IMAGES IN NEUROLOGY
Year : 2007 | Volume
: 10 | Issue : 3 | Page : 187--188
Isolated complete third nerve palsy due to midbrain hemorrhage: Clinico-radiological correlation
Sudhir Kumar, Garikapati Rajshekher, Subhashini Prabhakar
Stroke Unit, Department of Neurological Sciences, Apollo Hospitals, Hyderabad, India
Apollo Hospitals, Jubilee Hills, Hyderabad - 500 033, Andhra Pradesh
|How to cite this article:|
Kumar S, Rajshekher G, Prabhakar S. Isolated complete third nerve palsy due to midbrain hemorrhage: Clinico-radiological correlation.Ann Indian Acad Neurol 2007;10:187-188
|How to cite this URL:|
Kumar S, Rajshekher G, Prabhakar S. Isolated complete third nerve palsy due to midbrain hemorrhage: Clinico-radiological correlation. Ann Indian Acad Neurol [serial online] 2007 [cited 2020 Sep 21 ];10:187-188
Available from: http://www.annalsofian.org/text.asp?2007/10/3/187/34802
Isolated complete third nerve palsy (TNP) usually occurs due to extraaxial lesions affecting the oculomotor nerve. Intraaxial lesions of the midbrain causing TNP are usually associated with pyramidal or cerebellar signs or tremors. Isolated TNP due to midbrain pathology is uncommon and occurs either due to nuclear or fascicular lesions of oculomotor nerve. Here, we report a patient with isolated right-sided TNP with pupillary involvement due to a small midbrain hemorrhage.
A 67-year-old man with coronary artery disease was admitted for coronary angioplasty. PTCA was attempted, but blood flow could not be resumed even after crossing the stenosis with the wire and balloon dilatation. He was given intra-coronary urokinase and tirofiban and the procedure abandoned. Postprocedure, he was noted to have right-sided ptosis. Neurological examination revealed right-sided complete ptosis, impaired elevation, depression and adduction of right eyeball and 4.5 mm, non-reactive right pupil. There was no ptosis in left eye and extraocular movements were normal [Figure 1]. There were no other neurological deficits. Computerized tomogram (CT) scan of the brain revealed a small hemorrhage in the midbrain, in the region of right anterior tegmentum, possibly affecting the right oculomotor fascicle before it exited the midbrain [Figure 2].
Isolated unilateral TNP due to small midbrain hemorrhage has been reported earlier. In the above cases, the hemorrhage was diagnosed by either CT brain  or magnetic resonance imaging (MRI) brain.  Though MRI has been suggested as the modality of choice to detect small midbrain hemorrhage, a CT scan suffices in most cases. Intra-axial involvement of the oculomotor nerve may present with , or without  pupillary involvement. This is because of the topographic arrangement of the fibers for various extraocular muscles in the oculomotor nerve fascicle, with the pupillomotor fibers being placed the most medially. The arrangement for other muscles in the third nerve fascicle in ventral mesencephalon from lateral to medial include inferior oblique, superior rectus, medial rectus, levator palpebrae and inferior rectus.  This arrangement can also explain the occurrence of paresis of individual extraocular muscles alone or in combination or even a unilateral fixed and dilated pupil without other neurological dysfunction. Nuclear third nerve involvement in the midbrain results in bilateral superior rectus paresis and ptosis in addition to ipsilateral TNP;  however a fascicular involvement does not lead to any symptom/sign on the contralateral side.
This case is presented for its unique clinical presentation and interesting correlation of clinical and imaging findings.
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