ODOQuiz - One Day One Question

Quiz.no 14 -12 September 2025

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1. What is the radiological (MRI) abnormality

Tonsillar herniation is where the cerebellar tonsils descend through the foramen magnum into the spinal canal. This can compress the brainstem, potentially leading to various neurological symptoms.

2. Name the type of ……. observed here

Arnold Chiari type 1: Least severe and often found incidentally, characterized by one or both pointed (not rounded) cerebellar tonsils that project 5 mm below the foramen magnum.

3. Describe the other types

Other types: Chiari II - brainstem herniation and open distal spinal dysraphism/myelomeningocele.
Chiari III involves herniation of the hindbrain (cerebellum with or without the brainstem) into a low occipital or high cervical meningoencephalocele.

4. Describe the two most common – location, structures affected, clinical presentation, etiology) ?

i) Uncal and tonsillar herniation are both types of brain herniation, but they involve different structures and locations. The uncus is the most medial part of the temporal lobe. The cerebellar tonsil, is a rounded lobule located on the inferior surface of each cerebellar hemisphere
ii) Uncal herniation, also known as transtentorial herniation, occurs when the medial temporal lobe herniates through the tentorial notch, compressing the brainstem, including the oculomotor nerve, and disrupting consciousness and pupillary function (Unequal pupils)
iii) Tonsillar herniation, on the other hand, involves the descent of the cerebellar tonsils through the foramen magnum, compressing the medulla and potentially the upper cervical spinal cord