A patient presents to the emergency room with the acute onset of vertigo, incoordination and left facial numbness. On examination the patient has loss of pinprick sensation over the left hemiface and the right hemibody. There is left-sided dysmetria and rotatory nystagmus as well as left-sided ptosis and miosis. Dysfunction of which of the following brainstem regions is likely responsible for this constellation of symptoms?

A. left basilar pons
B. left lateral medulla
C. left midbrain tegmentum
D. right basilar pons
E. right lateral medulla