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Eye and Vision Care

Healing 4th nerve palsy

07/09/2009

Question:

I`m 24 years old, 2 months ago I suffered a head injury. I hit my face on a stair and the contact was made just over my right eye and below the eyebrow (directly over the supraorbital foramen). I had a CT test which came back with nothing.

Initially I had pretty severe double vision and was only able to see without double vision by tilting my head. My vision has improved greatly since the accident happened ie. the double vision is affecting a smaller area of my vision and I hardly need to tilt my head when looking straight ahaead. The affected eye (right eye) has the ability to look downwards and inwards which leads me to believe that the superior oblique muscle isn`t completely paralyzed. However, upon looking downward the double vision becomes more noticible.

I`m wondering if there are any eye exercises or vitamins/medicines that I can take which may speed up or assist in the healing process. I am also curious about the differences in the typical healing process based on the injury; whether it was just a head trauma or a direct trauma to the nerve itself.

-Thank you very much for your help

Answer:

Though one can only be certain after a complete eye exam, your symptoms are consistent with a Trochlear or IV nerve palsy. I assume you had an exam if you also had a CT, which ruled out other problems like cracks in the wall of the orbit that can occur from a blunt orbital blow.

Though the muscle that the IV nerve innervates is near the point of your orbital injury, the nerve itself is not located in that area. Likely, the whiplash-like effect that your head and neck suffered when you fell was the cause of the injury.

The IV nerve is the only cranial nerve that exits off the dorsal or back part of your brainstem. This subjects it to damage whenever the head suffers from an acceleration/decelleration injury as the nerve is compressed as the brainstem moves backward. This compression typically causes a partial parlysis or paresis as opposed to a total paralysis of the nerve.

Compressive lesions do have a higher incidence of healing as the nerve is not cut or deprived of oxygen. The fact that your symptoms are improving is consistent with that fact.

Spontaneous recovery can continue for 6 months to a year and therapy would consist of you continuing to do what you are doing. Start at a head positon where you can achieve single vision and then try to expand this zone by tilting your head or by looking down. In this way you are forcing the paretic muscle to work and are also expanding your vergence system which will allow you to achieve single vision even if the nerve does not fully recover and you are left with a vertical phoria. If you remain symptomatic after some time, then glasses with prism may allow you a wider range of single vision.

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Response by:

Michael  Earley, OD, PhD, FAAO Michael Earley, OD, PhD, FAAO
Assistant Dean for Clinical Services
Professor of Clinical Optometry
College of Optometry
The Ohio State University