Open and stereotactic transfrontal or transcerebellar approaches have been used to biopsy brainstem lesions.
Method In this report, a stereotactic posterior and midline approach to the distal medulla oblongata under microscopic view is described. The potential advantages and limitations are discussed, especially bilateral damage of the X nerve nuclei.
Conclusion This approach should be considered for biopsy of distal and posterior lesions. We strongly recommend the use of direct microscopic view to identify the medullary vessels, confirm the midline entry point, and avoid potential shift of the medulla. Further experience is needed to confirm safety and success rate of this approach.
Chiari 1 malformation is diagnosed if the cerebellar tonsils extend at least 5 mm below the opisthion-basion line.
Objective To examine the correlation of the extent of tonsillar ectopia with the prevalence and severity of the symptoms associated with the Chiari malformation.
Methods Patients (N = 428) were grouped according to the extent of tonsillar ectopia on the mid-sagittal MRI image (group 1, 0–< 3 mm; group 2, 3–5 mm; group 3, > 5 mm). Groups were compared regarding demographics, symptoms, neurological signs, pain score, and response to HADS and sf-36 questionnaires.
Results were analyzed using one-way ANOVA, chi-square, and two sample Z test, and Student’s t test for pairwise comparison, (statistical significance p < 0.05). A logistic regression analysis was performed to determine the relationship between tonsillar ectopia and the probability of a patient reporting any particular symptom. Results There were 97,148 and 183 patients in groups 1, 2, and 3 respectively. Groups did not differ with regard to antecedent trauma or female preponderance. Patients in group 1 were more symptomatic than those in groups 2 and 3 with regard to some symptoms, (p = 0.04–p = 0.000). Regression analysis confirmed an inverse relationship between the extent of tonsillar ectopia and the likelihood of many symptoms. The pain score was greatest in group 1, (p = 0.006). Prevalence of objective signs of myelopathy did not differ between groups except for Hoffmann sign which was more prevalent in group 1, (p = 0.034). HADS and sf-36 scores did not differ between groups.
Conclusion The severity of the symptoms associated with the Chiari malformation does not correlate directly with the extent of tonsillar ectopia. The extent of tonsillar ectopia should be re-evaluated as the threshold for diagnosis of Chiari 1 malformation.
Chiari 1 malformation is diagnosed if the cerebellar tonsils extend at least 5 mm below the opisthion-basion line. Objective To examine the correlation of the extent of tonsillar ectopia with the prevalence and severity of the symptoms associated with the Chiari malformation.
Methods Patients (N = 428) were grouped according to the extent of tonsillar ectopia on the mid-sagittal MRI image (group 1, 0–< 3 mm; group 2, 3–5 mm; group 3, > 5 mm). Groups were compared regarding demographics, symptoms, neurological signs, pain score, and response to HADS and sf-36 questionnaires. Results were analyzed using one-way ANOVA, chi-square, and two sample Z test, and Student’s t test for pairwise comparison, (statistical significance p < 0.05). A logistic regression analysis was performed to determine the relationship between tonsillar ectopia and the probability of a patient reporting any particular symptom.
Results There were 97,148 and 183 patients in groups 1, 2, and 3 respectively. Groups did not differ with regard to antecedent trauma or female preponderance. Patients in group 1 were more symptomatic than those in groups 2 and 3 with regard to some symptoms, (p = 0.04–p = 0.000). Regression analysis confirmed an inverse relationship between the extent of tonsillar ectopia and the likelihood of many symptoms. The pain score was greatest in group 1, (p = 0.006). Prevalence of objective signs of myelopathy did not differ between groups except for Hoffmann sign which was more prevalent in group 1, (p = 0.034). HADS and sf-36 scores did not differ between groups.
Conclusion The severity of the symptoms associated with the Chiari malformation does not correlate directly with the extent of tonsillar ectopia. The extent of tonsillar ectopia should be re-evaluated as the threshold for diagnosis of Chiari 1 malformation.
The purpose of this paper is to assess the value of 7 Tesla (7 T) MRI for the depiction of brain stem and cranial nerve (CN) anatomy.
Methods Six volunteers were examined at 7 T using highresolution SWI, MPRAGE, MP2RAGE, 3D SPACE T2, T2, and PD images to establish scanning parameters targeted at optimizing spatial resolution. Direct comparisons between 3 and 7 T were performed in two additional subjects using the finalized sequences (3 T: T2, PD, MPRAGE, SWAN; 7 T: 3D T2,MPRAGE, SWI, MP2RAGE). Artifacts and the depiction of structures were evaluated by two neuroradiologists using a standardized score sheet.
Results Sequences could be established for high-resolution 7 T imaging even in caudal cranial areas. High in-plane resolution T2, PD, and SWI images provided depiction of inner brain stem structures such as pons fibers, raphe, reticular formation, nerve roots, and periaqueductal gray. MPRAGE and MP2RAGE provided clear depiction of the CNs. 3D T2 images improved depiction of inner brain structure in comparison to T2 images at 3 T. Although the 7-T SWI sequence provided improved contrast to some inner structures, extended areas were influenced by artifacts due to image disturbances from susceptibility differences.
Conclusions Seven-tesla imaging of basal brain areas is feasible and might have significant impact on detection and diagnosis in patients with specific diseases, e.g., trigeminal pain related to affection of the nerve root. Some inner brain stem structures can be depicted at 3 T, but certain sequences at 7 T, in particular 3D SPACE T2, are superior in producing anatomical in vivo images of deep brain stem structures.
Acta Neurochir (2010) 152:827–834. DOI 10.1007/s00701-009-0591-z
From a surgical perspective, tentorial fold (TF) meningiomas (TFM) are a unique entity of tumors. They involve the supra- and infratentorial space and often are in close contact to the cavernous sinus, cranial nerves, and the mesencephalon. Complete resection is challenging and can be hazardous. We present our experience with this rare tumor entity and demonstrate the surgical outcome related to a topographical classification.
Methods A retrospective analysis on 21 consecutive patients (female/male ratio 17/4) with meningiomas originating from the TF, who underwent surgery between 1992 and 2005 in our clinic, was performed. The follow-up period ranged from 6 to 93 months. The cases were classified according to tumor extension in three different types: type I, TF meningiomas with compression of the brain stem; type II, with extension into the anterior portion of middle fossa; and type III, a combination of type I and II. Depending on tumor location, surgical approaches consisted of pterional (nine cases), subtemporal (nine cases), or combined subtemporal–pterional craniotomies (three cases). We defined transient and persistent operative complications in relation to Simpson grade and TF classification.
Results Tumor size ranged from 1 to 6 cm in diameter, with a median at 2.5 cm. The presenting symptoms of the patients were anisocoria (six cases), diplopia (six cases), ptosis (five cases), hemianopia (four cases), and ataxia (two cases). Extent of tumor resection was Simpson grade II in 19 patients, grade III in one patient, and grade IV in one patient. There was no operative mortality (first 30 days after surgery). The rate of postoperative transient new neurological deficits was found at 9.5%, the rate of permanent at 33%. The neurological deficits at admission recovered in two patients.
Conclusion In the majority of patients with TF meningiomas, total resection can be achieved through a pterional, subtemporal, or combined approaches but at a substantial toll in terms of permanent morbidity. Radiotherapy after volume reductive surgery in TFM type II and III and decompression of eloquent anatomical structures with low tolerance of radiation should be considered.
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