Paralytic Strabismus: Third, Fourth, and Sixth Nerve Palsy

Paralytic Strabismus 811
Fig. 7. An 8-year-old girl with idiopathic postviral left inferior divisional third nerve palsy,
causing isolated dysfunction of the medial rectus, inferior rectus, and pupillary constrictor
muscles. Brain MRI and spinal fluid constituents were normal. (A) Left mydriasis and exotropia.
(B) Complete left adduction deficit on right gaze. (C) Normal left gaze. (D) Normal upgaze
bilaterally (not fully seen in this photograph). (E) Left depression deficit. (F) At 3-month
follow-up, there was marked improvement of the motility deficit, with residual left mydriasis
(anisocoria greatest in light). (G) Left adduction deficit has resolved. (H) Left gaze
remains normal. (I) Upgaze remains normal. (J) Slight left depression deficit persists.
typically accompanied by miosis, rather than mydriasis, which probably results from
anomalous innervation of the pupillary constrictor. Cyclic oculomotor spasms may
occur, which are characterized by brief (10–30 seconds), involuntary contractions of
third nerve innervated structures, causing periods of adduction, lid elevation, and
miosis. 41 This condition rarely occurs with acquired third nerve palsy, typically due
to a compressive lesion.
Third nerve palsy frequently occurs in combination with other cranial nerve deficits.
The disorders capable of affecting multiple cranial nerves include cavernous sinus
lesions, neoplasms of the base of the skull, carcinomatous meningitis, sinus mucoceles,
infections, and inflammatory conditions. These conditions are discussed later
in this article.