Posterior fossa decompression for Chiari type 1 deformity

Posterior fossa decompression for Chiari type 1 deformity

Despite decades of experience and research, the etiology and management of Chiari type 1 deformity (CM-I) continue to raise more questions than answers. Controversy abounds in every aspect of management, including the indications, timing, and type of surgery, as well as clinical and radiographic outcomes.

A review of recent literature on the management of CM-I in pediatric patients was presented by Alexander et al., along with the experience in managing 1073 patients who were diagnosed with CM-I over the past two decades (1998-2018) at Children’s National Medical Center.

The general trend reveals an increase in the diagnosis of CM-I at younger ages with a significant proportion of these being incidental findings (0.5-3.6%) in asymptomatic patients as well as a rise in the number of patients undergoing Chiari posterior fossa decompression surgery (PFD). The type of surgical intervention varies widely. At there institution, 104 (37%) Chiari surgeries were bone-only PFD with/without outer leaf durectomy, whereas 177 (63%) were PFD with duraplasty. They did not find a significant difference in outcomes between the PFD and PFDD groups (p = 0.59). An analysis of failures revealed a significant difference between patients who underwent tonsillar coagulation versus those whose tonsils were not manipulated (p = 0.02).

While the optimal surgical intervention continues to remain elusive, there is a shift away from intradural techniques in favor of a simple, extradural approach (including dural delamination) in pediatric patients due to high rates of clinical and radiographic success, along with a lower complication rate. The efficacy, safety, and necessity of tonsillar manipulation continue to be heavily contested, as evidence increasingly supports the efficacy and safety of less tonsillar manipulation, including there own experience 1).


An accurate and reliable selection of patients based on clinical and neuroimaging findings is paramount for the success of neurosurgical treatment2).


The preferred treatment for Chiari type 1 deformity is foramen magnum decompression (FMD), and it is assumed to normalise ICP and craniospinal pressure dissociation.

Observations suggest that anatomical restoration of cerebrospinal fluid pathways by FMD does not lead to immediate normalisation of preoperatively altered pulsatile and static ICP in patients with CMI. This finding may explain persistent symptoms during the early period after FMD3).


A variety of surgical techniques for CM-I have been used, and there is a controversy whether to use posterior fossa decompression with duraplasty(PFDD) or posterior fossa decompression without duraplasty (PFD) in CM-I patients.

Chen et al., compared the clinical results and effectiveness of PFDD and PFD in adult patients with CM-I. The cases of 103 adult CM-I patients who underwent posterior fossa decompression with or without duraplasty from 2008 to 2014 were reviewed retrospectively. Patients were divided into 2 groups according to the surgical techniques: PFDD group (n = 70) and PFD group (n = 33). We compared the demographics, preoperative symptoms, radiographic characteristics, postoperative complications, and clinical outcomes between the PFD and PFDD patients. No statistically significant differences were found between the PFDD and PFD groups with regard to demographics, preoperative symptoms, radiographic characteristics, and clinical outcomes(P > 0.05); however, the postoperative complication aseptic meningitis occurred more frequently in the PFDD group than in the PFD group (P = 0.027). We also performed a literature review about the PFDD and PFD and made a summary of these preview studies. Our study suggests that both PFDD and PFD could achieve similar clinical outcomes for adult CM-I patients. The choice of surgical procedure should be based on the patient’s condition. PFDD may lead to a higher complication rate and autologous grafts seemed to perform better than nonautologous grafts for duraplasty 4).


The purpose of a study was to examine the utility of iMRI in determining when an adequate decompression had been performed.

Patients with symptomatic Chiari I malformations with imaging findings of obstruction of the CSF space at the foramen magnum, with or without syringomyelia, were considered candidates for surgery. All patients underwent complete T1, T2, and cine MRI studies in the supine position preoperatively as a baseline. After the patient was placed prone with the neck flexed in position for surgery, iMRI was performed. The patient then underwent a bone decompression of the foramen magnum and arch of C-1, and the MRI was repeated. If obstruction was still present, then in a stepwise fashion the patient underwent dural splitting, duraplasty, and coagulation of the tonsils, with an iMRI study performed after each step guiding the decision to proceed further.

Eighteen patients underwent PFD for Chiari I malformations between November 2011 and February 2013; 15 prone preincision iMRIs were performed. Fourteen of these patients (93%) demonstrated significant improvement of CSF flow through the foramen magnum dorsal to the tonsils with positioning only. This improvement was so notable that changes in CSF flow as a result of the bone decompression were difficult to discern.

The authors observed significant CSF flow changes when simply positioning the patient for surgery. These results put into question intraoperative flow assessments that suggest adequate decompression by PFD, whether by iMRI or intraoperative ultrasound. The use of intraoperative imaging during PFD for Chiari I malformation, whether by ultrasound or iMRI, is limited by CSF flow dynamics across the foramen magnum that change significantly when the patient is positioned for surgery 5).

Complications

References

1)

Alexander H, Tsering D, Myseros JS, Magge SN, Oluigbo C, Sanchez CE, Keating RF. Management of Chiari I malformations: a paradigm in evolution. Childs Nerv Syst. 2019 Jul 27. doi: 10.1007/s00381-019-04265-2. [Epub ahead of print] PubMed PMID: 31352576.
2)

Poretti A, Ashmawy R, Garzon-Muvdi T, Jallo GI, Huisman TA, Raybaud C. Chiari Type 1 Deformity in Children: Pathogenetic, Clinical, Neuroimaging, and Management Aspects. Neuropediatrics. 2016 Jun 23. [Epub ahead of print] PubMed PMID: 27337547.
3)

Frič R, Eide PK. Perioperative monitoring of pulsatile and static intracranial pressure in patients with Chiari malformation type 1 undergoing foramen magnum decompression. Acta Neurochir (Wien). 2016 Feb;158(2):341-7. doi: 10.1007/s00701-015-2669-0. Epub 2015 Dec 28. PubMed PMID: 26711284.
4)

Chen J, Li Y, Wang T, Gao J, Xu J, Lai R, Tan D. Comparison of posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation type I in adult patients: A retrospective analysis of 103 patients. Medicine (Baltimore). 2017 Jan;96(4):e5945. doi: 10.1097/MD.0000000000005945. PubMed PMID: 28121938.
5)

Bond AE, Jane JA Sr, Liu KC, Oldfield EH. Changes in cerebrospinal fluid flow assessed using intraoperative MRI during posterior fossa decompression for Chiari malformation. J Neurosurg. 2015 May;122(5):1068-75. doi: 10.3171/2015.1.JNS132712. Epub 2015 Feb 20. PubMed PMID: 25699415.

Supratentorial Epidural Hematoma after Posterior Fossa Surgery

Supratentorial Epidural Hematoma after Posterior Fossa Surgery

Non-traumatic, non-arterial origin delayed Epidural Hematoma after posterior fossa surgery is extremely rare. Moreover, the pathogenesis of its supratentorial extension is obscure.

The possible causes include sudden decompression of ventricular pressure in the supratentorial compartment, rupture of cortical veins in the sitting positioncoagulopathy, hemodynamic fluctuations during surgery, and position-related ischemia 1).

The lowering of the ventricular pressure by the ventricular tapduring the operation may play significant role in the formation of the extradural hematoma.

The younger age of the cases and the long history of increased intracranial pressure were stressed in the literature2).

Wolfsberger et al., stressed the importance of early postoperative CT scan and optimal management of ventricular pressure and coagulation status to detect and prevent this possibly life-threatening complication 3).

Avci et al., from Mersin, reported a case during removal of a huge Posterior fossa dermoid cyst 4).

Pandey et al., from Bangalore reported in 2008 a large bifrontal extradural hematoma following posterior fossa surgery for a vermian medulloblastoma5).

Tsugane et al., reported five cases of the supratentorial extradural hematomas secondary to the posterior fossa craniectomy.

The site of the hematoma was far from the operative field and two cases showed acute course and three were rather mild. The symptoms of this complication were the unsuspected sensorium disturbance, anisocoria and the non-functioning ventricular drainage. Two cases died of this complication and two were severely disabled 6).

Multiple Supratentorial Epidural Hematomas

Tyagi et al., from Bangalore published Multiple Remote Sequential Supratentorial Epidural Hematoma7).

Wolfsberger et al., from Vienna published a 31-year-old female who presented with a history of chronic hydrocephalus due to fourth-ventricular plexus papilloma. Following resection of the posterior fossa tumor with intraoperative placement of a ventricular drainage, she consecutively developed four supratentorial epidural haematomas at different locations, all necessitating evacuation. The clinical manifestations ranged from subtle neurological deficits to signs of tentorial herniation; the ultimate outcome was complete recovery. Rapid tapering of CSF pressure after long-standing hydrocephalus and clotting disorders could be implicated as causative factors. They stressed the importance of early postoperative CT scan and optimal management of ventricular pressure and coagulation status to detect and prevent this possibly life-threatening complication 8).

References

1) , 5)

Pandey P, Madhugiri VS, Sattur MG, Devi B I. Remote supratentorial extradural hematoma following posterior fossa surgery. Childs Nerv Syst. 2008 Jul;24(7):851-4. doi: 10.1007/s00381-007-0573-5. Epub 2008 Jan 31. PubMed PMID: 18236051.
2) , 6)

Tsugane R, Sugita K, Sato O. [Supratentorial extradural hematomas following posterior fossa craniectomy (author’s transl)]. No Shinkei Geka. 1976 Apr;4(4):401-3. Japanese. PubMed PMID: 944882.
3) , 8)

Wolfsberger S, Gruber A, Czech T. Multiple supratentorial epidural haematomas after posterior fossa surgery. Neurosurg Rev. 2004 Apr;27(2):128-32. Epub 2003 Dec 2. PubMed PMID: 14652780.
4)

Avci E, Dagtekin A, Baysal Z, Karabag H. Intraoperative supratentorial epidural haematoma during removal of a huge posterior fossa dermoid cyst. Neurol Neurochir Pol. 2010 Nov-Dec;44(6):609-13. PubMed PMID: 21225525.
7)

Tyagi G, Bhat DI, Indira Devi B, Shukla D. “Multiple Remote Sequential Supratentorial Epidural Hematomas – An Unusual and Rare Complication Following Posterior Fossa Surgery”. World Neurosurg. 2019 May 6. pii: S1878-8750(19)31225-2. doi: 10.1016/j.wneu.2019.04.228. [Epub ahead of print] PubMed PMID: 31071445.

Pipeline embolization device for posterior circulation aneurysm

Pipeline embolization device for posterior circulation aneurysm

The use of the pipeline embolization device (PED) for posterior circulation aneurysms remains controversial. In a meta-analysis, Liang et al., from the Beijing Tiantan Hospital and Beijing Tsinghua Changgung Hospital, aimed to explore the safety and efficacy of PED for these aneurysms. Meta regression was used to identify predictors for incomplete aneurysm occlusion and procedure-related complications.

PubMedWeb of Science, and OVID databases were searched to identify all published references evaluating the treatment effect of PED for posterior circulation aneurysms. Only studies written in English, reporting original data, and including more than 10 cases were considered for inclusion. Patient demographics, aneurysm characteristics, angiographic, and clinical outcomes were extracted. A random effects model was adopted to pool the obliteration rates and complications rates across selected studies. Finally, they conducted meta-regression analysis to identify the predictors of the angiographic outcomes.

12 studies, including 358 patients with 365 aneurysms were included. The pooled complete aneurysm obliteration rate was 82% (95% confidence interval [CI], 73%-90%) and the pooled procedure-related complication rate was 18% (95% CI, 14%-22%). Increasing age predicted incomplete obliteration of aneurysms after PED treatment in these patients (P=0.01).

PED is an alternative to treat intracranial aneurysms of the posterior circulation, achieving high complete occlusion rates, but less effective in senile patients. However, the risk of procedure-related complications is not negligible. Further larger and long-term follow-up studies are needed before definitive conclusions might be drawn 1).


From November 2015 to November 2016, 35 patients with 38 posterior circulation aneurysms were treated with the PED in this retrospective study. We evaluated the angiographic and clinical outcomes of these aneurysms at last follow-up, and made a comparison between anterior (n = 163) and posterior circulation (n = 38) aneurysms regarding the technical nuances, occlusion rate, complications rate, and time to occlusion to explore whether we should rationalize the use of the PED for these aneurysms.

With a median follow-up time of 5.5 months, complete occlusion was achieved in 33 aneurysms (91.7%). Aneurysms with stenosis parent artery tended to have lower occlusion rate (P = 0.064; odds ratio, 0.074; 90% confidence interval, 0.001-1.781), and V4 segment aneurysms tended to occlude themselves much faster than vertebrobasilar junction aneurysms (median, 148 vs. 246 days, respectively; P = 0.076). The periprocedural complication rate was 10.8%, and no major adverse events occurred. Compared with anterior circulation aneurysms, shorter procedure time (116.0 vs. 135.4 minutes, P = 0.012) and higher occlusion rate (91.4% vs. 72.8%, P = 0.023) were achieved for posterior circulation aneurysms. Besides, technical event rate (8.1% vs. 14.1%, P = 0.424) and complication rate (10.8% vs. 18.4%, P = 0.338) tended to be lower. Survival analysis indicated a shorter interval to complete occlusion for V4 segment aneurysms compared with anterior circulation (148 vs. 191 days, respectively; P = 0.047).

PED has a favorable performance at posterior circulation, and it is rational to expand the indication to include these aneurysms. However, a case-control study is still needed to further expatiate whether the PED has advantages over traditional endovascular treatment 2).


In 2018, a retrospective review of prospectively maintained databases at 8 academic institutions was performed for the years 2009 to 2016 to identify patients with posterior circulation aneurysms treated with PED placement.

A total of 129 consecutive patients underwent 129 procedures to treat 131 aneurysms; 29 dissecting, 53 fusiform, and 49 saccular lesions were included. At a median follow-up of 11 months, complete and near-complete occlusion was recorded in 78.1%. Dissecting aneurysms had the highest occlusion rate and fusiform the lowest. Major complications were most frequent in fusiform aneurysms, whereas minor complications occurred most commonly in saccular aneurysms. In patients with saccular aneurysms, clopidogrel responders had a lower complication rate than did clopidogrel nonresponders. The majority of dissecting aneurysms were treated in the immediate or acute phase following subarachnoid hemorrhage, a circumstance that contributed to the highest mortality rate in those aneurysms.

In the largest series till 2018, fusiform aneurysms were found to have the lowest occlusion rate and the highest frequency of major complications. Dissecting aneurysms, frequently treated in the setting of subarachnoid hemorrhage, occluded most often and had a low complication rate. Saccular aneurysms were associated with predominantly minor complications, particularly in clopidogrel nonresponders 3).


In 2015, a case series publication of Albuquerque et al. stated that patient selection is essential for safe and effective PED treatment of posterior circulation aneurysms. The PED is equally effective in achieving aneurysm obliteration with an acceptable risk profile as it is in the anterior circulation. Dolichoectatic aneurysms were not included in this treatment cohort. PED may be a preferable alternative to open surgical treatment of posterior circulation aneurysms 4).

References

1)

Liang F, Zhang Y, Yan P, Ma C, Liang S, Jiang C. Outcomes and complications after the use of the pipeline embolization device in the treatment of intracranial aneurysms of the posterior circulation: A systematic review and meta-analysis. World Neurosurg. 2019 Apr 5. pii: S1878-8750(19)30972-6. doi: 10.1016/j.wneu.2019.03.291. [Epub ahead of print] PubMed PMID: 30959253.
2)

Liang F, Zhang Y, Guo F, Zhang Y, Yan P, Liang S, Jiang Y, Jiang P, Jiang C. Use of Pipeline Embolization Device for Posterior Circulation Aneurysms: Single-Center Experiences with Comparison with Anterior Circulation Aneurysms. World Neurosurg. 2018 Apr;112:e683-e690. doi: 10.1016/j.wneu.2018.01.129. Epub 2018 Feb 2. PubMed PMID: 29410337.
3)

Griessenauer CJ, Ogilvy CS, Adeeb N, Dmytriw AA, Foreman PM, Shallwani H, Limbucci N, Mangiafico S, Kumar A, Michelozzi C, Krings T, Pereira VM, Matouk CC, Harrigan MR, Shakir HJ, Siddiqui AH, Levy EI, Renieri L, Marotta TR, Cognard C, Thomas AJ. Pipeline embolization of posterior circulation aneurysms: a multicenter study of 131 aneurysms. J Neurosurg. 2018 Apr 1:1-13. doi: 10.3171/2017.9.JNS171376. [Epub ahead of print] PubMed PMID: 29726768.
4)

Albuquerque FC, Park MS, Abla AA, Crowley RW, Ducruet AF, McDougall CG. A reappraisal of the Pipeline embolization device for the treatment of posterior circulation aneurysms. J Neurointerv Surg. 2015 Sep;7(9):641-5. doi: 10.1136/neurintsurg-2014-011340. Epub 2014 Aug 4. PubMed PMID: 25092926.
WhatsApp WhatsApp us
%d bloggers like this: