1. Case Presentation Beth Burlage

2. History 75-year-old male Reports constant dizziness and imbalance Problems initially began after a serious auto accident in 1998 Immediately after the accident, the dizziness was present and over time became progressively worse Had a CT scan (imaging) and is scheduled for his first MRI following VNG 75-year-old male Reports constant dizziness and imbalance Problems initially began after a serious auto accident in 1998 Immediately after the accident, the dizziness was present and over time became progressively worse Had a CT scan (imaging) and is scheduled for his first MRI following VNG

3. Audiogram

4. VNG testing VNG - video nystagmography Records eye movements such as nystagmus - a type of eye movement characterized by alternating slow phase movements in one direction quick phases in the other direction. There are two types of nystagmus: Physiologic nystagmus- normal - slow phases are vestibulo-ocular reflex movements that stabilize vision during head movement, whereas the fast phases are re-setting movements. Pathologic nystagmus - abnormal-the slow phases may be due to a vestibular imbalance or due to failure in the eye position-holding mechanisms of the oculomotor system. “nystagmus production is a complex phenomenon that involves many neuronal centers and the changes in nystagmus characteristics are often of diagnostic value” Jacobsen, et. al. 2000 VNG - video nystagmography Records eye movements such as nystagmus - a type of eye movement characterized by alternating slow phase movements in one direction quick phases in the other direction. There are two types of nystagmus: Physiologic nystagmus- normal - slow phases are vestibulo-ocular reflex movements that stabilize vision during head movement, whereas the fast phases are re-setting movements. Pathologic nystagmus - abnormal-the slow phases may be due to a vestibular imbalance or due to failure in the eye position-holding mechanisms of the oculomotor system. “nystagmus production is a complex phenomenon that involves many neuronal centers and the changes in nystagmus characteristics are often of diagnostic value” Jacobsen, et. al. 2000

5. Pertinent Findings All eye-movement systems depend on the same cranial nerves and ocular muscles to effect the specific type of eye motion desired. The brain stem cranial nerve nuclei, cranial nerves, and extra-ocular muscles are the final common pathway for all eye movements Ocular motor tests include: Gaze, Saccades, tracking, OKN Gaze testing - this portion of the test is one of various test conditions that assesses the vestibulo-ocular function. The patient is asked to focus on a light (without moving his/her head). The light remains stable in either a horizontal or vertical position and then rebounds to a center position. All eye-movement systems depend on the same cranial nerves and ocular muscles to effect the specific type of eye motion desired. The brain stem cranial nerve nuclei, cranial nerves, and extra-ocular muscles are the final common pathway for all eye movements Ocular motor tests include: Gaze, Saccades, tracking, OKN Gaze testing - this portion of the test is one of various test conditions that assesses the vestibulo-ocular function. The patient is asked to focus on a light (without moving his/her head). The light remains stable in either a horizontal or vertical position and then rebounds to a center position.

6. Gaze Tracings

8. Right directed gaze shows right beating nystagmus, upon rebounding, the nystagmus is direction changing In the left directed condition, nystagmus is left beating and direction changing upon rebounding Bilateral horizontal gaze nystagmus Right directed gaze shows right beating nystagmus, upon rebounding, the nystagmus is direction changing In the left directed condition, nystagmus is left beating and direction changing upon rebounding Bilateral horizontal gaze nystagmus

9. Pertinent Findings, cont. Saccade - vestibulo-ocular assessment. The patient is asked to follow the light with their eyes without moving their head as it randomly moves across a vertical plane

10. Saccadic tracing

11. The saccades display direction changing nystagmus beating in the direction of the light’s movement (ex. When the light bounces towards the left, nystagmus is left-beating)

12. Pertinent findings, cont. Caloric stimulation- using air irrigation, the horizontal semi-circular canal is stimulated by temperature changes in the ear. Even those with normal vestibular function will present with nystagmus and sensations of dizziness during caloric testing Caloric stimulation- using air irrigation, the horizontal semi-circular canal is stimulated by temperature changes in the ear. Even those with normal vestibular function will present with nystagmus and sensations of dizziness during caloric testing

13. Normal findings show that upon fixating their eyes on an object (in this case, a small light inside of the video goggles), the patient will be able to suppress the nystagmus.

14. Caloric tracings

17. Upon fixation, the patient not only was unable to suppress, the nystagmus actually became stronger It is noted that failure to fixate bilaterally is an implication of brainstem or cerebellar disease Upon fixation, the patient not only was unable to suppress, the nystagmus actually became stronger It is noted that failure to fixate bilaterally is an implication of brainstem or cerebellar disease

18. Interpretation Results indicate a Central Nervous System (CNS) lesion CNS lesions can often be the result of drug intoxication, abnormal growths, or likely in this case, traumatic brain injury Results indicate a Central Nervous System (CNS) lesion CNS lesions can often be the result of drug intoxication, abnormal growths, or likely in this case, traumatic brain injury

19. Management Refer to Neurology for MRI After neurologic assessment and possible treatment, reassess central vestibular function Hearing loss - hearing aids? –VAMC policy is to provide hearing aid to those who express interest/need Refer to Neurology for MRI After neurologic assessment and possible treatment, reassess central vestibular function Hearing loss - hearing aids? –VAMC policy is to provide hearing aid to those who express interest/need