Duplication of hypoglossal canal in North Indian human skulls

Abstract

Background: The hypoglossal canal is one among the permanent components of occipital bone of both human being and animal skull, which transmits the twelfth cranial nerve, meningeal branch of ascending pharyngeal artery and emissary veins. This is commonly known as anterior condylar canal. In some cases, this canal is divided by a bony spicule leading to a variant known as double hypoglossal canal. Such partition of hypoglossal canal predisposes the roots of twelfth cranial nerve to entrapment in the occipital bone during ossification which subsequently may leads to an alteration in the tongue movement as well as speech. The objectives of the present study were to obtain the incidence of the variant of double hypoglossal canal in north Indian population especially in Bihar and compare the incidence of such type of variation in skull of different parts of our country as well as various races of the world.Methods: The present study was carried out on 110 undamaged dry adult human crania of unknown age and sex for any variations in the hypoglossal canal or incidence of double hypoglossal canal.Results: We observed 15 cases (13.63%) of double hypoglossal canal in which 8 (7.27%) specimens had unilateral while 7 (6.36%) specimens had bilateral double hypoglossal canal. Double hypoglossal canal was more common in right side. In 5 cases (4.54%) unilateral bony spicules were seen.Conclusions: The study about the hypoglossal canal and its different variation is very important to clinicians, anatomist, forensic experts as well as anthropologists too. The knowledge about the different dimensions of hypoglossal canal is also very essential for neurosurgeons and radiologist for the planning of the surgeries around the posterior cranial fossa for tumors like schwannoma of hypoglossal nerve and treatment of sleep apnea syndrome. Hence the detailed morphometric study of hypoglossal canal will be helpful for the planning of surgical intervention around the base of skull becomes easier and safer.

Morphometric Analysis of the Occipital Condyles and Their Correlation With Hypoglossal Canal in Dry Skulls of South Indians

“…While observing the occipital condyles we also found duplication of hypoglossal canal in 12.27% of skulls, 10.99% unilaterally, only one skull (1.81%) showed bilateral duplication. This observation was also found by Fathima et al [17], they found similar incidence of 13.63%, unilateral 7.27% and bilateral being 6.36%. Duplication of hypoglossal canal may cause compression of hypoglossal nerve leading to paralysis of tongue muscles there by affect the speech too.…”

Variant Anatomy of Hypoglossal Canal: An Osteological Study in North Indian Population

“…They reported unilateral duplication in 7.27%and bilateral duplication in 6.36% of specimens. [14] A case of bilateral internal triplication of hypoglossal canal was also reported by Raghunath M et al in India. [15] Singh V et al studied 625 skulls and observed and classified the bridging pattern of hypoglossal canal.…”

Division pattern of the hypoglossal canal in human fetuses

“…Ayrıca epigenetik bir karakter olan hipoglossal kanalda septum varlığının veya iki ya da daha fazla sayıda kanal varlığının ırksal ve bölgesel farklılıklar gösterebileceği bildirilmektedir. 1,8,9,11,12,22,27,29…”

“…Dodo'nun 7 çalışmasındaki (160 Japon fetüsü) çift hipoglossal kanal insidansı (%10), bizim verilerimizden (%36) daha azdır. Erişkinlerde sağ (%0-25 aralığında), sol (%2.7-20 aralığında) ve bilateral (%0-11.9 aralığında) hipoglossal kanal bölmelenme paterninin geniş bir aralıkta verildiği 1,2,[7][8][9]11,12,14,16,23,27 ve verilerimizin bu aralık içerisinde olduğu belirlendi. Bu geniş aralığın nedeninin cinsiyet, taraf, yaş, bölge ve ırk gibi demografik verilerin farklılığı olabileceği bildirilmektedir.…”

“…3,5 Septum veya çıkıntı varlığı ve duplikasyon gibi hipoglossal kanalın bölmelenme biçimi, klinik ve gelişimsel anatomi açısından irdelenmektedir. 1,2,[6][7][8][9][10][11][12][13][14][15][16] Oksipital kemik kırıkları, genişlemiş emisser ven ve persistan artera hipoglossi gibi vasküler anomaliler veya nörinom gibi tümörler nedeni ile hipoglossal kanala cerrahi müdahale gerekebilir. 9,17-20 Hipoglossal kanalın şekilsel varyasyonlarının, bu cerrahi prosedürlerin (infratemporal fossa yaklaşım, genişletilmiş posterolateral yaklaşım, suprakondiler yaklaşım, aşırı lateral transkondiler transtuberküler yaklaşım, transkondiler yaklaşım, aşırı lateral parakondiler yaklaşım) uygulanmasını etkileyebileceği ve nöroradyologlar ile nörocerrahlar için risk faktörü olabileceği ifade edilmektedir.…”