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Frontal Bone Fractures

Overview
Fractures of the frontal bones can be broadly categorized based on sites of fracture, anterior and/or posterior table involvement, frontal sinus outflow tract involvement, and degree of displacement. When fractures involve the anterior table of the frontal sinus alone, the primary concerns relate to frontal sinus function and outflow as well as facial deformity secondary to a posteriorly displaced or impacted fracture. Chronic obstruction of the frontal outflow tract may lead to chronic sinusitis or mucocele formation, potentially with intracranial or intraorbital extension as a late sequelae. This complication is avoided by careful exploration and management of the frontal sinus outflow tract. Fracture of the posterior table of the frontal sinus can affect not only sinus function if displaced but, as with any skull fracture, is frequently associated with intracranial injury. This type of fracture is usually managed in concert with neurosurgery. Non-displaced posterior table fractures can be managed with observation alone though herniation of brain or dura into the sinus and/or CSF leak should be ruled out before consideration of conservative management. Traumatic anosmia is also relatively common through shearing of the olfactory neurons as they pass through the cribriform plate. Various classification systems have been devised for fractures involving the frontal sinus including Stanley and Becker’s system for prediction of frontal sinus outflow tract obstruction, though no system is consistently used in clinical practice. Supraorbital rim involvement or orbital roof involvement of the fracture can present with various orbital concerns such as reduced ocular motility or injury to the supratrochlear or supraorbital nerves leading to forehead hypoesthesia. Additionally, fractures of the orbital rim as well as the nasoethmoidal complex have high association with lacrimal system obstruction.

Key Supplies for Frontal Bone Fracture Consultation

  • Appropriate PPE including mask, eye protection, gloves, and gown

  • Headlight

  • Nasal Speculum

  • Flexible scope or rigid endoscope (with monitor & tower, if possible)

  • Antifog solution (Fred)

  • Oxymetazoline

  • Flashlight for pupil exam (or can use headlight)

Management

  • Full head and neck exam beginning with ABC’s and with attention to associated lacerations, sensation to forehead, presence of bony step off along orbital rims/frontal sinuses, facial contour over the frontal sinuses and glabella, extra ocular movements and visual acuity, presence of rhinorrhea or post nasal drip (may indicate CSF leak especially if clear and salty) and consideration of sinus evaluation with rigid endoscopy

  • High resolution maxillofacial CT is the imaging modality of choice with attention to involvement of the anterior and posterior tables, frontal sinus outflow tract, intracranial findings (pneumocephalus, epidural/subdural/subarachnoid hemorrhage, meningocele or encephalocele), fracture extension into the NOE complex, supraorbital rims, or anterior skull base

  • Make recommendation for appropriate consults to include ophthalmology, if orbital involvement, and neurosurgery for significant posterior table fractures with associated pneumocephalus or intracranial injury or hemorrhage 

  • Antibiotics are often considered for all posterior table fractures with coverage of common sinus organisms (e.g. amoxicillin/clavulanate or clindamycin) 

  • Conservative CSF leak treatments options:

    • Over 50% of traumatic CSF leaks will spontaneously resolve in 1 week with conservative management

    • Less likely to spontaneously resolve if posterior table displaced >5 mm

    • Conservative management: bedrest, head elevation, stool softeners, avoid Valsalva and nose blowing

    • CSF diversion (lumbar drain or EVD) may be added through neurosurgery if conservative management not working

    • Antibiotics: prophylactic antibiotics have not been shown to reduce risk of meningitis, data suggest surgical repair after 7 days of no spontaneous resolution minimizes risk of meningitis

  • Isolated anterior table fracture without high risk of outflow obstruction or facial contour deformity can be managed conservatively with observation and radiographic follow up. If forehead contour deformity is appreciated once the overlying soft tissue edema dissipates, this can be repaired secondarily

  • Depressed anterior table fracture with high risk of frontal sinus outflow tract obstruction (NOE fractures, fontal sinus floor fractures, or inferior medial anterior table displaced fractures) or forehead contour deformity are usually managed with surgery

    • For contour deformity, ORIF with plates, autologous bone from the outer table of the calvarium or iliac crest, mesh, or a custom implant

    • Most common approach is the coronal incision while other options include extension of an existing overlying laceration, bilateral brow incision (mid-forehead, pretrichial, etc.), or less commonly an upper blepharoplasty incision or gullwing/ spectacle incision

    • For sinus outflow tract obstruction, this can be managed with functional endoscopic sinus surgery or frontal sinus obliteration if severely comminuted (see AO surgery reference for management specifics)

  • For isolated anterior table fractures that may impinge on the frontal outflow tract without cosmetic deformity, consideration may be given to observation with serial imaging. If obstruction develops radiographically, endoscopic management may be considered to re-establish normal outflow and preserve sinus function.  This is often accomplished via a unilateral Draf IIB or Draf III frontal sinusotomy 

  • Displaced Posterior table fractures or patients with persistent CSF leak through the involved sinus are usually managed with cranialization of the sinus; frontal sinus obliteration has fallen out of favor at most centers secondary to the risk of late complications

    • Usually approached jointly with neurosurgery with a coronal incision and frontal craniotomy

    • Posterior table bony fragments are removed

    • Dura is inspected and any tears repaired primarily or with a fascia lata graft sutured to dura

    • Removal of all sinus mucosa including mucosal invaginations into the remaining bone

    • This is vital to reduce the risk of mucocele development as a late complication 

    • Smoothing of the bony surface of the frontal table (brain gradually fills the void left in the anterior cranial fossa)

    • A pericranial flap is often utilized as a second layer over the repaired dura or fascia lata graft

  • Follow Up:

    • Short and long term follow up is important because complications can develop; there is no strong consensus on timing of follow up

    • CT scans can be used for surveillance unless the frontal sinus is obliterated, then MRI is needed:

      • Fat: T1 Bright, T2 dark

      • Scar: T1 and T2 intermediate to dark

      • Mucosa/Mucocele: T1 hypo- to intermediate intensity and T2 intermediate to hyperintense (depending on the relative fluid content of the mucocele), but T1 gad bright peripherally in surrounding mucosa but hypointense centrally within the mucocele

References

1. Fokkens, W.J., Harvey, R. (2020). Management of the Frontal Sinuses. In Flint, P.W., et al (Eds.), Cummings Otolaryngology Head and Neck Surgery 7e (pp. 719-732). Philadelphia, PA: Elsevier.

2. Fusetti, S., et al. “Skull Base and Cranial Vault.” AO Foundation Surgery Reference, https://surgeryreference.aofoundation.org/cmf/trauma/skull-base-cranial-vault

3. Strong, E.B. (2013). Frontal Sinus Fractures. In J.J. Johnson, C.A. Rosen. (Eds.), Bailey’s Head and Neck Surgery-Otolaryngology 5e (pp. 1255-1271). Baltimore, MD: Lippincott Williams & Wilkins.