Sequential Enlargement of Posterior Fossa After Duraplasty for Chiari Malformation Type 1

Duraplasty using a combination of a pedicled dural flap and collagen matrix in posterior fossa decompression for pediatric Chiari malformation type 1 with syrinx

PURPOSE

In posterior fossa decompression for pediatric Chiari malformation type 1 (CM-1), duraplasty methods using various dural substitutes have been reported to improve surgical outcomes and minimize postoperative complications. To obtain sufficient posterior fossa decompression without cerebrospinal fluid-related complications, we developed a novel duraplasty technique using a combination of a pedicled dural flap and collagen matrix. The objective of this study was to describe the operative nuances of duraplasty using a combination of a pedicled dural flap and collagen matrix in posterior fossa decompression for pediatric CM-1.

METHODS

We reviewed the clinical and radiographic records of 11 consecutive pediatric patients who underwent posterior fossa decompression with duraplasty using a combination of a pedicled dural flap and collagen matrix followed by expansile cranioplasty for CM-1. The largest area of the syrinx and the size of the posterior fossa were calculated.

RESULTS

The maximum syrinx area was reduced by a mean of 68.5% ± 27.3% from preoperatively to postoperatively. Four patients (36.4%) had near-complete syrinx resolution (> 90%, grade III reduction), five (45.5%) had 50% to 90% reduction (grade II), and two (18.2%) had < 50% reduction (grade I). The posterior fossa area in the midsagittal section increased by 8.9% from preoperatively to postoperatively. There were no postoperative complications, including cerebrospinal fluid leakage, pseudomeningocele formation, or infection.

CONCLUSION

Duraplasty using a combination of a pedicled dural flap and collagen matrix in posterior fossa decompression is a promising safe and effective surgical technique for pediatric CM-1 with syrinx.

Chiari Type 1 Malformation and Syringomyelia in Children: Classification and Treatment Options

Chiari type 1 malformation (CIM) is defined as tonsillar ectopia of >5 mm, while syringomyelia (SM) is defined as a cerebrospinal fluid (CSF)-filled cavity larger than 3 mm dissecting the spinal cord. Over the last decades, our understanding of these pathologies has grown; however, many controversies still exist almost in every aspect of CIM and SM, including etiology, indication for treatment, timing of treatment, surgical technique, follow-up regime, and outcome. This chapter provides a comprehensive overview on different aspects of CIM and SM and on the still existing controversies, based on the evidence presently available. Future directions for clinical research concerning CIM and SM treatment and outcome are elaborated and discussed as well.

Interlayer dural split technique for Chiari I malformation treatment in adult-Technical note

OBJECTIVE

To present an alternative surgical technique in treating cases of Chiari I Malformation with mild-to-moderate syringomyelia after decompressive suboccipital craniectomy: incising only the outer layer of the dura mater, then dissecting it from the inner layer without opening the latter.

PATIENTS AND METHODS

We utilized this technique in a short series of three cases who were admitted to our department for mild symptoms such as intermittent headache and dissociated sensory loss in the upper limbs, caused by a Chiari Malformation Type I. The patients were placed in the sitting position. We performed a reduced median suboccipital craniectomy and resection of the posterior arch of C1 adapted to the level of tonsil descent, from a limited superior half to complete resection. Afterward, we incised the outer dural layer, while sparing the inner one. Using a fine dissector, we then split apart the outer and inner layers to the margin of the craniectomy. Through the transparency of the inner layer and the arachnoid, the cerebellum and the medulla were visible and pulsating. An autologous fascia duraplasty was then performed.

RESULTS

The postoperative course was favorable in all cases, the patients being discharged without any deficits and with complete symptom resolution. Follow-up at 3, 6, and 12 months after surgery revealed a significant reduction in brainstem compression and syringomyelia.

CONCLUSIONS

Interlayer dural split technique can be used effectively in treating symptomatic cases of type I Chiari malformation in adults, with mild-to-moderate syringomyelia. It is less invasive than opening the dura and possibly more effective than decompressive craniectomy and C1 laminectomy alone. This technique must be validated in a larger case-control series.

Posterior Fossa Decompression and Duraplasty with and without Arachnoid Preservation for the Treatment of Adult Chiari Malformation Type 1: A Systematic Review and Meta-Analysis

BACKGROUND

The best surgical treatment for adult Chiari malformation type 1 remains widely debated.

OBJECTIVE

This study aimed to assess the efficacy of posterior fossa decompression and duraplasty with arachnoid preservation compared with arachnoid dissection for the treatment of adult Chiari malformation type 1.

METHODS

Two reviewers (M.O.-G. and M.A.) performed a PubMed, MEDLINE, and Embase literature search using the following terms: ("Chiari" OR "Chiari 1") AND ("duraplasty" OR "arachnoid preservation" OR "arachnoid spar∗" OR "posterior fossa surgery" OR "posterior fossa decompression" OR "foramen magnum decompression"). Studies assessing the efficacy of posterior fossa decompression with duraplasty for the treatment of patients aged >18 years with Chiari malformation type 1 were included. Case reports with <10 patients, editorials, and non-English studies were excluded.

RESULTS

Of 195 studies identified, 24 were included for meta-analysis. In the 1006 participants, there was no difference in postoperative clinical or radiologic improvement between the 2 techniques. Patients who underwent posterior fossa decompression with duraplasty and arachnoid dissection had a greater prevalence of total complications (0.20, 95% confidence interval [CI], 0.13-0.29 vs. 0.09, 95% CI, 0.05-0.14; Q = 6.47; P = 0.01) and cerebrospinal fluid-related complications (0.15, 95% CI, 0.10-0.22 vs. 0.05, 95% CI, 0.02-0.12; Q = 4.88; P = 0.03) compared with arachnoid preservation. Furthermore, the prevalence of reoperation in the arachnoid dissection group was 25 times greater than in the arachnoid preservation group (0.08, 95% CI, 0.06-0.10 vs. 0.003, 95% CI, 0.00-0.02; Q = 10.73; P > 0.001).

CONCLUSIONS

Posterior fossa decompression and duraplasty with arachnoid preservation is a beneficial technique to treat Chiari malformation type 1 and reduces the risk of complications, particularly cerebrospinal fluid-related complications and the rate of reoperation.

Type I Chiari Malformation Without Concomitant Bony Instability: Assessment of Different Surgical Procedures and Outcomes in 73 Patients

OBJECTIVE

Posterior fossa decompression is the treatment of choice in type 1 Chiari malformation (CM-1) without bony instability. Although surgical fixation has been recommended by a few authors recently, comparative studies to evaluate these treatment strategies using objective outcome tools are lacking.

METHODS

Seventy-three patients with pure CM-1 (posterior fossa bony decompression [PFBD], n = 21; posterior fossa bony and dural decompression [PFBDD], n = 40; and posterior fixation [PF], n = 12) underwent a postoperative outcome assessment using Chicago Chiari Outcome Score (CCOS). Logistic regression analysis detected predictors of an unfavorable outcome.

RESULTS

Minimally symptomatic patients generally underwent a PFBD while most of the clinically severe patients underwent a PFBDD (p = 0.049). The mean CCOS score at discharge was highest in the PF (12.0 ± 1.41) and lowest in PFBDD group (10.98 ± 1.73, p = 0.087). Patients with minimal preoperative clinical disease severity (adjusted odds ratio [AOR], 4.58; 95% confidence interval [CI], 1.29-16.31) and PFBDD (AOR, 7.56; 95% CI, 1.70-33.68) represented risks for an unfavorable short-term postoperative outcome. Though long-term outcomes (CCOS) did not differ among the 3 groups (p = 0.615), PFBD group showed the best long-term improvements (mean follow-up CCOS, 13.71 ± 0.95), PFBDD group improved to a comparable degree despite a poorer short-term outcome while PF had the lowest scores. Late deteriorations (n = 3, 4.1%) occurred in the PFBDD group.

CONCLUSION

Minimally symptomatic patients and PFBDD predict a poor short-term postoperative outcome. PFBD appears to be a durable procedure while PFBDD group is marred by complications and late deteriorations. PF does not provide any better results than posterior fossa decompression alone in the long run.

Additional Assessment of Developed Occipital Sinus Using Intraoperative Indocyanine Green Videoangiography for a Safe Foramen Magnum Decompression—Technical Case Report

BACKGROUND AND IMPORTANCE

Although foramen magnum decompression (FMD) with expansive duraplasty is a popular procedure for treating chiari malformation (CM), the common Y-shaped dural incision can lead to a life-threatening cerebral venous circulation disturbance in patients with a developed occipital sinus. Here, we describe the effectiveness of intraoperative indocyanine green video angiography (ICG-VA) for a CM type 1 (CM1) patient with a highly developed unilateral occipital sinus.

CLINICAL PRESENTATION

A 40-yr-old woman presented with sensory disturbance on the left side of the body. Magnetic resonance imaging (MRI) revealed cerebellar tonsil herniation into the foramen magnum with cervical syringomyelia, and computed tomography additionally revealed skull anomalies: fontanel closure insufficiencies, cranial dysraphism, thin cranial bone, and dentition abnormalities. We diagnosed as symptomatic CM1 with syringomyelia associated with cleidocranial dysplasia, which is a dominantly inherited autosomal bone disease. Cerebral angiography revealed a developed right occipital sinus and hypoplasia of the bilateral transverse sinus. We performed FMD, paying special attention to the developed occipital sinus using ICG-VA to ensure a safe duraplasty. The angiography clearly highlighted a right-sided occipital sinus with a high contrast ratio, and no left-sided occipital sinus was visible. After a dural incision in a unilateral curvilinear fashion was safely completed, expansive duraplasty was performed. The sensory disorders experienced by the patient disappeared postoperatively. Postoperative MRI revealed elevation of the cerebellar tonsil and decreasing of the syringomyelia.

CONCLUSION

Additional assessment using intraoperative ICG-VA provides useful information for a safe FMD, particularly in patients with complicated cerebral venous circulation anomalies.