There is left sided arm and leg weakness although the face is spared, and you note right sided loss of vibration and proprioception sense

A 72-year-old man with a 2-day history of severe neck pain and headache presents to the Emergency Department with protrusion of his tongue and left arm and leg weakness. He has a history of hypertension for which his GP has prescribed 3 anti-hyptmensive agents, although he admits that his compliance with therapy is poor. On examination his BP is 175/100 mmHg, pulse is SO/min and regular. There is weakness of the tongue with protrusion towards the right hand side. There is left sided arm and leg weakness although the face is spared, and you note right sided loss of vibration and proprioception sense.
Where is the most likely site of the lesion?

A Basilar artery
B Carotid artery
C Posterior communicating artery
D Posterior inferior cerebellar artery
E Vertebral artery

Explanation
Vetrebral artery
This patient has features consistent with the medtal medullary (also known as Dejerine) syndrome. The cause is occlusion of the vertebral artery or its branch to the anterior spinal artery with involvement of the pyramid, medial lemniscus and they hypoglossal nerve.
Posterior inferior cerebellar artery, (Option O),os incorrect. PICA lesions present with the classical features of lateral medullary syndrome, rather than those of medial medullary syndrome seen here
Basolar artery, (Option A), is incorrect. Basilar artery lesions more usually present with ischaemia affecting the upper brainstem or Pons, with infarction of the upper ventral Pons leading to presentation with 'lockedĀ·in" syndrome.
Carotid artery, (Option B), is incorrect. Carotid territory lesions present with hemiparesis without facial sparing and sensory loss on the same side. accompanied by other features such as dysphasia.
Posterior communicating artery, (Option C). is incorrect. Posterior communicating artery lesions can present with dorsal midbrain syndrome. leading to ipsilateral oculomotor palsy, ptosis, and mydriasis and contralateral involuntary movements