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Clinical picture
Congenital right third nerve palsy aligned surgically . A small residual right exotropia and ptosis of the right upper lid remain.
History
This 14-month-old boy was brought by his parents for examination because his right eye deviated outward and downward. This had been present and unchanging since birth. They also thought the right upper lid “drooped.” The child is otherwise healthy and is developing normally, with all milestones reached on time or early.
Examination
This patient fixed and followed well with either eye. While fixing with the left eye, the right eye was down and out and a mild right ptosis was present. When fixing with the right eye, a large left hypertropia with exotropia was present. With the left eye fixing, the right eye was 20 prism diopters exotropic and 15 prism diopters hypotropic. With the right eye fixing, the left eye was 30 prism diopters exotropic and 25 prism diopters hypertropic. Levator function in the right eye was only mildly limited. The right pupil responded normally. The remainder of the eye examination was normal.
Diagnosis
Congenital incomplete right third nerve palsy.
Treatment/Surgery
First procedure (14 months of age): recession of the right lateral rectus 8 mm, resection of the right medial rectus 8 mm with 1/2 muscle width upshift of both muscles. Second procedure (18 months of age): resection of right superior rectus 6.0 mm, recession of left superior rectus 4.0 mm.
Comment
After the first surgical procedure, the child’s eyes were aligned horizontally but he persisted with a large right hypotropia. After the second procedure, the patient has only a small right hypotropia or left hypertropia and slight ptosis of the right upper lid. This patient was treated initially with a recess/resect procedure of the right eye with upshift because adduction was only moderately limited. There was no limitation to passive ductions in either eye.
Congenital third nerve palsy has many expressions. This patient had fairly mild congenital third nerve palsy that was treatable with a recession/resection and did not require a muscle transfer procedure. Since the ptosis in this case is mild, no treatment is indicated now. Before school-age, it may be appropriate to do a small right levator resection.
Free alternation in this patient rules out amblyopia. I have treated several infants with congenital third nerve palsy who preferred fixation with the paretic eye because vision was better in this eye. If vision is equal in patients with congenital third nerve palsy, they frequently alternate fixation having a large secondary deviation when fixing with the paretic eye. The potential for amblyopia in the patients with congenital third nerve palsy should not be ignored while focusing on the strabismus alone. If fixation preference is noted and the non-preferred eye appears normal, occlusion therapy should be carried out. However, it should be closely monitored. I saw a patient with third nerve palsy who developed intractable occlusion amblyopia after several weeks of full-time occlusion at six months of age. In addition to the amblyopia, a grotesque secondary deviation was created by fixing with the paretic eye. I believe that imaging studies with CT scan or MRI should be done in all cases of congenital third nerve palsy to rule out structural brain abnormalities. |
