A patient develops intention tremor, dysmetria, and dysdiadochokinesia following a cerebellar stroke. Which cerebellar output nucleus is most likely damaged?

Explanation

## Cerebellar Output Pathways and Clinical Correlation ### Cerebellar Deep Nuclei Organization | Nucleus | Input From | Output Target | Function | |---------|-----------|----------------|----------| | **Dentate** | Cerebellar hemispheres | VL thalamus → motor cortex | Fine voluntary movement coordination | | **Interposed (Globose + Emboliform)** | Intermediate zone | Red nucleus → spinal cord | Limb movement control, intermediate precision | | **Fastigial** | Vermis | Brainstem reticular nuclei, vestibular nuclei | Postural control, balance, proximal muscles | | **Vestibular** | Flocculonodular lobe | Vestibular nuclei directly | Eye movements, equilibrium | ### Key Point: **The dentate nucleus receives input from the cerebellar hemispheres and projects to the motor cortex via the ventral lateral (VL) thalamus.** This pathway is essential for the planning and coordination of voluntary, skilled movements. ### High-Yield: Dentate nucleus lesions produce **contralateral** motor deficits (intention tremor, dysmetria, dysdiadochokinesia) because of the double decussation of cerebellar pathways — the superior cerebellar peduncle decussates at the midbrain level, and pyramidal tract fibers decussate in the medulla. ### Mnemonic: **DIME** — Dentate nucleus → Intention tremor, dysMetria, dysdiadochokinEsia (fine motor signs) ### Clinical Pearl: Intention tremor and dysmetria are hallmark signs of cerebellar hemisphere dysfunction, specifically implicating the dentate nucleus output. These signs worsen as the patient approaches the target (intention tremor increases near the goal).