corneal reflex

[MudPhud20XX]

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A neurologic exam of a 47 yr old woman reveals a normal corneal reflex in her Rt. eye, but no consensual corneal reflex in her Lt. eye. Where is the most likely location of the lesion?

So is it the same way as in pupilary reflex that if you are not getting any consensual reflex, it's the motor problem so thus, a lesion in the CN VII? Many thanks in advance.

 

[seminoma]

A neurologic exam of a 47 yr old woman reveals a normal corneal reflex in her Rt. eye, but no consensual corneal reflex in her Lt. eye. Where is the most likely location of the lesion?

So is it the same way as in pupilary reflex that if you are not getting any consensual reflex, it's the motor problem so thus, a lesion in the CN VII? Many thanks in advance.

Yup, bilaterally innervated through the reticular formation.

 

[aspiringmd1015]

so the pupillary reflex which is cn2 afferent and cn3 is B/L innervated via pretectal nuclei, but CN 5(opthalmic divison afferent) and cn7(orbicularis oculi) is also B/L via reticular formation? is this in FA?

 

[pathologyDO]

A neurologic exam of a 47 yr old woman reveals a normal corneal reflex in her Rt. eye, but no consensual corneal reflex in her Lt. eye. Where is the most likely location of the lesion?

So is it the same way as in pupilary reflex that if you are not getting any consensual reflex, it's the motor problem so thus, a lesion in the CN VII? Many thanks in advance.

I agree with the above, but it could also be the left nucleus of VII in the brainstem, but as an isolated problem not likely so yeah... I agree with a problem with the left CN VII

 

[MudPhud20XX]

so the pupillary reflex which is cn2 afferent and cn3 is B/L innervated via pretectal nuclei, but CN 5(opthalmic divison afferent) and cn7(orbicularis oculi) is also B/L via reticular formation? is this in FA?

FA15 page 476 lists afferent as V1 (nasociliary branch) and efferent as CN7 (temporal branch: orbicularis oculi), but doesn't really explain it in detail. Thanks guys!

 

[notbobtrustme]

two different things
pupillary -> responds to light
corneal -> responds to touch/pressure.

That's why they have different afferents/efferents.

Light sensed by CNII -> CNIII responds by constricting pupils b/l

Touch/pressure sensed by CNV -> CNVII responds by shutting both eyes.

 

[aspiringmd1015]

i see, so the cnv has afferent to the reticular formation then?

 

[seminoma]

Yup, bilaterally innervated through the reticular formation.

i see, so the cnv has afferent to the reticular formation then?

Yes. The reticular formation integrates tons of stuff. It's not likely to be a tested point.

 

[masaraksh]

the 'corneal reflex' is when you touch the tip of one eye with a piece of cotton (CN V afferent) and both eyes blink (CN VII). Thus, if you have a normal reflex when stimulating one eye, then that means both CN VII are fine. Most likely a problem with CN V, specifically V1 afferent.

 

[aspiringmd1015]

i thought that was the solitary nucleus?

 

[pathologyDO]

the 'corneal reflex' is when you touch the tip of one eye with a piece of cotton (CN V afferent) and both eyes blink (CN VII). Thus, if you have a normal reflex when stimulating one eye, then that means both CN VII are fine. Most likely a problem with CN V, specifically V1 afferent.

The stem states the consensual reaction in the opposite eye is not functioning, and that the ipsilateral eye is still closing upon stimulation. If it were an afferent problem (CN V) then neither eye would respond.