The following is an aid for the diagnosis of spontaneous nystagmus that depends on bedside observations only. While
these observations are simple enough, they need to be recorded carefully. For
each of the five cardinal directions of gaze, note whether there is nystagmus
or not, and note its character (jerking, pendular, or rotatory) and the direction
of any fast phase.
The observations can be summarized in a small table, or two
tables, if nystagmus is dissociated, as in the above schematic example:
Right eye
Left eye
0
0
0
0
No adduction
0
0
Jerk ->
0
0
The example depicts the combination of an adduction defect in the right eye with an abduction nystagmus in the other eye. The nystagmus is of the jerk type and the direction of the rapid phase is towards the left. There is no nystagmus in other directions of gaze. This is the typical picture of a complete, unilateral, internuclear ophthalmoplegia, INO. Additional schematic representations of nystagmus can be viewed in separate windows [
1,
2,
3,
4].
Note: the examples contain sets of moving images (animated GIFs). Technical limitations may prevent the set members to synchronize properly.
Although poor sync is distractive, it is still possible to arrive at a correct evaluation. Just concentrate on each direction of gaze separately.
A large collection of live video recordings of nystagmus is maintained at
NOVEL,
the Neuro-Ophthalmology Virtual Education Library. A smaller collection is maintained elsewhere on
this site.
There are several forms of non-spontaneous nystagmus, i e, nystagmus that has to be induced by one maneuver or another. The diagnostic aid does not cover non-spontaneous forms of nystagmus. Perhaps some common variants should be mentioned briefly:
This diagnostic aid for spontaneous nystagmus works by a successive elimination of alternatives. Read the various alternatives carefully and click on the one that is appropriate for the situation. Each selected alternative will be appended to the window top line to provide a terse summary. An erroneous selection will naturally lead to an erroneous diagnosis. An erroneous choice can be undone by clicking the browser's BACK button. If you happen to go astray, use the TOP link to return to the starting point.
Note that the diagnosis presupposes that only one form of nystagmus is present
and that all entries are correct. To begin, select one of the following:
This form of nystagmus is most often congenital but can also occur in
advanced demyelinating disease. In the former case nystagmus tends to
remain horizontal on upgaze, and it is often combined with compensatory
head turning. In advanced demyelinating disease nystagmus is often
irregular and dissociated, and combined with oscillopsia.
This is so-called Bruns nystagmus, which is typical of a cerebello-pontine angle lesion, e g, an acoustic neurinoma. The nystagmus is
coarser in amplitude on gaze to the side of the lesion.
This transient form of nystagmus is most commonly seen in the primary
position after sustained horizontal gaze, in cerebellar lesions. It is termed rebound nystagmus.
Dissociated horizontal nystagmus in adults is most commonly due to demyelinating disease
or Wernicke's disease. In children, diencephalic lesions and spasmus nutans need to be considered.
Dissociated vertical nystagmus is usually due to demyelinating disease
in adults, or to bilateral blindness. Diencephalic tumors and spasmus
nutans need to be considered in children.
This is so-called Bruns nystagmus, which is typical of a cerebellopontine angle lesion, e g, an acoustic neurinoma.
The nystagmus is coarser in amplitude on gaze to the side of the lesion.
Unilateral and bilateral internuclear ophthalmoplegia signifies a lesion
in the pontomesencephalic area, and is usually due to demyelinating
disease or a microvascular lesion. Myopathy may mimic INO. Bilateral INO
is typically combined with up-beating nystagmus on upgaze.
