Neurooncology Flashcards
Types of Gliomas
Astrocytoma
Oligodendroglioma
Oligoastrocytoma
Ependymoma
WHO Grades of malignany
WHO Grade 1 Pilocytic Astrocytoma (children) WHO Grade 2 Low-grade Glioma WHO Grade 3 Anaplastic Glioma WHO Grade 4 Glioblastoma multiforme
Why is a Glioblastoma called ‘multiform’?
Different parts of of the tumor looks different (necrosis, bleeding)
When do people get Glioblastomas?
In their 60’s
What are the established methods of treatment?
surgery, radiotherapy and chemotherapy
What types of treatments are currently being tested?
TT fields and immunotherapies
What is the best treatment for brain tumors?
Surgery
By how much does adjuvant Radiotherapy increase life expectancy?
6 months (from 5 to 11)
By how much does Chemotherapy with temozolomide increase life expectancy?
2 months (from 12 to 14)
What’s the biggest issue with glioblastomas?
They come back and infiltrate healthy tissue
What charatherizes a low grade glioma?
It’s a continuously growing lesion
How much does a low grade glioma grow per year?
3-4 mm in diameter per year
low grade gliomas are usually present in?
Eloquent areas of the brain (area for speech)
What is typically the first symptom of a low grade glioma?
Seizures
What is best: taking a biopsy of the tumor or resection?
Resection
How do we diagnose tumors?
MRI, MR Proton Spectroscopy, PET
What is MR proton spectroscopy?
MR proton spectroscopy gives us the concentrations of important substances
What substances are present in the brain for malignant tumors?
Laktate and Lipids. Additionally, the decrease of N-acetyl-asparate & Cholin with an increase in Creatine is a sign of malignant tumor growth.
What tracer do we use for PET and why?
Fluor-Ethyltyrosin - it is taken up by the part of the tumor with the highest level of metabolism while also showing the difference between tumor and radiation-affected tissue
What is the trade-off when it comes to surgery?
Removing a lot of tissue leads to longer survival time, but removing a lot of tissue can also affect functionality, which decreases quality of life
What happens to brain functions during tumor growth?
As tissue dies, functions are relocated (brain plasticity)
What functional domains should we be careful about when operating?
sensorimotor function
language function
visiuo-spatial function
socio-cognitive function
Which fascicle connects brocas and Wernickes area?
The arcuate fascicle
What’s the problem with the classical Brocas-Wernickes model?
lesions studied were often much larger than those of the specific region studied and there might have been functional reorganization between damage and meeting the researchers
Association fibers constitute which 2 streams?
Meaning: semantic ventral pathway
Naming: phonological dorsal pathway
The phonological dorsal pathway includes which fascicles?
Dorsal ILF (inferior lateral fascicle - connecting V1 an posterior parietal) Arcuate fascicle (connects the posterior parietal to the pars opercularis) SLF (superior lateral fascicle - projects from the object recognition center in the posterior temporal to the supramarginal gyrus and premotor areas)
Phonemic Paraphasia is caused by?
Damage to the Arcuate fascicle in the phonological dorsal pathway
The semantic ventral pathway includes which fascicles?
IFOF (inferior fronto-occipital fascicle - from the V1 to the pars orbitaris (longest fascicle)) Ventral ILF (inferior longitudinal fascicle - connects the posterior temporal to the temporal pole) The uncinate fascicle (from the temporal pole to the pars orbitaris)
Semantic paraphasia is caused by?
Damage to the IFOF
Sort the following fascicles from superior to inferior:
IFOF, ILF, SLF, SFOF
SFOF, SLF, IFOF, ILF
The longest fascicle?
IFOF (inferior fronto-occipital fascicle)
Preoperative diagnostics
Neuropsychological assessment
fMRI
Navigated transcranial magnetic stimulation
MR diffusion tensor imaging based tractography
What does the preoperative neuropsychological assessment look at?
Preoperative: affection of language attentional deficits deficits in visuospatial cognition deficits in social cognition
What does fMRI measure?
The BOLD signal
Issues with fMRI
Artifacts near tumors, depends on statistics for border of the signal
Navigated repetitive transcranial magnetic stimulation
TMS on areas we can find based on our MRI scan - locating the important functional aras so we don’t remove them during surgery
The principles of DTI
Water molecules will follow the tracts, which we can measure with MR. Our fractional anisotropy (FA) becomes a number for wether a voxel is a part of a tract or not (degree of directionality). An algorithm can track the fibers from one region to another.
Problems with DTI
It’s purely anatomic, is prone to false negatives when 2 tracts come close to each other and whether we’re in an a voxel with a tract of not is depended on algorithm specifications
Intraoperative safety strategies
Electrophysiological monitoring and mapping (cortex stimulation and mapping of the results)
Sending light into the patients eyes to have visual evoked potentials
Awake mapping for language functions
When is the patient awake during surgery?
From post-craniotomy to after tumor is removed
What’s the most important awake-task?
Picture naming task. We can test for Dysarthria, Speech arrest, Anomia.
What’s the 2nd most important awake-task?
Pyramid and palm tree test
What’s the pyramid and palm tree test?
1 top image is presented and the patient has to choose from 2 bottom pictures which matches the semantic context of the first image
What’s the 3rd most important awake-task?
Visual field test: you have to name objects in your peripheral vision
In what localization of the brain are there indications for performing awake surgery?
Classically left temporal, frontal or insular lesions
Phonological disorders induced by right-hemisphere stimulation
Occipital lesions to preserve visual field, reading ability and semantic dysfunction (IFOF, ILF)
Parietal lesion to preserve space orientation and phonologic dysfunction (SLF)
Which tumor types benefit from awake surgery?
Greatest effect in low-grade glioma
Enhances safety and resection result in glioblastoma multiforme
Metastases
cavernomas in eloquent regions
Who can’t have an awake surgery?
Age: over 60 years Large mass effect with significant midline shift High vascularization Severe aphasia Psychological instability
Intraoperative neuronavigation
We have a pointer to show us where in our pre-operative MRI image we are
Is navigated tractography a good idea for surgery?
Yes, the more modern version gives probabilities of being in the tracts, which has shown to increase safety of the procedure
Drawbacks of navigated tractography
The fractional anisotropy (FA) decreases unintentionally when the fibers cross or “kiss”. Similar issue with perifocal edema
How can we improve navigated tractography?
By using probabilistic DTI with continuous ultrasound images to overlay on the MRI
Why is continuous navigated ultrasound smart?
It allows us to track the brain shift that happens when we open the cranium
