| BackgroundStyloid process of the temporal bone is a spiny bony protrusion below the styloid hole, and extending into the neck. A series of symptoms caused by the abnormalities in morphology, length, orientation of styloid process and ossification of the stylohyoid called styloid process syndrome (SPS). It was first reported by Eagle in 1937, so it also called Eagle’s syndrome. Common symptoms of the syndrome include sore throat in one or both sides, referred pain in ear or mastoid area. Other symptoms include pain occur when head rotating, recurrent headaches, dizziness, facial pain and earache.Recently, imaging observation of styloid process are usually by X-ray radiography, CT, oral panoramic and Digital tomosynthesis (DTS), cone beam CT (CBCT), etc.SPS is usually diagnosed by X-ray radiography and MSCT scan. The main defects of X-ray radiography are low success rate, difficult to fully display the styloid process and ossification of the stylohyoid caused by great variation of styloid process and complex structures surrounding. MSCT can show more details of the anatomy clearly, especially show the relationships with styloid process and surrounding structures and vascular. Many scholars have observed the styloid process by MSCT, but there are many differences and argument in data of styloid in health people and in SPS patient. Measurement methods, especially method of measuring the azimuth, are not integrated.Digital Tomosynthesis is a new imaging method combined with traditional tomosynthesis technique and modern digital technology. Contrast with CT, it will has several advantages, such as smaller dose of radiation, higher spatial resolution of bone, simplier in operation and lower-cost. There are few studies in scan methods of DTS and in research the SPS by DTS currently.Purpose1. Using MSCT studies styloid process of healthy people, research the best method for measuring length, azimuth and form, provide the basic data for the SPS diagnosis, and provide basic data for the project position of DTS.2. Collect styloids data of SPS patients scan by MSCT, and compared with data by X-ray. Summarize the superiority of MSCT on SPS, and provide help for the clinical treatment to SPS3. Collect styloids data of SPS patients scan by DTS, and compared with data collected by X-ray radiography and MSCT, to clarify the advantages and disadvantages of DTS in SPS, and provide scientific basis for the application of DTS in the diagnosis of SPS.Part I:Styloid observations in healthy people by MSCTMaterials and Methods1. MaterialsCollected 146 cases (292 sides styloid process) of neck, nasopharynx CT scan due to non-SPS patients from January 2013 to May 2015. including 170 sides styloid process in 85 male patients, and 122 sides in 61 female patients,5-91 years old(average 43.18±18.46 years old). Collect length data of styloid in 292 sides, inner inclination in 281 sides, and anteversion in 257 sides. Patients were divided into three groups by ages,<20 years old,20-40 years old and≥40 years old.2. MethodsUsing volume reproduction (VR) and multi-planer reconstruction (MPR) technology of 64-slice spiral CT to assess and measure the styloid process, stylohyoid ligament ossification whether or not confirmed by imaging examination treated as part of styloid process. collect data in mophology, length and azimuth of styloid process. SPSS 20.0 software is used for statistical analysis.ResultsHealthy people divided into three group by ages,<20 years old,20 to 40 years old and above 40 years old. Average length of styloid process in the three group is 21.27±17.44mm,32.00±8.52mm and 30.33±7.77mm, length of<20 years old group is less than other group, and the difference is statistically significant (P<0.05). Comparison differences of inclination by gender within the age group≥40, 72.80±3.77 degrees for male,69.57±4.72 degrees for female, the difference was statistically significant (P<0.05). The difference of morphology in three groups is statistically significant (pairwise comparison P<0.05). Along with the age growth, number of complete type increases.Conclusion1. MSCT is the most accurate method to observe and measure the styloid process currently. The morphology of styloid process should observed by VR and MPR. Length and azimuth should be measured by MPR. Before measurement, the baseline should be unified to avoid errors.2. Length of styloid process in adult is longer than in juveniles, while length of styloid in young and elder adult has no statistically differences. Along with the age growth, number of complete type increases. We can infer that length of styloid increases with growth and development in juveniles, and the amount of ossification increases with age growth.3. The inward angle of styloid in women over 40-year old is less than in men, infer that less inward angle is factor why SPS ocurr more offen in eldly wemen than in men.Part II:Application of MSCT in the diagnosis of styloid process syndromeMaterials and Methods1. MaterialsCollected data of styloid scan by MSCT in 50 SPS patients,31-69 years old (median age is 47 years old), including 14 males and 36 females, and including 22 patients with unilateral SPS (10 cases on the left,12 cases on the right),28 cases with bilateral SPS, total 78 sides styloid observed. The data of shape and length is collected in all patients, inward angle in 75 sides, anteversion angle in 49 sides. Length of 59 sides styloid which can be clearly observed in X-ray simultaneously used to compare with data of MSCT.2. MethodsMSCT scan used Siemens 64-slice CT. Using Siemens workstation for post-processing, VR and MPR for 3D reconstruction. X-ray examination to styloid used Siemens AXIOM Aristos X-ray machine.3. Control groupThe over 40 years old healthy adults in the first part is as the control group.ResultsStyloid length in SPS Group is 35.79±8.78mm, inward angle is 67.85±3.59°, forward angle is 69.77±4.84°, using independent-sample t test to compare with SPS group and control group. Contrast styloid length in two group, P=0.000 (P<0.005), there is statistical difference, length in SPS group styloid is longer than the control group. Contrast the inward angle P=0.000 (P<0.005), there is statistical difference, inward angle in SPS group styloid is less than the control group. Contrast the forward angle P=0.094 (P>0.005), has no statistical difference.78 cases styloid process of SPS group included 52 cases (66.7%) completed type, 19 cases (24.3%) section type,7 cases (9.0%) hypoplasia type, compared with type in control group using the Chi-square test, morphology in two groups has no statistical difference (P=0.985,P>0.005).Analyse 24 patients with unilateral SPS styloid, compair the length and inward angle in pathological and healthy side, comparison of length P=0.362, P>0.005, and comparison of inward angle P=0.256, P>0.005, has no statistical difference.Paired-samples t-test used in comparing length of same styloid measured by MSCT and X-ray simultaneous, the difference is statistically significant (P=0.000, P<0.005), the length measured by X-ray is longer than by MSCT.ConclusionElongated styloid process and the small inward angle are related with the occurrence of SPS. Amount of styloid ossification is increasing with age increasing, increasing of ossification is a factor of SPS, too. Styloid process developed by MSCT is much easier to success than by X-ray. MSCT has advantage of high success rate, intuitive and accurate in diagnosing SPS. It is ideal imaging exam for SPS, and can provide accurate assessment in preoperation and postoperation.Part Ⅲ:Application of DTS in the diagnosis of styloid process syndromeMaterials and Methods1. MaterialsCollect data of 72 SPS patients (144 sides styloid process) scan by DTS,18-67 years old (median 43 years old),21 males and 51 females,34 bilateral SPS patients, 38 unilateral cases.40 cases scan with anteroposterior, lateral DTS simultaneously,32 cases only with anteroposterior DTS project. All patients were examined by DTS and X-ray, while 10 patients underwent CT examination simultaneously.2. MethodsX-ray examination to styloid used Siemens AXIOM Aristos X-ray machine. MSCT scanning used Siemens 64-slice CT. DTS scan used Shimadzu’s Sonialvision Safire II digital tomosynthesis system.The method of length measurement is from tip of the styloid process to the point that 1cm under external ear canal when anteroposterior X-ray image can clearly show the styloid process, while measure by lateral projection when anteroposterior can’t develop styloid clearly. The software of workstation in the Shimadzu’s DTS system is used to measure length of styloid by DTS, method of measurement is from the root of the styloid process to the tip. Measuring method of inclination by CT and DTS is as same as the method in the first part, too.Results1. Comparison of styloid length collected by DTS anteroposterior, lateral projection and length revised through inward angle is used paired-sample T test. Length measured by anteroposterior projection is 29.19±7.06mm, by lateral projection is 28.69±6.70mm, statistical analysis P=0.064 (P>0.005), the difference has no statistical significant. Revised length of styloid is 30.67±7.76mm, compared with each other P=0.000 (P<0.05), has no statistical differences.2. Analyze length and inward angle of SPS styloid process displayed by DTS, length is 30.25±6.8mm, less than the length measured by MSCT in second part (P=0.000), the inward angle of styloid process measured by DTS is 69.62±3.52 degrees, the inward angle measured by DTS is greater than MSCT(P=0.001), there has statistical difference (P<0.05).3. Analyze the styloid data examined with DTS and MSCT simultaneously, length and inward angle has no statistical difference.4. Compare styloid length data scan by DTS and X-ray simultaneously, length in X-ray is longer than in DTS (P=0.001, P<0.05), the difference has statistical significant.Conclusion1. DTS can devolop the styloid process clearly while unclearly caused by overlapping organizations in X-ray exam. DTS scan should take not only anteroposterior but also lateral projection when be used in SPS diagnosis, to evaluate the styloid process morphology and length more comprehensive and accurately.2. Length of the styloid process can be measured roughly by DTS anteroposterior projection. Length of the styloid process can be calculated precisely with trigonometric conversed by inward angle and styloid length measured in lateral projection.3. DTS is a convenient, economic, particularly much lower radiation doses imaging examing method in SPS than MSCT. DTS has proximity effectiveness in assess morphology, length, angle of styloid process with MSCT. DTS can fulfil most requirements of SPS diagnosis, it can replace the ordinary X-ray in styloid process scan, should be popularized.The conclusions1. It should be combined with VR and MPR images while observing morphology of the styloid process by CT. VR is more intuitive than the MPR in evaluating the morphology, but it is possible miscarriage because the surrounding bone overlapping,.2. While research the length, the anterior angle and the inward angle, it should determine the baseline and uniform measurement plane first to avoid error caused by plane deviation,3. Elongated Styloid process and small inward angle are related to the occurrence of SPS. The styloid anterior angle in SPS group greater than healthy adults, but there has no significant differences, it can be inferred that variation of styloid anterior angle has no significant correlation with SPS.4. The length of styloid process in adult is longer than in juveniles, and has no different in young and elderly adult, it can be infered that length of styloid increases with growth and development in juveniles, and the amount of ossification increases with age growth. While form in SPS group is insignificant with control group, it can be infered that the increase of ossification of styloid has relevance with SPS.5. DTS scan in SPS diagnosis should take not only anteroposterior but also lateral projection to evaluate the styloid process morphology and length more comprehensive and accurately. Length of the styloid process can measured roughly by DTS anteroposterior projection. Length of the styloid process can be calculated precisely with trigonometric conversed by inward angle and styloid length measured by DTS lateral projection.6. DTS can devolop the styloid process clearly while unclearly caused by overlapping organizations in X-ray exam. DTS is a method of imaging examination with convenient, economic, particular much lower radiation doses in SPS compare with MSCT. DTS has proximity effectiveness in assess morphology, length, angle of styloid process as MSCT. DTS can fulfil most requirements of SPS diagnosis, it can replace the ordinary X-ray in styloid process scan, should be popularized. |
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