A 60-year-old man presents to the emergency department because one hour ago he suddenly became very dizzy, started vomiting then fell on his left side. He states that his left arm and leg “just aren’t working properly.” His history is significant for hypertension for which he is prescribed Lisinopril but only takes when his wife reminds him. Physical examination reveals that the left side of his face is drooping, and he cannot raise his eyebrows. Examination of the eyes reveals that he has nystagmus in his left eye and his left pupil is dilated with drooping of the lid. Pain sensation is absent on the left side of his face and in the right extremities. During the examination, he asks for questions to be repeated and states that his left ear “stopped working” at the onset of the rest of his symptoms.
A) Anterior inferior cerebellar artery (AICA)
Occlusion of this artery causes lateral pontine syndrome, one of the brainstem stroke syndromes of the lateral aspect of the pons. It is characterized by sudden onset of vertigo, nausea and vomiting, and falling to the side of the lesion (vestibular nuclei) as well as ipsilateral hearing loss (cochlear nuclei), facial weakness (facial nucleus and nerve), loss of pain and temperature to the face (spinal trigeminal nucleus and tract), and limb and gait ataxia (middle/inferior cerebellar peduncles). Contralateral loss of pain and temperature sensation to the extremities from the lateral spinothalamic tract also occurs. Horner’s syndrome is common due to damage of the descending sympathetic tract. Overall, when thinking of lateral pontine syndrome think of someone with sudden onset vertigo, nausea, vomiting and falling to the side of the lesion as well as ipsilateral facial weakness and numbness and contralateral body loss of pain and temperature sensation.
Answer choice B: Distal basilary artery, is incorrect. Occlusion of the distal basilar artery causes top of the basilar syndrome, also known as rostral brainstem infarction. This damages the thalamus, hippocampus, and occipital lobes. It presents with visual, pupillary, and oculomotor issues and changes in mental status.
Answer choice C: Lenticulostriate artery, is incorrect. Occlusion of the lenticulostriate artery stroke is a type of lacunar infarct. Lenticulostriate arteries are small, deep penetrating branches of the middle cerebral artery (MCA) that supply the basal ganglia and internal capsule. It usually presents with contralateral hemiparesis, slurred speech, and upward gaze deviation with attempted lateral gaze.
Answer choice D: Middle-upper basilar artery, is incorrect. Occlusion of this artery causes infarct of the upper ventral pons and is known as locked-in syndrome. It presents with quadriplegia. Patients are unable to move, speak, look laterally, or make facial movements. However, consciousness is maintained along with vertical eye movements and blinking.
Answer choice E: Posterior inferior cerebellar artery (PICA), is incorrect. Occlusion of this artery causes Wallenberg syndrome, also known as lateral medullary syndrome. It presents with ipsilateral Horner syndrome, loss of pain and temperature sensation to the face, hearing loss, vertigo, ataxia, nausea, vomiting, hoarseness and dysphagia. It also includes contralateral loss of pain and temperature sensation to the trunk and extremities. While very similar, lateral pontine syndrome does not present with hoarseness or dysphagia.
Key Learning Point
Occlusion of the anterior inferior cerebellar artery (AICA) causes lateral pontine syndrome and results in vertigo, nausea, vomiting, and falling to the side of the lesion as well as psilateral facial weakness and numbness and contralateral body loss of pain and temperature sensation.
