Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Case Presentation Beth Burlage 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 Audiogram 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 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. Gaze Tracings • 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 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 Saccadic tracing • 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) 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 • 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. Caloric tracings • 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 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 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