Letter to the Editor: Durotomy and foramen magnum decompression

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TO THE EDITOR: We read with interest the article by Kennedy et al.8 (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 16:150–158, August 2015). The authors discuss a relatively large series of patients with Chiari malformation Type I (CM-I) who were treated by foramen magnum decompression without resorting to opening of the dura mater. The authors report a positive outcome of symptoms following such a strategy of treatment. They discuss the potential negative issues related to opening the dura and intradural manipulations.

In 1998 we presented a series of 190 patients with basilar invagination.6 Of these, 102 patients had CM-I. Twenty-three patients with CM-I were below the age of 21 years. This article was among the first few that related small posterior cranial fossa volume to CM-I. According to my information, this article was among the first in the literature that discussed treatment of CM-I by foramen magnum decompression without opening of the dura. In the series, the dura was not opened even when CM-I was associated with syringomyelia. We also discussed in our subsequent articles that the issue of CM-I and small posterior cranial fossa volume was relevant only in cases with basilar invagination.1,5,7,9 Considering the direct relevance to the issue under discussion, the authors should have referenced our work.

In our more recent article, we identified the relationship of CM-I with atlantoaxial instability.3 We hypothesized that a herniated cerebellar tonsil is like “Nature’s air bag” and functions to cushion the craniocervical cord against manifest or potential atlantoaxial instability.4 Our analysis identified that the posterior fossa volume is not small in these cases. Moreover, the superior vermis and superior part of the cerebellum are atrophic in these cases, and the concept that the CM-I is a result of the presence of a smaller volume of posterior cranial fossa does not seem to be relevant in these cases. It would have been interesting if the authors had evaluated the posterior fossa volume and the status of the cerebellum in the cases discussed. After our experience with several patients with CM-I over more than 30 years, we conclude that foramen magnum decompression is necessary only rarely.2

References

  • 1

    Goel A: Basilar invagination, Chiari malformation, syringomyelia: a review. Neurol India 57:2352462009

  • 2

    Goel A: Can foramen magnum decompression surgery become historical?. J Craniovertebr Junction Spine 6:49502015

  • 3

    Goel A: Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation. J Neurosurg Spine 22:1161272015

    • Search Google Scholar
    • Export Citation
  • 4

    Goel A: Is Chiari malformation nature’s protective “air-bag”? Is its presence diagnostic of atlantoaxial instability?. J Craniovertebr Junction Spine 5:1071092014

    • Search Google Scholar
    • Export Citation
  • 5

    Goel AAchawal S: The surgical treatment for Chiari malformation associated with atlantoaxial dislocation. Br J Neurosurg 9:67721995

    • Search Google Scholar
    • Export Citation
  • 6

    Goel ABhatjiwale MDesai K: Basilar invagination: a study based on 190 surgically treated cases. J Neurosurg 88:9629681998

  • 7

    Goel ADesai KI: Surgery for syringomyelia: An analysis based on 163 surgical cases. Acta Neurochir (Wien) 142:2933022000

  • 8

    Kennedy BCKelly KMPhan MQBruce SSMcDowell MMAnderson RCE: Outcomes after suboccipital decompression without dural opening in children with Chiari malformation Type I. J Neurosurg Pediatr 16:1501582015

    • Search Google Scholar
    • Export Citation
  • 9

    Kothari MGoel A: Maternalizing the meninges: A pregnant Arabic legacy. Neurol India 54:3453462006

Response

We thank Dr. Goel for his interest and comments regarding our recent article. We are very familiar with Dr. Goel’s publications, but did not reference them because they primarily include adult patients and are neither the first27 nor the largest14 reports of children undergoing suboccipital decompression without dural opening for CM-I. Furthermore, perhaps in part due to his geographic location, we believe that Dr. Goel has a unique practice, and it is unlikely that the outcomes of his patients would reflect the majority of other patients with CM-I around the world. This notion is supported by the very high percentage of patients in his series presenting with basilar invagination, occipitalization of the atlas, and advanced neurological deficits.10

Dr. Goel discusses several times in his letter his work investigating the relationship between CM-I and posterior fossa volume, and mentions that it would have been interesting for us to have evaluated the posterior fossa volume in our cases. We chose instead to focus primarily on clinical rather than radiographic outcomes, because the relationship between posterior fossa volume and CM-I has already been extensively investigated and reviewed.3,7,8,15,17,21,22,24,25

Dr. Goel also mentions his recent article in which he states that the “pathogenesis of CM … is primarily related to atlantoaxial instability,” that “surgical treatment in these cases should be directed toward atlantoaxial stabilization and segmental arthrodesis,” and that “foramen magnum decompression is not necessary and may be counter-effective in the long run.”10 Contrary to Dr. Goel’s conclusions, we believe that: 1) there is overwhelming medical evidence supporting suboccipital decompression for children with CM-I, regardless of whether the dura is opened;1,2,4–6,9,12–14,16,18,23,26 2) decompression is accepted by the vast majority of pediatric neurosurgeons across the world;11,19,20 and 3) the incidence of immediate or delayed symptomatic atlantoaxial instability in the general pediatric population with CM-I is extremely rare.14,16,18,23 Our thoughts are echoed by the experience of many members of the Pediatric Craniocervical Society, which led the Society to write a statement in response to Dr. Goel’s paper that has been published in the Journal of Neurosurgery: Spine.28

Last, Dr. Goel hypothesizes that in patients with CM-I, the cerebellar tonsils act as “Nature’s air bag” to “cushion the craniocervical cord.” We did not design our study to support or refute Dr. Goel’s hypothesis. Rather, the primary aim of our study was to report the clinical outcomes after suboccipital decompression without dural opening in children with CM-I, in what is, to our knowledge, the largest reported series in the literature.

References

  • 1

    Alzate JCKothbauer KFJallo GIEpstein FJ: Treatment of Chiari I malformation in patients with and without syringo-myelia: a consecutive series of 66 cases. Neurosurg Focus 11:1E32001

    • Search Google Scholar
    • Export Citation
  • 2

    Attenello FJMcGirt MJGathinji MDatoo GAtiba AWeingart J: Outcome of Chiari-associated syringomyelia after hindbrain decompression in children: analysis of 49 consecutive cases. Neurosurgery 62:130713132008

    • Search Google Scholar
    • Export Citation
  • 3

    Badie BMendoza DBatzdorf U: Posterior fossa volume and response to suboccipital decompression in patients with Chiari I malformation. Neurosurgery 37:2142181995

    • Search Google Scholar
    • Export Citation
  • 4

    Caldarelli MNovegno FVassimi LRomani RTamburrini GDi Rocco C: The role of limited posterior fossa craniectomy in the surgical treatment of Chiari malformation Type I: experience with a pediatric series. J Neurosurg 106:3 suppl1871952007

    • Search Google Scholar
    • Export Citation
  • 5

    Dure LSPercy AKCheek WRLaurent JP: Chiari type I malformation in children. J Pediatr 115:5735761989

  • 6

    Ellenbogen RGArmonda RAShaw DWWinn HR: Toward a rational treatment of Chiari I malformation and syringomyelia. Neurosurg Focus 8:3E62000

    • Search Google Scholar
    • Export Citation
  • 7

    Furtado SVReddy KHegde AS: Posterior fossa morphom-etry in symptomatic pediatric and adult Chiari I malformation. J Clin Neurosci 16:144914542009

    • Search Google Scholar
    • Export Citation
  • 8

    Furtado SVThakre DJVenkatesh PKReddy KHegde AS: Morphometric analysis of foramen magnum dimensions and intracranial volume in pediatric Chiari I malformation. Acta Neurochir (Wien) 152:2212272010

    • Search Google Scholar
    • Export Citation
  • 9

    Genitori LPeretta PNurisso CMacinante LMussa F: Chiari type I anomalies in children and adolescents: minimally invasive management in a series of 53 cases. Childs Nerv Syst 16:7077182000

    • Search Google Scholar
    • Export Citation
  • 10

    Goel A: Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation. J Neurosurg Spine 22:1161272015

    • Search Google Scholar
    • Export Citation
  • 11

    Haroun RIGuarnieri MMeadow JJKraut MCarson BS: Current opinions for the treatment of syringomyelia and Chiari malformations: survey of the Pediatric Section of the American Association of Neurological Surgeons. Pediatr Neurosurg 33:3113172000

    • Search Google Scholar
    • Export Citation
  • 12

    Klekamp J: Surgical treatment of Chiari I malformation-analysis of intraoperative findings, complications, and outcome for 371 foramen magnum decompressions. Neurosurgery 71:3653802012

    • Search Google Scholar
    • Export Citation
  • 13

    Krieger MDMcComb JGLevy ML: Toward a simpler surgical management of Chiari I malformation in a pediatric population. Pediatr Neurosurg 30:1131211999

    • Search Google Scholar
    • Export Citation
  • 14

    McGirt MJAttenello FJAtiba AGarces-Ambrossi GDatoo GWeingart JD: Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases. Childs Nerv Syst 24:133313392008

    • Search Google Scholar
    • Export Citation
  • 15

    Milhorat THChou MWTrinidad EMKula RWMandell MWolpert C: Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 44:100510171999

    • Search Google Scholar
    • Export Citation
  • 16

    Navarro ROlavarria GSeshadri RGonzales-Portillo GMcLone DGTomita T: Surgical results of posterior fossa decompression for patients with Chiari I malformation. Childs Nerv Syst 20:3493562004

    • Search Google Scholar
    • Export Citation
  • 17

    Nishikawa MSakamoto HHakuba ANakanishi NInoue Y: Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. J Neurosurg 86:40471997

    • Search Google Scholar
    • Export Citation
  • 18

    Park JKGleason PLMadsen JRGoumnerova LCScott RM: Presentation and management of Chiari I malformation in children. Pediatr Neurosurg 26:1901961997

    • Search Google Scholar
    • Export Citation
  • 19

    Rocque BGGeorge TMKestle JIskandar BJ: Treatment practices for Chiari malformation type I with syringomyelia: results of a survey of the American Society of Pediatric Neurosurgeons. J Neurosurg Pediatr 8:4304372011

    • Search Google Scholar
    • Export Citation
  • 20

    Schijman ESteinbok P: International survey on the management of Chiari I malformation and syringomyelia. Childs Nerv Syst 20:3413482004

    • Search Google Scholar
    • Export Citation
  • 21

    Sgouros SKountouri MNatarajan K: Posterior fossa volume in children with Chiari malformation Type I. J Neurosurg 105:2 suppl1011062006

    • Search Google Scholar
    • Export Citation
  • 22

    Trigylidas TBaronia BVassilyadi MVentureyra EC: Posterior fossa dimension and volume estimates in pediatric patients with Chiari I malformations. Childs Nerv Syst 24:3293362008

    • Search Google Scholar
    • Export Citation
  • 23

    Tubbs RSBeckman JNaftel RPChern JJWellons JC IIIRozzelle CJ: Institutional experience with 500 cases of surgically treated pediatric Chiari malformation Type I. J Neurosurg Pediatr 7:2482562011

    • Search Google Scholar
    • Export Citation
  • 24

    Tubbs RSHill MLoukas MShoja MMOakes WJ: Volumetric analysis of the posterior cranial fossa in a family with four generations of the Chiari malformation Type I. J Neurosurg Pediatr 1:21242008

    • Search Google Scholar
    • Export Citation
  • 25

    Tubbs RSWellons JC IIISmyth MDBartolucci AABlount JPOakes WJ: Children with growth hormone deficiency and Chiari I malformation: a morphometric analysis of the posterior cranial fossa. Pediatr Neurosurg 38:3243282003

    • Search Google Scholar
    • Export Citation
  • 26

    Valentini LVisintini SSaletti VChiapparini LEstienne MSolero CL: Treatment for Chiari 1 malformation (CIM): analysis of a pediatric surgical series. Neurol Sci 32:Suppl 3S321S3242011

    • Search Google Scholar
    • Export Citation
  • 27

    Yundt KDPark TSTantuwaya VSKaufman BA: Posterior fossa decompression without duraplasty in infants and young children for treatment of Chiari malformation and achondroplasia. Pediatr Neurosurg 25:2212261996

    • Search Google Scholar
    • Export Citation
  • 28

    Brockmeyer DLOakes WJRozzelle CJohnston JRocque BGAnderson RCE: Chiari malformation Type 1 and atlantoaxial instability: a letter from the Pediatric Craniocervical Society. J Neurosurg Spine epub ahead of printSeptember42015. (Letter)

    • Search Google Scholar
    • Export Citation

If the inline PDF is not rendering correctly, you can download the PDF file here.

Article Information

INCLUDE WHEN CITING Published online September 18, 2015; DOI: 10.3171/2015.6.PEDS15339.

DISCLOSURE The author reports no conflict of interest.

© AANS, except where prohibited by US copyright law.

Headings

References

  • 1

    Goel A: Basilar invagination, Chiari malformation, syringomyelia: a review. Neurol India 57:2352462009

  • 2

    Goel A: Can foramen magnum decompression surgery become historical?. J Craniovertebr Junction Spine 6:49502015

  • 3

    Goel A: Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation. J Neurosurg Spine 22:1161272015

    • Search Google Scholar
    • Export Citation
  • 4

    Goel A: Is Chiari malformation nature’s protective “air-bag”? Is its presence diagnostic of atlantoaxial instability?. J Craniovertebr Junction Spine 5:1071092014

    • Search Google Scholar
    • Export Citation
  • 5

    Goel AAchawal S: The surgical treatment for Chiari malformation associated with atlantoaxial dislocation. Br J Neurosurg 9:67721995

    • Search Google Scholar
    • Export Citation
  • 6

    Goel ABhatjiwale MDesai K: Basilar invagination: a study based on 190 surgically treated cases. J Neurosurg 88:9629681998

  • 7

    Goel ADesai KI: Surgery for syringomyelia: An analysis based on 163 surgical cases. Acta Neurochir (Wien) 142:2933022000

  • 8

    Kennedy BCKelly KMPhan MQBruce SSMcDowell MMAnderson RCE: Outcomes after suboccipital decompression without dural opening in children with Chiari malformation Type I. J Neurosurg Pediatr 16:1501582015

    • Search Google Scholar
    • Export Citation
  • 9

    Kothari MGoel A: Maternalizing the meninges: A pregnant Arabic legacy. Neurol India 54:3453462006

  • 1

    Alzate JCKothbauer KFJallo GIEpstein FJ: Treatment of Chiari I malformation in patients with and without syringo-myelia: a consecutive series of 66 cases. Neurosurg Focus 11:1E32001

    • Search Google Scholar
    • Export Citation
  • 2

    Attenello FJMcGirt MJGathinji MDatoo GAtiba AWeingart J: Outcome of Chiari-associated syringomyelia after hindbrain decompression in children: analysis of 49 consecutive cases. Neurosurgery 62:130713132008

    • Search Google Scholar
    • Export Citation
  • 3

    Badie BMendoza DBatzdorf U: Posterior fossa volume and response to suboccipital decompression in patients with Chiari I malformation. Neurosurgery 37:2142181995

    • Search Google Scholar
    • Export Citation
  • 4

    Caldarelli MNovegno FVassimi LRomani RTamburrini GDi Rocco C: The role of limited posterior fossa craniectomy in the surgical treatment of Chiari malformation Type I: experience with a pediatric series. J Neurosurg 106:3 suppl1871952007

    • Search Google Scholar
    • Export Citation
  • 5

    Dure LSPercy AKCheek WRLaurent JP: Chiari type I malformation in children. J Pediatr 115:5735761989

  • 6

    Ellenbogen RGArmonda RAShaw DWWinn HR: Toward a rational treatment of Chiari I malformation and syringomyelia. Neurosurg Focus 8:3E62000

    • Search Google Scholar
    • Export Citation
  • 7

    Furtado SVReddy KHegde AS: Posterior fossa morphom-etry in symptomatic pediatric and adult Chiari I malformation. J Clin Neurosci 16:144914542009

    • Search Google Scholar
    • Export Citation
  • 8

    Furtado SVThakre DJVenkatesh PKReddy KHegde AS: Morphometric analysis of foramen magnum dimensions and intracranial volume in pediatric Chiari I malformation. Acta Neurochir (Wien) 152:2212272010

    • Search Google Scholar
    • Export Citation
  • 9

    Genitori LPeretta PNurisso CMacinante LMussa F: Chiari type I anomalies in children and adolescents: minimally invasive management in a series of 53 cases. Childs Nerv Syst 16:7077182000

    • Search Google Scholar
    • Export Citation
  • 10

    Goel A: Is atlantoaxial instability the cause of Chiari malformation? Outcome analysis of 65 patients treated by atlantoaxial fixation. J Neurosurg Spine 22:1161272015

    • Search Google Scholar
    • Export Citation
  • 11

    Haroun RIGuarnieri MMeadow JJKraut MCarson BS: Current opinions for the treatment of syringomyelia and Chiari malformations: survey of the Pediatric Section of the American Association of Neurological Surgeons. Pediatr Neurosurg 33:3113172000

    • Search Google Scholar
    • Export Citation
  • 12

    Klekamp J: Surgical treatment of Chiari I malformation-analysis of intraoperative findings, complications, and outcome for 371 foramen magnum decompressions. Neurosurgery 71:3653802012

    • Search Google Scholar
    • Export Citation
  • 13

    Krieger MDMcComb JGLevy ML: Toward a simpler surgical management of Chiari I malformation in a pediatric population. Pediatr Neurosurg 30:1131211999

    • Search Google Scholar
    • Export Citation
  • 14

    McGirt MJAttenello FJAtiba AGarces-Ambrossi GDatoo GWeingart JD: Symptom recurrence after suboccipital decompression for pediatric Chiari I malformation: analysis of 256 consecutive cases. Childs Nerv Syst 24:133313392008

    • Search Google Scholar
    • Export Citation
  • 15

    Milhorat THChou MWTrinidad EMKula RWMandell MWolpert C: Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 44:100510171999

    • Search Google Scholar
    • Export Citation
  • 16

    Navarro ROlavarria GSeshadri RGonzales-Portillo GMcLone DGTomita T: Surgical results of posterior fossa decompression for patients with Chiari I malformation. Childs Nerv Syst 20:3493562004

    • Search Google Scholar
    • Export Citation
  • 17

    Nishikawa MSakamoto HHakuba ANakanishi NInoue Y: Pathogenesis of Chiari malformation: a morphometric study of the posterior cranial fossa. J Neurosurg 86:40471997

    • Search Google Scholar
    • Export Citation
  • 18

    Park JKGleason PLMadsen JRGoumnerova LCScott RM: Presentation and management of Chiari I malformation in children. Pediatr Neurosurg 26:1901961997

    • Search Google Scholar
    • Export Citation
  • 19

    Rocque BGGeorge TMKestle JIskandar BJ: Treatment practices for Chiari malformation type I with syringomyelia: results of a survey of the American Society of Pediatric Neurosurgeons. J Neurosurg Pediatr 8:4304372011

    • Search Google Scholar
    • Export Citation
  • 20

    Schijman ESteinbok P: International survey on the management of Chiari I malformation and syringomyelia. Childs Nerv Syst 20:3413482004

    • Search Google Scholar
    • Export Citation
  • 21

    Sgouros SKountouri MNatarajan K: Posterior fossa volume in children with Chiari malformation Type I. J Neurosurg 105:2 suppl1011062006

    • Search Google Scholar
    • Export Citation
  • 22

    Trigylidas TBaronia BVassilyadi MVentureyra EC: Posterior fossa dimension and volume estimates in pediatric patients with Chiari I malformations. Childs Nerv Syst 24:3293362008

    • Search Google Scholar
    • Export Citation
  • 23

    Tubbs RSBeckman JNaftel RPChern JJWellons JC IIIRozzelle CJ: Institutional experience with 500 cases of surgically treated pediatric Chiari malformation Type I. J Neurosurg Pediatr 7:2482562011

    • Search Google Scholar
    • Export Citation
  • 24

    Tubbs RSHill MLoukas MShoja MMOakes WJ: Volumetric analysis of the posterior cranial fossa in a family with four generations of the Chiari malformation Type I. J Neurosurg Pediatr 1:21242008

    • Search Google Scholar
    • Export Citation
  • 25

    Tubbs RSWellons JC IIISmyth MDBartolucci AABlount JPOakes WJ: Children with growth hormone deficiency and Chiari I malformation: a morphometric analysis of the posterior cranial fossa. Pediatr Neurosurg 38:3243282003

    • Search Google Scholar
    • Export Citation
  • 26

    Valentini LVisintini SSaletti VChiapparini LEstienne MSolero CL: Treatment for Chiari 1 malformation (CIM): analysis of a pediatric surgical series. Neurol Sci 32:Suppl 3S321S3242011

    • Search Google Scholar
    • Export Citation
  • 27

    Yundt KDPark TSTantuwaya VSKaufman BA: Posterior fossa decompression without duraplasty in infants and young children for treatment of Chiari malformation and achondroplasia. Pediatr Neurosurg 25:2212261996

    • Search Google Scholar
    • Export Citation
  • 28

    Brockmeyer DLOakes WJRozzelle CJohnston JRocque BGAnderson RCE: Chiari malformation Type 1 and atlantoaxial instability: a letter from the Pediatric Craniocervical Society. J Neurosurg Spine epub ahead of printSeptember42015. (Letter)

    • Search Google Scholar
    • Export Citation

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