Overview

This lecture introduces brainstem stroke syndromes, covering stroke terminology, key anatomical rules (the "Rule of 4"), major syndromes, clinical features, investigation, and management.

Stroke Terminology

• Ischemic core: area of irreversible brain tissue damage due to blocked end artery.
• Ischemic penumbra: area of potentially salvageable brain tissue, target for thrombolysis and thrombectomy.
• Hemorrhagic transformation: bleeding into an area of infarction, relevant for thrombolysis decisions.

The Rule of 4 for Brainstem Anatomy

• Four cranial nerves above the pons, four from the pons, four from the medulla.
• Four midline (M) structures: motor pathway, medial lemniscus, medial longitudinal fasciculus, motor nuclei.
• Four lateral (S) structures: spinocerebellar tract, spinothalamic tract, sensory nucleus of cranial nerve V, sympathetic pathway.

Cranial Nerve Nuclei Localization

• Midbrain: nuclei for CN 3, 4, partial 5.
• Pons: nuclei for CN 5, 6, 7, 8.
• Medulla: nuclei for CN 5, 9, 10, 11, 12.
• Lateral motor nuclei innervate branchial arches (except CN 11).

Major Brainstem Stroke Syndromes

• Weber syndrome: ipsilateral third nerve palsy + contralateral limb weakness; often due to PCA occlusion.
• Wallenberg (lateral medullary) syndrome: vestibular, sensory, cerebellar, and sympathetic deficits; mnemonic "DANVER" for symptoms; caused by PICA stroke.
• Locked-in syndrome: quadriplegia, preserved consciousness, usually from basilar artery stroke.
• Millard-Gubler syndrome: affects CN 6/7 and descending pathways; pontine infarct.
• Medial medullary (Dejerine) syndrome: contralateral limb weakness + ipsilateral hypoglossal palsy.

Investigations

• CT head to exclude hemorrhage before thrombolysis.
• Bedside glucose to rule out hypoglycemia.
• ECG and blood tests to identify cardiac causes or mimics.
• Further imaging (chest X-ray, echocardiogram) as indicated.

Management Principles

• ABC assessment (airway, breathing, circulation).
• Keep nil by mouth until swallow assessed; prevent aspiration.
• Aspirin 300 mg for 2 weeks, then switch to clopidogrel for long-term.
• IV thrombolysis (tPA) or mechanical thrombectomy if eligible.
• Transfer to stroke unit for rehabilitation and multidisciplinary care.

Key Terms & Definitions

• Ischemic core — brain area with irreversible infarction.
• Ischemic penumbra — salvageable brain tissue at risk in stroke.
• Rule of 4 — mnemonic for remembering key brainstem structures.
• DANVER — mnemonic for Wallenberg syndrome symptoms.
• Locked-in syndrome — paralysis with preserved awareness.
• Medial longitudinal fasciculus — brainstem tract involved in eye movements.

Action Items / Next Steps

• Revise the "Rule of 4" for brainstem anatomy.
• Memorize key one-sentence summaries for common stroke syndromes.
• Review NICE guidance on acute stroke management.
• Read relevant textbook chapters on stroke pathophysiology (e.g., Davidson’s).

Certainly! Here is a comprehensive, detailed summary and review of the lecture on brainstem stroke syndromes by George Richardson:

Comprehensive Summary and Review: Brainstem Stroke Syndromes

Introduction

• Speaker: George Richardson, integrated medical student, University of Liverpool.
• Focus: Brainstem stroke syndromes, including stroke terminology, brainstem anatomy, clinical syndromes, investigations, and management.
• Contact: Email provided for further questions.

Stroke Terminology and Concepts

• Ischemic Core: Area of irreversible brain tissue damage caused by occlusion of an end artery (an artery that is the sole supply to a region).
• Ischemic Penumbra: Surrounding area of potentially salvageable brain tissue; target for acute interventions like thrombolysis and mechanical thrombectomy.
• Hemorrhagic Transformation: Bleeding into an infarcted area, a risk when thrombolysis is administered; timing is critical.
• Example: Homonymous hemianopia with macular sparing due to dual blood supply of the occipital pole (middle and posterior cerebral arteries).

Brainstem Anatomy: The Rule of Four

A mnemonic to simplify the complex brainstem anatomy, divided into four rules, each with four components:

Rule 1: Cranial Nerves

• Four cranial nerves arise above the pons:
  • CN I and II (above midbrain)
  • CN III and IV (from midbrain)
• Four cranial nerves arise from the pons:
  • CN V, VI, VII, VIII
• Four cranial nerves arise from the medulla:
  • CN IX, X, XI, XII
• Note: Vestibular nucleus is located in the lateral medulla, relevant for vestibular symptoms.

Rule 2: Cranial Nerve Motor Nuclei

• Four midline motor nuclei: CN III, IV, VI, XII (these nuclei are located medially).
• Five lateral motor nuclei: CN V, VII, IX, X, XI (innervate branchial arches except CN XI).
• Motor nuclei are important for understanding deficits in brainstem strokes.

Rule 3: Midline Structures Beginning with "M"

• Motor pathway (corticospinal tract)
• Medial lemniscus (proprioception and vibration)
• Medial longitudinal fasciculus (MLF): involved in eye movement coordination; lesions cause internuclear ophthalmoplegia (INO) characterized by impaired abduction of the ipsilateral eye with nystagmus and diplopia on contralateral gaze.
• Motor nuclei (as above)

Rule 4: Side (Lateral) Structures Beginning with "S"

• Spinocerebellar tract (coordination)
• Spinothalamic tract (pain and temperature sensation)
• Sensory nucleus of CN V (facial sensation)
• Sympathetic pathway (lesions cause Horner’s syndrome: ptosis, miosis, anhidrosis)

Cranial Nerve Nuclei Localization

• Midbrain: CN III, IV, and part of V nuclei.
• Pons: CN V, VI, VII, VIII nuclei.
• Medulla: CN V, IX, X, XI, XII nuclei.
• Lateral motor nuclei correspond to branchial arch innervation except CN XI.

Major Brainstem Stroke Syndromes

1. Weber Syndrome (Superior Alternating Hemiplegia)

• Lesion: Midbrain, occlusion of paramedian branch of posterior cerebral artery.
• Structures affected: Corticospinal tract, corticobulbar tract, oculomotor nerve (CN III).
• Clinical features:
  • Ipsilateral CN III palsy (ptosis, eye movement abnormalities)
  • Contralateral hemiparesis (limb weakness)
• Overlaps with:
  • Benedikt syndrome: ipsilateral CN III palsy + contralateral ataxia and choreoathetosis.
  • Claude syndrome: ipsilateral CN III palsy + contralateral limb ataxia.

2. Wallenberg Syndrome (Lateral Medullary Syndrome / Inferior Alternating Hemiplegia)

• Cause: Occlusion of posterior inferior cerebellar artery (PICA).
• Structures involved:
  • Vestibular nuclei
  • Inferior cerebellar peduncle
  • Central tegmental tract
  • Lateral spinothalamic tract
  • Spinal trigeminal nucleus
  • Nucleus ambiguus
  • Descending sympathetic fibers
• Clinical features summarized by mnemonic DANVER:
  • Dysphagia and ataxia
  • Anterolateral nystagmus (ipsilateral)
  • Nystagmus (lateral)
  • Vertigo
  • Extinction of pain and temperature sensation (contralateral body, ipsilateral face)
  • Rossolateral Horner’s syndrome (ipsilateral)
• Symptoms include ipsilateral facial numbness, contralateral body pain/temperature loss, vertigo, dysphagia, hoarseness, and Horner’s syndrome.

3. Locked-In Syndrome

• Cause: Basilar artery stroke causing ventral pontine infarct.
• Features:
  • Quadriplegia (paralysis of all limbs)
  • Preserved consciousness and vertical eye movements.
• Also caused by central pontine myelinolysis (rapid correction of hyponatremia).

4. Millard-Gubler Syndrome

• Lesion: Ventral pons.
• Affects CN VI and VII nuclei and corticospinal tract.
• Clinical features:
  • Ipsilateral facial paralysis (CN VII)
  • Ipsilateral lateral rectus palsy (CN VI)
  • Contralateral hemiparesis.

5. Medial Medullary Syndrome (Dejerine Syndrome)

• Cause: Occlusion of anterior spinal artery.
• Structures affected:
  • Corticospinal tract
  • Medial lemniscus
  • Hypoglossal nerve (CN XII)
• Clinical features:
  • Contralateral hemiparesis
  • Contralateral loss of proprioception and vibration
  • Ipsilateral hypoglossal palsy (tongue deviation to side of lesion)

6. Top of Basilar Syndrome

• Features:
  • Visual and oculomotor symptoms
  • Behavioral changes
  • Often no motor deficits (missing motor component)

One-Sentence Summaries for Key Syndromes

• Weber: Ipsilateral CN III palsy + contralateral limb weakness.
• Benedikt: Ipsilateral CN III palsy + contralateral choreoathetosis and ataxia.
• Claude: Ipsilateral CN III palsy + contralateral limb ataxia.
• Wallenberg: Ipsilateral facial pain/temp loss + contralateral body pain/temp loss + ataxia + Horner’s syndrome.
• Dejerine: Contralateral hemiplegia + ipsilateral hypoglossal palsy.

Investigations for Brainstem Stroke

• CT Head: To exclude hemorrhage before thrombolysis.
• Bedside blood glucose: To exclude hypoglycemia (stroke mimic).
• ECG: To detect cardiac embolic sources.
• Blood tests: Full blood count, coagulation, group and save.
• Additional imaging: Chest X-ray, echocardiogram if indicated.

Management Principles

• Initial assessment: ABC (Airway, Breathing, Circulation).
• Oxygen: Only if hypoxic; unnecessary oxygen can be harmful.
• Nil by mouth: Until swallow assessment to prevent aspiration.
• Medical treatment:
  • Aspirin 300 mg daily for 2 weeks.
  • Switch to clopidogrel 75 mg daily for long-term secondary prevention.
• Thrombolysis: IV tPA (alteplase) within 4.5 hours if eligible.
• Mechanical thrombectomy: Considered in selected cases.
• Stroke unit care: Multidisciplinary rehabilitation including speech and language therapy, occupational therapy, physiotherapy.

Summary and Key Takeaways

• The Rule of Four is a powerful mnemonic to understand brainstem anatomy and localize lesions.
• Brainstem stroke syndromes have overlapping but distinct clinical features; learning key syndromes and their one-sentence summaries aids diagnosis.
• Investigations focus on excluding hemorrhage and mimics, and identifying stroke etiology.
• Management follows general stroke protocols with attention to airway protection and secondary prevention.
• Resources recommended for further study include Life in the Fast Lane, Radiopaedia, NICE guidelines, and Davidson’s Principles and Practice of Medicine.

Additional Notes

• The lecture emphasizes the complexity of brainstem anatomy and the importance of systematic approaches.
• The speaker acknowledges reviewers and encourages contact for further questions.
• The mnemonic DANVER is highlighted as a useful tool for remembering Wallenberg syndrome features.

If you want, I can help you create a detailed study guide or help clarify any specific syndrome or concept from this lecture!