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World Neurosurgery May 2023To compare the measured odontoid tip violation above Chamberlain's line described in the literature to diagnose basilar invagination (BI) and to establish the normal... (Meta-Analysis)
Meta-Analysis
OBJECTIVE
To compare the measured odontoid tip violation above Chamberlain's line described in the literature to diagnose basilar invagination (BI) and to establish the normal placement of the dens tip defining individuals without BI (normal subjects).
METHODS
A systematic literature review was performed to identify clinical or radiological studies that expressed the amount of odontoid violation above Chamberlain's line in patients with a BI diagnosis. In addition, a meta-analysis was performed to evaluate normal subjects' values of Chamberlain's line violation (CLV).
RESULTS
There were 23 studies included (13 radiological and 10 clinical). Most studies used computed tomography and/or magnetic resonance imaging. Eight different cutoff values were used to measure dislocated odontoid apexes above Chamberlain's line regardless of the radiological modality. The mean measured amount of CLV was 3.95 mm (median 5 mm; range, 0-9 mm). The meta-analysis included 8 studies (1233 patients) with a normal sample population with a mean normal CLV of -0.63 mm (below the line) (95% confidence interval [-0.8, 1.18 mm], random effects model).
CONCLUSIONS
Different values were found in the assessed studies used for CLV in BI diagnosis. This variability is especially important for type B BI, as type A BI has other craniocervical diagnostic parameters. Considering the results obtained in this meta-analysis, BI should be diagnosed in the case of any dens violation >1.18 mm.
Topics: Humans; Platybasia; Radiography; Tomography, X-Ray Computed; Magnetic Resonance Imaging; Reference Values
PubMed: 36822399
DOI: 10.1016/j.wneu.2023.02.057 -
Revista Da Associacao Medica Brasileira... Mar 2020Symptomatic Chiari Type I Malformation (CM) is treated with posterior fossa decompression with or without duroplasty. We have noticed some cases with concomitant severe...
BACKGROUND
Symptomatic Chiari Type I Malformation (CM) is treated with posterior fossa decompression with or without duroplasty. We have noticed some cases with concomitant severe cerebellar ataxia due to cerebellar atrophy. The aim of this study is to review the literature of CM associated with severe cerebellar atrophy and discuss its potential physiopathology.
METHODS
A systematic literature review in the Pubmed Database was performed using the following key-terms: "cerebellar atrophy Chiari", and "cerebellar degeneration Chiari". Articles reporting the presence of cerebellar degeneration/atrophy associated with CM were included.
RESULTS
We found only six studies directly discussing the association of cerebellar atrophy with CM, with a total of seven cases. We added one case of our own practice for additional discussion. Only speculative causes were described to justify cerebellar atrophy. The potential causes of cerebellar atrophy were diffuse cerebellar ischemia from chronic compression of small vessels (the most mentioned speculative cause), chronic raised intracranial pressure due to CSF block, chronic venous hypertension, and association with platybasia with ventral compression of the brainstem resulting in injury of the inferior olivary nuclei leading to mutual trophic effects in the cerebellum. Additionally, it is not impossible to rule out a degenerative cause for cerebellar atrophy without a causative reason.
CONCLUSIONS
Severe cerebellar atrophy is found in some patients with CM. Although chronic ischemia due to compression is the most presumed cause, other etiologies were proposed. The real reasons for cerebellar degeneration are not known. Further studies are necessary.
Topics: Arnold-Chiari Malformation; Atrophy; Cerebellar Diseases; Cerebellum; Decompression, Surgical; Female; Humans; Magnetic Resonance Imaging; Male
PubMed: 32520161
DOI: 10.1590/1806-9282.66.3.375 -
World Neurosurgery Jun 2020Chiari malformation (CM) is defined as a herniation of cerebellar tonsils below the foramen magnum and is considered to be due to underdevelopment of posterior fossa... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Chiari malformation (CM) is defined as a herniation of cerebellar tonsils below the foramen magnum and is considered to be due to underdevelopment of posterior fossa (PF) bone components. There is overcrowding of neural structures, and normal cerebrospinal fluid circulation is frequently blocked. Although several publications exist of measurements of dimensions and volumes from bone components of PF in CM, there is no systematic review evaluating quantitatively these dimensions. The aim of this study was to evaluate PF dimensions and volumes in a meta-analysis.
METHODS
An electronic search using PubMed and Google Scholar was done. Study eligibility criteria were defined by the PICO strategy, which selected patients and interventions. Studies comparing PF dimensions between patients with CM and normal subjects were selected. A meta-analysis of pooled data was done using statistical software.
RESULTS
Data for pooled analysis were obtained from 12 studies. Data synthesis was based on small published sample sizes in the majority of studies. Key findings included smaller measurements of clivus, supraoccipital bone, and PF area dimensions in patients with CM compared with normal subjects. Brainstem and cerebellar length was not different between groups.
CONCLUSIONS
This review provides evidence of smaller measurements of clivus, supraoccipital bone, and PF area dimensions in patients with CM compared with normal subjects. An implication of the key findings is that surgical treatment of CMs should consider the smaller dimensions of PF in planning.
Topics: Arnold-Chiari Malformation; Case-Control Studies; Cephalometry; Cranial Fossa, Posterior; Humans; Magnetic Resonance Imaging; Occipital Bone; Organ Size; Platybasia; Reference Values; Tomography, X-Ray Computed
PubMed: 32156591
DOI: 10.1016/j.wneu.2020.02.182