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Saccades, Pursuit and OKN: Review Overview of Tests Theseones indicates Central Lesion Yp - Saccades: Rapid eye movements between fixed points - S...

Saccades, Pursuit and OKN: Review Overview of Tests Theseones indicates Central Lesion Yp - Saccades: Rapid eye movements between fixed points - Smooth Pursuit: Following a moving target - Optokinetic Nystagmus (OKN): Response to moving visual patterns Saccade Testing Key Parameters are: Velocity: Peak movement speed between targets (+ de 400 o 350) - Normal: >400 degrees/sec for large amplitudes - Normal: >200 degrees/sec for small amplitudes Accuracy: Distance moved relative to target distance (+ de 75) - Hypometria: 120% accuracy (overshoot) Latency: Reaction time to target movement (- de 200, 250) - Normal: 30% ha - Can be due to gain asymmetry (true directional preponderance, peripheral or central lesion) or baseline shift (baseline shift: when there is spontaneous nystagmus present, peripheral or central lesion) - Non-localizing finding  - Often associated with BPPV, Meniere's disease, or migrainous vertigo Clinical Significance: ‣ Peripheral: ◦Lesion in labyrinth or vestibular nerve ◦Will typically show a UW in the opposite ear DP ‣ Central: ◦Asymmetry in the horizontal VOR pathways. ◦LEsion in vestibular nuclei or CNS. Solo para saber que, en gain symmetry definición es: between neurons in the medial vestibular nucleus on either side, caused either by increased sensitivity on one side or by reduced sensitivity on the other, perhaps as an adaptive change in response to abnormal input. “Halmagyi, et al. 2000” Fórmulaestablece cuánto 4. Fixation Index aptifó - Abnormal if >60% NQfjffffffff.fi - Indicates central lesions involving parietal-occipital cortex, pons, or cerebellum -If nystagmus was suppressed completely, the FI will be 0%. If its greater than 100%, it means fixation increased the nystagmus. 5. Hyperactive Response - Total (R/L or both) response >140 deg/sec  - Rare finding (typically due to perforated TM or altered mastoid). - True hyperactive calorics usually indicates central lesions due to VOR inhibitory function at the vestibular nuclei or technical factors. Special Considerations: - Ice calorics used when traditional responses are