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.

Posterior fossa epidural hematoma in children

Posterior fossa epidural hematoma in children

Clinical features

Because of the non-specific symptoms and the potential for rapid and fatal deterioration of Posterior fossa epidural hematoma in children, an early computed tomography (CT) scanning is necessary for all suspicious cases.

In nine cases.The clinical picture was dominated by headache, vomiting, and gait ataxia. An occipital fracture was seen in 77.7% of the patients. In all cases, the diagnosis was made by computed tomography. 1).

Treatment

see Review and Management Guidelines 2).

Although some patients have been successfully treated with conservative approach, most studies support timely management of posterior fossa epidural hematoma by surgical intervention in children.

The absence of an occipital skull fracture or the presence of normal pulse rate and blood pressure should not influence the decision. Lumbar puncture is absolutely contraindicated 3).

Little evidence is available regarding the feasibility of using trephination mini-craniectomy for traumatic PFEDH in children 4).

Outcome

The overall prognosis normally is excellent 5) 6) 7).

Torrential venous bleeding can be a major problem due to rupture of the adjacent sinuses. Timely intervention is crucial for achieving good outcome, keeping in view a low threshold for surgical evacuation 8).

Case series

References

1) , 7)

Ciurea AV, Nuteanu L, Simionescu N, Georgescu S. Posterior fossa extradural hematomas in children: report of nine cases. Childs Nerv Syst. 1993 Jul;9(4):224-8. PubMed PMID: 8402704.
2)

Kaushik S, Sandip C. Posterior Fossa Acute Extradural Hematoma in Children: Review and Management Guidelines. J Pediatr Neurosci. 2018 Jul-Sep;13(3):289-293. doi: 10.4103/JPN.JPN_86_18. Review. PubMed PMID: 30271459; PubMed Central PMCID: PMC6144610.
3)

Arkins TJ, McLennan JE, Winston KR, Strand RD, Suzuki Y. Acute posterior fossa epidural hematomas in children. Am J Dis Child. 1977 Jun;131(6):690-2. PubMed PMID: 868823.
5)

Chaoguo Y, Xiu L, Liuxun H, Hansong S, Nu Z. Traumatic Posterior Fossa Epidural Hematomas in Children : Experience with 48 Cases and a Review of the Literature. J Korean Neurosurg Soc. 2019 Mar;62(2):225-231. doi: 10.3340/jkns.2016.0506.007. Epub 2019 Feb 27. PubMed PMID: 30840978.
6)

Sencer A, Aras Y, Akcakaya MO, Goker B, Kiris T, Canbolat AT. Posterior fossa epidural hematomas in children: clinical experience with 40 cases. J Neurosurg Pediatr. 2012 Feb;9(2):139-43. doi: 10.3171/2011.11.PEDS11177. PubMed PMID: 22295917.
8)

Prasad GL, Gupta DK, Sharma BS, Mahapatra AK. Traumatic Pediatric Posterior Fossa Extradural Hematomas: A Tertiary-Care Trauma Center Experience from India. Pediatr Neurosurg. 2015;50(5):250-6. doi: 10.1159/000438488. Epub 2015 Aug 20. PubMed PMID: 26287640.
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