nystagmus

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nystagmus

  1. 1. Nystagmus <ul><li>a rythmic oscillation of the eyes. It has many different patterns, and may arise in 3 situations </li></ul><ul><ul><li>Physiologically </li></ul></ul><ul><ul><li>Sensory Deprivation </li></ul></ul><ul><ul><li>Motor Imbalance </li></ul></ul>
  2. 2. Classification <ul><li>Nystagmus can be either: </li></ul><ul><ul><li>Jerk - fast one direction, slow the other </li></ul></ul><ul><ul><li>Pendular - equal velocity in both directions </li></ul></ul><ul><ul><li>Mixed - of above </li></ul></ul><ul><li>And can be </li></ul><ul><li>Horizontal/Vertical/Oblique or Rotary </li></ul><ul><li>In overwhelming majority of cases both eyes move in a co-ordinated manner </li></ul>
  3. 3. Classification Pendular jerk
  4. 4. Physiological Nystagmus <ul><li>not due to a disease process </li></ul><ul><li>Has no benefit, except as a diagnostic tool </li></ul><ul><li>Not associated with reduced VA </li></ul><ul><li>Examples include </li></ul><ul><ul><li>End point nystagmus </li></ul></ul><ul><ul><li>Postrotational nystagmus </li></ul></ul><ul><ul><li>Induced caloric testing </li></ul></ul><ul><ul><li>Optokinetic nystagmus </li></ul></ul><ul><ul><li>Voluntary nystagmus </li></ul></ul>
  5. 5. Sensory deprivation <ul><li>Due to a defect in the neural control of fixation </li></ul><ul><li>Poor macular function that cannot be restored and therefore of little clinical significance </li></ul><ul><li>Typically pendular and horizontal </li></ul><ul><li>Reduced by convergence and head posture </li></ul><ul><li>If a child loses vision before 2 yrs they will invariably develop nystagmus </li></ul><ul><li>After 6 yrs they do not </li></ul><ul><li>In between ??? Less predictable </li></ul>
  6. 6. Motor Imbalance <ul><li>Congential </li></ul><ul><li>Spasmus Nutans </li></ul><ul><li>Latent nystagmus </li></ul><ul><li>Ataxic nystagmus </li></ul><ul><li>Downbeat nystagmus </li></ul><ul><li>Upbeat nystagmus </li></ul><ul><li>Convergence retraction nystagmus </li></ul><ul><li>See-Saw nystagmus </li></ul><ul><li>Periodic alternating nystagmus </li></ul>
  7. 7. CONGENITAL NYSTAGMUS <ul><li>due to a congenital anomaly of the motor system or to a congenital disorder of vision </li></ul><ul><li>Inherited as X-link recessive or autosomal dominant trait </li></ul><ul><li>may appear during early childhood but is rarely present at birth. </li></ul><ul><li>Generally horizontal jerk type </li></ul><ul><li>Absent in sleep </li></ul><ul><li>Visual impairment is variable </li></ul>
  8. 8. Spasmus Nutans <ul><li>Nystagmus, involuntary head movements, AHP </li></ul><ul><li>Onset 3-18 months of age </li></ul><ul><li>Fine rapid eye movements; jerky, small amplitude, high frequency </li></ul><ul><li>Horizontal, vertical or rotary, or a combination of these </li></ul><ul><li>Considerable variation in nystagmus in different positions of gaze </li></ul><ul><li>Involuntary head movements comprising nodding or shaking, or a combination of both; variable. </li></ul>
  9. 9. Spasmus Nutans <ul><li>Head movements do not appear to compensate for eye movement as they are of a different frequency </li></ul><ul><li>Most cases resolve spontaneously by age 3 years. </li></ul><ul><li>Benign, but can be associated with CNS disease, therefore should be investigated. </li></ul>
  10. 10. Latent Nystagmus <ul><li>Horizontal jerk nystagmus presents when the light stimulus is reduced to either eye (eg by occluding). </li></ul><ul><li>In latent, no observable movement is present on uncovering and full BSV is restored. </li></ul><ul><li>Jerk nystagmus with fast phase towards the uncovered eye </li></ul><ul><li>Often noted in early childhood but can be observed in adults (especially if they have had strabismus surgery or in DVD) </li></ul>
  11. 11. Ataxic Nystagmus <ul><li>Occurs in abducting eye in internuclear ophthalmoplegia </li></ul>
  12. 12. Downbeat Nystagmus <ul><li>Has a fast downward beat </li></ul><ul><li>Pathognomic of a brain lesion at the cervicomedullary junction at the foramen magnum </li></ul>
  13. 13. Upbeat Nystagmus <ul><li>Commonly caused by drug intoxication (eg phenytoin - used a san anticonvulsant) </li></ul><ul><li>May be associated with a brain lesion at the posterior fossa </li></ul>
  14. 14. Convergence Retraction Nystagmus <ul><li>Jerk nystagmus </li></ul><ul><li>Fast phase generating convergence and retraction of globe into orbit </li></ul><ul><li>Usually associated with brain lesion in the pretectal area </li></ul>
  15. 15. See-Saw nystagmus <ul><li>Usually an acquired motility disorder associated with chiasmal lesions </li></ul><ul><li>where one eye elevates and intorts followed by depression and extorsion of the other eye </li></ul><ul><li>May be associated with a chiasmal lesion (bitemporal hemianopia could be present) </li></ul><ul><li>Rare </li></ul>
  16. 16. Periodic Alternating nystagmus <ul><li>Very rare jerk nystagmus </li></ul><ul><li>Nystagmus changes amplitude and direction </li></ul><ul><li>Associated with vascular or demylinating brainstem disease </li></ul>
  17. 17. Fundamental questions when you see a Px with nystagmus <ul><li>What type </li></ul><ul><ul><li>May help provisional diagnosis </li></ul></ul><ul><li>How long has it been present </li></ul><ul><ul><li>Recent = refer </li></ul></ul><ul><li>The cause </li></ul><ul><li>The activity of the lesion </li></ul><ul><ul><li>Some may produce deficient inhibitory neural activity leading to neurologic hypofunction other excessive excitory neural activity - hyperfunction </li></ul></ul>
  18. 18. <ul><li>Any form of nystagmus which is of recent onset requires fairly urgent referral for an ophthalmic opinion and if necessary further neurological investigation </li></ul>
  19. 19. Clinical procedure for nystagmus cases <ul><li>Close questioning as to the onset of the nystagmus, family history, general health, medication, history of CNS disorders, associated symptoms (oscillopsia, vertigo, unsteadiness and loss of vision all imply acquired forms) </li></ul><ul><li>Carefully note the type of nystagmus, distance/near, latency, AHP etc </li></ul><ul><li>VA recorded uni- and binocularly, with and without AHP, dist and near and compared </li></ul><ul><li>Full ophthalmoscopic, slit-lamp (transillumination), and binocular vision assessment </li></ul>

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