Pneumatization of the temporal bone, its petromastoid part and related vasculature in a South African population from early childhood to early adulthood: an anatomical and radiological study.

Abstract

Introduction: The pneumatization of the temporal bone is important in various clinical settings. These include serving as a prognostic factor in middle ear surgeries and acting as a shock absorber in patients sustaining lateral skull trauma. The size and growth rate of its air cell system have been associated with middle-ear pathology. The degree of temporal bone pneumatization is highly relevant when planning temporal bone-related surgeries and has been hypothesized to influence anatomical variations of temporal bone-related vessels. This study aimed to investigate the size of temporal bone pneumatization (air cell volume) with age, the association between temporal bone pneumatization and the morphologies of some temporal bone-related vessels, as well as their morphometrical relationship with ear regions, and to propose a simple and concise classification of the degree of temporal bone pneumatization using reference structures and landmarks. Materials and Methods: A retrospective review of 496 temporal bone computed tomography (CT) images of 248 head and neck/brain CTs of patients from public hospitals in KwaZulu-Natal, South Africa, was conducted. The sample consisted of 133 males and 115 females, 0 to 35 years old (median age 13.0 years) of three population groups (202 South African Black, 28 South African Indian, and 18 South African White). The age range of 0 to 35 years was further divided as follows: 0-2 (infant); 3-5 (young child); 6-9 (middle child); 10-14 (early adolescent); 15-18 (middle adolescent); 19-25 (young adult stage I); 26-35 (young adult stage II). High-resolution CT images with fine slices of ≤ 0.625 mm were analyzed using IntelliSpace Portal (ISP) Version 11.1 viewer software. The volume of temporal bone pneumatization was achieved using three dimensional (3D) volumetric rendering technique. At the same time, the morphologies of the sigmoid sinus, jugular bulb, and internal carotid artery and their morphometrical relationships with ear regions were analyzed using the measuring tools on the ISP. Additionally, an inter-observer assessment was conducted among otologists to classify the degree of temporal bone pneumatization utilizing temporal bone CT images at two levels (landmarks): the malleoincudal junction and the lateral semicircular canal using sigmoid sinus as a reference. Results: Size (volume) of temporal bone pneumatization with age: The volume of temporal bone pneumatization increased significantly (p<0.001) with age up to the adult stage I (19-25 years), followed by a significant decline in young adult stage II (26-35 years). Females showed a significant early increase compared to males. Regarding population groups, Black South Africans (SA) showed a higher increase in volume with age than the SA Whites and Indian population groups. Influence of pneumatization on temporal bone-related vessels: Four degrees of pneumatization (hypo, moderate, good, and hyper) were analyzed. Hyper-pneumatization was observed to be more common. Vascular variants such as high jugular bulb, jugular bulb dehiscence, and internal carotid artery dehiscence were observed and significantly associated (p<0.01) with hyper-pneumatization. Also, as pneumatization increases, sigmoid sinus and jugular bulb distances to ear regions were observed to increase significantly (p<0.01, p<0.05). The sigmoid sinus and its variant shapes were also observed but were not significantly associated with the degrees of pneumatization (right- p=0.070; left- p= 0.645). Classification of degree of pneumatization: In the survey conducted among cohort otologists, the percentage of participants that correctly rated temporal bone CT images taken at the level of lateral semicircular canal according to their respective degrees of pneumatization was significantly higher (p < 0.05) regardless of their year of experience compared to those that correctly rated corresponding images taken at the level of malleoincudal junction. A 76% positivity in their agreement with the use of sigmoid sinus in evaluating mastoid pneumatization was observed. Discussion and Conclusion: This study concludes that the pneumatization of a healthy temporal bone is expected to show a significant linear increase from infant up until at least the early adult stage I (19-25 years) in the South African population. The high incidence of high JB, JB dehiscence, and internal carotid artery dehiscence, and the increase in distances of sigmoid sinus and JB to ear regions reported in this study population due to increased pneumatization validates temporal bone pneumatization as a factor that influences jugular bulb variants and internal carotid artery dehiscence as well as the distances of sigmoid sinus and jugular bulb to ear regions. The study also concludes that using the lateral semicircular canal as a landmark on axial CT, and evaluating air cells around the sigmoid sinus was suitable in classifying the degree of temporal bone pneumatization into hypo-, moderate, good, and hyper-pneumatization. This study proposes this classification system as an easier and quicker method for clinical applications.

Iqoqa Isingeniso: Izikhala zomoya ezisethanjeni elaziwa ngetemporal bone zibalulekile kwezokwelapha ezihlukahlukene. Lokhu kubandakanya ukuba usizo kwalezi zikhala lapho kuhlinzwa indlebe futhi zinciphisa umonakalo odalekayo lapho umuntu eshaywa yinto ethile ekhanda. Ubukhulu nezinga lokukhula kwamangqamuzana omoya kuye kwahlotshaniswa nesifo sendlebe. Ubungako bezikhala zomoya ethanjeni itemporal bone kubaluleke kakhulu lapho kuhlelwa ukuhlinza okuzothinta leli thambo futhi kucatshangwa ukuthi kunomthelela oshintshweni oluba semithanjeni yegazi esondelene naleli thambo. Lolu cwaningo luhlose ukuthola ukuthi zinkulu kangakanani izikhala zomoya ezisethanjeni itemporal bone (umthamo wamangqamuzana omoya) kuye ngobudala bomuntu, ukuthola ukuhlobana phakathi kwezikhala zomoya ezisethanjeni itemporal bone noshintsho oluba khona emithanjeni yegazi esondelene naleli thambo, ukuthola indlela ubukhulu nokuma kwalezi zinto okuchaphazela ngayo ezinye izindawo eziseduze kwendlebe, kanye nokwenza iziphakamiso ezilula nokunikeza incazelo efingqiwe yokuthi zingakanani ubukhulu izikhala zomoya ethanjeni itemporal bone, kusetshenziswa izingxenye okuzobhekiselwa kuzo. Okuzosetshenziswa Nezinqubo: Kwacutshungulwa izithombe ezingama-496 zetemporal bone ezithwetshulwe ngomshini owaziwa ngecomputed tomography (CT) zamakhanda nezintamo/nobuchopho okungama-248 eziguli zasezibhedlela zikahulumeni KwaZulu-Natali, eNingizimu Afrika. Isampula lalihlanganisa abesilisa abayi-133 nabesifazane abayi-115, abaneminyaka esukela e-0 kuya kwengama-35 ubudala (iminyaka emaphakathi eyi-13.0) bezinhlanga ezintathu (abaNsundu baseNingizimu Afrika abangama-202, amaNdiya aseNingizimu Afrika angama-28, naBelungu baseNingizimu Afrika abayi-18). Iminyaka yobudala esukela e-0 kuya kuma-35 yaphinde yahlukaniswa ngale ndlela elandelayo: 0-2 (usana); 3-5 (ujahidada); 6-9 (ingane encane); 10-14 (ingane esizothomba noma esithomba); 15-18 (intsha); 19-25 (isigaba sokuqala sabantu abadala); 26-35 (isigaba sesibili sabantu abadala). Kwacutshungulwa izithombe ze-CT ezigqamile eziwugqinsana oluncane luka-≤ 0.625 mm kusetshenziswa uhlelo lwekhompyutha okuthiwa yi-IntelliSpace Portal (ISP) Version 11.1. Umthamo womoya osethanjeni itemporal bone watholakala ngokusetshenziswa kwendlela yokuhlola umthamo engumumo onxantathu, othree dimensional (3D). Ngesikhathi esifanayo, kwacutshungulwa ukwakheka kwesigmoid sinus, ijugular bulb, nomthambo i-internal carotid kanye nokuhlobana kwalezi zinto nezingxenye eziseduze kwendlebe kusetshenziswa amathuluzi okukala e-ISP, okuwuhlelo lwekhompuyutha. Ukwenezela kulokho, kwaqoqwa umbiko walokho okuphawulwe odokotela bezifo zendlebe ukuze kukalwe ubukhulu bezikhala zomoya ethanjeni itemporal bone kusetshenziswa izithombe ze-CT zethambo itemporal bone ezindaweni ezimbili: imalleoincudal junction kanye nelateral semicircular canal kusetshenziswa isigmoid sinus njengesibonelo. Imiphumela: Usayizi (umthamo) wezikhala zomoya ezisethanjeni itemporal bone kuya ngobudala bomuntu: Umthamo wezikhala zomoya ezisethanjeni itemporal bone ukhuphuka kakhulu (p<0.001) njengoba umuntu ekhula kuze kufike esigabeni sokuqala sabantu abadala (iminyaka eyi-19-25), bese wehla ngokuphawulekayo kubantu abadala besigaba sesibili (abaneminyaka engama-26-35). Kwabesifazane kwaphawulwa ukuthi ushesha kakhulu ukukhuphuka uma kuqhathaniswa nabesilisa. Ngokuphathelene nezinhlanga, kubantu abaNsundu base-South Africa (SA), umthamo unyuka kakhulu njengoba bekhula uma kuqhathaniswa naBelungu namaNdiya ase-SA. Umthelela wokwakheka kwezikhala zomoya emithanjeni yegazi ehlobene nethambo itemporal bone: Kwacutshungulwa amazinga amane obukhulu bezikhala zomoya (eliphansi, elilingene, elikahle neliphakeme). Ukwakheka kwezikhala zomoya ngezinga eliphakeme kwabonakala kuvame kakhulu. Kwaphawuleka izinkinga ezihlukahlukene zemithambo yegazi ezifana nenkinga yomthambo osuka ekhanda wehlele entanyeni obizwa ngehigh jugular bulb, inkinga yomthambo odlula engxenyeni engaphakathi yendlebe, ebizwa ngejugular bulb dehiscence, kanye nenkinga yomthambo omkhulu oyisa igazi ebuchosheni ebizwa nge-internal carotid artery dehiscence futhi lezi zinkinga zahlotshaniswa kakhulu (p<0.01) nokwakheka ngamandla kwezikhala zomoya. Kanti futhi njengoba zikhula izikhala zomoya, kwaphawuleka ukuthi ukuqhelelana phakathi kwesigmoid sinus nejugular bulb kanye nezindawo ezakhelene nendlebe nako kukhula ngokuphawulekayo (p<0.01, p<0.05). Kwaphawuleka nesikhala somoya okuthiwa yisigmoid sinus nezindlela ezihlukahlukene esakheke ngazo kodwa lokhu akuzange kuhlotshaniswe kakhulu nobukhulu bezikhala zomoya (kwesokudla- p= 0.070; kwesobunxele- p= 0.645). Ukuhlukaniswa ngezigaba kwamazinga ezikhala zomoya ezisemathanjeni: Kunhlolovo eyenziwa eqenjini lochwepheshe bezifo zendlebe, kulabo ababamba iqhaza ayephakeme kakhulu amaphesenti abanikeza isilinganiso esinembile sobukhulu bezikhala zomoya lapho behlola izithombe ze-CT zethambo itemporal bone ezathwetshulwa maqondana nengxenye engaphakathi yendlebe ebizwa ngokuthi yilateral semicircular canal (p <0.05), noma ngabe base bechithe isikhathi esingakanani bekulo mkhakha uma kuqhathaniswa nalabo ababekale kahle izithombe ezihambisanayo ezithathwe maqondana nemalleoincudal junction. Kwaphawuleka ukuthi abangamaphesenti angama-76 bavumelana nokuba kusetshenziswe isikhala somoya okuthiwa yisigmoid sinus lapho kuhlolwa isikhala somoya esisethanjeni imastoid. Ingxoxo nesiphetho: Lolu cwaningo luphetha ngokuthi izikhala zomoya ezisethanjeni eliphile kahle itemporal bone kulindeleke ukuba zikhule ngokuphawulekayo kusukela lapho umuntu eselusana kuze kufike okungenani esigabeni sokuqala sabantu abadala (iminyaka eyi-19-25) kubantu baseNingizimu Afrika. Amazinga aphakeme ezinkinga zemithambo yegazi njengenkinga okuthiwa yi-JB, inkinga ebizwa nge-JB dehiscence nenkinga ebizwa nge-internal carotid artery dehiscence kanye nokukhula kwezikhala ezihlukanise isigmoid sinus nejugular bulb nezingxenye ezisendlebeni ezibikiwe kubantu abahlolwe kulolu cwaningo ngenxa yokukhula kwezikhala zomoya emathanjeni kuqinisekisa ukuthi izikhala zomoya ezisethanjeni itemporal bone zinomthelela ekudalekeni kwezinkinga zemithambo yegazi ezihlukahlukene okuyijugular bulb ne-internal carotid artery dehiscence kuhlanganise nebanga eliphakathi kwesigmoid sinus nejugular bulb kanye nezinye izindawo esisendlebeni. Lolu cwaningo lufinyelele nesiphetho sokuthi ukusebenzisa ilateral semicircular canal lapho kwenziwa i-CT scan, nokuhlola amangqamuzana omoya ezindaweni eziseduze nesigmoid sinus kuyafaneleka lapho kubekwa ngezigaba ubukhulu bezikhala zomoya ezisethanjeni itemporal bone ngokwamazinga amane; izinga eliphansi, elilingene, elihle neliphakeme kakhulu lokwakheka kwezikhala zomoya. Lolu cwaningo luphakamisa ukuba kusetshenziswe le nqubo njengendlela elula nesheshayo kwezokwelapha.