In-Service Exam
Maxillo - Facial - 2002





A 35-year-old man has persistent enophthalmos 18 months after undergoing open reduction of a fracture of the orbital floor and zygoma. Forced duction testing shows no restriction of eye motion. Which of the following is the most likely cause of this patient's enophthalmos?

(A) Fat atrophy
(B) Fibrosis of the extraocular muscles
(C) Herniated contents of the orbit within the maxillary sinus
(D) Inadequate fracture reduction
(E) Scar contracture

The correct response is Option D.

Persistent enophthalmos following facial trauma is primarily caused by increased bony orbital volume secondary to inadequate fracture reduction. An appropriate anatomic reduction should be the initial goal of surgery; bone grafting may be required to restore orbital volume to normal levels.

Fat atrophy, extraocular muscle fibrosis, herniation of orbital contents, and scar contracture can also contribute to the discrepancy between traumatic and nontraumatic orbital volume, but are less likely to contribute to postoperative enophthalmos than inadequate fracture reduction. In addition, extraocular muscle fibrosis and/or scarring would typically be associated with limited motion of the globe on forced duction testing.

References
1. Manson PN, Grivas A, Rosenbaum A, et al. Studies on enophthalmos: II: the measurement of orbital injuries and their treatment by quantitative computed tomography. Plast Reconstr Surg. 1986;77:203-214.
2. Manson PN. Reoperative facial fracture repair. In: Grotting JC, ed. Reoperative Aesthetic and Reconstructive Plastic Surgery. Saint Louis, Mo: Quality Medical Publishing, Inc; 1995;1:677-759.
3. Pearl RM. Treatment of enophthalmos. Clin Plast Surg. 1992;19:99.

A 25-year-old man sustains a fracture of the frontal sinus in a motor vehicle collision. A CT scan of the frontal sinus shows a comminuted fracture of the anterior table and a linear nondisplaced fracture of the posterior table. There is no evidence of cerebrospinal fluid leak. Following removal of the anterior table fragments during surgical exploration, methylene blue is instilled into the sinus and passes into the nasal cavity.

Which of the following is the most appropriate management?

(A) Fixation of the anterior table bone fragments only
(B) Enlargement of the nasofrontal duct
(C) Ablation of the frontal sinus
(D) Cranialization of the frontal sinus
(E) Obliteration of the frontal sinus

The correct response is Option A.

In this patient who has sustained a frontal sinus fracture, the most appropriate management is fixation of the anterior table fragments. Intraoperative testing showing unobstructed passage of methylene blue into the nasal cavity indicates an intact sinus that should remain functional postoperatively.

Enlargement of the nasofrontal duct with stent placement is a new procedure that has not yet gained wide acceptance and is only indicated for patients with compromise of the nasofrontal duct. Ablation of the frontal sinus involves removal of the anterior table, which allows the forehead skin to collapse into the sinus. This procedure is no longer used because of its resultant cosmetic defects.
With cranialization of the frontal sinus, the posterior wall is removed and the intracranial contents (dura and brain) gradually expand anteriorly to fill the open space within the cranium. This procedure is often recommended for patients with severe comminution of the posterior table of the frontal sinus, particularly in the presence of a cerebrospinal fluid leak. Frontal sinus obliteration is appropriate for correction of nasofrontal duct obstruction, which in patients with frontal sinus fractures can be confirmed by failure of the methylene blue to pass into the nasal cavity.

References
1. Rohrich RJ, Hollier LH. Management of frontal sinus fractures: changing concepts. Clin Plast Surg. 1992;19:219-232.
2. Wolfe SA, Johnson P. Frontal sinus injuries: primary care and management of late complications. Plast Reconstr Surg. 1988;82:781-791.

A 25-year-old woman is brought to the emergency department after sustaining injuries in a motor vehicle collision. The patient is alert on initial evaluation and has a Glasgow Coma Scale score of 15. On physical examination, there is periorbital ecchymosis on the right, loss of sensation in the area of the left forehead, ptosis of the right upper eyelid, right-sided ophthalmoplegia, and a fixed, dilated pupil. Consensual light reflex is intact.

These findings are most consistent with which of the following?

(A) Dehiscence of the levator palpebrae superioris muscle
(B) Entrapment of the inferior rectus muscle
(C) Orbital apex syndrome
(D) Retrobulbar hematoma
(E) Superior orbital fissure syndrome

The correct response is Option E.

This patient has findings most consistent with superior orbital fissure syndrome, a high-velocity injury caused by extension of an orbital fracture into the superior orbital fissure. The oculomotor (III), trochlear (IV), and abducens (VI) nerves, and the ophthalmic division of the trigeminal nerve (V1) pass through the superior orbital fissure, which is formed from the greater and lesser wings of the sphenoid bone. Affected patients typically have paralysis of the extraocular muscles and the levator palpebrae superioris muscle resulting from injury to multiple nerves. If the ophthalmic division of the trigeminal nerve is involved, the patient will have anesthesia of the forehead, eyebrow, and upper eyelid.

The other conditions listed above would result in some but not all of the findings seen in this patient. Dehiscence of the levator palpebrae superioris muscle manifests as isolated ptosis of the eyelid. In patients with entrapment of the inferior rectus muscle, complete ophthalmoplegia would not be seen. Orbital apex syndrome is characterized by the findings associated with superior orbital fissure syndrome as well as blindness resulting from involvement of the optic nerve. Patients with retrobulbar hematomas may also experience the onset of blindness caused by increased intraocular pressure and proptosis.

References
1. Lettieri S. Facial trauma. In: Achauer BM, Eriksson E, Guyuron B, et al, eds. Plastic Surgery: Indications, Operations, and Outcomes. Saint Louis, Mo: Mosby Ð Year Book, Inc; 2000;2:923-940.
2. Perrott DH, Kaban LB. Acute management of orbitozygomatic fractures. Oral Maxillofac Surg Clin North Am. 1993;5:475-493.

During the application of rigid fixation in a 9-year-old child who has sustained a Le Fort I fracture, which of the following permanent tooth buds is at greatest risk for injury?

(A) Canine
(B) Central incisor
(C) First molar
(D) First premolar
(E) Lateral incisor

The correct response is Option A.

A 9-year-old child has mixed dentition; deciduous (primary) and permanent (secondary) teeth are present within the oral cavity simultaneously. This commonly occurs between ages 8 and 10 years. As a result, it is imperative for the surgeon to be aware of the potential for injury to the tooth buds when applying rigid fixation for management of pediatric maxillofacial fractures. The permanent canine teeth, or cuspids, erupt between ages 10 and 11 years. Therefore, the tooth buds can be injured during the application of rigid fixation in the region of the nasomaxillary buttress.

The central and lateral incisors erupt between ages 6 and 8 years. The permanent first molars erupt between ages 6 and 7 years, and the first premolars erupt between ages 8 and 9 years. Therefore, in a 9-year-old child, all of these teeth should have already begun erupting into the oral cavity, and the risk for injury to the tooth bud will be minimal.

References
1. Ash MM, Ramfjord S. Clinical occlusion. In: Occlusion. 4th ed. Philadelphia, Pa: WB Saunders Co; 1995:52-55.
2. Dufresne CR, Manson PN. Pediatric facial trauma. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:1142-1187.
3. Posnick JC. Management of facial fractures in children and adolescents. Ann Plast Surg. 1994;33:442-457.

A 24-year-old man sustains a Le Fort I fracture on the left and a Le Fort III fracture on the right in a motor vehicle collision. In this patient, which of the following bones is most likely to be fractured on both sides of the face?

(A) Ethmoid
(B) Orbital floor
(C) Palate
(D) Pterygoid plate
(E) Zygoma

PHOTO

Reproduced with permission of Cohen M, ed. Mastery of Plastic and Reconstructive Surgery. Boston, Mass: Little, Brown & Co; 1994.

The correct response is Option D.

In patients with Le Fort I fractures, the pterygoid plate is most likely to be affected, regardless of the type of fracture, because it lies posterior and thus forms the most posterior aspect of the fracture. The ethmoid, orbital floor, palate, and zygoma are each involved in some but not all types of Le Fort I fractures; an illustration is shown above.

References
1. Haug RH, Indresano AT. Management of maxillary fractures. In: Peterson LJ, ed. Oral and Maxillofacial Surgery. Philadelphia, Pa: JB Lippincott Co: 1992;1:469-489.
2. Yaremchuk MJ. Fractures of the maxilla. In: Cohen M, ed. Mastery of Plastic and Reconstructive Surgery. Boston, Mass: Little, Brown & Co; 1994;2:1156-1165.

Which of the following is a late complication following frontal sinus fracture?

(A) Cerebrospinal fluid leak
(B) Epistaxis
(C) Meningitis
(D) Mucocele
(E) Sinusitis

The correct response is Option D.

Patients with frontal sinus fractures, especially those involving the posterior table, can develop complications secondary to nasofrontal duct obstruction, dural injury, or entrapment of the sinus mucosa. Acute complications within the first few hours after injury can include epistaxis, cerebrospinal fluid leak, meningitis, and intracranial injury. The most common subacute complications occurring within the first few weeks following fracture are frontal sinusitis, mucocele, and meningitis. Long-term complications, such as osteomyelitis, mucocele, and chronic intracranial or orbital abscesses, can occur as late as several years after injury. Cosmetic deformities may also be seen late.

Because most complications occur in patients with fractures of the posterior table, appropriate reduction of all posterior fragments and repair of all dural tears are recommended. Reconstruction with pericranial flaps can decrease the risk for development of complications by distancing the brain tissue from the fracture site. Cranialization, which involves removal of mucosa and plugging of the nasofrontal ducts, can also be used to minimize complications. In patients who have nonfunctioning nasofrontal ducts, obliteration of the frontal sinus may be considered.

References
1. Wilson BC, Davidson B, Corey JP, et al. Comparison of complications following frontal sinus fractures managed with exploration with or without obliteration over 10 years. Laryngoscope. 1988;98:516.
2. Wolfe SA, Johnson P. Frontal sinus injuries: primary care and management of late complications. Plast Reconstr Surg. 1988;82:781-791.

In a 32-year-old man who sustained a panfacial fracture in a high-speed motor vehicle collision, what is the approximate risk for concomitant cervical spine injury?

(A) 5%
(B) 10%
(C) 15%
(D) 20%
(E) 25%
The correct response is Option B.

Patients who are involved in high-speed motor vehicle collisions have a risk for concomitant cervical spine injury that is closest to 10%. The incidence of associated cervical spine injury is greatly increased in these patients. Therefore, a patient who has sustained a facial fracture in a high-speed collision should be evaluated for a potential cervical spine injury prior to treatment of the facial fracture.

References
1. Dufresne CR, Manson PN. Pediatric facial trauma. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:1142-1187.
2. Manson PN. Facial injuries. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:867-1141.

In a patient who has sustained a fracture of the zygomaticomaxillary complex (tripod fracture), accurate reduction of the fracture components is most likely to be accomplished with the use of which of the following anatomic structures?

(A) Inferior orbital rim
(B) Lateral orbital wall
(C) Orbital floor
(D) Zygomatic arch
(E) Zygomaticomaxillary plane

The correct response is Option B.

Appropriate reduction of a fracture of the zygomaticomaxillary complex involves a three-dimensional process. In order to obtain the most accurate reduction, the lateral orbital wall and sphenoid wing should be visualized from inside the orbit. This will allow for visualization of the relatively flat plane of the orbital portion of the zygoma and the relatively flat portion of the sphenoid wing; accurate reduction is obtained when these two areas are aligned completely.

Although the inferior orbital rim, orbital floor, zygomatic arch, and zygomaticomaxillary plane are helpful sites for alignment individually, use of any of the sites as a landmark for accurate fracture reduction can result in significant rotational malalignment at the other sites.

References
1. Kelly KJ. Pediatric facial trauma. In: Achauer BM, Eriksson E, Guyuron B, et al, eds. Plastic Surgery: Indications, Operations, and Outcomes. Saint Louis, Mo: Mosby Ð Year Book, Inc; 2000;2:941-969.
2. Manson PN. Facial injuries. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:867-1141.

Which of the following fixation materials causes the LEAST amount of scatter on CT scan?

(A) Polylactic acid
(B) Stainless steel
(C) Tantalum
(D) Titanium
(E) Vitallium

The correct response is Option A.

The copolymer of polylactic acid and L-glycolic acid (Lactasorb) is a nonmetallic substance that is currently used in craniomaxillofacial fixation, is not visible on plain radiographs and/or CT scans, and is completely resorbed within one year following implantation.

Among metals used in fixation, stainless steel alloy (comprised of chromium, nickel, and molybdenum) exhibits the most scatter, while titanium and Vitallium (cobalt-chromium alloy) produce the least scatter. Tantalum is not currently used for craniomaxillofacial fixation because it exhibits inadequate mechanical properties.

References
1. Goldstein JA. Fixation principles. In: Achauer BM, Eriksson E, Guyuron B, et al, eds. Plastic Surgery: Indications, Operations, and Outcomes. Saint Louis, Mo: Mosby Ð Year Book, Inc; 2000;2:651-655.
2. Holmes RE. Alloplastic implants. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;1:698-731.