Here's the case: 5 year old cat that cannot blink one eye. What cranial nerve is affected?

To answer this question, of course you must do a cranial nerve exam. This is simply a process of elimination. If you touch the medial and lateral canthus and the cat does not blink what cranial nerves are you testing?

It's CN 5 (sensory) and 7 (motor).

How can you isolate these two nerves from each other to see which is the affected nerve? Well, if you do corneal reflex you're testing CN 5 (sensory) and 6 (motor). Voila! So, if the cat does not blink when you touch the medial or lateral canthus, but DOES retract the globe when you do corneal reflex which nerve is affected? Think you know... scroll (or read!) to the bottom to see the answer.

Need a little refresher on the cranial nerves and their jobs? The table below has all nerves, and their main jobs, for quick easy reference. (See Fall isn't just for KIDS to go back to school. We can too!)

Sorry—— the table doesn’t post here. Email me for the table if you’re interested in having a copy or join the weekly mailer list to have it emailed (along with all TidBit Tuesday’s)!

Answer: Cranial nerve 7 is affected. (5 is normal in corneal reflex therefore it is not the problem in the blink reflex either.)

Did you know you can schedule a 1 hour neuro exam refresher for your entire staff with me?
Have a great week!