Eijiro Okada

Aging of the Cervical Spine in Healthy Volunteers : A 10-Year Longitudinal Magnetic Resonance Imaging Study

Study Design. Prospective longitudinal study, mean follow-up period; 11.7 ± 0.8 years was conducted from 1995 to 2007. Objective. To clarify normal aging process of cervical spine and correlation between progression of disc degeneration and development of clinical symptoms. Summary of Background Data. Aging of the cervical spine can inevitably occur in anyone. Long-term longitudinal studies following the same individuals are necessary to elucidate the accurate aging processes of the cervical spine. Methods. Two hundred twenty-three subjects of 497 original cohorts (123 men, 100 women, mean age: 39.0 ± 15.0, follow-up rate: 44.9%). Subjects, who underwent MRI 10 years ago, underwent another MRI, neurologic examination, and questionnaire survey regarding symptoms related to cervical spine and life style. Following 5 MR findings representing intervertebral disc degeneration were evaluated: (1) decrease in signal intensity of disc, (2) anterior compression of dura and spinal cord, (3) posterior disc protrusion (PDP), (4) disc space narrowing (DSN), and (5) foraminal stenosis (FS). Results. Progression of degenerative findings was observed in 189 subjects (81.1%). Progression of decrease in signal intensity of disc was observed in 59.6%, anterior compression of dura and spinal cord in 61.4%, PDP in 70.0%, DSN in 26.9%, and FS in 9.0%. Logistic regression analysis revealed that incidence of progression of PDP, DSN, FS was higher in elderly subjects. There were no correlations between any degenerative MR findings and sex, smoking, alcohol, sport, or body mass index. Neck pain, shoulder stiffness, and numbness in upper extremities were recognized in 9.9%, 30.0%, and 4.0% of subjects, and 1 or more clinical symptoms have developed in 34.1% during 10 years. Conclusion. Progression of degeneration of cervical spine on MRI was frequently observed during 10-year period, with development of symptoms in 34% of subjects. No factor related to progression of degeneration of cervical spine was identified except for age.

Anterior Cervical Decompression and Fusion Accelerates Adjacent Segment Degeneration: Comparison With Asymptomatic Volunteers in a Ten-Year Magnetic Resonance Imaging Follow-up Study

Study Design. Prospective 10-year follow-up magnetic resonance imaging (MRI) study of patients who underwent anterior cervical decompression and fusion (ACDF) and healthy control subjects. Objective. To clarify the incidence of adjacent segment degeneration during 10 years after ACDF. Summary of Background Data. There have been few studies which investigated incidence of progression of degenerative changes at adjacent segments in patients treated by ACDF comparing with healthy subjects. Methods. Sixty-four patients who underwent ACDF (48 males, 16 females, mean age 47.3 years, mean follow-up 12.1 year) and 201 asymptomatic volunteers who underwent MRI in our previous study (113 males, 88 females, mean age; 41.1 year, mean follow-up; 11.7 years) were included in this study. The patients and control subjects underwent follow-up MRI in this study. Following MR findings were evaluated using a numerical grading system from C2–C3–C7–T1: (1) Decrease in signal intensity of disc (DSI), (2) Posterior disc protrusion (PDP), (3) Disc space narrowing, and (4) Foraminal stenosis. When an increase in at least one grade in any of the radiographic parameters was detected between the 2 time points, progression of disc degeneration was judged as present at the level of interest. Results. Progression of DSI was significantly more frequent in ACDF group than in control group at C4–C5, while progression of PDP was significantly more frequent in ACDF group than in control group at all levels except for C5–C6. Progression of disc space narrowing and foraminal stenosis was significantly more frequent in ACDF group at C3–C4 and at C6–C7, respectively. Conclusion. Although both ACDF patients and control subjects demonstrated progression of disc degeneration during 10 years, ACDF patients had significantly higher incidence of progression of disc degeneration at adjacent segments than control subjects, while progression of disc degeneration at adjacent segments was not always related to development of clinical symptoms.

Postoperative outcome after modified unilateral-approach microendoscopic midline decompression for degenerative spinal stenosis : Clinical article

OBJECT The object of this study was to assess the feasibility and efficacy of a novel, minimally invasive spinal surgery technique to correct degenerative lumbar spinal stenosis involving a modified unilateral-approach microendoscopic midline decompression. METHODS In this prospective study, 41 patients with lumbar stenosis were randomly assigned to undergo either a novel, median-approach microendoscopic laminectomy (20 patients) or a conventional laminectomy (21 patients). Spinal anteroposterior diameter, cross-sectional area, lateral recess distance, spinal stability, postoperative back pain, functional outcomes, and muscle trauma were evaluated. Follow-up ranged from 16 to 24 months, with a mean of 17.8 months for the novel procedure group and 18.6 months for the conventional laminectomy group. RESULTS Compared with patients in the conventional laminectomy group, patients who received the novel procedure had a reduced mean duration of hospital stay, a lower mean creatine phosphokinase muscular-type isoenzyme level, a lower visual analog scale score for back pain at 1-year follow-up, and a faster recovery rate. These patients also had less mean blood loss compared with the conventionally treated group. Satisfactory neurological decompression and symptom relief were achieved in 90% of these patients. There was no significant clinical difference compared with the conventional laminectomy groups results. There was no evidence of spinal instability in any patient, and no patient required a follow-up conventional laminectomy. CONCLUSIONS This novel procedure provides effective spinal decompression. Although this method requires more operating time than a conventional method, it requires only minimal muscle trauma and spinal stability maintenance, and allows for early mobilization. This shortens the hospital stay, reduces postoperative back pain, and leads to satisfactory neurological and functional outcomes. Moreover, with the midline approach, decompression was accomplished without compromising the facet joints, even with a narrow width of lamina.

Age-related changes of thoracic and cervical intervertebral discs in asymptomatic subjects.

Study Design. Magnetic resonance imaging (MRI) study on degeneration of the thoracic spine in asymptomatic subjects. Objective. To investigate the incidence of degenerative MRI findings of the thoracic spine in asymptomatic subjects and to identify factors related to the degeneration of the thoracic discs. Summary of Background Data. Studies on age-related degenerative changes of the thoracic spine are scarce. Methods. Ninety-four asymptomatic Japanese volunteers (48 men and 46 women, mean age of 48.0 ± 13.4 years) underwent MRI of the thoracic and cervical spine and filled the questionnaire regarding life styles. The items evaluated on MRI using a numerical grading system were (1) decrease in the signal intensity of the intervertebral discs (DSI), (2) posterior disc protrusion (PDP), (3) anterior compression of the dural sac (ACD), and (4) disc space narrowing. Association between each degenerative MRI finding and several factors, including age, sex, smoking, sports, body mass index, and degeneration of cervical spine was investigated. Results. Forty-four (46.8%) patients demonstrated positive degenerative MRI findings at 1 or more thoracic intervertebral levels. The percentage of the subjects with positive MRI findings was 37.2% in DSI, 30.9% in PDP, 29.8% in ACD, and 4.3% in disc space narrowing. The percentages of all MRI findings increased with aging. In 85 (90.4%) patients, degenerative MRI findings were positive in the cervical spine. DSI was significantly associated with age (odds ratio, 11.21, 95% confidence interval, 2.70–46.5), PDP with age (3.44, 1.02–16.61), smoking (4.94, 1.55–15.71) and presence of PDP in the cervical spine (4.25, 1.01–17.92), and ACD was associated with smoking (3.99, 1.28–12.44). Conclusion. Degenerative changes in the thoracic spine on MRI was observed in approximately half of the asymptomatic subjects, whereas their incidences were less frequent than those in the cervical spine. Factors significantly associated with degenerative changes in the thoracic spine included age, smoking, and degeneration in the cervical spine.

A Functional SNP in BNC2 Is Associated with Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity. We previously conducted a genome-wide association study (GWAS) and detected two loci associated with AIS. To identify additional loci, we extended our GWAS by increasing the number of cohorts (2,109 affected subjects and 11,140 control subjects in total) and conducting a whole-genome imputation. Through the extended GWAS and replication studies using independent Japanese and Chinese populations, we identified a susceptibility locus on chromosome 9p22.2 (p = 2.46 × 10(-13); odds ratio = 1.21). The most significantly associated SNPs were in intron 3 of BNC2, which encodes a zinc finger transcription factor, basonuclin-2. Expression quantitative trait loci data suggested that the associated SNPs have the potential to regulate the BNC2 transcriptional activity and that the susceptibility alleles increase BNC2 expression. We identified a functional SNP, rs10738445 in BNC2, whose susceptibility allele showed both higher binding to a transcription factor, YY1 (yin and yang 1), and higher BNC2 enhancer activity than the non-susceptibility allele. BNC2 overexpression produced body curvature in developing zebrafish in a gene-dosage-dependent manner. Our results suggest that increased BNC2 expression is implicated in the etiology of AIS.

Cross-sectional area of the posterior extensor muscles of the cervical spine in whiplash injury patients versus healthy volunteers – 10 year follow-up MR study

INTRODUCTION Long-term follow-up studies focusing on the posterior extensor muscles in patients suffering from whiplash injury are scarce. The purpose of this study was to elucidate the changes in the posterior extensor muscles 10 years after whiplash injury. METHODS Twenty-three patients who had suffered from whiplash injury in 1994-1996 and had undergone MRI using a 1.5-T superconductive imager participated in this follow-up study (13 males, 10 females, mean age 51.8 years, mean follow-up 11.5 years). In addition, 60 healthy volunteers who had undergone MRI in the same period were included as controls (36 males, 24 females, mean age 47.8 years, mean follow-up 11.1 years). All participants underwent follow-up MRI. The cross-sectional areas of the deep posterior muscles (CSA) including the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis were digitally measured at C3-4, C4-5, and C5-6 using NIH image. The long-term changes in the CSA were compared between the two groups. In addition, correlations between the CSA and cervical spine-related symptoms were evaluated. RESULTS The mean total CSA per patient (the sum of the area from C3-4 to C5-6) was 4811.6±878.4 mm(2) in the whiplash patients and 4494.9±1032.7 mm(2) in the controls at the initial investigation (p=0.20), and 5173.4±946.1 mm(2) and 4713.0±1065.3 mm(2) at the follow-up (p=0.07). The mean change in CSA over time was 361.8±804.9 mm(2) in the whiplash patients and 218.1±520.7 mm(2) in the controls (p=0.34). Ten whiplash patients (43.5%) had neck pain and 11 (47.8%) had shoulder stiffness. However, there was no difference in the change in CSA over time between the symptomatic and asymptomatic patients. CONCLUSIONS There was no significant difference in the change in CSA between whiplash patients and healthy volunteers after a 10-year follow-up period. In both groups, the cross-sectional area slightly increased at follow-up. In addition, there was no association between the change in CSA and clinical symptoms such as neck and shoulder pain. These results suggest that whiplash injury is not associated with symptomatic atrophy of the posterior cervical muscles over the long term.

Prospective Ten-Year Follow-up Study Comparing Patients With Whiplash-Associated Disorders and Asymptomatic Subjects Using Magnetic Resonance Imaging

Study Design. A prospective 10-year follow-up study of patients with whiplash-associated disorders (WAD) and asymptomatic volunteers. Objective. To clarify long-term impact of whiplash injury on patients symptoms and on magnetic resonance imaging (MRI) findings of the cervical spine. Summary of Background Data. Long-term prognosis of WAD has not been fully elucidated. Methods. Between 1993 and 1996, we conducted cross-sectional comparative study of 508 acute WAD patients and 497 asymptomatic volunteers, all of whom underwent MRI of the cervical spine. For this follow-up study, 133 WAD patients and 223 control subjects were recruited again. All participants underwent follow-up MRI and physical examination, and answered to questionnaires regarding neck symptoms. Evaluation of MRI included decrease in signal intensity of discs, posterior disc protrusion, disc space narrowing, and foraminal stenosis using 2 to 4 numerical grades. Increase in the numerical grades by one or more was considered to be progression of degenerative changes. Results. Progression of decrease in signal intensity was observed in 109 WAD patients (82.0%), and 132 control subjects (59.2%), (age, sex adjusted odds ratio [OR]: 3.06), posterior disc protrusion in 101 (75.9%) and in 155 (69.5%) (OR = 1.46), disc space narrowing in 33 (24.8%) and in 59 (26.5%) (OR = 0.98), and foraminal stenosis in 6 (4.5%), and in 20 (9.0%) (OR = 0.52), respectively. Neck pain was observed in 34 WAD patients (25.6%) and 22 control subjects (9.9%) (P < 0.0001). There was no statistically significant correlation between neck pain and progression in each MR finding in either group. Conclusion. The results of this study suggest that, although some WAD patients are more likely to suffer from long-lasting neck pain, MRI findings cannot explain the symptoms.

Longitudinal magnetic resonance imaging study on whiplash injury patients: Minimum 10-year follow-up

BackgroundWe conducted a prospective long-term follow-up study to assess associations between magnetic resonance imaging (MRI) findings and changes in clinical symptoms, as well as factors relating to the prognosis of symptoms.MethodsA total of 133 patients with acute whiplash injury between 1993 and 1996 participated in this follow-up study. They underwent neurological examinations by spine surgeons and second MRI scans of the cervical spine were obtained. They also filled out a questionnaire regarding cervical symptoms and the accident details. The items evaluated by MRI were (1) a decrease in the signal intensity of the intervertebral disc; (2) anterior compression of the dura and the spinal cord; (3) posterior disc protrusion; (4) disc space narrowing; and (5) foraminal stenosis. Relations between the presence/absence of degenerative changes on MRI, accident details, and patients’ symptoms were assessed by calculating the adjusted odds ratio (OR).ResultsProgression of some degenerative changes was recognized on MRI in 98.5% of the 133 whiplash injury patients, and clinical symptoms diminished in more than a half of the 133 patients. There were no statistically significant associations between MRI findings and changes in clinical symptoms. The prognosis for neck pain tended to be poor after accidents with double collisions (rear-end collision followed by frontend collision) [adjusted OR 5.83, 95% confidence interval (CI) 1.15-29.71] and accidents with serious car damage (2.87, 1.03–7.99). The prognosis for stiff shoulders tended to be poor in women (2.83, 1.23–6.51); and the prognosis for numbness in the upper extremities tended to be poor after accidents with serious car damage (3.39, 1.14–10.06).ConclusionsThis study demonstrated that progression of degenerative changes of the cervical spine on MRI was not associated with clinical symptoms during the 10-year period after whiplash injury.

Modic changes in the cervical spine

We conducted a prospective follow-up MRI study of originally asymptomatic healthy subjects to clarify the development of Modic changes in the cervical spine over a ten-year period and to identify related factors. Previously, 497 asymptomatic healthy volunteers with no history of cervical trauma or surgery underwent MRI. Of these, 223 underwent a second MRI at a mean follow-up of 11.6 years (10 to 12.7). These 223 subjects comprised 133 men and 100 women with a mean age at second MRI of 50.5 years (23 to 83). Modic changes were classified as not present and types 1 to 3. Changes in Modic types over time and relationships between Modic changes and progression of degeneration of the disc or clinical symptoms were evaluated. A total of 31 subjects (13.9%) showed Modic changes at follow-up: type 1 in nine, type 2 in 18, type 3 in two, and types 1 and 2 in two. Modic changes at follow-up were significantly associated with numbness or pain in the arm, but not with neck pain or shoulder stiffness. Age (≥ 40 years), gender (male), and pre-existing disc degeneration were significantly associated with newly developed Modic changes. In the cervical spine over a ten-year period, type 2 Modic changes developed most frequently. Newly developed Modic changes were significantly associated with age, gender, and pre-existing disc degeneration.

Factors affecting the postoperative progression of thoracic kyphosis in surgically treated adult patients with lumbar degenerative scoliosis.

Study Design. A retrospective case series of patients treated surgically for degenerative lumbar scoliosis (DLS). Objective. To determine incidence and risk factors of progressive global thoracic kyphosis (pGTK) after surgery for DLS. Summary of Background Data. Sagittal balance affects the surgical treatment of spinal deformity in adults. Little is known about the loss of sagittal balance due to pGTK, or about the risk factors for pGTK, after surgery for DLS. Methods. We reviewed records from a multicenter database of adults with DLS, treated with posterior spinal fusion. Inclusion required an age of 50 years or more at the time of surgery, an upper instrumented vertebra at T9 and below, more than 5 fused segments, and at least 2 years of follow-up. We included 73 patients with a mean age of 68.3 years (range, 51–77 yr) and a mean follow-up period of 3.6 years (range, 2–11 yr). Independent risk factors for pGTK were identified by logistic regression analysis. Results. Significant pGTK, defined as an increase in thoracic kyphosis of more than 10° from before surgery to the time of final follow-up, was observed in 41% of the patients. Loss of the sagittal vertical axis was larger in patients with pGTK than without (4.7 vs. 1.5 cm; P = 0.02). Risk analysis showed larger lumbar lordosis correction in patients with pGTK. Multivariate logistic regression analysis identified an age greater than 75 (odds ratio, 5.53; P = 0.02, 95% confidence interval [1.4–22.4]) and sacropelvic fusion (odds ratio = 2.66, P = 0.02, 95% confidence interval [1.5–11.1]) as independent risk factors for pGTK. Conclusion. The pGTK incidence after surgery for DLS was 41%. Age, sacropelvic fusion, and a larger sagittal correction were identified as pGTK risk factors. Long-term follow-up will provide more data on the clinical impact of pGTK in elderly patients. Level of Evidence: 3