Complaints & connections · borters.ch
Paresis nervi oculomotorii · trochlearis · abducentis
Sudden double vision that disappears as soon as one eye is covered. A widened pupil on the same side changes everything.
Also known as: cranial nerve palsy · sixth · fourth · third nerve palsy · double vision with a squint
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
Six muscles move each eye, and three nerves drive them. If one of these nerves fails, one eye lags behind the movement of the other. The brain then receives two pictures that no longer sit on top of one another, and shows both — double vision.
From this follows the single most important move: cover one eye. If the second image disappears, it arises from the two eyes working together, and a nerve or a muscle is in the foreground. If the second image stays although only one eye is open, it comes from that eye itself — the cornea, the lens or a clouding. This one distinction cuts the whole field in half, and it is the first question in any consultation.
Which nerve is affected is given away by the direction. If the sixth fails, the eye cannot turn outwards; the images stand side by side and get worse looking towards the affected side and into the distance. If the fourth fails, the images stand above one another or tilted, clearest looking down — stairs become the problem —, and the head is often held tilted to the other side. If the third fails, the lid droops as well, and the eye sits out and down.
The commonest cause in later life is a blockage of the tiny vessels that supply the nerve itself — usually with high blood pressure or diabetes, often painful, and as a rule it resolves on its own over eight to twelve weeks. Beside it stand other reasons that are handled differently: inflammation of the temporal arteries beyond fifty, raised pressure in the skull, muscle fatigability, a thyroid condition with thickened eye muscles, a stroke in the brainstem — and, in the third nerve with a wide, light-fixed pupil, a bulge in a vessel that tolerates no delay.
Check at home and write it down: double image with both eyes open — yes. Right eye shut — gone or not. Left eye shut — gone or not. Three lines, and the consultation starts one step further along.
Look straight ahead, left, right, up, down — and each time: more, the same, less? That is the map from which the affected nerve can be read, and it takes two minutes to make.
Inflammation of the temporal arteries can cause double vision before it takes sight. ESR and CRP cost little and decide much — especially with a headache at the temple, a tender artery or pain on chewing.
With the vessel blockage at the nerve, alignment usually recovers fully within eight to twelve weeks. What is unchanged after three months no longer counts as that case and is looked at again. That deadline is the real value of the number.
While the double vision lasts, a matt strip on one spectacle lens makes daily life walkable again — stairs, kerbs, cups. In an adult this does the eye no harm. In a child it is different: there any patching belongs discussed first.
Double vision removes depth perception and changes how distances are judged. While it lasts, driving belongs discussed — not tried out.
The decisive move, and it costs nothing. If the double image vanishes as soon as either eye is shut, it is about the two working together — nerve, muscle, alignment. If it stays with one eye open, it lies in that eye. The two lead to entirely different work-ups.
Side by side and worse looking sideways and into the distance points to the sixth nerve. Above one another or slanted and worse looking down, on the stairs for instance, points to the fourth. This observation is worth more than any description of severity.
If a drooping upper lid and a pupil that is larger on the same side and hardly reacts to light join the double vision, that is the third nerve with the pupil involved. It is the one case in this whole field that belongs in imaging without delay.
If the strength varies through the day, gets clearer while reading or watching television and improves after a rest with the eyes closed, it is more about fatigability of the muscles than a failed nerve. A drooping lid that varies with it belongs to the same picture.
A dull ache above or behind the eye often accompanies the vessel blockage at the nerve and by itself means nothing bad. A very sudden, severe headache together with double vision is another matter and belongs assessed at once.
Speech, swallowing, gait, one side of the body, numbness in the face, dizziness or a sense that everything is spinning — if one of these joins, it is no longer only about the nerve but about the place in the brainstem it comes from.
Blood sugar over two to three months. It stands right at the front here, because an unrecognised diabetes is the commonest basis for the vessel blockage at the nerve.
Beyond fifty it belongs with every new eye-muscle palsy, so that inflammation of the temporal arteries is not missed.
Measured together with the ESR; the two complement each other, and one of them can be off.