Anatomical analysis of cervical spinal canal morphometry in a group of normal subjects in Nineveh province Iraq using MRI

Abstract EN

Objective : (1) To determine the midsagittal diameter of cervical spinal canal in a group of normal population in Ninevah province/North of Iraq and identify the narrowest vertebral level for each gender.

(2) To set the normal range of the sagittal diameter of cervical spinal canal/vertebral body diameter ratio (Torg’s ratio) in healthy adults and determine the variations of Torg’s ratios by gender and the lowest value in the different vertebral levels for each gender.

(3) To know if there are any differences in the cervical spinal canal size and Torg’s ratios of the cervical vertebrae between people enrolled in this study compared to other populations.

(4) To examine the relationship between the Torg’s ratio and the midsagittal diameter of cervical spinal canal in normal subjects.

Methods : This prospective study was carried out in Radiology and Ultrasound Waves Unit in Al- Jumhori Teaching Hospital, Ninevah Health Office and Department of Anatomy, Histology and Embryology, College of Medicine, University of Mosul, Iraq during the period from 1st July 2010 to 1st September 2010.

It included 52 subjects (21 women and 31 men) who were reported to that hospital for ultrasonic assessments for problems rather than cervical.

The sagittal spinal canal diameter and vertebral body diameter of the cervical spine were measured using a lateral cervical plain radiographs.

X-ray films were taken with the neck in a neutral position in standing postures.

The sagittal spinal canal diameter and vertebral body diameter were measured from C3 to C7 vertebrae.

The measurement of both diameters was in mm.

All values were reported and the Torg’s ratio for each subject was found.

The Torg’s ratio was determined by dividing the sagittal spinalcanal diameter by the corresponding sagittal vertebralbody diameter.

Then all subjects were positioned supine on a spine board with no occipital padding for the MRI to determine the true diameter of the cervical canal at each level from C3 to C7.

All imaging and measurements were performed and evaluated by the same observer -a member of the research team U.T.Y- a diagnostic radiologist.

Pearson correlation analysis was applied to determine if any significant relationship existed among the Torg’s ratio and the midsagittal diameter of cervical spinal canal in normal subjects using the Statistical Package for the Social Sciences (SPSS).

P-value less than 0.05 was considered statistically significant .The term “abnormal” or “positive Torg's index” were used to indicate that vertebral canal/body relationship was less than 0.80.

Results : Mean ages of male and female participants were 36.4 ± 2.3 and 41.1±1.6 years respectively.

The mean sagittal spinal canal diameter in male participants (starting from C3 to C7) was 14.4 mm (ranged from 12.7 mm to 16.5 mm), and 14.2 mm in females (ranged from 12.6 to 16.1 mm).

The smallest mean sagittal spinal canal diameters in male and female participants were 12.6 mm, 12.7 mm respectively.

This study revealed no significant statistical differences in the sagittal’s diameters by gender.

The narrowest sagittal spinal canal diameters were at C7 which was 12.7 mm for males and 12.6 mm for females.

Females had smaller sagittal spinal canal diameter at all levels except C7.

The mean Torg’s ratio value from C3 to C7 was 0.8 in both genders.

Torg’s ratio less than 0.8 existed in at least one vertebral level in 42 (80.7%) out of 52 subjects.

This study revealed that the smallest values of Torg’s ratio in male and female participants (from C3 to C7) were 0.78, 0.77 respectively and both of them were present at the level of C4.

Poor correlation was found between Torg’s ratio and the mid-sagittal diameter of cervical spinal canal (significant 2-tailed is >0.05).

Conclusions : This study showed that the mean sagittal spinal canal diameter from C3 to C7 was 14.4 mm in males and 14.2 mm in females.

This diameter was smallest at C7 and the smallest sagittal diameter from C3 to C7 in both sexes was 12 mm and there was a significant difference between the sagittal diameters between the males and females.

The mean Torg’s ratio values was 0.8 in both sexes with the smallest Torg’s ratio of males and females participants being 0.78, 0.77 respectively and both of them were at the level of C4.

This study concluded that there is a poor correlation between the true diameter of the canal and the ratio of its sagittal diameter to that of the vertebral body.

The variability in anatomical morphology means that the use of ratios from anatomical measurements within the cervical spine is not reliable in determining the true diameter of the cervical canal.