Prevertebral Soft Tissue Measurements on Lateral Roentgenogram of Cervical Spine in Chinese

Transcription

1 Chin J Radiol 2002; 27: Prevertebral Soft Tissue Measurements on Lateral Roentgenogram of Cervical Spine in Chinese LONG-JIN CHI 1 ALEXANDER DAH-JIUM WANG 3 LIANG-KUANG CHEN 2,4 Department of Neurosurgery 1, Department of Radiology 2, Shin Kong WHS Memorial Hospital Department of Neurosurgery 3, Taipei Medical University Hospital Department of Radiotechnology 4, Yuanpei Institude of Science and Technology College Very few references mentioned about the cervical prevertebral soft tissue density in Asian population. We examined 150 patients with routine cervical spine radiographic films from January 2000 to July The prevertebral soft tissue thicknesses were measured from C1 to C7 to measure the prevertebral soft tissue thickness to compare with the data between the oriental people and western people in normal subjects. The results were recorded for statistical analysis and compared with western population. 131 patients were recorded. We found that there were significant difference noted at C6 prevertebral soft tissue thickness between young (n=106) and old (n=25) aged population (p<0.01). There was also significant difference between female (n=79) and male (n=52) at C6 prevertebral soft tissue thickness (p<0.01). The prevertebral soft tissue thickness was founded statistically thicker in male than female in C6 level. It was also thicker at C6 level in elderly than young ones. There was no difference at other cervical levels. There is no difference between our data and data from western population. Key wards: Cervical spine; Prevertebral; Soft tissue thickness Reprint request to: Dr. Liang-Kuang Chen Department of Radiology, Shin Kong Wu Ho-Su Memorial Hospital. No. 95, Wen Chang Road, Taipei 111, Taiwan, R.O.C. The cervical prevertebral soft tissue measurement has been commonly used as a diagnostic parameter after injury. Very little reference mentioned about the prevertebral soft tissue density in Asian population. The main purpose of this study is to measure the normal prevertebral soft tissue thickness from C1 to C7 and to compare the data between the Chinese people with western people in normal subjects. Related literatures were reviewed. MATERIALS AND METHODS We examined 150 adult patients who visited our outpatient clinics for having routine cervical spine check up for myofascial pain during the period from January 2000 to July There was no trauma history in between. Their ages ranged from 17 to female and 52 male were included. Their medical records were retrospectively reviewed. The subjects were drawn from a cosmopolitan population comprising all of Chinese. 150 adults had radiographs taken using cross-table technique with the neck in the neutral position. All of their consecutive lateral soft-tissue radiographs of the cervical spine were reviewed. An 8x10-in film was used and the tube-film distance was 40 inches. 131 radiographs were considered normal. 19 patients were excluded due to having trauma, rheumatoid arthritis, infection, malignancy, ankylosing spondylosis. Measurements were made along the distance between: the anterior arch of atlas and the anteroinferior edges of the vertebral bodies of C2 to C7 and the air shadows of pharynx and trachea (Fig.1, 2). Measurements of the film were taken with a 1/500- m unit caliber by one investigator. The magnification effects were corrected. The results were then recorded for analysis according to age and sex. Our main interests were concentrated at C2 and C6 level. The results were also compared with western population. Paired t- tests were used for statistical analysis.

2 152 Cervical Spine Prevertebral Soft Tissue Thickness in Chinese RESULTS The range, mean and standard deviation of all measurements were listed in Table 1. The retropharyngeal soft tissue thickness at C1 averaged 3.72 ± 1.21 mm (range mm), C2 averaged 2.99 ± 0.91 mm (range mm), C3 averaged 3.36 ± 0.91 mm (range mm), C4 averaged 6.29 ± 3.54 mm (range mm), C5 averaged ± 3.16 mm (range mm), C6 averaged ± 2.46 mm (range mm), and C7 averaged ± 3.07 mm (range mm). According to young age below 59 year-old (n=106) and over 60 year-old people (n=25), the C2 prevertebral soft tissue thickness showed 3.00 ± 0.83 mm in young aged people and 2.77 ± 0.85 mm in old people (Table.2) (p= 0.2). The C6 prevertebral soft tissue thickness was ± 2.25 mm in young and ± 3.06 mm in old (p< 0.01). We also compared the difference between male (n=52) and female (n=79). We found that C2 prevertebral soft tissue thickness was 2.84 ± 0.78 mm in female and 3.13 ± 0.88 mm in male (p=0.04). C6 prevertebral soft tissue thickness in female was ± 1.64 mm and ± 2.39 mm in male (P<0.01). Again, there was significant difference between Table 1. The prevertebral soft tissue thickness of cervical spine from C1 to C7 (n=131). Table 2. The prevertebral soft tissue thickness of cervical spine according to young and old aged population at C2 and C6 levels. Figure 1. Normal adult cervical spine lateral radiograph showing sites of C2 and C6 prevertebral soft tissue measurement. Figure 2. Forty-nine years-old male with traumatic cervical spine injury. His cervical spine lateral radiograph showed increased prevertebral soft tissue thickness.

3 Cervical Spine Prevertebral Soft Tissue Thickness in Chinese 153 gender at C6 level (Table. 3). We could not find any statistical significant difference at any other cervical levels. DISCUSSION The measurement of the width of the prevertebral soft tissue of the cervical spine has received a great deal of attention in the literature. Enlargement of soft Table 3. The differences of prevertebral soft tissue thickness of cervical spine between male and female population at C2 and C6 levels. tissue width might suggest significant cervical spine injury. Rogers [1] and Harris [2] suggested that 4 or 5 mm at C3 level should be considered as the upper limit of normal. The measurements in previous reports were mostly in western population [3, 4, 5, 6, 7]. The previous reports were all focused on C2 and C6 levels due to the criciod cartilage may cause distortion of C3-C5 thickness. C7 prevertebral soft tissue thickness was not easy to measure because the level was sometimes too low to be measured. Various radiographic sign have been used for evaluating trauma of cervical spine in adults. Hay [8] measured various soft tissue structures of the neck including the retropharyngeal and retrotracheal space in a small series of children and adults. Wholey MH et al. [3] in 1958 reviewed 700 cases with their lateral radiographs of the neck. In this study, there were 480 adults and 120 children below the age of 15. The thickness between C2 and retropharyngeal soft tissue was 3.4 mm (range 1-7 mm) and that between C6 and retrotracheal soft tissue was 14 mm (range 9-22 mm). Since Clark WM et al. [1] introduced twelve significant signs of cervical Table 4. Reported prevertebral soft tissue thickness of normal cervical spine in C2. Table 5. Reported prevertebral soft tissue thickness of normal cervical spine in C6.

4 154 Cervical Spine Prevertebral Soft Tissue Thickness in Chinese spine trauma, prevertebral soft tissue thickness measurement has been used as a first line indication of cervical spine pathology. Later Penning [5] reviewed radiographs in 50 normal adults. The measurement of retropharyngeal soft tissue thickness at C2 was 3.2 mm (range 1-5mm), and retrotracheal soft tissue thickness at C6 was 15.1 mm (range mm). Haug RH et al [6] reported 75 normal adult radiographs which showed retropharyngeal soft tissue thickness at C2 level measured 3.7 ± 1.0mm(range 2-6 mm) and C6 retrotracheal soft tissue thickness measured 12.1 ± 3.2 mm (range 5-18 mm). The previous three reports were all carried out in North American population. Oon et al [4] presented radiographics of 150 normal adults, which includes Chinese, Indians and Malays. Their report showed retropharyngeal soft tissue thickness to be 3.1 ± 0.7 mm (range mm) at C2 level and retrotracheal soft tissue thickness 12.4 ± 1.9 mm (range 8-17 mm) at C6 level. Several reports and textbook published their own normal cervical prevertebral soft tissue thickness data. Standard textbooks stated that the width of the prevertebral tissue measured at C2 level should not exceed 4-5 mm in normal adults [2, 9]. Widening of the soft tissue thickness above those values could be considered as indirect evidence of cervical spine injury. Wholey et al. [3] measured the thickness of C6 retrotracheal space and found that to be 14 mm (range 9-22 mm). Schumarker et al [10] presented a similar result for the thickness of retrotracheal soft tissue in normal patients, which was 14 ± 1 mm. Movement of the larynx with postural change, respiration, and swallowing would compromise the measurement of the prevertebral soft tissue at this level [10]. Injury of the cervical spine might be accompanied by marked increase in width of the prevertebral soft tissue [11, 12, 13, 14, 15]. Widening of the prevertebral soft tissues on lateral cervical spine radiographs has been proved to reflect edema and hemorrhage into this space. We compared the values of C2 and C6 prevertebral soft tissue thickness among several published series from North America, Singapore and with our data [16]. The results were similar and without statistically significant difference (Table 4, 5). The data showed that C6 prevertebral soft tissue thickness was statistically significantly thicker in male than female. The difference was also noted between young and elderly people. It was thicker in elder people at C6 level while there was no difference at C2 level. Wide range and large standard deviation were noted in our data, while similar problem was also noted in the published data. The radiographic technique would have some magnification and distortion effects on cervical spine soft tissue measurements. According to Templeton et al. [17], variability in the focus-film distance would have minimal effect on soft tissue measurements, whereas the object-film distance (increased in broad-shouldered subjects) could have a significant effect. The clinical significance of these measurements would need further studies. REFERENCES 1. Rogers LF: Radiology of Skeletal Trauma. New York, Churchill-Livingstone, 1982, Harris JH, Edeiken-Monroe B; The radiology of Acute Cervical Spine trauma (ed 2). Baltimore, MD, Williams and Wilkins, Wholey MH, Bruwer AJ, Baker HL. The lateral roentgenograpgy of the neck. Radiology 1958; 77: Oon CL. Some sagittal measurements of the neck in normal adults. Br J Radiol 1964; 37: Penning L. Prevertebral hematoma in cervical spine injury: incidence and etiologic significance. AJR 1981; 136: Haug RH, Wible RT, Liberman J. Measurement standards for the prevertebral region in the lateral soft-tissue radiography of the neck. J Oral Maxillofac Surg 1991; 49: Chen MY, Bohrer SP. Radiographic measurement of prevertebral soft tissue thickness on lateral radiographs of the neck. Skeletal Radiol. 1999; 28: Hay PD. Annals of Roentgenology. Vol. 9. New York: Paul B Hoeber, Committee on Trauma, American College of Surgeon: Advanced Trauma Life Support Manual. Chicago, IL, American College of Surgeons, Schumarker HM, Doris PE, Birnbaum G. Radiographic parameter in adult epiglottis. Ann Emerg Med. 1984; 13: Clark WM, Gehweiler JA, Laib R. Twelve significant signs of cervical spine trauma. Skeletal Radiol. 1979; 3: Miles KA, Maimaris C, Finlay D, Barnes MR. The incidence and prognostic significance of radiological abnormalities in soft tissue injuries to the cervical spine. Skeletal Radiol. 1988; 17: Herr CH, Ball PA, Sargent SK, Quinton HB. Sensitivity of prevertebral soft tissue measurement of C3 for detection of cervical spine fractures and dislocations. Am J Emerg Med. 1998; 16: DeBehnke DJ, Havel CJ. Utility of prevertebral soft tissue measurements in identifying patients with cervical spine fractures. Ann Emerg Med. 1994; 24: Meakem TD, Meakem TJ, Rappaport W. Airway compromise from prevertebral soft tissue swelling during placement of halo-traction for cervical spine injury. Anesthesiology. 1990; 73: Templeton PA, Young JWR, Mirvis SE, et al: The value of retropharyngeal soft tissue measurements in trauma of adult cervical spine. Skeletal Radiol. 1987; 16: Sistrom CL, Southall EP, Peddada SD, Shaffer HA Jr. Factors affecting the thickness of the cervical prevertebral soft tissues. Skeletal Radiol. 1993; 22:

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