A 67 year old man after a stroke, presents with left sided ptosis and constricted pupil. He also has loss of pain and temp on the right side of his body and left side of his face. Which part of the brain is most likely affected?

The key is D. Medulla. [The name of the condition is “Lateral medullary syndrome”. Lateral

medullary syndrome is a neurological disorder causing a range of symptoms due to ischemia in the

lateral part of the medulla oblongata in the brainstem. The ischemia is a result of a blockage most

commonly in the vertebral artery or the posterior inferior cerebellar artery. This syndrome is

characterized by sensory deficits that affect the trunk and extremities contralaterally and sensory

deficits of the face and cranial nerves ipsilaterally. Specifically a loss of pain and temperature sensation

if the lateral spinothalamic tract is involved. The cross body finding is the chief symptom from which a

diagnosis can be made (in short ipsilateral Horner syndrome and contralateral loss of pain and

temperature sense). The patient may have ataxia (cerebellar involvement), dysphagia (nucleus ambigus

that involve vagus and glossopharyngeal nerve dysfunction) and slurred speech. Vestibular nuclei

dysfunction may cause vomiting, vertigo and nystagmus].