Neurosurgery notes/Trauma/Primary head Injury/Fractures/Base of skull fractures

Base of skull fractures

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Fractures

Basal skull fractures

General information

  • Most basal (AKA basilar) skull fractures (BSF) are extensions of fractures through the cranial vault.
  • Severe basilar skull fractures may produce shearing injuries to the pituitary gland.
  • BSF, especially those involving the clivus, may be associated with traumatic aneurysms.
  • This rarely occurs in paediatrics.

Specific fracture types

Frontal bone

  • Frontal sinuses are involved in up to 15% of facial fractures

Temporal bone fractures

  • Types: Often mixed
      • Longitudinal fracture:
      • More common (70–90%).
      • Usually through petro-squamosal suture, parallel to and through EAC.
      • Can often be diagnosed on otoscopic inspection of the EAC.
      • Usually passes between cochlea and semicircular canals (SCC), sparing the VII and VIII nerves, but may cause conductive hearing loss (ossicular chain disruption, tympanic membrane rupture)
      Transverse fracture:
      • Perpendicular to EAC.
      • Often passes through cochlea and may place stretch on geniculate ganglion, resulting in VIII and VII nerve deficits
        • The so- called otic capsule– violating fractures involve the labyrinth (i.e. cochlea, vestibule, or semicircular canals) and patients were found to be 2x develop facial paralysis, 4x CSF leak, and 7x more likely to develop profound hearing loss
      • Posttraumatic unilateral peripheral facial nerve palsy
        • Associated with transverse petrous bone fractures as noted above.
      • Greater force
        • They have other associated injuries (epidural hematoma, diffuse axonal injury)
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  • Management
    • Management is often complicated by multiplicity of injuries (including head injury requiring endotracheal intubation) making it difficult to determine the time of onset of facial palsy.
    • Guidelines:
      • Regardless of time of onset:
          • a) Steroids (glucocorticoids) are often utilized (efficacy unproven)
          b) Consultation with ENT physician is usually indicated
      • Immediate onset of unilateral peripheral facial palsy: facial EMG ( AKA electroneuronography or ENOG ) takes at least 72 hrs to become abnormal. These cases are often followed and are possible candidates for surgical VII nerve decompression if no improvement occurs with steroids (timing of surgery is controversial, but is usually not done emergently)
      • Delayed onset of unilateral peripheral facial palsy: follow serial ENOGs, if continued nerve deterioration occurs while on steroids, and activity on ENOG drops to less than 10% of the contralateral side, surgical decompression may be considered (controversial, thought to improve recovery from ≈ 40% to ≈ 75% of cases)

Clival fractures

  • 3 categories (75% are longitudinal or transverse):
    • Longitudinal:
      • May be associated with injuries of vertebrobasilar vessels, including:
        • Dissection or occlusion: may cause brainstem infarction
        • Traumatic aneurysms
    • Transverse:
      • May be associated with injuries to the anterior circulation
    • Oblique
  • Clinical features
    • Highly lethal.
    • Cranial nerve deficits:
      • Especially III through VI;
      • Bitemporal hemianopsia
    • CSF leak
    • Diabetes insipidus
    • Delayed development of traumatic aneurysms

Occipital condyle fractures

Radiographic diagnosis

  • BSF appear as linear lucencies through the skull base.
  • CT scan with multiplanar projections
    • Most sensitive means for directly demonstrating BSF.
  • Water-soluble intrathecal contrast or from a nuclear cisternogram with nasal pledgets for small or questionable leaks.

Clinical diagnosis: Some of these signs may take several hours to develop.

  • CSF otorrhea or rhinorrhea
  • Hemotympanum or laceration ofexternal auditory canal
  • Postauricular ecchymoses (Battle’s sign)
  • Periorbital ecchymoses (raccoon’s eyes) in the absence ofdirect orbital trauma, especially if bilateral
  • Cranial nerve injury:
    • CN VII and/or VIII: usually associated with temporal bone fracture
    • CN I injury: often occurs with anterior fossa BSF and results in anosmia, this fracture may extend to the optic canal and cause injury to the optic nerve (CN II)
    • CN VI injury: can occur with fractures through the clivus

Management

NG tubes
  • ❌ Caution: cases have been reported with BSF where an NG tube has been passed intracranially through the fracture and is associated with fatal outcome in 64% of cases.
  • Possible mechanisms include:
    • A cribriform plate that is
      • Thin (congenitally or due to chronic sinusitis) OR
      • Fractured (due to a frontal basal skull fracture or a comminuted fracture through the skull base).
  • Suggested contraindications to blind placement of an NG tube include:
    • Trauma with possible basal skull fracture
    • Ongoing or history of previous CSF rhinorrhea
    • Meningitis with chronic sinusitis.
Prophylactic antibiotics
  • The routine use of prophylactic antibiotics is controversial.
    • This remains true even in the presence of a CSF fistula
    • However, most ENT physicians recommend treating fractures through the nasal sinuses as open contaminated fractures, and they use broad spectrum antibiotics (e.g. ciprofloxacin) for 7–10 days.
  • Pneumococcal vaccine
    • If there is CSF leak is recommended for adults age 2–65 years
Steroids
  • Often used without good evidence for facial nerve palsy

Treatment

  • Most do not require treatment by themselves.
  • However, conditions that may be associated with BSF that may require specific management include:
    • “Traumatic aneurysms”
      • Posttraumatic carotid-cavernous fistula
    • CSF fistula:
      • Operative treatment may be required for persistent CSF rhinorrhea
    • Meningitis or cerebral abscess:
      • May occur with BSF into air sinuses (frontal or mastoid) even in the absence of an identifiable CSF leak.
      • May even occur many years after the BSF was sustained
    • Cosmetic deformities
  • Observation
    • (Bed rest, avoid straining, pneumococcal vaccination)
    • For 5-7 days.
    • Most traumatic CSF leaks resolve spontaneously within the first week.
    • Avoid prophylactic antibiotics in well patients as they do not prevent meningitis and select for resistant organisms.
    • Detailed auditory, vestibular, and facial nerve function examination.
      • Immediate complete facial nerve paralysis and temporal bone fracture are considered for high-dose steroid treatment or surgical exploration to decompress or graft the nerve,
        • Whereas delayed onset of the facial paralysis or those who initially have only facial paresis are treated with steroids, and observed, because some spontaneous recovery frequently occurs.
  • If CSF leak persists,
    • Attempt serial lumbar puncture to exclude hydrocephalus and perform therapeutic tap.
    • If lumbar puncture fails, insert lumbar drain and continue with bed rest.
      • Once no leak for 24-48 h can challenge lumbar drain.
      • If no CSF leak can remove lumbar drain and monitor for a period before discharge.
      • If pneumocephalus develops during the course of the CSF drainage, the drainage procedure is terminated and the dural leak is surgically closed.
  • Surgical repair
    • Indicated
      • If leak persists/recurs despite lumbar drainage.
      • Enlarging pneumocephalus with Lumbar drain
  • Repeat auditory, vestibular, and facial nerve function examination 6-8 weeks after trauma to diagnose abnormalities and determine treatment or sequence progress.

Posttraumatic facial palsy

  • More common in transverse temporal bone fractures
  • Assessment
    • Clinically, with facial motion,
    • Electrodiagnostic testing
      • Aim
        • In differentiating a neurapraxic injury from a neural degenerative injury and to assess the proportion of degenerated axons.
      • Methods
          • Feature
          Hilger facial nerve stimulator
          Electroneuronography (EnoG)
          Standard electromyography (EMG)
          Stimulates or records
          Stimulates nerve
          Records nerve response
          Records muscle response
          Measurement
          Muscle contraction
          Nerve conduction time and amplitude
          Muscle activity at rest and during contraction
          Focus
          Facial nerve function
          Facial nerve function
          Any muscle
          Needle insertion
          No needles
          No needles
          Needles inserted into muscles
      • Can only be reliable after days 3-14
        • After nerve is injured it takes time for Wallerian degeneration to kick in and a consequent decrease or loss of stimulability.
          • The distal segment of the nerve maintains electrical stimulability for 3-5 days
  • Nash et al., 2010 (systematic review): Natural history of 189 patients managed with observation, who, 66% had an outcome equivalent to House- Brackmann (HB) I, one- quarter had HB II- V, and only two patients had an HB VI score
  • Clinical decision
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