Reevaluation of the Pavlov Ratio in Patients with Cervical Myelopathy

BACKGROUND: This study was designed to reevaluate the effectiveness of the Pavlov ratio in patients with cervical myelopathy. METHODS: We studied 107 patients who underwent open door laminoplasty for the treatment of cervical myelopathy between the C3 to C7 levels. We determined the Pavlov ratio on preoperative and postoperative cervical spine lateral radiographs, the vertebral body-to-canal ratio on sagittal reconstruction CT scans, and the vertebral body-to-cerebrospinal fluid (CSF) column ratio on T2-weighted sagittal MR images from C3 to C6. The severity of myelopathy was determined using the JOA score on both preoperative and postoperative images. The recovery rate was also calculated. The Pavlov ratio in plain radiographs from patients with myelopathy was compared with the ratio of the vertebral body to the spinal canal on CT and MRI. RESULTS: The average Pavlov ratio between C3 and C6 ranged from 0.71 to 0.76. On CT scan, the average vertebral body-to-canal ratio between C3 and C6 ranged from 0.62 to 0.66. On MRI, the vertebral body-to-CSF column ratio between C3 and C6 ranged between 0.53 and 0.57. A positive correlation was noted between the Pavlov ratio and the vertebral body-to-canal ratio on sagittal-reconstruction CT (correlation coefficient = 0.497-0.627, p = 0.000) and between the Pavlov ratio and the vertebral body-to-CSF column ratio on MRI (correlation coefficient = 0.511-0.649, p = 0.000). CONCLUSIONS: We demonstrated a good correlation between the Pavlov ratio and both the vertebral body-to-canal ratio on CT and the vertebral body-to-CSF column ratio on MRI. Therefore, the Pavlov ratio can be relied upon to predict narrowing of the cervical spinal canal in the sagittal plane.

The Relationship between Spinal Stenosis and Neurological Outcome in Traumatic Cervical Spine Injury: An Analysis using Pavlov's Ratio, Spinal Cord Area, and Spinal Canal Area

BACKGROUND: This study examined the relationship between four radiological parameters (Pavlov's ratio, sagittal diameter, spinal cord area, and spinal canal area) in patients with a traumatic cervical spine injury, as well as the correlation between these parameters and the neurological outcome. METHODS: A total of 212 cervical spinal levels in 53 patients with a distractive-extension injury were examined. The following four parameters were measured: Pavlov's ratio on the plain lateral radiographs, the sagittal diameter, the spinal cord area, and the spinal canal area on the MRI scans. The Pearson correlation coefficients between the parameters at each level and between the levels of each parameter were evaluated. The correlation between the radiological parameters and the spinal cord injury status classified into four categories, A (complete), B (incomplete), C (radiculopathy), and D (normal) was assessed. RESULTS: The mean Pavlov's ratio, sagittal diameter, spinal cord area and spinal canal area was 0.84, 12.9 mm, 82.8 mm2 and 236.8 mm2, respectively. An examination of the correlation between the radiological spinal stenosis and clinical spinal cord injury revealed an increase in the values of the four radiological parameters from cohorts A to D. Pavlov's ratio was the only parameter showing statistically significant correlation with the clinical status (p = 0.006). CONCLUSIONS: There was a correlation between the underlying spinal stenosis and the development of neurological impairment after a traumatic cervical spine injury. In addition, it is believed that Pavlov's ratio can be used to help determine and predict the neurological outcome.

A study of pavlov ratio in Thai people.

A study of lateral cervical spine x-rays in 50 normal Thai volunteers was carried out to find the Pavlov ratio in Thai people. The results were compared with the standard values commonly used as reference values. These values are derived from published figures obtained in Westerners whose build and bone structure are quite different from Thais. The results of this study showed that the corresponding values of the Pavlov ratio at spinal levels C3, C4, C5, C6 and C7 were 0.96, 0.96, 0.98, 0.95 and 0.91. The average Pavlov ratio for all levels was found to be 0.95. There is no different from the foreign results. Hence, the use of published reference of the narrow status of the cervical canal can be confidently compared to reference values now known to be appropriate to Thais.

The Significance of Space Available for the Spinal cord at the Injured Level in the Lower Cervical Spine Fractures and Dislocations / 대한정형외과학회잡지

PURPOSE: To evaluate the degree of injury of the spinal cord in relation with the space available for the spinal cord at the level of injury, the sagittal diameter of the spinal canal at the uninjured levels, and the Pavlov ratio at the uninjured levels in fractures and dislocations of the lower cervical spine. MATERIALS AND METHODS: We retrospectively reviewed the records and radiographs of patients who had sustained an acute fracture or dislocation of the cervical spine from 1990 to 1995. We collected patients from Orthopedic and Neurosurgical department of Chonbuk University Hospital and at Orthopedic department of Presbyterian Medical Center. Of the 69 patients analyzed, twelve had no neurological deficit, eleven had an isolated nerve-root injury, twenty-two had an incomplete injury of the spinal cord, and twenty-four had a complete injury. We measured above three parameters from the plain lateral radiographs and assessed the difference by one-way ANOVA and unpaired t-test. RESULTS: 1. The mean space available for the spinal cord at the level of injury was 12.9 millimeter for the complete injury of the spinal cord,13.8 millimeter for the incomplete injury, 14.7 millimeter for an isolated nerve-root injury, and 15.7 millimeter for no neurological deficit group. The overall difference among the groups was significant (F=6.98, P=0.0004). The patients who had a complete injury of the spinal cord and those who had an incomplete injury of the spinal cord were significantly different from the patients who had an isolated nerve-root injury and those who had no neurologic deficit (P=0.002). 2. The mean sagittal diameter of the canal at the proximal and distal uninjured level was 14.3 and 14.6 millimeter for the complete injury of the spinal cord, 14.9 and 14.9 millimeter for the incomplete injury, 15.5 and 16.6 millimeter for an isolated nerve-root injury, and 16.9 and 16.5 millimeter for no neurological deficit group. The patients who had a complete injury of the spinal cord and those who had an incomplete injury of the spinal cord were significantly different from the patients who had an isolated nerve-root injury and those who had no neurologic deficit (P=0.001). 3. The mean Pavlov ratio at the proximal and distal uninjured level was 0.90 and 0.86 for no neurologic deficit group, 0.85 and 0.87 for an isolated nerve-root injury, 0.76 and 0.75 for the incomplete injury of the spinal cord, and 0.76 and 0.76 for the complete injury. The patients who had a complete injury of the spinal cord and those who had an incomplete injury of the spinal cord were significantly different from the patients who had an isolated nerve-root injury and those who had no neurologic deficit (P=0.001). CONCLUSIONS: The patients who sustained a permanent injury of the cord usually had had a narrower sagittal diameter (<14mm) and a lower Pavlov ratio (<0.80) of the spinal canal before injury. Patients who had a large sagittal diameter of the canal may be more likely to be spared a permanent injury of the spinal cord following a fracture or dislocation of the cervical spine compared with patients who have a narrow canal. These findings demonstrated that the severity of the injury of the spinal cord was in part associated with the space available for the cord (at risk:<13mm) after the injury, as measured on plain lateral radiographs.

Pavlov's Ratio of Cervical Spine of Normal Koreans : Determining Spinal Stenosis on Routine Lateral Roentgenograms / 대한정형외과학회잡지

The accepted radiographic method to determine cervical spinal stenosis is the direct measurement of the sagittal diameter of the spinal canal on the routine lateral view of the cervical spine. The reported normal and abnormal values for this measurement are inconsistent because of various methods of obtaining the roentgenograms and different body types which affect the size of the X-ray image. According to Pavlow, the ratio method of determining crevical spinal stenosis, in which the sagittal diameter of the spinal canal is divided by the sagittal diameter of the corresponding vertebral body, is independent of technical factor variables and is a reliable method for determining cervical spinal stenosis. In order to determine the Pavlov's ratio of normal Koreans, and compare it with that of radiculopathic group, we measured the diameter of cervicl canal in 47 normal persons(28 male, 19 female), and 32 patients( 9 male, 23 female) who had transient tingling sensation and radiculopathic symtom from the second to fifth decades. The results were as follows :1) The average Pavlov's ratio from C3 to C7 in normal Korean men are 0.906(0.70–1.13), 0.899 (0.070–1.13),0.948(0.70–1.67) and 0.948(0.67–1.17), respectively, and those of normal Korean women are 0.977(0.83–1.15), 1.021(0.83–1.13), 1.014(0.84–1.33) and 1.055(0.88–1.18), respectively. 2) The average Pavlov's ratio from C3 to C7 in radiculopathic Korean men are 0.88(0.65–1.12), 0.90(0.68–1.12), 0.95(0.79–1.12) and 0.95(0.78–1.06), respectively, and those of radiculopathic Korean women are 0.902(0.70–1.27), 0.905(0.69–1.27), 0.939(0.70–1.33) and 0.931(0.70–1. 18), respectively. 3) There are not statistically differences of the Pavlov's ratio between the control group and the radiculopathic group. 4) We believe that the Pavlov's ratio is an effective method in detection of cervical stenosis and is able to eliminate technical factor such as body position, target and object-to-film distanc.