J Neurol Surg A Cent Eur Neurosurg 2017; 78(04): 344-349
DOI: 10.1055/s-0037-1599841
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Symptomatic Outcome after Bone-only Suboccipital Decompression in Adult Patients with Chiari Type I Malformations in the Absence of Hydromyelia or Hydrocephalus

Nicolas Olmo Koechlin
1   Centre for Minimally Invasive Neurosurgery, Prince of Wales Private Hospital, Sydney, New South Wales, Australia
2   Endoskopische und Minimal Invasive Neurochirurgie, Klinik Birshof, Munchenstein, Switzerland
Hazem J. Abuhusain
1   Centre for Minimally Invasive Neurosurgery, Prince of Wales Private Hospital, Sydney, New South Wales, Australia
Manuri Gunawardena
1   Centre for Minimally Invasive Neurosurgery, Prince of Wales Private Hospital, Sydney, New South Wales, Australia
Tyler S. Auschwitz
1   Centre for Minimally Invasive Neurosurgery, Prince of Wales Private Hospital, Sydney, New South Wales, Australia
3   Department of Neurosurgery, University of Tennessee Health Science Center, Tennessee, United States
Charles Teo
4   Department of Neurosurgery, Centre for Minimally Invasive Neurosurgery, Sydney, New South Wales, Australia
› Author Affiliations
Further Information

Publication History

24 February 2016

30 December 2016

Publication Date:
24 April 2017 (online)


Background Type I Chiari malformation presents without an associated hydromyelia in 30 to 70% of cases, yet there is no agreement regarding the optimal surgical treatment for these patients. We review our experience for treating symptomatic adult type I Chiari malformation without hydromyelia using a suboccipital bone decompression of the hindbrain and no duraplasty in 12 adult patients. Outcome was measured according to the Chicago Chiari Outcome Scale (CCOS).

Results Nine of 12 patients were female; average age at surgery was 34.4 years (range: 17–67 years). Average duration of symptoms prior to surgery was 9.6 years (2 months–29 years). The most common symptom was head and/or neck pain (11/12 patients). All patients additionally presented with at least one non-pain symptom. Mean degree of tonsillar herniation on magnetic resonance imaging was 6.8 mm (range: 5–12 mm) below McRae's line. Operative time was on average 68 minutes (range: 47–120 minutes). No surgical complications were noted in any patient. Length of hospital stay was 2 days (1 overnight) for all patients. Mean follow-up was 167 weeks (range: 13–378 weeks). CCOS for all patients on average was 14.50 (range: 12–16). Pain symptoms underwent improvement (7/11 [63.6%]) or complete resolution (4/11 [36.4%]) in all affected patients. A shorter duration of preoperative symptoms significantly correlated with a better CCOS (p = 0.03). Degree of tonsillar herniation had no significant effect on CCOS (p = 0.67). Of non-pain symptoms, paresthesias/dysesthesias and visual symptoms improved or resolved completely in all affected patients. No patient experienced a worsening of either pain or non-pain symptoms.

Conclusion In the subset of adult patients with a type I Chiari malformation and no associated hydromyelia, a craniectomy without an additional opening of the dura may achieve good overall results according to the CCOS.

  • References

  • 1 Rocque BG, George TM, Kestle J, Iskandar BJ. Treatment practices for Chiari malformation type I with syringomyelia: results of a survey of the American Society of Pediatric Neurosurgeons. J Neurosurg Pediatr 2011; 8 (05) 430-437
  • 2 Sindou M, Chávez-Machuca J, Hashish H. Cranio-cervical decompression for Chiari type I-malformation, adding extreme lateral foramen magnum opening and expansile duroplasty with arachnoid preservation. Technique and long-term functional results in 44 consecutive adult cases—comparison with literature data. Acta Neurochir (Wien) 2002; 144 (10) 1005-1019
  • 3 Takayasu M, Takagi T, Hara M, Anzai M. A simple technique for expansive suboccipital cranioplasty following foramen magnum decompression for the treatment of syringomyelia associated with Chiari I malformation. Neurosurg Rev 2004; 27 (03) 173-177
  • 4 Durham SR, Fjeld-Olenec K. Comparison of posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation Type I in pediatric patients: a meta-analysis. J Neurosurg Pediatr 2008; 2 (01) 42-49
  • 5 Hayhurst C, Richards O, Zaki H, Findlay G, Pigott TJ. Hindbrain decompression for Chiari-syringomyelia complex: an outcome analysis comparing surgical techniques. Br J Neurosurg 2008; 22 (01) 86-91
  • 6 Lam FC, Kasper E. Augmented autologous pericranium duraplasty in 100 posterior fossa surgeries—a retrospective case series. Neurosurgery 2012; 71 (02) , Suppl Operative): ons302-ons307
  • 7 Krishna V, McLawhorn M, Kosnik-Infinger L, Patel S. High long-term symptomatic recurrence rates after Chiari-1 decompression without dural opening: a single center experience. Clin Neurol Neurosurg 2014; 118: 53-58
  • 8 Munshi I, Frim D, Stine-Reyes R, Weir BK, Hekmatpanah J, Brown F. Effects of posterior fossa decompression with and without duraplasty on Chiari malformation-associated hydromyelia. Neurosurgery 2000; 46 (06) 1384-1389 , discussion 1389–1390
  • 9 James HE, Brant A. Treatment of the Chiari malformation with bone decompression without durotomy in children and young adults. Childs Nerv Syst 2002; 18 (05) 202-206
  • 10 Ogiwara H, Morota N. Surgical decompression without dural opening for symptomatic Chiari type II malformation in young infants. Childs Nerv Syst 2013; 29 (09) 1563-1567
  • 11 Aliaga L, Hekman KE, Yassari R. , et al. A novel scoring system for assessing Chiari malformation type I treatment outcomes. Neurosurgery 2012; 70 (03) 656-664 , discussion 664–665
  • 12 Kalb S, Perez-Orribo L, Mahan M, Theodore N, Nakaji P, Bristol RE. Evaluation of operative procedures for symptomatic outcome after decompression surgery for Chiari type I malformation. J Clin Neurosci 2012; 19 (09) 1268-1272
  • 13 Yarbrough CK, Greenberg JK, Smyth MD, Leonard JR, Park TS, Limbrick Jr DD. External validation of the Chicago Chiari Outcome Scale. J Neurosurg Pediatr 2014; 13 (06) 679-684
  • 14 Hekman KE, Aliaga L, Straus D. , et al. Positive and negative predictors for good outcome after decompressive surgery for Chiari malformation type 1 as scored on the Chicago Chiari Outcome Scale. Neurol Res 2012; 34 (07) 694-700
  • 15 Mutchnick IS, Janjua RM, Moeller K, Moriarty TM. Decompression of Chiari malformation with and without duraplasty: morbidity versus recurrence. J Neurosurg Pediatr 2010; 5 (05) 474-478
  • 16 Koechlin NO, Burkhardt JK, Scherer M. , et al. Cerebrospinal fluid leaks after planned intradural spine surgery: a single-center analysis of 91 cases. J Neurol Surg A Cent Eur Neurosurg 2013; 74 (04) 216-221
  • 17 Caldarelli M, Novegno F, Vassimi L, Romani R, Tamburrini G, Di 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 2007; 106 (3, Suppl): 187-195
  • 18 Genitori L, Peretta P, Nurisso C, Macinante L, Mussa F. Chiari type I anomalies in children and adolescents: minimally invasive management in a series of 53 cases. Childs Nerv Syst 2000; 16 (10-11): 707-718
  • 19 Yundt KD, Park TS, Tantuwaya VS, Kaufman BA. Posterior fossa decompression without duraplasty in infants and young children for treatment of Chiari malformation and achondroplasia. Pediatr Neurosurg 1996; 25 (05) 221-226
  • 20 Cui LG, Jiang L, Zhang HB. , et al. Monitoring of cerebrospinal fluid flow by intraoperative ultrasound in patients with Chiari I malformation. Clin Neurol Neurosurg 2011; 113 (03) 173-176
  • 21 Chen JA, Coutin-Churchman PE, Nuwer MR, Lazareff JA. Suboccipital craniotomy for Chiari I results in evoked potential conduction changes. Surg Neurol Int 2012; 3: 165
  • 22 Roser F, Ebner FH, Liebsch M, Tatagiba MS, Naros G. The role of intraoperative neuromonitoring in adults with Chiari I malformation. Clin Neurol Neurosurg 2016; 150: 27-32