Predicted cervical canal enlargement and effective cord decompression following expansive laminoplasty using cervical magnetic resonance imaging.

BACKGROUND: Posterior translation of the spinal cord occurs passively following laminoplasty with the presence lordotic spine and availability of a space for the spinal cord to shift. This study is to predict the distance of posterior spinal cord migration after expansive laminoplasty at different cervical levels based on measurement of posterior translation of the spinal cord in normal cervical morphometry. METHODS: Measurements were performed from C34, C45, C56 and C67 disc using magnetic resonance imaging (MRI) images. Apical level of the cervical curve, lordotic angle, spinal cord diameter, spinal canal diameter, space anterior to the cord and spinal canal/cord ratio were determined before and after postulated laminoplasty. Statistical analysis was performed to assess the significance of the canal enlargement and effective spinal cord decompression at each level. RESULTS: The predicted spinal canal decompression achieved at C34, C4C5, C56 and C67 levels were 48.8, 71.9, 84 and 86.5%, respectively. The mean measurement of spinal canal after laminoplasty was 16.7 mm with spinal canal diameter increased between 3.5 and 5.6 mm. Space anterior to the cord after laminoplasty increased to between 8.6 and 10.9 mm. There was significant correlation between Cobb's angle and spinal canal diameter post laminoplasty at C45, C56 and C67 but no significant correlation between Cobb's angle and space anterior to the cord post laminoplasty was found. CONCLUSIONS: Laminoplasty may produce larger canal expansion at the lower cervical spine compared to the upper cervical area; therefore, the outcomes of those who have predominantly higher cervical myelopathy were inferior to those who have lower cervical myelopathy.

Internal morphometry of thoracic pedicles in the immature spine.

STUDY DESIGN: A cross sectional study of thoracic pedicle morphometry in the immature spine of Malaysian population using reformatted computed tomographic (CT) images. OBJECTIVE: To quantify the isthmus endosteal width and height in the thoracic pedicle of the immature spine. SUMMARY OF BACKGROUND DATA: Previous studies of thoracic pedicle morphology in the adults showed that pedicle screw fixation in the thoracic spine has a higher risk of spinal cord and segmental vessel injury because of the smaller pedicle diameter. Anatomic study of the thoracic pedicle morphology in the immature spine is lacking. Thus, the safety and feasibility of transpedicular fixation in the immature spine are still questionable. METHODS: T1-T12 vertebral pedicles were studied in 25 Malay ethnic patients (age range, 4-18 years). Measurements of the isthmus endosteal width and isthmus endosteal height were made on reformatted CT images using linear measurement tools of Workstation software with a precision of 0.1 mm. The data collected were analyzed using SPSS software version 12.0. The patients were grouped into 3 age groups; group 1 (4-9 years), group 2 (10-14 years), and group 3 (15-18 years). Statistical differences between the age groups were analyzed using analysis of variance (ANOVA) test. RESULTS: In group 1, none of the pedicles have an isthmus endosteal width exceeding 3.0 mm. In group 2, >50% of the pedicles from T1-T11 have an endosteal width of less than 3.0 mm. In group 3, >50% of the pedicles from T1-T10 have an endosteal width of less than 3.0 mm. CONCLUSION: The isthmus endosteal width in >50% of the pedicles studied were less than 3.0 mm. We conclude that transpedicular fixation in the thoracic spine using pedicle screw of >3.0 mm diameter is not feasible in children and adolescents of <18 years old in our population.

Spinal tuberculosis: the association between pedicle involvement and anterior column damage and kyphotic deformity.

STUDY DESIGN: Pedicle involvement in spinal tuberculosis (TB), the prevertebral abscess formation, severity of vertebral body, and disc collapse were evaluated from magnetic resonance imaging (MRI) of the patients. OBJECTIVE: To study the pedicle involvement in spine TB in relation to the degree of vertebral body and disc collapse, prevertebral abscess collection, and degree of kyphosis; and to correlate the occurrence of pedicle involvement and the degree of spinal deformity. SUMMARY OF BACKGROUND DATA: There are a few reports describing the posterior element involvement in spinal TB. Typically, the infection resides in the anterior part of the vertebral body endplates and rarely involved the pedicles. METHODS: There were 31 patients, who had been diagnosed and treated for spinal TB from 2003 to 2007 at our center. Critical evaluation of each patient's MRI was carried out for the pedicle involvement, prevertebral abscess formation, severity of vertebral body, and disc collapse. RESULTS: Spinal TB mostly involved the thoracic level (48.4%). Pedicle involvement was noted in 64.5% of patients, and the highest involvement was at thoracic level. The mean vertebral body, disc collapse, prevertebral abscess, and kyphosis were more severe in pedicle involved group. CONCLUSION: The posterior spinal element, specifically the pedicle is not uncommonly involved in spinal TB. Pedicle involvement is part of the disease process and usually associated with relatively severe vertebral body and disc destruction, wide prevertebral abscess, and severe kyphosis. Pedicle involvement can be detected early from MRI and need to be documented as it may influence the treatment strategy.