Surgical treatment of Chiari syrinx: goals and outcome assessment
The technical goals of surgery for Chiari malformation Type 1 (CM1) with syringomyelia are to reverse symptoms associated with tonsillar impaction, to eliminate the mechanism that causes syringomyelia and to arrest progression of neurological deficits. Surgery is considered 'successful' when there is evidence of resolution of the syrinx and its related symptoms. Technically, this occurs by eliminating the obstruction to free, pulsatile subarachnoid CSF flow at the craniovertebral junction: a goal that is achieved by any procedure that allows for an increase in the space at the foramen magnum. Radiologically, this technical 'success' is reflected as restoration of CSF pathways…
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Structural Integrity (DTI) and Functional Connectivity (Resting-State fMRI) in Chiari Malformation Type I: The Effects of Pain and Cognition
Background We report DTI and resting-state fMRI results on a sample of adults diagnosed with Chiari malformation Type I (CM1) and eligible for decompression surgery and 18 age- and education-matched controls. The goals of the present study were to test for group differences in structural integrity (DTI) and functional connectivity (resting-state fMRI), and to assess whether group differences were moderated by self-reported pain and cognitive effects. Methods We scanned 18 CM1 individuals and 18 age- and education-matched controls using a 3T Siemens scanner with Prisma software. All participants were also assessed on the McGill Pain Questionnaire-Short Form…
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The drainage of cerebrospinal fluid: new insights into lymphatic clearance pathways
Background Cerebrospinal fluid (CSF) is produced by choroid plexuses within the ventricles of the brain and circulates throughout the subarachnoid space surrounding the brain and spinal cord. From the subarachnoid space, CSF has long been considered to clear through arachnoid villi directly to venous sinuses within the dura mater meningeal lining of the central nervous system. However, evidence for lymphatic vessels draining at least some component of this fluid has been presented in studies dating back 150 years. The pathways through which the CSF can reach lymphatic vessels are currently an area of great controversy. The bulk of the literature…
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Mechanisms of syrinx formation in SAS pathology: Engineering and imaging studies
Subarachnoid space pathology, such as arachnoiditis, which can have many different causes, is associated with syringomyelia. This is widely assumed to occur because the SAS pathology obstructs cerebrospinal fluid flow around the spinal cord. The precise mechanisms by which this ocur remain enigmatic. Clinical and laboratory studies have confirmed the association between subarachnoid space pathology and fluid accumulation in the spinal cord, and both human imaging and computational modelling studies have been used to try to understand the mechanisms of this association. Imaging studies have measured CSF flow in the spinal canal in the presence of arachnoiditis, such as occurs…
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Comparison of Brain Morphology for Chiari I Malformation Subjects With and Without Ehlers-Danlos Syndrome
Background Many patients with Chiari malformation type I (CM) also have Ehlers-Danlos syndrome (EDS). EDS is characterized as a connective tissue disorder with patients diagnosed demonstrating joint hypermobility and recurrent joint dislocations. Our Chiari1000 database shows that 9.4% of the CM subjects also have EDS (CM+EDS). In addition, 26% score high (>4) on a hypermobility index (Beighton Scale). While there are differences between the biomechanical properties of connective tissue for people with CM+EDS and CM without EDS (CMEDS), it is unclear if this translates to differences between brain morphology for CM+EDS compared to CMEDS. Methods Midsagittal morphological characteristics of CM+EDS…
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Surgical goals in treating Chiari headache
Chiari I malformation headaches are triggered by alterations in intracranial hydrodynamics and compliance. Three types of CMI headaches have been described: suboccipital-headaches induced by Valsalva maneuvers (the most common), non-Valsalva related suboccipital-headaches, and non-suboccipital non-Valsalva induced headaches. The overarching goal in the surgical treatment of CMI is reduction of altered intracranial hydrodynamics and compliance by obtaining adequate expansion of the posterior craniocervical junction. Adequate relief of the anatomic obstruction generally results in good relief of Chiari headaches. Our approach to posterior craniocervical expansion is focused on the malformation’s “choke point.” In our patient population (14 years of age and older),…
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Management of Chiari Malformation in Children
By definition, Chiari Type 1 Malformation is considered the same entity in both children and adults. However, the distinct features present in children including their developing nervous system, blossoming verbal skills and ongoing skeletal growth present a unique situation compared to adults. This can culminate in a specific set of pathologic presentations isolated to children and should be taken into account during the operative and non operative management strategies used to treat this condition. Common examples include progressive scoliosis, abnormal cyring and feeding patterns and challenges in identifying mild neurologic deficits. Additionally, many chiari malformations are being identified incidentally during…
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Chiari, CSF flow, and upper cervical misalignment; observations from upright MRI studies
Background Impaired CSF flow may occur when the borders of the foramen magnum are impinged upon by low hanging or ectopic cerebellar tonsils and brainstem, effectively acting as a cork-stopper and potentially restricting normal flow of CSF between the 4th ventricle and central canal of the spinal cord, as well as the extraventricular CSF flow between the intradural cranium and spinal canal. Although a commonly used radiological definition for Chiari malformation Type I (CMI) is a 5mm descent of the tonsil below the foramen magnum, the threshold has not been validated in the context of CMI symptoms, CSF flow alteration,…
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Surgical treatment of spinal cord and rootlet tethering
Spinal cord and rootlet tethering to the surrounding dura by arachnoidal scarring from any cause will alter normal spinal cord and rootlet elasticity as well as CSF flow. Such change in dynamic can lead to a progressive myelopathy with presenting symptoms of progressive sensory, motor, and functional loss, spasticity, neuropathic pain, and autonomic dysfunction. Common causes of spinal arachnoidal scarring include trauma, hemorrhage, infection, chronic stenosis, and prior spinal cord surgery. Spinal cord and rootlet tethering can also lead to progressive spinal cord myelomalacia and cystic cavitation (syringomyelia), as a result of tensile injury to the neural elements and alteration…
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The causal role of spinal cord pulsation in the development of syringomyelia
Objective Current theories on the causes of syringomyelia have only one aspect in common, namely that syringomyelia results from cerebrospinal fluid (CSF) flow obstruction in all diseases associated with syringomyelia. Tethered cord syndrome is known to cause syringomyelia also in the absence of an obstruction to cranial-to-spinal CSF flow. We conducted this study to investigate this phenomenon in our patient population. We included not only patients with primary tethered cord syndrome but also patients with (posttraumatic or postoperative) secondary tethered cord syndrome although (or because) these patients have both CSF flow obstruction and tethered cord syndrome. Methods From 2003 to…
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