# Brainstem Stroke Syndromes > Brainstem stroke syndromes for NEET-PG Medicine: Weber, Benedikt, Wallenberg, Millard-Gubler and locked-in syndromes, localised by nuclei and tracts. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/brainstem-stroke-syndromes - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-08 - Last updated: 2026-10-08 - Reference basis: Adams and Victor's Principles of Neurology; Harrison's Principles of Internal Medicine; Davidson's Principles and Practice of Medicine - How to cite: "Brainstem Stroke Syndromes", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/brainstem-stroke-syndromes ## Direct answer Brainstem stroke syndromes are recognised clinical patterns produced by infarction of defined midbrain, pontine or medullary territories. They typically combine cranial nerve deficits on the side of the lesion with long-tract signs on the opposite side. Weber, Benedikt, Wallenberg, Millard-Gubler and locked-in syndromes are the examiner's favourites, each localised by the nucleus or tract involved. ## What you must remember - **Weber syndrome:** midbrain infarction causing ipsilateral third nerve palsy with contralateral hemiplegia through the cerebral peduncle. - **Benedikt syndrome:** midbrain tegmentum infarction with ipsilateral third nerve palsy and contralateral tremor or choreoathetosis from red nucleus involvement. - **Wallenberg syndrome:** lateral medullary infarction, usually from the vertebral or posterior inferior cerebellar artery, with ipsilateral facial pain and temperature loss, Horner syndrome, ataxia, dysphagia and vertigo, plus contralateral body pain and temperature loss. - **Millard-Gubler syndrome:** ventral pontine infarction with ipsilateral sixth and seventh nerve palsies and contralateral hemiplegia. - **Locked-in syndrome:** bilateral ventral pontine infarction, usually from basilar artery occlusion, with quadriparesis and anarthria but preserved consciousness and vertical eye movements. - **Localisation rule:** the side of the cranial nerve palsy is the side of the lesion, while long-tract signs appear on the opposite side of the brainstem. - **Acute care:** urgent CT or MRI with diffusion imaging, and CT or MR angiography of the posterior circulation; basilar occlusion may warrant thrombectomy in selected patients. - **Aetiology work-up:** ECG, echocardiography and vascular imaging seek cardioembolic and large-artery causes. ## Worked example: vertigo, hoarseness and a numb face A 63-year-old hypertensive diabetic wakes with vertigo, vomiting, hoarseness and choking on fluids. Examination shows right-sided Horner syndrome, right facial numbness, nystagmus and right-sided ataxia, with loss of pain and temperature sensation over the left half of the body. This combination is a right lateral medullary infarct, Wallenberg syndrome. 1. **Secure the airway:** Nucleus ambiguus involvement makes aspiration likely, so nil by mouth and a bedside swallow assessment come first, with a nasogastric tube if swallowing fails. 2. **Image the infarct:** Diffusion-weighted MRI confirms the infarct, and CT angiography of the neck checks for vertebral artery dissection, a common cause in younger patients. 3. **Consider thrombolysis:** If the patient is inside the treatment window, thrombolysis is considered, but haemorrhage must be excluded on imaging first. 4. **Start secondary prevention:** Antiplatelet therapy, a statin and blood pressure control follow. 5. **Plan rehabilitation:** Rehabilitation focuses on swallowing, balance and speech. The family is counselled that vertigo and ataxia often improve over weeks while the sensory deficit can persist. 6. **Seek a cardioembolic source:** Cardioembolic sources are sought with ECG and echocardiography. ## Where the localisation questions bite Brainstem localisation is largely a test of crossing. - **Trap:** Reversing the sides of the lesion. — **Correct:** The examiner wants the side of the cranial nerve lesion first, then the opposite long-tract signs. - **Trap:** Confusing the two third-nerve syndromes. — **Correct:** Both have ipsilateral third nerve palsy, but Weber gives contralateral weakness while Benedikt gives contralateral involuntary movements, so the stem's finding decides the answer. - **Trap:** Reading Millard-Gubler as a simple sixth nerve palsy. — **Correct:** The added seventh nerve weakness and hemiplegia distinguish it. - **Trap:** Calling locked-in syndrome coma. — **Correct:** Consciousness is preserved, and communication is through vertical eye movements or blinking. Wallenberg's sensory pattern is the cross, with facial loss on the lesion side and body loss on the other, which candidates often misremember. ## Frequently asked questions ### Which brainstem syndrome has ipsilateral third nerve palsy with contralateral hemiplegia? Weber syndrome has ipsilateral third nerve palsy with contralateral hemiplegia, caused by midbrain infarction involving the cerebral peduncle. Benedikt syndrome has a similar third nerve palsy but with contralateral involuntary movements instead of weakness. ### What distinguishes Benedikt syndrome from Weber syndrome? Benedikt syndrome involves the midbrain tegmentum and red nucleus, producing contralateral tremor or choreoathetosis, while Weber syndrome involves the cerebral peduncle and produces contralateral hemiplegia. Both cause ipsilateral third nerve palsy, so the movement disorder decides the diagnosis. ### What are the features of Wallenberg lateral medullary syndrome? Wallenberg syndrome causes ipsilateral facial pain and temperature loss, Horner syndrome, ataxia, dysphagia, hoarseness and vertigo, with contralateral body pain and temperature loss. It is usually caused by occlusion of the vertebral or posterior inferior cerebellar artery. ### Why is locked-in syndrome often mistaken for coma? Locked-in syndrome is often mistaken for coma because the patient is fully conscious but cannot move or speak, apart from vertical eye movements and blinking. The pontine lesion spares consciousness, and careful examination of eye movements reveals the true state. ### What does Millard-Gubler syndrome involve? Millard-Gubler syndrome involves ventral pontine infarction causing ipsilateral sixth and seventh nerve palsies with contralateral hemiplegia. The combination of abducens and facial palsies with hemiplegia localises the lesion to the lower pons.