Craniotomy indications and techniques

Craniotomy indications and techniques

Craniotomy indications and techniques

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🧠 Clinical - Why Open the Box?

Craniotomy is indicated for accessing intracranial structures to treat pathology.

  • Tumor Resection:
    • Primary (glioma) or metastatic brain tumors.
    • Benign tumors (meningioma) causing mass effect.
  • Traumatic Brain Injury (TBI):
    • Evacuation of space-occupying hematomas (epidural, subdural).
    • Decompressive craniectomy for refractory intracranial pressure (↑ICP).
  • Vascular Lesions:
    • Clipping of cerebral aneurysms.
    • Resection of arteriovenous malformations (AVMs).
  • Infection:
    • Drainage of brain abscesses or subdural empyema.

⭐ An epidural hematoma (EDH) with neurological decline, pupillary changes, or volume >30 cm³ requires emergent craniotomy and evacuation, especially following a "lucid interval."

🗺️ Anatomy - Skull's Surgical Atlas

Key Surgical Landmarks (Craniometric Points):

  • Pterion: "H"-shaped junction of frontal, parietal, temporal, & sphenoid bones; weakest point of the skull.
  • Bregma: Junction of coronal & sagittal sutures; site of anterior fontanelle.
  • Lambda: Junction of sagittal & lambdoid sutures; site of posterior fontanelle.
  • Asterion: Junction of lambdoid, occipitomastoid, & parietomastoid sutures; key for retrosigmoid approach.
  • Stephanion: Junction of coronal suture & superior temporal line.

Craniotomy Approaches and Skull Landmarks

Common Surgical Approaches & Targets:

  • Pterional: "Workhorse" approach for Circle of Willis aneurysms, suprasellar tumors.
  • Retrosigmoid/Suboccipital: Cerebellopontine Angle (CPA) tumors (e.g., acoustic neuroma).
  • Bifrontal: Anterior skull base tumors (e.g., olfactory groove meningioma).
  • Transsphenoidal: Pituitary adenomas (via nasal cavity).

Pterion fracture is a neurosurgical emergency. It can lacerate the underlying anterior division of the middle meningeal artery, leading to a life-threatening epidural hematoma.

🛠️ Clinical - The Neurosurgeon's Toolkit

A craniotomy is a surgical procedure where a bone flap is temporarily removed from the skull to access the brain.

  • Positioning: Patient's head is immobilized using a Mayfield clamp (3-pin skull fixation). Mayfield clamp for rigid skull fixation in neurosurgery
  • Access:
    • An incision is made, and a scalp flap is reflected.
    • Burr holes are drilled into the skull.
    • A craniotome (foot-plated drill) connects the burr holes to create the bone flap.
  • Exposure & Closure:
    • The dura mater is opened (C-shaped flap) and later closed (watertight).
    • The bone flap is replaced using titanium plates and screws.

Pearl: The base of the C-shaped dural flap is typically oriented towards major venous sinuses (e.g., superior sagittal sinus) to preserve venous drainage and reduce bleeding risk.

⚠️ Complications - Post-Op Pitfalls

  • Immediate (Hours-Days)

    • Hemorrhage (EDH, SDH, IPH): Presents with new focal deficits or ↓LOC. Requires urgent CT scan.
    • Cerebral Edema: Worsening neuro status. Manage with steroids, osmotherapy.
    • Ischemic Stroke: From direct vessel injury or vasospasm.
  • Early (Days-Weeks)

    • CSF Leak: Clear rhinorrhea/otorrhea (test for β-2 transferrin), postural headache.
    • Meningitis: Fever, nuchal rigidity, altered mental status.
    • Seizures: Prophylaxis is common (e.g., levetiracetam).
    • VTE (DVT/PE): High risk due to immobility.
  • Late (Weeks-Months)

    • Hydrocephalus: Impaired CSF absorption/flow.
    • Syndrome of the Trephined: Sunken flap with neuro decline; cranioplasty is curative.

⭐ Post-op fever workup: Rule out non-neuro causes first (wind, water, wound, walking, wonder drugs). If negative, consider meningitis/ventriculitis; obtain CSF if safe.

Post-craniotomy epidural hematoma: diagrams and CT scans

⚡ Biggest Takeaways

  • Craniotomy involves removing and replacing a bone flap for definitive treatment of tumors, hematomas, or vascular lesions.
  • Craniectomy is removal of the bone flap without immediate replacement, primarily for decompression in severe TBI or malignant stroke.
  • The pterional approach is a workhorse for anterior circulation aneurysms (e.g., ACoA, PCoA) and suprasellar tumors.
  • The suboccipital approach provides access to the posterior fossa (cerebellum, brainstem).
  • Major risks include post-operative hematoma, infection, seizures, and new neurological deficits.

Practice Questions: Craniotomy indications and techniques

Test your understanding with these related questions

The surgical equipment used during a craniectomy is sterilized using pressurized steam at 121°C for 15 minutes. Reuse of these instruments can cause transmission of which of the following pathogens?

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Flashcards: Craniotomy indications and techniques

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A _____ is indicated when an emergency airway is required or orotracheal / nasotracheal intubation is unsuccessful / contraindicated

TAP TO REVEAL ANSWER

A _____ is indicated when an emergency airway is required or orotracheal / nasotracheal intubation is unsuccessful / contraindicated

cricothyrotomy

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