Extradural decompression versus duraplasty in Chiari malformation type I with syrinx: outcomes on scoliosis from the Park-Reeves Syringomyelia Research Consortium

Abstract

OBJECTIVE Scoliosis is common in patients with Chiari malformation type I (CM-I)–associated syringomyelia. While it is known that treatment with posterior fossa decompression (PFD) may reduce the progression of scoliosis, it is unknown if decompression with duraplasty is superior to extradural decompression. METHODS A large multicenter retrospective and prospective registry of 1257 pediatric patients with CM-I (tonsils ≥ 5 mm below the foramen magnum) and syrinx (≥ 3 mm in axial width) was reviewed for patients with scoliosis who underwent PFD with or without duraplasty. RESULTS In total, 422 patients who underwent PFD had a clinical diagnosis of scoliosis. Of these patients, 346 underwent duraplasty, 51 received extradural decompression alone, and 25 were excluded because no data were available on the type of PFD. The mean clinical follow-up was 2.6 years. Overall, there was no difference in subsequent occurrence of fusion or proportion of patients with curve progression between those with and those without a duraplasty. However, after controlling for age, sex, preoperative curve magnitude, syrinx length, syrinx width, and holocord syrinx, extradural decompression was associated with curve progression > 10°, but not increased occurrence of fusion. Older age at PFD and larger preoperative curve magnitude were independently associated with subsequent occurrence of fusion. Greater syrinx reduction after PFD of either type was associated with decreased occurrence of fusion. CONCLUSIONS In patients with CM-I, syrinx, and scoliosis undergoing PFD, there was no difference in subsequent occurrence of surgical correction of scoliosis between those receiving a duraplasty and those with an extradural decompression. However, after controlling for preoperative factors including age, syrinx characteristics, and curve magnitude, patients treated with duraplasty were less likely to have curve progression than patients treated with extradural decompression. Further study is needed to evaluate the role of duraplasty in curve stabilization after PFD.

Reappraisal of intradural findings in Chiari malformation type I

“…At a minimum, bone-only decompression (PFD) is performed to enlarge the extradural cisterna magna, usually the myodural bridges (atlantooccipital membrane) are removed, and sometimes partial-thickness dural splitting is used for additional expansion. 3,7,14,18,22 Dural opening is an option that may be chosen for all patients with either Chiari (as our institution does), syringomyelia, or intraoperative ultrasound appearance after bony decompression. Dural opening procedures usually involve expansile duraplasty to further enlarge the intradural cisterna magna, 31 arachnoid resection, 32,35 tonsillar reduction (pial coagulation or subpial resection), 11,35 and exploration of the obex, FoM, and basolateral cisterns.…”

“…Decades of Chiari research have examined these techniques, and the findings suggest that dural opening in syringomyelia patients, as well as in some patients without syringomyelia, may be associated with fewer revision PFDD procedures and greater syrinx and symptom improvements. [3][4][5][6][7]9,12,[17][18][19][20][21][22]26,[32][33][34] The reported complication rates are low overall, but many report lower CSF-related complications in patients who undergo bone-only decompression or arachnoid-sparing dural opening techniques. 3,7,14,18,22 Some also report very low complication rates in dural opening and full intra-arachnoid microsurgical exploration procedures, as we do here.…”

“…[3][4][5][6][7]9,12,[17][18][19][20][21][22]26,[32][33][34] The reported complication rates are low overall, but many report lower CSF-related complications in patients who undergo bone-only decompression or arachnoid-sparing dural opening techniques. 3,7,14,18,22 Some also report very low complication rates in dural opening and full intra-arachnoid microsurgical exploration procedures, as we do here. 34 Nevertheless, practice patterns remain mixed, with many surgeons performing mostly dural opening procedures.…”

“…Definitive surgical management aims to functionally restore the cisterna magna and can be accomplished through either bone-only posterior fossa decompression (PFD) or PFD with duraplasty (PFDD). Although reported practices are mixed between bony decompression only versus bony decompression with dural opening and expansile duraplasty, 6,12,19,29 many case series and a recent trial 3,22,30,31 have demonstrated that PFD alone may not be enough for certain patients, particularly those with syringomyelia but also some without.…”

Dual Dural Patch Graft With AlloDerm and DuraGen Underlay for Duraplasty in Chiari Malformation Results in Significantly Decreased Cerebrospinal Fluid Leak Complications

“…Most recent studies have described outcome advantages with duraplasty, particularly in the presence of syringomyelia. [1][2][3][4][5][6] However, the same studies document a significantly higher risk of cerebrospinal fluid (CSF) complications with duraplasty, which can lead to reoperation and longer postoperative hospitalization. Persistent pseudomeningocele may also prevent or limit symptomatic improvement of patients with Chiari malformation.…”