Clinical StudyAn efficacy analysis of posterior fossa decompression techniques in the treatment of Chiari malformation with associated syringomyelia
Introduction
Chiari malformation (CM) is a congenital disease that manifests as a narrow posterior cranial fossa and an obstruction of the foramen magnum. Approximately 50% to 70% of patients with CM present with associated syringomyelia (SM).[1], [2] CM with associated SM is a common congenital neurosurgical disease,3 which often presents in patients aged 20 years to 50 years and is slightly more prevalent in females than in males.
To date, no hypothesis has provided an entirely satisfactory explanation for the pathogenesis of CM with SM.4 The most widely accepted view is that a narrow posterior fossa and obstruction of the foramen magnum lead to this disease.[5], [6], [7], [8] Thus, the primary goal of treatment is the expansion of the posterior fossa volume to release the compression of the brain stem and spinal cord. This approach seeks to restore the normal cerebrospinal fluid (CSF) circulation, and to balance the pressure difference between the brain and the spine to prevent further neurological damage and to promote recovery.
Currently, the elements of the operative approaches for the treatment of CM with associated SM include the following: posterior fossa decompression (PFD);9 posterior fossa dural dilation duraplasty;10 resection of displaced cerebellar tonsils and dural suture;11 and resection of displaced cerebellar tonsils to free the original width of the central canal and dural suture. Although the surgical details of the above-described approaches differ, a crucial element in all approaches is determining the extent of decompression. However, there is no universal standard for determining the appropriate extent of PFD. Further, there is disagreement regarding the relative efficacy of extended decompression of the squama occipitalis and local decompression.[10], [12]
In this retrospective study, we recruited 132 patients with Chiari I malformation and SM who received surgical treatment at Daping Hospital (Third Affiliated Hospital of Third Military Medical University) from June 1997 to June 2008. The short-term and long-term efficacies of the two modes of PFD were evaluated.
Section snippets
Patient demographics and clinical signs
Of the 132 patients, 58 were male and 74 were female (male:female, 1:1.3); their ages ranged from 14 years to 62 years (average ± standard deviation [SD], 33 ± 13 years). The duration of disease ranged from 10 months to 12 years (average ± SD, 2.3 ± 1.2 years). The PFD with extended craniotomy plus dural repair (decompression size: 5 cm × 6 cm) was routinely performed in 69 patients from June 1997 to August 2002 (large craniotomy group), and PFD with local craniotomy plus dural repair (decompression size: 3 cm × 4
Results
According to Tator outcome scoring,13 patients with improved symptoms and physical signs were graded “excellent”; those with stable symptoms and signs were graded “good”; and those with worsening symptoms and signs were graded “poor.” Patients with excellent and good outcomes were classified as receiving effective treatment. All patients were available at follow-up. The follow-up time ranged from 6 months to 11 years (mean, 2.3 years).
Discussion
Posterior fossa reconstruction for the treatment of CM is the only surgical technique that achieves foramen magnum decompression,14 reconstruction of normal CSF circulation channels, and restoration of normal CSF circulation. PFD with dural reconstruction can expand the posterior fossa volume, thereby restoring normal cranial–spinal CSF circulation.15 For this reason, PFD has historically been the primary surgical technique for treating SM.16
The CSF circulation can be damaged by obstruction of
References (22)
The pathogenesis of syringomyelia associated with lesions at the foramen magnum: a critical review of existing theories and proposal of a new hypothesis
J Neurol Sci
(2004)- et al.
Posterior fossa morphometry in symptomatic pediatric and adult Chiari I malformation
J Clin Neurosci
(2009) - et al.
Possa decompression in syringomyelia associated with a Chiari malformation: a retrospective analysis of 22 patients
Clin Neurol Neurosurg
(2000) - et al.
Pain improvement in patients with syringomyelia and Chiari I malformation treated with suboccipital decompression and tonsillar coagulation
J Clin Neurosci
(2009) - et al.
Chiari malformations, syringohydromyelia and scoliosis
Neurosurg Clin N Am
(2007) Chiari I malformation with syringomyelia: evaluation of surgical therapy by magnetic resonance imaging
J Neurosurg
(1988)- et al.
Surgical treatment of “hindbrain related” syringomyelia: long-term results
Acta Neurochir
(1993) - et al.
Magnetic resonance imaging in the management of primary and secondary syringomyelic cavities and of other cystic lesions of the spinal cord
Acta Neurochir
(1988) - et al.
Malformations of the craniocervical junction (Chiari type I and syringomyelia: classification, diagnosis and treatment)
BMC Musculoskelet Disord
(2009) On the pathogenesis of syringomyelia: a review
J R Soc Med
(1980)
A unifying hypothesis for hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida
Cerebrospinal Fluid Res
Cited by (24)
Individualized surgical treatment of Chiari 1 malformation: A single-center experience
2023, Clinical Neurology and NeurosurgeryThe 270° Circumferential Microsurgical Decompression of the Foramen Magnum in Adult Chiari Malformation Type I: Single Surgeon Series of 130 Patients with Syringomyelia, Neurologic, and Headache Outcomes
2021, World NeurosurgeryCitation Excerpt :In addition, our study has a longer follow-up (approximately 6 months longer than the mean of other studies; Table 3) and is the only prospective study. Our study period was almost 2 times longer than the average length of other adult studies (15 vs. 8 years).1-33,37-72 The goal of our study was to precisely measure, radiologically and clinically, the surgical outcomes regarding resolution/improvement of syringomyelia, neurologic status, and preoperative headaches and to compare those outcomes with our reported systematic review of surgical outcomes of studies of CM-I in adults reported in 1963–2013 and included additional studies from 2014–2019.1
No significant difference between chiari malformation type 1.5 and type I
2017, Clinical Neurology and NeurosurgerySurgical outcomes after posterior fossa decompression with and without duraplasty in Chiari malformation-I
2014, Clinical Neurology and NeurosurgeryCitation Excerpt :The technique for decompression, however, varies based on the varied understanding of pathophysiology, surgeons’ preference and patient characteristics [10,16–23]. Several techniques that have been advocated for PFD includes bone decompression only; extradural lysis of sclerotic tissue and removal of the outer dural layer [17,24–26]; intradural extra-arachnoid durotomy with and without duraplasty; intra-arachnoid lysis of the scarring and adhesions around the herniated tonsil [10,12,27–31]; reduction of the herniated tonsil by coagulation or partial tonsillectomy [11,21,31]; as well as opening the foramen of magendie and obex plugging [9,32,33]. The intradural techniques are associated with increased risk of complications including wound infection, CSF leak, pseudomeningocele, meningitis and complication associated with dural graft [5,13,16,29,34–39].
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These authors contributed equally to this work.