2. NEOPLASMS - TUMOR OF THE CEREBELLAR VERMIS
A Sample Case: A 6 year old was brought to the doctor because she was clumsy in walking and would sway and even topple over when seated. She also complained of nausea. Up to that point in time her growth and development was normal.
The neurological exam showed that she was alert and oriented with no signs of mental disturbance. There was papilledema. On attempting directed lateral gaze to either side the eyes showed horizontal oscillating movements. Cranial nerves were normal; motor strength and reflexes were normal as were all sensory systems.
When standing she was very unstable and would tumble to the left or right side. When seated she had trouble maintaining he head and torso in a stable vertical posture but if supported her finger-to-nose and heel-to-shin tests were nearly normal. When walking her gait was broad-based.
Mental status was normal and the cerebral hemispheres are intact. Cranial nerves are not involved and the sensory and motor systems are largely normal except for the truncal ataxia. The incoordinate movements in standing and sitting, walking, nystagmoid eye movements, are indicative of incoordination of the muscles of the trunk, i.e., truncal ataxia, which is controlled principally by the cerebellar vermis; lack of significant limb involvement suggests that the cerebellar hemispheres are not involved.
The headaches, long duration, and slow progression suggests a neoplasm rather than a vascular problem. Medulloblastoma is a common childhood malignancy which arises rapidly from the midline cerebellum to impact on the cerebellum, fills the 4th ventricle, and later affects the pons/medulla.