What are the physical findings in fascicular midbrain third cranial nerve palsy (oculomotor cranial nerve palsy)?

Updated: Oct 08, 2018
  • Author: James Goodwin, MD; Chief Editor: Andrew G Lee, MD  more...
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Answer

Ask the patient to hold both arms outstretched in front of them.

Patients with Benedikt syndrome have a gross "flapping" tremor that has been attributed to red nucleus involvement, usually from midbrain infarction. The tremor and ataxia are ipsilateral to the lesion and to the third cranial nerve palsy.

In Weber syndrome, the patient usually has a dense hemiplegia contralateral to the third cranial nerve palsy resulting from a lesion that also involves the pyramidal tract motor pathways in the cerebral peduncle. This should be obvious on simple inspection of the patient, since it is usually a fairly prominent hemiplegia.

Subtle hemiparesis may be observed by asking the patient to hold both arms outstretched forward with palms rotated upward. Slight pronation of the turned-up hand and downward drift of the outstretched arm are sensitive indicators of even very mild hemiparesis.

The hemiparetic gait is also characteristic with foot drop causing circumduction as the involved leg is swung out and forward before the next step. The arm on the involved side typically is held semiflexed at the elbow and wrist as the patient walks.

Another subtle sign in very mild hemiparesis is loss of the associated arm swing on the involved side as the patient walks.


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