Please wait a minute...
Journal of Neurorestoratology  2019, Vol. 7 Issue (3): 109-115    doi: 10.26599/JNR.2019.9040019
Opinion & Comment     
The significance of occipitocervical dura angulation in selection of surgery procedures for Chiari malformation type I
Bo Xiu1,(✉)(),Rui Zhang2
1 Department of Neurosurgery, The 7th Medical Center of PLA General Hospital, Beijing 100700, China
2 Department of Neurosurgery, Shandong Provincial Hospital Affiliated to Shandong University, Ji’nan 250021, Shandong, China
Download: PDF (4263 KB)      HTML
Export: BibTeX | EndNote (RIS)      

Abstract  

At present, the common surgical procedures for the Chiari malformation type I are comprised of posterior fossa decompression, duraplasty and tonsillectomy. Some neurosurgeons prefer these so called minimally invasive surgeries. However, there are still some failures for patients undergoing the above surgeries in clinical practice. Analyzing causes of many surgical failures, the author put forward the anatomical concept of occipitocervical dura angulation (ODA). The ODA is defined as the included angle between the cerebral dura mater and spinal dura mater at the posterior foramen magnum on the median sagittal plane. For Chiari malformation type I without atlantoaxial instability, the selection of appropriate surgeries and accurate evaluation on the effect of the decompression can be realized after the comprehensive analysis both on the severity of tonsil herniation and the ODA. Tonsillectomy may be needed to add to posterior fossa decompression (PFD) and duraplasty for Chiari malformation type I with the ODA being the larger obtuse angle and/or the tonsil herniation to the level of arcus posterior atlantis.



Key wordsChiari malformation type I      occipitocervical dura angulation      posterior fossa decompression      duraplasty      tonsillectomy     
Received: 08 August 2019      Published: 09 October 2019
Corresponding Authors: Bo Xiu     E-mail: boxiu@scsurgery.com
About author: Bo Xiu, professor and chief neurosurgeon of Neurosurgical Department, the 7th Medical Center of Chinese PLA General Hospital. He is a deputy chairman of China Committee of the International Association of Neurorestoratology (IANR), and a member of International Spinal Cord Society. He focuses on neural tube defect (NTD) research and has performed operations for more than 3000 NTD patients. E-mail: boxiu@scsurgery.com.|Rui Zhang, Ph.D, attending Physician of Neurosurgical Department, Shandong Provincial Hospital Affiliated to Shandong University. He is a member of the youth committee of the Neuromodulation Society of Christian Medical & Dental Associations (CMDA). He focuses on Parkinson’s disease and spine disorders, and has published 5 SCI papers as first author or corresponding author.
Cite this article:

Bo Xiu,Rui Zhang. The significance of occipitocervical dura angulation in selection of surgery procedures for Chiari malformation type I. Journal of Neurorestoratology, 2019, 7: 109-115.

URL:

http://jnr.tsinghuajournals.com/10.26599/JNR.2019.9040019     OR     http://jnr.tsinghuajournals.com/Y2019/V7/I3/109

Fig. 1The MRI of Chiari malformation type I shows that the volume of posterior cranial fossa is significantly larger than that of hindbrain, and ODA was an acute angle.
Fig. 2The MRI of Chiari malformation type I showed cerebellar atrophy and larger cranial fossa space.
Fig. 3The MRIs of Chiari malformation type I.
(A) and (B) Tonsillar hernia was lower to C1 and occipitocervical dura angulation was a larger obtuse angle before surgery. (C) and (D) Syringomyelia and tonsillar hernia were not significantly improved half a year after PFD plus duraplasty.
Fig. 4MRI of Chiari malformation type I.
(A) and (B) Cerebellar atrophy and cerebellar ptosis after improper PFD. The ODA was an acute angle and the outlet of the fourth ventricle located below vertex of ODA. (C) After occipital bone repair, atlas posterior arch excision and duraplasty, ODA was increased, hernia and ptosis were recoiled, and syringomyelia became obviously smaller.
Fig. 5ODAs before and after duraplasty. Angle α: ODA before duraplasty; Angle β: ODA after duraplasty; Shadow: newly added subdura space by foramen after operation.
Fig. 6MRI of Chiari malformation type I.
(A) and (B) ODA is close to a right angle. (C) and (D) After PFD and duraplasty, ODA was increased, reconstruction of the occipital cistern was obtained and syringomyelia became obviously smaller.
Fig. 7The MRI of Chiari malformation type I.
(A) and (B) ODA was nearly a straight line and its vertex located at the rear edge of the foramen magnum. Posterior fossa was funnel-shaped, with obvious tonsillar herniation. (C) and (D) After PFD with the small bone window plus duraplasty, ODA was about the same as before the operation. The space of the foramen magnum region did not increase significantly, with the tonsillar hernia retracted slightly and syringomyelia not improved.
Fig. 8The MRI of Chiari malformation type I.
(A) and (B) Before the operation, ODA was at a large obtuse angle, and the tonsillar hernia was lower to the arcus posterior atlantis. (C) and (D) One year after PFD, duraplasty and tonsillectomy, reconstruction of the occipital cistern was obtained and syringomyelia almost disappeared.
Fig. 9The MRI of Chiari malformation type I.
(A) and (B) Before operation, ODA was smaller, and occipital cistern magna disappeared and syringomyelia was obvious. (C) and (D) One year after PFD, duraplasty and syrinx-shunting, reconstruction of occipital cistern was obtained and syringomyelia disappeared.
[1]   Xiu B, Li CC, Lin HP, et al. Microsurgery for Chiari malformations (report of 113 cases) (In Chinese). Chin J Clin Neurosurg. 2017, 22(7): 460-462.
[2]   Wang HB, Jin B, Wang KD, et al. Diagnosis of Chiari malformation type I by cranial base morphological descriptions with head CT (In Chinese). Chin J Neurosurg Dis Res. 2015, 14(5): 405-408.
[3]   Sabba MF, Renor BS, Ghizoni E, et al. Posterior Fossa decompression with duraplasty in Chiari surgery: A technical note. Rev Assoc Med Bras (1992). 2017, 63(11): 946-949.
doi: 10.1590/1806-9282.63.11.946 pmid: 29451656
[4]   Zhang ZY, Tan YT, Ouyang TH et al. Surgical strategies for patients of Chiari malformation type I with syringomyelia (In Chinese). Chin J Neurosurg Dis Res. 2017, 16(1): 69-71.
[5]   Yilmaz A, Kanat A, Musluman AM, et al. When is duraplasty required in the surgical treatment of Chiari malformation type I based on tonsillar descending grading scale? World Neurosurg. 2011, 75(2): 307-313.
doi: 10.1016/j.wneu.2010.09.005
[6]   Lu VM, Phan K, Crowley SP, et al. The addition of duraplasty to posterior Fossa decompression in the surgical treatment of pediatric Chiari malformation Type I: a systematic review and meta-analysis of surgical and performance outcomes. J Neurosurg Pediatr. 2017, 20(5): 439-449.
doi: 10.3171/2017.6.PEDS16367 pmid: 28885133
[7]   Jiang EZ, Sha SF, Yuan XX, et al. Comparison of clinical and radiographic outcomes for posterior Fossa decompression with and without duraplasty for treatment of pediatric Chiari I malformation: A prospective study. World Neurosurg. 2018, 110: e465-e472.
doi: 10.1016/j.wneu.2017.11.007 pmid: 29133007
[8]   Gallo P, Sokol D, Kaliaperumal C, et al. Comparison of three different cranio-cervical decompression procedures in children with Chiari malformation type I: does the surgical technique matter? Pediatr Neurosurg. 2017, 52(5): 289-297.
doi: 10.1159/000479327 pmid: 28848212
[9]   Kennedy BC, Kelly KM, Phan MQ, et al. Outcomes after suboccipital decompression without dural opening in children with Chiari malformation Type I. J Neurosurg Pediatr. 2015, 16(2): 150-158.
doi: 10.3171/2014.12.PEDS14487 pmid: 25932779
[10]   Geng LY, Liu X, Zhang YS, et al. Dura-splitting versus a combined technique for Chiari malformation type I complicated with syringomyelia. Br J Neurosurg. 2018: 1-5.
doi: 10.1080/02688697.2019.1704220 pmid: 31875723
[11]   Del Gaudio N, Vaz G, Duprez T, et al. Comparison of dural peeling versus duraplasty for surgical treatment of Chiari type I malformation: results and complications in a monocentric patients’ cohort. World Neurosurg. 2018, 117: e595-e602.
doi: 10.1016/j.wneu.2018.06.093 pmid: 29933087
[12]   Liu H, Yang CL, Yang J, et al. Pediatric Chiari malformation type I: long-term outcomes following small-bone-window posterior Fossa decompression with autologous-fascia duraplasty. Exp Ther Med. 2017, 14(6): 5652-5658.
doi: 10.3892/etm.2017.5211 pmid: 29285106
[13]   Deng XF, Yang CL, Gan JH, et al. Long-term outcomes after small-bone-window posterior Fossa decompression and duraplasty in adults with Chiari malformation type I. World Neurosurg. 2015, 84(4): 998-1004.
doi: 10.1016/j.wneu.2015.02.006 pmid: 25701768
[14]   Bhimani AD, Esfahani DR, Denyer S, et al. Adult Chiari I malformations: an analysis of surgical risk factors and complications using an international database. World Neurosurg. 2018, 115: e490-e500.
doi: 10.1016/j.wneu.2018.04.077 pmid: 29684513
[15]   Ramnarayan R, Ganesh CVS, Kumar R. Spontaneous resolution of Chiari 1-associated syringomyelia: A report of two cases. Pediatr Neurosurg. 2018, 53(4): 238-242.
doi: 10.1159/000488461 pmid: 29734193
No related articles found!