Basic Science Clinical
Vascular Headache Epilepsy Immunology Movement Neuromuscular Dementia Other Topics Neurosurgery
Clinical
Neurosurgery
8 notes available
1 Cranial Emergencies 2 Hemorrhagic Stroke Surgery 3 SAH & Aneurysm Management 4 Brain Tumor Surgery 5 Spine Surgery 6 Hydrocephalus & CSF Diversion 7 Epilepsy Surgery Indications 8 Functional Neurosurgery
Clinical › Neurosurgery

Cranial Emergencies

Cranial Emergencies

What You'll Learn

  • Acute SDH: surgical evacuation (craniotomy) if thickness >10 mm, midline shift >5 mm, or GCS drop ≥2 points; best outcomes when operated within 4 hours
  • Epidural hematoma: classic lucid interval → rapid deterioration; urgent craniotomy if >15 mm thick, midline shift >5 mm, or GCS <9 with anisocoria
  • Chronic SDH: burr hole drainage (liquefied collection); craniotomy reserved for organized/septated clots
  • Decompressive craniectomy: malignant MCA infarction (DECIMAL/DESTINY/HAMLET — age <60, within 48 h) reduces mortality but increases disability; also for refractory elevated ICP in TBI (RESCUE-ICP)
  • ICP management ladder: stepwise approach from HOB elevation → sedation → osmotherapy → CSF drainage → barbiturate coma → decompressive craniectomy
  • Monroe-Kellie doctrine: fixed cranial vault volume = brain + CSF + blood; increase in one component must be offset by decrease in another or ICP rises
  • Posterior fossa lesions: low threshold for surgical evacuation — small volume changes cause brainstem compression and obstructive hydrocephalus
HighYield Pearls
  • TBI severity by GCS: mild 13–15, moderate 9–12, severe ≤8 — severe TBI requires airway protection and neurocritical care; ICP monitoring is recommended for salvageable severe TBI with abnormal head CT, and consider it with normal CT when risk factors (age, motor posturing, hypotension) are present (BTF)
  • ICP & CPP targets (BTF): keep ICP <22 mmHg and CPP 60–70 mmHg; CPP = MAP − ICP
  • Uncal herniation triad: ipsilateral CN III palsy (down-and-out eye + fixed dilated pupil) + contralateral hemiparesis — surgical emergency
  • Kernohan notch phenomenon: ipsilateral hemiparesis from contralateral cerebral peduncle compression against tentorium — false localizing sign in uncal herniation
  • Subfalcine herniation: cingulate gyrus under falx → contralateral ACA territory infarct (medial frontal → contralateral leg weakness)
  • Cushing’s triad: hypertension + bradycardia + irregular respirations = impending herniation; intubate, hyperosmolar therapy, neurosurgery STAT
  • Osmotherapy: mannitol 0.25–1 g/kg IV bolus OR 3% hypertonic saline; target Na 145–155, serum osm 295–320, osm gap <20
  • Hyperventilation: brief bridge only (PaCO2 30–32) for impending herniation; sustained hyperventilation causes ischemia — default PaCO2 35–40
  • Post-traumatic seizure prophylaxis: levetiracetam or phenytoin for 7 days after severe TBI (BTF); no benefit beyond 7 days for late PTS prevention
  • Brain death determination (2023 BD/DNC): coma + absent brainstem reflexes + positive apnea test (PaCO2 ≥60 AND ≥20 above baseline AND pH <7.30); adults require complete neurologic exam plus at least one apnea test; children require two exams and two apnea tests; must exclude hypothermia (<36°C), sedatives, paralytics, and metabolic/electrolyte derangement
  • Decompressive craniectomy (DECRA, RESCUE-ICP): reduces mortality in refractory ICP but at cost of severe disability survivors — consent conversation matters
  • Secondary insult prevention: avoid SBP <90, SpO2 <90, hyperglycemia, hyperthermia — each single hypotensive episode doubles TBI mortality
🔍 Quick ReferenceClinical syndromes · ICP / monitoring · Treatment
Herniation / clinical
  • Down-and-out eye + fixed dilated pupil + contralateral hemiparesis → Uncal (transtentorial) herniation with CN III compression
  • Ipsilateral hemiparesis with uncal herniation → Kernohan notch phenomenon (false localizing)
  • Contralateral leg weakness after mass effect → Subfalcine herniation → ACA territory infarct
  • Progressive rostrocaudal deterioration (pupils → posturing → apnea) → Central transtentorial herniation
  • Sudden apnea and cardiovascular collapse → Tonsillar herniation through foramen magnum
  • Obliterated quadrigeminal cistern + small posterior fossa mass → Upward (reverse) transtentorial herniation
  • Hypertension + bradycardia + irregular respirations → Cushing’s triad (impending herniation)
  • Lucid interval → rapid deterioration + anisocoria → Epidural hematoma with uncal herniation
ICP / monitoring
  • ICP <22 mmHg, CPP 60–70 mmHg → BTF (4th edition) targets in severe TBI
  • Papilledema + vomiting + decreased LOC + 6th nerve palsy → Elevated ICP syndrome
  • Lundberg A waves (plateau waves >50 mmHg × 5–20 min) → Critical loss of intracranial compliance
  • External ventricular drain (EVD) → Gold standard ICP monitor — allows therapeutic CSF drainage
  • Apnea test: PaCO2 ≥60 AND ≥20 above baseline AND pH <7.30, no respiratory effort → Positive for brain death (2023 BD/DNC)
  • No cerebral blood flow on cerebral angiography / radionuclide perfusion scan / TCD oscillating-reverberating flow / CT angiography → Ancillary brain death confirmation when apnea test cannot be completed (EEG and evoked potentials are NOT recommended ancillary tests in the 2023 guideline)
  • Hypothermia <36°C, sedatives, paralytics, severe electrolyte/acid-base derangement → Confounders — do NOT declare brain death
Treatment / pearls
  • HOB 30° + normothermia + normocapnia + normonatremia + sedation/analgesia → Tier 1 ICP management
  • Mannitol 0.25–1 g/kg IV bolus → Osmotic diuresis (avoid if hypotensive or osm >320)
  • 3% hypertonic saline (target Na 145–155) → Preferred osmotherapy when hypovolemic/hypotensive
  • Pentobarbital coma (burst suppression on EEG) → Refractory ICP tier 3 therapy
  • Decompressive craniectomy (DECRA, RESCUE-ICP) → Refractory ICP elevation despite maximal medical therapy
  • Levetiracetam or phenytoin × 7 days → Early post-traumatic seizure prophylaxis (severe TBI)
  • NEXUS criteria / Canadian C-spine rule → Clinical cervical spine clearance in alert trauma patient
  • One complete neurologic exam + at least one apnea test by qualified examiner (adults); two exams + two apnea tests (children) → 2023 unified BD/DNC declaration protocol
Subdural Hematoma (SDH)

Classification by Timing

TypeTime from InjuryCT AppearanceClot ConsistencyTypical Surgical Approach
Acute<3 daysHyperdense (bright white) crescentSolid clotCraniotomy
Subacute3–21 daysIsodense (may be missed on CT)Mix of solid + liquidCraniotomy or burr hole
Chronic>21 daysHypodense (dark) crescentLiquefiedBurr hole drainage
  • Mechanism: tearing of bridging veins between cortex and dural sinuses; blood collects between dura and arachnoid
  • Acute SDH: high-velocity injury (falls, MVA, assault); 50–90% mortality in severe cases; often associated with underlying brain contusion
  • Chronic SDH: elderly, anticoagulated, or brain atrophy patients; minor or unrecalled trauma; neomembrane with fragile vessels → recurrent bleeding and gradual enlargement
  • Bilateral SDH: think coagulopathy, anticoagulation, alcohol use, or elderly with atrophy
  • Isodense subacute SDH: easily missed — look for effaced sulci, midline shift without obvious mass, and medial displacement of the gray-white junction

Surgical Indications

Indications for Surgical Evacuation

  • SDH thickness >10 mm
  • Midline shift >5 mm
  • GCS drop ≥2 points from time of injury to hospital arrival
  • ICP >20 mmHg
  • Posterior fossa SDH with any mass effect or neurological deterioration — very low threshold to operate

Surgical Approach

  • Acute SDH → craniotomy: solid clot requires open evacuation and direct hemostasis; large bone flap for adequate exposure
  • Chronic SDH → burr hole drainage: liquefied collection drains easily through 1–2 burr holes; subdural drain left for 24–48 h to prevent re-accumulation
  • Subacute SDH: may require either approach depending on clot consistency (assessed on imaging)
  • Timing: acute SDH should be evacuated within 4 hours of injury for best outcomes (mortality increases significantly with delays beyond 4 h)

Medical (Non-Operative) Management Criteria

  • SDH thickness <10 mm AND midline shift <5 mm
  • Neurologically stable (no GCS decline)
  • ICP <20 mmHg (if monitored)
  • No posterior fossa location
  • Requires serial imaging every 6–12 h initially, then daily
  • Correct coagulopathy; reverse anticoagulation; hold antiplatelets

Board Pearls

  • Acute SDH = craniotomy (solid clot); chronic SDH = burr hole (liquid) — this is a favorite board question
  • Isodense subacute SDH can be invisible on CT — look for unexplained midline shift, effaced sulci, or “missing” cortical ribbon
  • Chronic SDH recurrence rate after burr hole drainage is 10–20%; risk factors include bilateral SDH, coagulopathy, and brain atrophy
  • Posterior fossa SDH has a very low threshold for surgery — small volume changes can cause rapid brainstem compression and death
🔒

Continue reading — sign in

The full note has more clinical pearls, tables, and board-focused tips. Free account, no fee.

Sign in Create free account