Accepted
at 5:11 a.m. Sep, 18, 2025
by
yelbardisi
Author:
yelbardisi
Type of change:
Updated content
Rationale for change
The info in extra is wrong - truncal ataxia is not a wide-based gait, that's gait ataxia.
Added the correct description of truncal ataxia and how it compares to gait ataxia
Source: AMBOSS - https://next.amboss.com/us/article/BR0z6f?utm_source=navbar&utm_medium=anki&utm_campaign=anki&utm_term=truncal%2Bataxia&guid=G%253D_rnNcGG%255D&aid=79f7d232-7b36-4395-b059-e1ee1e13b104&uid=ehl1x19S0#Zdf4673a509a7d64a07dcbd82fd149d01
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Lesions of the {{c2::posterior}} cerebellar vermis usually result from medulloblastomas or ependymomas and present with {{c1::truncal}} ataxia
Lecture Notes
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Missed Questions
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Pathoma
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Boards and Beyond
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First Aid
Sketchy
Watch Pediatric CNS Tumors
Sketchy 2
Watch Pediatric CNS Tumors
Watch Pediatric CNS Tumors
Sketchy Extra
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Picmonic
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Pixorize
Review Ependymoma
Review Ependymoma
Physeo
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Bootcamp
Watch associated Bootcamp video - Cerebellum and Ventricles: Sensory vs Cerebellar Ataxia
Watch associated Bootcamp video - Pediatric Brain Tumors: Medulloblastoma
Watch associated Bootcamp video - Pediatric Brain Tumors: Medulloblastoma
OME
Additional Resources
Atlas: 
Medulloblastoma
T2-weighted cranial MRI (axial view) of a 7-year-old boy: isodense round lesion with hyperintense sections in the fourth ventricle (green overlay); grossly diminished gyration of the cerebellum (C). (P = poorly demarcated pons region; B = basilar artery, CS = external CSF space)
Medulloblastoma
T1-weighted cranial MRI of a 6-year-old child presenting with features of increased intracranial pressure (midsagittal section with contrast)
There is a large hypointense mass occupying the third (upper yellow overlay) and fourth (lower yellow overlay) ventricles that is causing obstructive hydrocephalus (pink overlay).The pink overlay also highlights the leakage of CSF into the periventricular space (transependymal edema) and into the occipital lobe due to the increased intraventricular pressure.
This appearance of a fourth ventricular mass in a child is characteristic of medulloblastoma.
Medulloblastoma
Cranial MRI (T1-weighted, with contrast)
There is a mass in the posterior cranial fossa. It features solid parts (green overlay) and cystic parts (red overlay).
Location and appearance are typical of a medulloblastoma.(D: diencephalon; P: pons; C: cerebellum; yellow outline: cerebellar tentorium)
Medulloblastoma
Photomicrograph of cerebellar vermis tissue (H&E stain)
Densely packed, small, blue anaplastic cells are present throughout the specimen. The cells have pleomorphic and hyperchromatic nuclei.On the right, a vessel (its lumen mostly obstructed by eosinophilic material) can be seen.
These are typical histopathological findings of medulloblastoma.
Medulloblastoma
Photomicrograph of cerebellar vermis tissue (H&E stain)
Numerous small, blue, round cells with scant cytoplasm can be seen throughout the specimen (classic examples: arrows, green overlay). Their nuclei vary in size and structure (nuclear pleomorphism) and many cells feature distinctly hyperchromatic nuclei.The majority of the cells are arranged in concentric clusters around lighter central areas consisting of neuropil (examples: dashed outlines and yellow overlay, magnified area). These clusters are referred to as Homer Wright rosettes.
These histopathological features, particularly the Homer Wright rosettes, are characteristic of a medulloblastoma.
One by one
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