| Part Ⅰ.Implications of HRCT measurements of the temporal bone for the classification of inner ear malformationsObjectiveMeasuring the structures of the inner ear with multiplanar reconstruction(MPR)on high-resolution computed tomography(HRCT)of the temporal bone,in order to investigate the differences between normal and malformed inner ears,as well as to explore the value of inner ear measurements in distinguishing between incomplete partition malformations(IP),cochlear hypoplasia malformations(CH)and in recognizing subtle inner ear malformations.Methods87 patients(169 ears)with inner ear malformations who were diagnosed as severe or very severe sensorineural deafness and underwent temporal bone HRCT in Guangdong Provincial People’s Hospital from July 2015 to December 2020 were selected.Of these,53 ears are IP malformations,22 ears are CH malformations,74 ears are Enlarged vestibular aqueduct malformations and 20 ears are cochlear foramen stenosis malformations.Also 25 sex-matched patients(50 ears)with normal bone conduction and normal inner ear were selected for the control study.The HRCT images of the temporal bone were processed by the MPR technique to obtain oblique axial images(cross-sectional baseline parallel to the horizontal semicircular canal),and the relevant indexes of the inner ear were measured: cochlear base length,cochlear base height,height of cochlea and diameter of the cochlear nerve foramen.Results1.Significantly smaller cochlear base diameter and height of cochlea were found in CH group compared to normal inner ear group(P < 0.001),and the height of cochlea of the CH-Ⅰ group was significantly lower than that of the CH-Ⅱ(P=0.001),CH-Ⅲ(P<0.001)and CH-Ⅳ groups(P < 0.001).In IP group,the cochlear base diameter was smaller than that in the normal inner ear group(P < 0.001),while the height of cochlea was larger significantly than that in the normal inner ear group(P < 0.001).2.The cochlear base length and the height of cochlea in EVA group were significantly greater than those in the normal inner ear group(P < 0.001).The width of the cochlear nerve canal and the cochlear base height in CNC stenosis group were significantly smaller than those in the normal inner ear group(P < 0.001).3.There was no correlation between the cochlear base length and height of cochlea in the CH and CNC stenosis groups(r=0.341,P=0.120;r=0.405,P=0.076),while there was a positive correlation between the cochlear base length and height of cochlea in the IP and normal inner ear groups(r=0.447,P=0.001;r=0.555,P<0.001).Conclusion1.HRCT measurements of the inner ear are useful in the differential diagnosis of CH and IP malformations.The increased height of cochlea may be taken as an important reference indicator for the diagnosis of IP malformations.The decline in cochlear base length and height of cochlea is an important indicator for the diagnosis of CH malformation.2.Cochlear overgrowth may be one of the features of isolated EVA.Part Ⅱ Significance of HRCT measurements of temporal bone in predicting intraoperative cerebrospinal fluid leakage during cochlear implantationObjective To measure inner ear structures in patients who underwent cochlear implantation on the preoperative HRCT of temporal bone in by using MPR techniques,as well as to investigate the predictive value of each inner ear structure data for predicting intraoperative cerebrospinal fluid leakage during cochlear implantationMethods From July 2015 to December 2020,32 patients(36 ears)who were diagnosed as severe or very severe sensorineural deafness and underwent cochlear implant in Guangdong Provincial People’s Hospital were included,among which bone defect between cochlea and internal auditory canal was found on the preoperative HRCT of temporal bone.According to the Loundon classification criteria,32 participants(36 ears)were assigned to two groups: non-gusher group(non-CSF leakage,oozing and trickling)and gusher group.There are 15 patients(15 ears)in gusher group while 17 patients(21 ears)in non-gusher group.Various inner ear structures were measured on HRCT of the temporal bone by combining MPR techniques: diameter of the cochlear nerve foramen,width of vestibular aqueduct,external opening width of cochlear aqueduct and relevant diameters of internal auditory canal(IAC): length of IAC,opening width of IAC,width of IAC,anteroposterior diameter(APD)of internal auditory canal fundus(FIAC),superior-inferior diameter(SID)of FIAC,area of FIAC.Results1.The diameter of the cochlear nerve foramen(2.58±0.33 mm vs 1.96±0.50 mm,P<0.001),APD of FIAC(4.91±1.53 mm vs 3.30±0.84 mm,P<0.001)and SID of FIAC(4.81±1.02 mm vs 3.98±0.96 mm,P=0.018)in gusher group were significantly greater than those in non-gusher group.There was no statistical difference between the two groups for opening width of IAC,length of IAC,width of IAC,width of vestibular aqueduct,and external opening width of cochlear aqueduct(P>0.05).2.Binary logistic regression showed that diameter of the cochlear nerve foramen(P=0.024,OR=1.735)and SID of FIAC(P=0.022,OR=6.119)were independent risk factors for cerebrospinal fluid gusher during cochlear implantation.3.ROC curve showed that the area under the curve of diameter of the cochlear nerve foramen was 0.851 with a sensitivity of 93.33% and a specificity of 61.90%,while ROC curves for SID of FIAC had an AUC of 0.848 with a sensitivity of 80.00% and a specificity of 80.95%.Together,the AUC was 0.930 with a sensitivity of 80.00% and a specificity of 95.24%.Conclusion For the patients with inner ear malformations whose preoperative HRCT indicating of a connection between the internal auditory canal and the cochlea,the prediction model of the cochlea aperture combined with the superior-inferior diameter of FIAC has an important value in predicting the cerebrospinal fluid gusher during cochlear implantation. |
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