Abstract
The authors report a patient who presented with the rare clinical syndrome consisting of left Horner's syndrome and contralateral trochlear nerve palsy. In addition, he suffered from hypersomnia, and transient left trochlear nerve palsy. Magnetic resonance imaging delineated an acute hematoma of the left dorsal midbrain. It is concluded that in patients with trochlear nerve palsy a search for additional neurological signs is important, since their detection calls for further diagnostic investigations.