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🧠 BRAINSTEM SYNDROMES — Complete Neurosurgery Viva Guide

Sources: Localization in Clinical Neurology 8e, Adams & Victor's Neurology 12e, Bradley & Daroff's Neurology, Harrison's 22e, Plum & Posner, Neuroanatomy through Clinical Cases 3e, Schwartz's Surgery 11e

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PART 1: FOUNDATION — Anatomy & Vascular Supply

Brainstem Anatomy Overview

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Vascular Supply — Key Points

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PART 2: CLASSIFICATION OF BRAINSTEM SYNDROMES

I. By Level

MIDBRAIN          PONS              MEDULLA
─────────         ────────          ──────────
Weber             Millard-Gubler    Wallenberg (Lateral)
Benedikt          Raymond-Foville   Dejerine (Medial)
Claude             Locked-In         
Nothnagel          (bilateral pons)  
Parinaud (dorsal)  

II. By Mechanism

• Vascular (most common): ischaemic infarct > haemorrhage
• Demyelinating: MS
• Compressive: tumour, AVM, abscess
• Traumatic: severe TBI, pontine haematoma

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PART 3: INDIVIDUAL SYNDROMES — Full Viva Detail

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🔴 SYNDROME 1: WEBER SYNDROME (Ventral Midbrain)

Demography

• Age: 50–70 years (atherosclerotic) | Young adults: PCA dissection, embolism
• Sex: M > F
• Risk factors: HTN, DM, hyperlipidaemia, atrial fibrillation

Lesion Location

• Ventromedial midbrain — damages the cerebral peduncle (corticospinal + corticobulbar) AND the CN III fascicle
• Artery: Paramedian perforators of PCA or top of basilar

Pathology of Clinical Features

Clinical Features

• Ipsilateral (same side as lesion):
  • Complete CN III palsy: ptosis, eye deviated "down and out," mydriasis (dilated unreactive pupil), loss of accommodation
• Contralateral (opposite side):
  • UMN hemiparesis/hemiplegia (arm, leg, lower face)

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🟠 SYNDROME 2: BENEDIKT SYNDROME (Midbrain Tegmentum)

Demography

• Same age/risk as Weber. Rarer — caused by PCA branch occlusion to tegmentum

Lesion Location

• Midbrain tegmentum — damages CN III fascicle + red nucleus + brachium conjunctivum (superior cerebellar peduncle)

Pathology of Clinical Features

Clinical Features — The Classic Triad

1. Ipsilateral CN III palsy (ptosis, mydriasis, "down and out")
2. Contralateral hemiataxia with intention tremor (rubral/Holmes tremor — coarse, 3–5 Hz)
3. Contralateral hemiparesis (milder than Weber)

Memory aid: Benedikt = CN III + Red nucleus involvement (contralateral Big tremor)

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🟡 SYNDROME 3: CLAUDE SYNDROME (Dorsal Midbrain)

Lesion Location

• Dorsal midbrain tegmentum — CN III fascicle + brachium conjunctivum (superior cerebellar peduncle)

Clinical Features

1. Ipsilateral CN III palsy
2. Contralateral cerebellar ataxia (prominent, no hemiplegia)
3. Dysmetria, dysdiadochokinesia

Claude = "Cerebellar" signs dominant (no tremor, no hemiplegia)

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🟢 SYNDROME 4: PARINAUD SYNDROME (Dorsal Midbrain / Tectum)

Also called: Sylvian Aqueduct Syndrome / Koerber–Salus–Elschnig Syndrome / Pretectal Syndrome

Demography

• Children/Young adults: Pineal tumour (germinoma, pineocytoma)
• All ages: Hydrocephalus (aqueductal stenosis), AVM, MS, haemorrhage
• Elderly: Midbrain infarct

Lesion Location

• Dorsal rostral mesencephalon — damages the posterior commissure and rostral interstitial nucleus of MLF (riMLF) — the vertical gaze centre
• NOT a crossed syndrome (bilateral structure compressed from above)
• Caused by compression from pineal region or hydrocephalus — NOT typically a stroke

Pathology of Clinical Features

Clinical Features (COONS mnemonic)

• Convergence-retraction nystagmus (pathognomonic — on attempted upgaze)
• Ophthalmoplegia — bilateral upgaze palsy (can look down, not up)
• Other: Eyelid retraction (Collier's sign = "sunset sign" or lid retraction on downgaze)
• Near-light dissociation of pupils (pupils react to convergence not to light)
• Signs of hydrocephalus (headache, vomiting, papilloedema)

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Investigations for Parinaud Syndrome

Management of Parinaud (Pineal Region)

Surgical Options

• Indications: Obstructive hydrocephalus from pineal/tectal mass; avoids CSF shunt
• Steps: Kocher's point burr hole → rigid endoscope into lateral ventricle → foramen of Monro → third ventricle floor fenestration → simultaneous biopsy via separate working channel
• Advantage: Diagnose AND treat in one session

• Indications: Large benign tumour (pineocytoma, teratoma), failed biopsy, residual disease
• Patient position: Sitting or park-bench position
• Steps: Midline incision → infratentorial craniotomy → approach under tentorium above cerebellum → microsurgical resection
• Contraindications: Radiosensitive tumour (germinoma responds to RT), poor performance status

Non-surgical:

• Germinoma: Radiation ± chemotherapy (cisplatin, etoposide) — highly radiosensitive
• Dexamethasone 0.1 mg/kg/dose QDS: reduces perilesional oedema (MOA: inhibits phospholipase A2, reduces arachidonic acid → ↓ prostaglandins + vascular permeability)

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🔵 SYNDROME 5: MILLARD-GUBLER SYNDROME (Ventral Pons)

Demography

• Age: 45–70 years
• Cause: Paramedian basilar perforator infarct, tumour, MS

Lesion Location

• Ventral pons — damages CN VII fascicle + CN VI nucleus/fascicle + corticospinal tract

Pathology of Clinical Features

Clinical Features

• Ipsilateral complete LMN CN VII palsy (brow, eye, mouth all involved)
• Ipsilateral CN VI palsy (esotropia, diplopia on lateral gaze)
• Contralateral UMN hemiparesis

Raymond Syndrome = CN VI palsy + contralateral hemiplegia (no VII involvement)

Foville Syndrome = CN VII palsy + conjugate horizontal gaze palsy (toward lesion) + contralateral hemiplegia (PPRF involvement)

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🟣 SYNDROME 6: LOCKED-IN SYNDROME (Bilateral Ventral Pons)

Demography

• Age: Any age; typically 40–60 (stroke), younger (trauma or basilar thrombosis)
• Cause: Bilateral basilar perforator infarction / basilar artery thrombosis / pontine haemorrhage / severe TBI
• Mortality: Extremely high acutely; survivors may live years with preserved consciousness

Lesion Location

• Bilateral ventral pons — bilateral corticospinal + corticobulbar tract destruction
• Spares: Dorsal pons (ARAS intact → consciousness preserved), vertical gaze pathways (riMLF in midbrain intact)

Pathology of Clinical Features

Clinical Features

• Awake and aware — fully conscious, cannot communicate verbally or move limbs
• Quadriplegia (all 4 limbs)
• Aphonia (no phonation)
• Preserved: Vertical gaze (upward + downward), blinking — used as YES/NO communication
• Preserved hearing, vision, reading ability
• Autonomic instability (HR, BP fluctuations)

Classic teaching: Patient appears comatose but is fully awake — ALWAYS test vertical eye movement in apparent coma!

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🟤 SYNDROME 7: WALLENBERG SYNDROME (Lateral Medullary)

The MOST COMMON and Clinically Important Brainstem Stroke Syndrome

Demography

• Age: 50–70 years (atherosclerotic); 30–50 years (vertebral artery dissection — after neck manipulation, trauma, chiropractic)
• Sex: M > F (2:1)
• Aetiology (from 130-patient series — Localization in Clinical Neurology):
  • Large vessel atherosclerosis: 50%
  • Arterial dissection: 15%
  • Small vessel disease: 13%
  • Cardioembolism: 5%

Lesion Location

• Lateral medulla — a wedge-shaped territory supplied by PICA and/or vertebral artery
• Structures damaged: spinothalamic tract, spinal nucleus/tract CN V, nucleus ambiguus, inferior cerebellar peduncle, descending sympathetic fibres, vestibular nuclei, dorsal motor nucleus of vagus

Pathology of Clinical Features

The Classic TRIAD (diagnostic):

Full Clinical Features (9 features — WALLED mnemonic)

1. Weakness — NOT a feature (pyramids spared!)
2. Ataxia ipsilateral + vertigo/nystagmus
3. Loss of pain/temp — crossed (face ipsilateral, body contralateral)
4. Laryngeal/palatal palsy → dysphagia, dysarthria
5. Eye signs: Horner (ipsilateral), skew deviation, ocular ipsipulsion
6. Dysphagia (aspiration risk — major complication!)

• Hiccups (singultus) — lateral dorsal medulla involvement
• Ocular ipsipulsion — saccades veer toward side of lesion (damage to climbing fibres from inferior olivary nucleus)
• Environmental tilt — room appears tilted or upside-down ("floor-on-ceiling" phenomenon)

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🔵 SYNDROME 8: DEJERINE SYNDROME (Medial Medullary)

Demography

• Rarer than Wallenberg
• Cause: Anterior spinal artery or vertebral artery occlusion (medial branches)

Lesion Location

• Medial medulla — damages: pyramid (corticospinal), medial lemniscus, CN XII nucleus/fascicle

Pathology of Clinical Features

Classic Triad:

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PART 4: APPROACH TO THE PATIENT

Step-by-Step Clinical Approach

STEP 1: CALL FOR HELP
→ Neurosurgery + Neurology + ICU

STEP 2: AIRWAY + BREATHING (most critical)
→ Nucleus ambiguus lesion → dysphagia → aspiration
→ Locked-in → respiratory failure
→ GCS ≤8 → INTUBATE immediately
→ Position: 30° head elevation

STEP 3: RAPID NEUROLOGICAL ASSESSMENT
→ Level of consciousness (GCS)
→ Pupils (size, reactivity, Horner)
→ Eye movements (gaze palsy, nystagmus)
→ Cranial nerve function (IX, X, XII, V, VI, VII)
→ Motor power + reflexes (crossed?)
→ Sensory (crossed pattern?)

STEP 4: VITAL SIGNS
→ Cushing response (HTN + bradycardia + irregular breathing) = 
  impending brainstem compression!

STEP 5: INVESTIGATIONS (see below)

STEP 6: MANAGEMENT

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PART 5: INVESTIGATIONS

Scoring Systems

• E1–4 + V1–5 + M1–6 = 3–15
• GCS ≤8 = severe brain injury / coma
• Use: Initial assessment, monitor deterioration, intubation threshold (GCS ≤8)

• 0–42 score; brainstem strokes can score disproportionately high
• Used to guide thrombolysis eligibility

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Investigations Table

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PART 6: MANAGEMENT

A. MEDICAL MANAGEMENT

1. Acute Ischaemic Stroke (Brainstem)

• MOA: Tissue plasminogen activator → converts plasminogen → plasmin → dissolves fibrin clot
• Indication: Ischaemic stroke ≤4.5 hours from onset, no contraindications; NIHSS ≥4
• Dose: 0.9 mg/kg IV (max 90 mg); 10% bolus over 1 min, rest over 60 min
• Special points: Contraindicated if: BP >185/110 (treat first), bleeding, recent surgery, INR >1.7, glucose <2.8 or >22.2 mmol/L

• Indication: Basilar artery occlusion (LOCKED-IN syndrome risk) — large vessel occlusion; within 24h (posterior circulation may have extended window)
• MOA: Catheter-based stent retriever or aspiration to retrieve clot
• Special points: Basilar artery thrombosis has mortality >90% without recanalization — KEY VIVA POINT

2. Antiplatelet Therapy

• Aspirin 300 mg loading → 75 mg OD maintenance
• MOA: Irreversibly inhibits COX-1 → ↓ TXA2 → ↓ platelet aggregation
• Start within 24h (if no thrombolysis)

3. Anticoagulation (Vertebral Artery Dissection)

• Heparin (IV infusion) or LMWH → then transition to warfarin or NOAC for 3–6 months
• MOA: Heparin — activates antithrombin III → inhibits thrombin + Xa; NOAC (e.g. rivaroxaban) — direct Xa inhibitor

4. Mannitol (ICP control)

• MOA: Osmotic diuretic → creates osmotic gradient across BBB → draws free water out of brain → ↓ ICP; also transient plasma expansion → ↓ viscosity → ↑ CBF
• Dose: 0.25–1 g/kg IV bolus over 15–20 minutes; repeat Q4–6h
• Serum osmolality target: 300–315 mOsm/L
• Special points: Avoid in hypotension; monitor renal function; avoid if intracranial haemorrhage before decompression (may expand haematoma)

5. Dexamethasone

• MOA: Reduces vasogenic oedema (tumour-related) by stabilising BBB; inhibits phospholipase A2 → ↓ arachidonic acid → ↓ prostaglandin-mediated vascular permeability
• Dose: 0.1 mg/kg/dose QDS (paediatric); Adults 4–8 mg IV QDS
• Special points: NOT effective for cytotoxic oedema (ischaemic stroke). Use only for tumour/abscess-related oedema and Parinaud syndrome from pineal tumour

6. Antihypertensives in Acute Stroke

• Target BP <180/105 during thrombolysis window; do NOT aggressively lower in first 24h (permissive hypertension)
• After 24h: target <130/80

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B. SURGICAL MANAGEMENT

1. ICP Monitoring — External Ventricular Drain (EVD)

• GCS 3–8 with abnormal CT scan
• Obstructive hydrocephalus from Parinaud/posterior fossa lesion
• Need for CSF drainage to control ICP

1. Patient supine, head in neutral position, head elevated 30°
2. Shave and prep scalp
3. Kocher's point: 1 cm anterior to coronal suture, 3 cm lateral to midline (mid-pupillary line)
4. Local anaesthetic ± GA if agitated
5. Burr hole drilled at Kocher's point
6. Catheter directed toward ipsilateral medial canthus in coronal plane, nasion in sagittal plane — depth ≈5.5–6.5 cm
7. Stylet removed → CSF should flow; connect to closed drainage system
8. Zero at level of external auditory meatus (EAM)
9. Drain at ICP threshold >20–25 mmHg

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2. Suboccipital Craniectomy (Posterior Fossa Decompression)

• Large cerebellar infarct/haemorrhage causing brainstem compression
• Fourth ventricle obstruction → hydrocephalus
• Cerebellar herniation through foramen magnum

1. Patient: Park-bench or prone position
2. Midline incision from inion to C2
3. Expose posterior fossa bone
4. Drill/remove posterior fossa bone (suboccipital craniectomy ≥3 × 4 cm)
5. Open dura (Y-shaped incision) + duraplasty if needed
6. Decompress cerebellum; if haematoma → evacuate
7. If hydrocephalus → concurrent EVD or VP shunt

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3. Decompressive Hemicraniectomy (Malignant MCA or Basilar territory)

• Not directly for brainstem syndromes but for their supratentorial correlates causing transtentorial herniation

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C. REHABILITATION

• Swallowing assessment (SALT) within 24h — Wallenberg (nucleus ambiguus) = aspiration risk
• Nasogastric tube if unsafe swallow
• PEG if prolonged dysphagia (>3 weeks)
• Eye patch (diplopia from CN VI palsy)
• Physiotherapy, OT, speech therapy

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PART 7: FOLLOW-UP

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📸 IMAGE GALLERY SUMMARY

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📋 SUMMARY TABLE — All Brainstem Syndromes at a Glance

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🔑 VIVA RAPID-FIRE POINTS

1. Brainstem rule: Ipsilateral CN + Contralateral long tract = lesion IN brainstem
2. Wallenberg: ONLY brainstem syndrome without hemiplegia (pyramids in medial medulla)
3. Parinaud: NOT a stroke syndrome — think PINEAL TUMOUR; check AFP/hCG; treat hydrocephalus first
4. Locked-in: Patient is CONSCIOUS — always test vertical gaze in apparent coma
5. Basilar thrombosis: Hyperdense basilar on plain CT → emergency thrombectomy
6. Vertebral dissection (Wallenberg in young): neck pain + Horner → MRI fat-sat T1 → crescent sign
7. Parinaud pupils: Light-near dissociation = pupils react to convergence/accommodation NOT to light (opposite of Argyll Robertson pupil of syphilis which is the same phenomenon but different aetiology)
8. Kocher's point for EVD: 1 cm anterior to coronal suture, 3 cm lateral to midline — aim at ipsilateral medial canthus
9. Dysphagia in Wallenberg = aspiration risk = NG tube + SALT assessment within 24h
10. Rubral tremor in Benedikt: Coarse, 3–5 Hz, worsens with intention — different from essential tremor

Sources: Localization in Clinical Neurology 8e (Brazis), Adams & Victor's Principles of Neurology 12e, Harrison's Principles of Internal Medicine 22e, Plum & Posner's Stupor and Coma, Schwartz's Principles of Surgery 11e, Neuroanatomy through Clinical Cases 3e (Blumenfeld), Bradley & Daroff's Neurology in Clinical PracticeHere is your complete viva guide. Let me highlight the key architecture:

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What's Covered

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• Demography + age + causative artery
• Pathology table linking structure → sign
• Full clinical features
• Investigations with indications + positive findings
• Drugs with MOA + dose + special points (Alteplase, Aspirin, Mannitol, Dexamethasone)
• Surgical options with steps/indications/contraindications (EVD at Kocher's point, Suboccipital craniectomy, ETV for Parinaud)
• Follow-up schedule + modality
• Images for every syndrome

1. Wallenberg = NO hemiplegia (pyramids spared)
2. Locked-in = conscious patient — test vertical gaze
3. Parinaud = PINEAL TUMOUR not a stroke — treat hydrocephalus first, check AFP/β-hCG