All are features of unilateral 3rd Cranial nerve nuclear injury except-(not sure of options)
Correct Answer: Unilateral Ptosis
Description: Pure unilateral lesions of the oculomotor nucleus are rare. Paresis of isolated muscles innervated by oculomotor branches is almost always due to a lesion of their branches within the orbit or to disease processes that affect the muscle or myoneural junction. Nuclear lesions, however, may cause isolated weakness of one of the muscles innervated by the oculomotor nerve, except the superior rectus muscle (crossed innervation noted previously), the levator palpebrae superioris (a single caudal subnucleus innervates the levators bilaterally), the pupillary constrictors (visceral nuclei are spread throughout the oculomotor nucleus), and the medial rectus muscle (three separate subnuclei). Thus, isolated unilateral palsies of the inferior rectus muscle have been associated with lesions of the inferior rectus subnucleus. More characteristic of nuclear involvement is unilateral palsy of the third cranial nerve in conjunction with weaknessf the ipsilateral and contralateral superior rectus muscles and bilateral incomplete ptosis. Occasionally, only the superior rectus muscle contralateral to the lesion is involved . Bilateral palsies of the third cranial nerve but with sparing of the levator muscles of the eyelid may be caused by bilateral nuclear lesions that spare the central caudal levator subnucleus. Conversely, isolated bilateral ptosis and sparing of the extraocular muscles and pupils have been described with lesions that involve the levator subnucleus and spare more rostral oculomotor subnuclei. Ref - Journal -Localization of Lesions of the Oculomotor Nerve: Recent Concepts by Paul W.Brazis
Category:
Anatomy
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