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Case 2.11
Published in Monica Fawzy, Plastic Surgery Vivas for the FRCS(Plast), 2023
A Chiari 1 malformation occurs when the one or both cerebellar tonsils descend through the foramen magnum. Treatment should be considered if symptomatic or associated with a syringomyelia. In children with raised ICP due to cephalocranial disproportion, teams may often consider posterior vault expansion, and if this is not successful, then progress to a foramen magnum decompression.
Disorders of Circulation of the Cerebrospinal Fluid
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Chiari's type I malformation is downward herniation of the cerebellar tonsils with an estimated prevalence of 1 in 1000 persons. The cerebellar tonsil herniation is at least 3 mm bilaterally or 5 mm unilaterally with variable obstruction of the foramen magnum. In addition to downward displacement, the cerebellar tonsils may have a peg-like configuration. The fourth ventricle is usually normal in size and morphology. (Figure 20.13)
Revision suboccipital decompression for complex Chiari malformation
Published in Gregory D. Schroeder, Ali A. Baaj, Alexander R. Vaccaro, Revision Spine Surgery, 2019
Jacob L. Goldberg, Ibrahim Hussain, Ali A. Baaj, Jeffrey P. Greenfield
At this point, intradural exploration should commence. Any arachnoid adhesions should be sharply excised using microscissors or an arachnoid knife. In situations where the cerebellar tonsils have extreme inferior migration into the upper cervical canal, tonsillopexy can be performed. Bipolar cautery on the dorsal surface of the tonsil while protecting the medulla is used to retract this tissue without clinical consequence. A side-to-side inspection of the cerebellar hemispheres should be performed to continue resecting any arachnoid adhesions. Once complete, the cerebellar tonsils should be carefully dissected and spread at the midline, where one continues to cut adhesions as needed. It is important to visualize the fourth ventricle with the tonsils retracted. CSF pulsatile flow consistent with inspirations should be noted, which confirms adequate CSF flow in this region. Sometimes adhesions are not encountered until deep in this area approaching the fourth ventricle, so careful inspection needs to be performed, and if necessary, a web or veil of arachnoid covering the obex can be identified and lysed, often in cases with unresolved syringomyelia (Figure 10.5a–e). Once completed, thorough irrigation is performed and hemostasis achieved.
Posterior fossa morphometry in 170 South Asian children and adults with Chiari malformation and its correlation with tonsillar descent
Published in British Journal of Neurosurgery, 2022
Bijesh Ravindran Nair, Vedantam Rajshekhar
Chiari malformation type 1(CM1) is characterized by various morphometric abnormalities resulting from a smaller posterior cranial fossa (PCF) and overcrowding of the neural structures. Neurological dysfunction occurs due to inferior displacement of the cerebellar tonsils causing hindbrain compression and hydrosyringomyelia. It is hypothesised that CM1 is primarily a mesodermal developmental anomaly, based on experimental observations of vitamin A-induced occipital bone undergrowth and cerebellar displacement in rodents.1 Various morphometric studies have confirmed the occurrence of hypoplastic PCF and normally developed hindbrain structures in CM1.2–11 Basilar invagination (BI) is often associated with CM1, and is seen in 5–13.6% of CM1 patients.5,6,10 However, most morphometric studies do not compare the posterior fossa morphology in patients with and without BI.
Experience with revision craniovertebral decompression in adult patients with Chiari malformation type 1, with or without syringomyelia
Published in British Journal of Neurosurgery, 2022
Adikarige Silva, Gopiga Thanabalasundaram, Ben Wilkinson, Georgios Tsermoulas, Graham Flint
Under magnification, the cerebellar tonsils are routinely reduced with bipolar coagulation. If judged to be necessary, in order to open Magendie, the tonsillar residues are also hitched superiorly and laterally, using fine silk sutures (usually one each side), passing from the tonsillar pia to the adjacent, cut dural edge. The use of silk sutures in this setting is owing to surgeon preference although an alternative fine non-absorbable suture can also suffice. Any arachnoid adhesions or webs, such as are sometimes encountered underneath the tonsils, are divided. The overall aim of these manoeuvres is to create an artificial cisterna magna, into which the 4th ventricle opens directly and which itself communicates freely with the basal cisterns and spinal subarachnoid channels. Duraplasty is not performed. Nor is any cranioplasty attempted. Wound closure consists of apposition of nuchal muscles in two layers, followed by fascia, fat and skin.
The factors affecting the outcomes of conservative and surgical treatment of chiari i adult patients: a comparative retrospective study
Published in Neurological Research, 2022
Anas Abdallah, İrfan Çınar, Meliha Gündağ Papaker, Betül Güler Abdallah, Özden Erhan Sofuoğlu, Erhan Emel
Chiari malformation type I (CM1) is a herniation of the cerebellar tonsils 5 mm below the foramen magnum[1]. In the last two decades, the number of diagnosed patients with CM1 interestingly has increased related to the advent of MRI. CM1 patients have a variant spectrum [1,2]. The responses for surgical intervention are not the same in CM1 adult patients. The necessary conditions to obtain an acceptable outcome include the patient selection and timing of the surgical intervention. Several authors have reported that applying a posterior fossa decompression with a duraplasty (PFDD) is sufficient surgery [3–5]. Other authors supposed that posterior fossa decompression (PFD) without a duraplasty is adequate[6]. However, some studies reported a progression of the syrinx and presenting symptoms after PFD [3,7]. There are no standardized guidelines to manage mild or moderate symptomatic CM1 adult patients [3,4].