and the patient needed more supplemental drugs after that. ED did not give the expected effect, with comparativelyhigh rates of side effects. Continuous epidural anesthesia did not seem to be suitable for preemptive analgesia. Continuous subcutaneous morphine brought some analgesic effects with a low rate of complications. It can be an attractive method for postoperative analgesia with technical ease.

Surgical outcome of ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine : Implication of the type of ossification and surgical options

Objective: Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine produces myelopathy through anterior spinal cord compression that is usually progressive and unaffected by conservative treatment. Therefore, early decompressive surgery is imperative. However, decompression surgery of thoracic myelopathy is difficult, and the outcome is often poor. A retrospective study was conducted to investigate the surgical outcome of 21 patients with thoracic OPLL to evaluate which type of surgical approach is better and which type of thoracic OPLL results in a better surgical outcome. Methods: A total of 21 patients with thoracic OPLL (10 men and 11 women; mean age 54 years), who underwent surgical treatment at our department from March 1985 to October 2000, were included in the study. Seven patients exhibited the flat-type OPLL and underwent either anterior decompression and fusion (one patient), anterior decompression via a posterior approach (three patients), or expansive laminoplasty (three patients). Fourteen patients exhibited the beak-type OPLL and also underwent either anterior decompression and fusion (two patients), anterior decompression via a posterior approach (six patients), or expansive laminoplasty (six patients). Results: Regarding of operative time and blood loss, there were no marked differences between the two types of OPLL, regardless of the type of surgical procedure; anterior decompression and fusion and anterior decompression via a posterior approach yielded longer operative times and larger blood loss volumes than expansive laminoplasty. Concerning clinical outcome, there were five cases of neurologic deterioration. All of the five deteriorated cases were of the beak-type OPLL treated by a posterior approach. Two of these patients were treated with expansive laminoplasty. Conclusions: There were five instances of neurologic deterioration in our thoracic OPLL series, and all of them exhibited beak-type OPLL. In the beak-type OPLL, a subtle alteration in the spinal alignment during posterior decompression procedures may increase spinal cord compression, leading to the deterioration of symptoms. A potential increase in kyphosis following laminectomy should be avoided by fixation with a temporary rod. If intraoperative monitoring suggests spinal cord dysfunction, an anterior decompression procedure should be attempted as soon as possible.

Cervical alignment and range of motion after laminoplasty: radiographical data from more than 500 cases with cervical spondylotic myelopathy and a review of the literature.

Study Design. A large-scale analysis of radiographical results of patients with cervical spondylotic myelopathy and a review of the literature. Objective. To identify changes in sagittal alignment and range of motion (ROM) after cervical laminoplasty. Summary of Background Data. Cervical laminoplasty is an effective procedure for decompressing multilevel spinal cord compression. It often induces postoperative complications such as loss of lordotic alignment and restriction of neck motion. Although numerous studies have reported the loss of flexion-extension ROM after laminoplasty, no large-scale study has been reported. Methods. Five hundred twenty consecutive patients with cervical spondylotic myelopathy (331 male and 189 female; mean age, 62.2 yr) who underwent modified double-door laminoplasty were enrolled. The average follow-up period was 33.3 months. All patients were allowed to sit up and walk on the first postoperative day using an orthosis, which could be removed within the first 2 weeks, even if long. Early cervical ROM exercises were performed as a part of the rehabilitation schedule. Radiography was performed before surgery and at the final follow-up. Cervical alignment in the neutral and flexion-extension view were measured by the Cobb method at C2–C7. The ROM was assessed by measuring the difference in alignment between flexion and extension. Results. The mean C2–C7 alignment in the neutral position was 11.9° lordotic preoperatively and 13.6° lordotic postoperatively; the alignment increased by 1.8° in lordosis. The mean total ROM decreased from a preoperative value of 40.1° to 33.5° at the final follow-up, showing a significant difference of 6.6°. The mean total ROM preservation after laminoplasty was 87.9%. Conclusion. Sagittal alignment was slightly changed, with only a 1.8° increase in lordosis. The ROM of the cervical spine was preserved by 87.9%. This preservation of alignment and ROM might be attributable to improvements including early removal of the cervical orthosis, postoperative neck exercises, and some surgical modifications.

Complications of cervical pedicle screw fixation for nontraumatic lesions: a multicenter study of 84 patients

OBJECT The cervical pedicle screw (PS) provides strong stabilization but poses a potential risk to the neurovascular system, which may be catastrophic. In particular, vertebrae with degenerative changes complicate the process of screw insertion, and PS misplacement and subsequent complications are more frequent. The purpose of this study was to evaluate the peri- and postoperative complications of PS fixation for nontraumatic lesions and to determine the risk factors of each complication. METHODS Eighty-four patients who underwent cervical PS fixation for nontraumatic lesions were independently reviewed to identify associated complications. The mean age of the patients was 60.1 years, and the mean follow-up period was 4.1 years (range 6-168 months). Pedicle screw malpositioning was classified on postoperative CT scans as Grade I (< 50% of the screw outside the pedicle) or Grade II (≥ 50% of the screw outside the pedicle). Risk factors of each complication were evaluated using a multivariate analysis. RESULTS Three hundred ninety cervical PSs and 24 lateral mass screws were inserted. The incidence of PS misplacement was 19.5% (76 screws); in terms of malpositioning, 60 screws (15.4%) were classified as Grade I and 16 (4.1%) as Grade II. In total, 33 complications were observed. These included postoperative neurological complications in 11 patients in whom there was no evidence of screw misplacement (C-5 palsy in 10 and C-7 palsy in 1), implant failure in 11 patients (screw loosening in 5, broken screws in 4, and loss of reduction in 2), complications directly attributable to screw insertion in 5 patients (nerve root injury by PS in 3 and vertebral artery injury in 2), and other complications in 6 patients (pseudarthrosis in 2, infection in 1, transient dyspnea in 1, transient dysphagia in 1, and adjacent-segment degeneration in 1). The multivariate analysis showed that a primary diagnosis of cerebral palsy was a risk factor for postoperative implant failure (HR 10.91, p = 0.03) and that the presence of preoperative cervical spinal instability was a risk factor for both Grade I and Grade II screw misplacement (RR 2.12, p = 0.03), while there were no statistically significant risk factors for postoperative neurological complications in the absence of evidence of screw misplacement or complications directly attributable to screw insertion. CONCLUSIONS In the present study, misplacement of cervical PSs and associated complications occurred more often than in previous studies. The rates of screw-related neurovascular complications and neurological deterioration unrelated to PSs were high. Insertion of a PS for nontraumatic lesions is surgically more challenging than that for trauma; consequently, experienced surgeons should use PS fixation for nontraumatic cervical lesions only after thorough preoperative evaluation of each patients cervical anatomy and after considering the risk factors specified in the present study.

Postoperative changes in spinal cord signal intensity in patients with cervical compression myelopathy: comparison between preoperative and postoperative magnetic resonance images

OBJECT Increased signal intensity of the spinal cord on magnetic resonance (MR) imaging was classified pre- and postoperatively in patients with cervical compressive myelopathy. It was investigated whether postoperative classification and alterations of increased signal intensity could reflect the postoperative severity of symptoms and surgical outcomes. METHODS One hundred and four patients with cervical compressive myelopathy were prospectively enrolled. All were treated using cervical expansive laminoplasty. Magnetic resonance imaging was performed in all patients preoperatively and after an average of 39.7 months postoperatively (range 12-90 months). Increased signal intensity of the spinal cord was divided into 3 grades based on sagittal T2-weighted MR images as follows: Grade 0, none; Grade 1, light (obscure); and Grade 2, intense (bright). The severity of myelopathy was evaluated according to the Japanese Orthopedic Association (JOA) score for cervical myelopathy and its recovery rate (100% = full recovery). RESULTS Increased signal intensity was seen in 83% of cases preoperatively and in 70% postoperatively. Preoperatively, there were 18 patients with Grade 0 increased signal intensity, 49 with Grade 1, and 37 with Grade 2; postoperatively, there were 31 with Grade 0, 31 with Grade 1, and 42 with Grade 2. The respective postoperative JOA scores and recovery rates (%) were 13.9/56.7% in patients with postoperative Grade 0, 13.2/50.7% in those with Grade 1, and 12.8/40.1% in those with Grade 2, and these differences were not statistically significant. The postoperative increased signal intensity grade was improved in 16 patients, worsened in 8, and unchanged in 80 (77%). There was no significant correlation between the alterations of increased signal intensity and surgical outcomes. CONCLUSIONS The postoperative increased signal intensity classification reflected postoperative symptomatology and surgical outcomes to some extent, without statistically significant differences. The alteration of increased signal intensity was seen postoperatively in 24 patients (23%) and was not correlated with surgical outcome.

Can magnetic resonance imaging reflect the prognosis in patients of cervical spinal cord injury without radiographic abnormality

Study Design. This is a prospective imaging study of adult patients with cervical spinal cord injury without radiographic abnormality (SCIWORA). Objective. The purpose of this study was to investigate the occurrence rate of intramedullary high-signal intensity (increased signal intensity [ISI]) and prevertebral hyperintensity (PVH) in patients with SCIWORA, and examine their relationship to symptom severity and surgical outcome. Summary of Background Data. SCIWORA is accompanied by the presence of neurologic symptoms in the absence of positive radiographic findings before the emergence of magnetic resonance imaging (MRI). There are few reports regarding the image features on MRI in these patients. Methods. One-hundred consecutive patients with SCIWORA who had undergone expansive laminoplasty were enrolled. There were 79 men and 21 women; the mean age was 55 years (range, 16–87 years). All patients underwent functional x-ray and MRI in the acute phase. On MR T2-weighted imaging sagittal view, occurrence of ISI and PVH was evaluated. Range of ISI and PVH was measured relative to C3 vertebral height. Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy (JOA score), its recovery rate, and ASIA impairment scale were used to evaluate neurological status. Results. ISI was observed in 92 patients and PVH in 90 patients on MRI preoperatively. The range of ISI and PVH tended to increase with scores on the preoperative ASIA scale. ISI and PVH were seen in all patients with ASIA A and B. There was a significant negative correlation between the range of ISI and preoperative JOA score. A significant negative correlation between the range of ISI and recovery rate of JOA score was also seen. Conclusion. ISI and PVH occurred in more than 90% of patients with SCIWORA. The range of ISI significantly reflected symptom severity and prognosis for neurologic outcome.