Pupil brainteaser Disorders of the afferent and efferent

Pupil brainteaser Disorders of the afferent and efferent (parasympathetic) pupillary pathways will follow. Please determine, if there is a afferent or efferent defect or both. If possible, make a diagnosis. Speculate about aetiology and suggest further tests. Move back and forth in the presentation. If a pupil does not react at all, you will need the near response.

Terms Direct lightreaction means the reaction of the illuminated eye. Indirect or consensual reaction is what the fellow eye does. direct consensual

N. III. N. opticus EWN PT Midbrain You will need this anatomical schedule. Located within the midbrain: Pretectum, Edinger Westphal Nuclei

direct consensual

consensual direct This is a normal finding: Pupils have same size (= are isocoric) react bilateral equally on light.

Your turn: Task 1

What happened? Go back and describe what you saw (direct/consensual). Interprete the findings. Solution follows on next slides.

Direct light reaction absent, consensual is missing too, if the patient‘s right eye (left on the slide) is illuminated.

Direct light reaction present, consensual works too, if the patient‘s left eye (right on the slide) is illuminated. Interpretation: The right eye is blind, amaurotic pupil, maximal form of an afferent defect PT EWK N. III. N. opticus

Task 2

What happened? Go back and describe what you saw (direct/consensual, near effort). Interprete the findings. Solution follows on next slides.

Direct light reaction absent, but consensual present, if the patient‘s right eye is illuminated. This proves, that the right is not blind inspite of missing light reaction. Anisocoria becomes obvious.

The right pupil does neither react if the left eye is illuminated. The light reaction of the left eye proves that the left eye is seeing. Innervation of the right pupil sphincter muscle must be impaired, an efferent defect.

PT As the light reaction doesn‘t work we try the near response. This works. We are dealing with a light-near dissociation. The would be a typical finding in a tonic pupil. EWK N. III. N. opticus

Task 3

What happened? Go back and describe what you saw (direct/consensual, near effort). Interprete the findings. Solution follows on next slides.

direct and consensual lightreaction cannot be elicited via the right eye

Directe und consensual Lichtreaktion can neither be eleicited via left eye. This patient might be blind or have had his pupils dilated. We need the near response.

PT Now the pupils react, again lightnear dissociation, this time bilateral, either bilateral tonic pupil (rarely so symmetric) or dorsal midbrain syndrome (Parinaud) or bilateral blind (unlikely, because he fixates the near target well) EWK N. III. N. opticus

Task 4

What happened? Go back and describe what you saw (direct/consensual, near effort). Interprete the findings. Solution follows on next slides.

Direct light reaction cannot be elicited via the right eye, but consensual reaction present. This shows that the right eye is not blind.

Nothing happens when the left eye is illuminated. This shows that the left eye is blind, becuuse its pupil has just demonstrated that it is able to react. Hence amaurotic pupil on the lest side and efferent problem on the right side. We need the near response additionally.

PT Even near resposne doesn‘t work, right pupil completely immobile, and left eye blind. This may be due to a parasellar tumour. EWK N. III. N. opticus

Task 5

What happened? Go back and describe what you saw (direct/consensual, near effort). Interprete the findings. Solution follows on next slides.

Directe light reaction cannot be elicited via right eye, neither the consensual reaction of the lest eye.

Light reaction of the right eye can neither be elicited consensually, but direct reaction on the left side works. So it is clear that the left eye is both blind and has a efferent defect additionally.

PT Near reaction of the right eye works. The right eye could be a blind eye with a tonic pupil. EWK N. III. N. opticus

I hope you liked it. Please construct more tasks out of the elements you may pick from the slides and send them to me. The animations were produced with Powerpoint on a Macintosh with OS 9 (this indicates that this is not new). Newer Powerpoint versions on Windows and OSX offer better animations („change size“), which were not available at the time when I did this. So feel free to use current possibilities. © Helmut Wilhelmut. wilhelm@med. uni-tuebingen. de