Oculomotor nerve palsy
Updates to Article Attributes
Oculomotor nerve palsies, or third nerve palsies, result in weakness of the muscles supplied by the oculomotor nerve, namely the superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris muscles.
Terminology
If the pupil is normal sized and reactive to light, it is called a pupil-sparing third nerve palsy; conversely if the pupil is enlarged and non-reactive, it is called a non-pupil sparing third nerve palsy.
Clinical presentation
Classically, patients present with diplopia and physical exam findings ipsilateral to the oculomotor nerve (CN III) lesion:
- "down and out" ocular positioning
- abduction, slight depression, and intorsion (due to paralysis of adduction, elevation, and depression)
- complete ptosis
- due to neuropathy affecting levator palpebrae superioris
- +/- enlarged unreactive pupil
- if present, suggests compression of CN III, because the parasympathetic pupillary fibres are located peripherally in the nerve and are more likely affected by external compression
Pathology
Aetiology
It has numerous possible aetiologies which can be divided according to which portion of the nerve is affected:
- dorsal midbrain (nuclear lesions): usually due to small regions of infarction; often no other neurological symptoms
- ventral midbrain (fascicular): Benedikt syndrome and Weber syndrome
- interpeduncular (subarachnoid)
-
posterior communicating artery aneurysm
- rapidly enlarging with or without SAH is the most common cause, and usually involves only the oculomotor nerve
- ischaemic involvement of the nerve will usually be pupil sparing whereas aneurysmal compression usually involves the pupil
- basal meningeal processes including infection, neoplastic infiltration, and inflammatory lesions (e.g. sarcoidosis) often involve additional cranial nerves
-
posterior communicating artery aneurysm
-
cavernous sinus portion
- neoplasms, most commonly pituitary macroadenomas extending into the sinus, meningiomas of the sella or sinus and any other sinus mass (e.g. trigeminal schwannomas) can compress the nerve against the interclinoid ligaments
- when the process is more diffuse, such as in cavernous sinus syndrome, other cranial nerves are also involved (e.g. Tolosa-Hunt syndrome)
- orbital portion
- usually there is associated proptosis or other focal orbital signs
- conditions include intraorbital tumours (optic nerve glioma, optic nerve meningioma) and inflammatory orbital pseudotumor
Treatment and prognosis
In post traumatic-traumatic oculomotor nerve palsy, gaze movement training and steroid injections may be helpful 2.
See also
-<p><strong>Oculomotor nerve palsies</strong>, or <strong>third nerve palsies</strong>, result in weakness of the muscles supplied by the <a href="/articles/oculomotor-nerve">oculomotor nerve</a>, namely the <a href="/articles/superior-rectus-muscle">superior rectus</a>, <a href="/articles/inferior-rectus-muscle">inferior rectus</a>, <a href="/articles/medial-rectus-muscle">medial rectus</a>, <a href="/articles/inferior-oblique-muscle">inferior oblique</a>, and <a href="/articles/levator-palpebrae-superioris-muscle">levator palpebrae superioris</a> muscles.</p><h4>Terminology</h4><p>If pupil is normal sized and reactive to light it is called a pupil-sparing third nerve palsy; conversely if the pupil is enlarged and non-reactive, it is called a non-pupil sparing third nerve palsy.</p><h4>Clinical presentation</h4><p>Classically, patients present with diplopia and physical exam findings ipsilateral to the oculomotor nerve (CN III) lesion:</p><ul>- +<p><strong>Oculomotor nerve palsies</strong>, or <strong>third nerve palsies</strong>, result in weakness of the muscles supplied by the <a href="/articles/oculomotor-nerve">oculomotor nerve</a>, namely the <a href="/articles/superior-rectus-muscle">superior rectus</a>, <a href="/articles/inferior-rectus-muscle">inferior rectus</a>, <a href="/articles/medial-rectus-muscle">medial rectus</a>, <a href="/articles/inferior-oblique-muscle">inferior oblique</a>, and <a href="/articles/levator-palpebrae-superioris-muscle">levator palpebrae superioris</a> muscles.</p><h4>Terminology</h4><p>If the pupil is normal sized and reactive to light, it is called a pupil-sparing third nerve palsy; conversely if the pupil is enlarged and non-reactive, it is called a non-pupil sparing third nerve palsy.</p><h4>Clinical presentation</h4><p>Classically, patients present with diplopia and physical exam findings ipsilateral to the oculomotor nerve (CN III) lesion:</p><ul>
-</ul><h4>Treatment and prognosis</h4><p>In post traumatic oculomotor nerve palsy, gaze movement training and steroid injections may be helpful <sup>2</sup>.</p><h4><strong>See also</strong></h4><ul>- +</ul><h4>Treatment and prognosis</h4><p>In post-traumatic oculomotor nerve palsy, gaze movement training and steroid injections may be helpful <sup>2</sup>.</p><h4><strong>See also</strong></h4><ul>