Expert’s Comment concerning Grand Rounds Case entitled “Congenital C1 arch deficiency: Grand Round Presentation” (by M. Elmalky, S. Elsayed, G. Arealis, H. Mehdian doi:10.1007/s00586-013-2682-z)

Posterior Arch Defects of the Atlas - A Report of Two Cases and Literature Review

“…Nevertheless, types C and D held the potential to cause symptoms as the posterior fragment may move anteriorly upon neck extension thus causing compressive symptomatology [9]. This was first documented by Sharma et al in their study using dynamic radiographs [1,10].…”

“…According to the literature most patients are completely asymptomatic and if not for the traumatic episode the condition would have gone completely undiagnosed [8]. Stability is unlikely to be affected by these defects as, anatomically; atlantoaxial stability is known to be maintained by the alar, apical and transverse ligaments whose attachments are not affected by posterior arch defects [9].…”

“…According to Dominic Thompson [9] another entity called true hypoplastic posterior arch which is not considered in Currarino classification might be held responsible for the development of neurological symptoms due to the diminution of the ring diameter.…”

“…Most of the existent literature on this matter is based on clinical reports, so conclusions are taken from Class III evidence [9].…”