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The Flared Mandible Sign of the Flail Mandible
1
•
Diagnostic Radiology
Amll James Gerlock, Jr., M.D. A useful radiographic finding is described for the diagnosis of a flail mandible. The flail mandible removes forward support for the tongue, which may result in airway obstruction. Immediate radiographic diagnosis allows quick surgical correction of the fractured mandible and relief of the obstruction, decreasing the time during which an endotracheal or tracheostomy tube is needed to keep the airway open. INDEX TERMS:
Jaws, fractures
Radiology 117:299-300, May 1976
•
• out to insert into the body of the tongue. Contraction of the genioglossus muscle causes the tongue to be pulled forward against the rigid support of the mandible, resulting in anterior movement of the base of the tongue and protrusion of its tip. In the presence of significant mandibular fractures, the patient may be unable to elevate or protrude the tongue by contracting the genioglossus muscles, so that the tongue falls backward and obstructs the oropharynx (Fig. 2). The preservation of mandibular integrity, to provide a rigid and fixed point of attachment for the genioglossus muscles, is therefore vital in providing an open airway. Fractures of the mandible are variable. The most common sites of fractures are the angle, the canine region, and the neck of the condyle (3). Two or more fractures of the mandible are commonly present, so that the
not usually life-threatening F injuries. The repair are and restoration of disfiguring faACIAL FRACTURES
cial trauma should not distract one's attention so strongly that coexisting injuries go unrecognized, such as subdural hematomas, pneumothoraces, ruptured viscera, or spinal fractures. Priority in the management of facial fractures is then assigned to the control of airway obstruction and hemorrhage. Airway obstruction often occurs with fractures of the mandible. It is important for the radiologist to examine this bone carefully and understand its role in airway obstructions, since it is the most frequently fractured bone of the face (2). This is especially true when trauma causes a flail mandible, which results when fractures destroy the ability of the mandible to maintain support for the mouth and forward support for the tongue. Figure 1 is a facial radiograph of a patient in respiratory difficulty following facial trauma, demonstrating some of the fractures which can cause a flail mandible. Note the fractures through the condylar neck and mandibular ramus and the characteristically flared appearance of the mandible, indicating a fracture through the symphysis menti region. An unstable fracture of the mandible such as this should lead to an immediate intubation of the patient in order to prevent possible complete obstruction of the airway. This patient underwent mandibular corrective surgery, following which no endotracheal or tracheostomy tube was needed in order to maintain an open airway. DISCUSSION
The genioglossus muscles, protruders of the tongue, are "safety muscles" which prevent the tongue from obstructing the airway. If these muscles are ineffective as a result of paralysis or fracture of the mandible, the tongue falls backward, occluding the oropharynx; suffocation may occur. The genioglossus muscle originates from the mental spine of the mandible (1), which is located on the inner surface where the two bodies of the mandible fuse. together at the symphysis to form the mandibular arch. From their origin, these muscles fan 1
Fig. 1. Anteroposterior view of the skull shows flaring of the mandibular bodies. Note the fractures to the condylar neck, symphysis menti region, and ramus of the mandible (solid arrows). Malocclusion is also present (open arrow).
From the Department of Radiology, The University of Texas Health Science Center, Dallas, Texas. Accepted for publication in August
1975.
ss
299
300
AMIL JAMES GERLOCK
May 1976
Fig. 2. A. The normal position of the tongue with the orpharynx nonobstructed. Labeled structures are: (1) mental spine; (2) symphysis manti region of the mandible; (3) genioglossi muscles; (4) posterior pharyngeal wall; and (5) base of the tongue. B. Posteriorly displaced fracture fragment of the mandible (arrow) resulting in occlusion of the space between the posterior pharyngeal wall and the base of the tongue.
bony fragments become less stable and their displace.ment is usually more severe. Outward flaring of the bodies of the mandible results from fractures of the symphysis region, which usually result from trauma to the chin. In addition to the symphysis fracture, one or both condylar necks or rami of the mandible may also be fractured (Fig. 3). When this occurs, the anterior portion' of the bodies of the mandible are retracted inward by the posterior pulling force of the diagnostic musculature. Internal rotation of the mandibular bodies causes the angles of the mandible to protrude outward. This deformity, combined with an expansion of the mandibular arch, causes the bodies of the mandible to be viewed en face on the Waters or anteroposterior projection of the skull (Figs. 1 and 3). This visualization of the mandibular bodies gives them a flared configuration and constitutes the flared mandibular sign, indicating that symphysis and bilateral condylar neck (or rami) fractures are present, although the fracture through the symphysis of .the mandible may not be seen due to superimposition of the cervical spine. The flared appearance of the mandi-
Fig. 3. Flaring of the bodies of the mandible as'a result of fractures of the condylar neck. ramus. and symphysis menti (solid arrows). Curved arrows indicate the internal rotation of the mandibular bodies.
ble as a result of facial trauma indicates an unstable, dangerous complex of multiple mandibular fractures which, if not stabilized, can lead to complete airway obstruction and suffocation. Department of Radiology Parkland Memorial Hospital 5323 Harry Hines Blvd. Dallas. Texas 75235
REFERENCES 1. Gray H: Anatomy of the Human Body. Philadelphia, Lea & Febiger, 26th Ed, 1956, P 1263 2. Pendergrass EP, Schaeffer JP: The Head and Neck in Roentgen Diagnosis. Springfield. Thomas, 2d Ed, Vol 1, 1956, P 215 3. Shanks SC, Kerley P: A Textbook of X-Ray Diagnosis. Philadelphia, Saunders, 4th Ed, Vol 1. 1969, P 503
The Flared Mandible Sign of the Flail Mandible
1
•
Diagnostic Radiology
Amll James Gerlock, Jr., M.D. A useful radiographic finding is described for the diagnosis of a flail mandible. The flail mandible removes forward support for the tongue, which may result in airway obstruction. Immediate radiographic diagnosis allows quick surgical correction of the fractured mandible and relief of the obstruction, decreasing the time during which an endotracheal or tracheostomy tube is needed to keep the airway open. INDEX TERMS:
Jaws, fractures
Radiology 117:299-300, May 1976
•
• out to insert into the body of the tongue. Contraction of the genioglossus muscle causes the tongue to be pulled forward against the rigid support of the mandible, resulting in anterior movement of the base of the tongue and protrusion of its tip. In the presence of significant mandibular fractures, the patient may be unable to elevate or protrude the tongue by contracting the genioglossus muscles, so that the tongue falls backward and obstructs the oropharynx (Fig. 2). The preservation of mandibular integrity, to provide a rigid and fixed point of attachment for the genioglossus muscles, is therefore vital in providing an open airway. Fractures of the mandible are variable. The most common sites of fractures are the angle, the canine region, and the neck of the condyle (3). Two or more fractures of the mandible are commonly present, so that the
not usually life-threatening F injuries. The repair are and restoration of disfiguring faACIAL FRACTURES
cial trauma should not distract one's attention so strongly that coexisting injuries go unrecognized, such as subdural hematomas, pneumothoraces, ruptured viscera, or spinal fractures. Priority in the management of facial fractures is then assigned to the control of airway obstruction and hemorrhage. Airway obstruction often occurs with fractures of the mandible. It is important for the radiologist to examine this bone carefully and understand its role in airway obstructions, since it is the most frequently fractured bone of the face (2). This is especially true when trauma causes a flail mandible, which results when fractures destroy the ability of the mandible to maintain support for the mouth and forward support for the tongue. Figure 1 is a facial radiograph of a patient in respiratory difficulty following facial trauma, demonstrating some of the fractures which can cause a flail mandible. Note the fractures through the condylar neck and mandibular ramus and the characteristically flared appearance of the mandible, indicating a fracture through the symphysis menti region. An unstable fracture of the mandible such as this should lead to an immediate intubation of the patient in order to prevent possible complete obstruction of the airway. This patient underwent mandibular corrective surgery, following which no endotracheal or tracheostomy tube was needed in order to maintain an open airway. DISCUSSION
The genioglossus muscles, protruders of the tongue, are "safety muscles" which prevent the tongue from obstructing the airway. If these muscles are ineffective as a result of paralysis or fracture of the mandible, the tongue falls backward, occluding the oropharynx; suffocation may occur. The genioglossus muscle originates from the mental spine of the mandible (1), which is located on the inner surface where the two bodies of the mandible fuse. together at the symphysis to form the mandibular arch. From their origin, these muscles fan 1
Fig. 1. Anteroposterior view of the skull shows flaring of the mandibular bodies. Note the fractures to the condylar neck, symphysis menti region, and ramus of the mandible (solid arrows). Malocclusion is also present (open arrow).
From the Department of Radiology, The University of Texas Health Science Center, Dallas, Texas. Accepted for publication in August
1975.
ss
299
300
AMIL JAMES GERLOCK
May 1976
Fig. 2. A. The normal position of the tongue with the orpharynx nonobstructed. Labeled structures are: (1) mental spine; (2) symphysis manti region of the mandible; (3) genioglossi muscles; (4) posterior pharyngeal wall; and (5) base of the tongue. B. Posteriorly displaced fracture fragment of the mandible (arrow) resulting in occlusion of the space between the posterior pharyngeal wall and the base of the tongue.
bony fragments become less stable and their displace.ment is usually more severe. Outward flaring of the bodies of the mandible results from fractures of the symphysis region, which usually result from trauma to the chin. In addition to the symphysis fracture, one or both condylar necks or rami of the mandible may also be fractured (Fig. 3). When this occurs, the anterior portion' of the bodies of the mandible are retracted inward by the posterior pulling force of the diagnostic musculature. Internal rotation of the mandibular bodies causes the angles of the mandible to protrude outward. This deformity, combined with an expansion of the mandibular arch, causes the bodies of the mandible to be viewed en face on the Waters or anteroposterior projection of the skull (Figs. 1 and 3). This visualization of the mandibular bodies gives them a flared configuration and constitutes the flared mandibular sign, indicating that symphysis and bilateral condylar neck (or rami) fractures are present, although the fracture through the symphysis of .the mandible may not be seen due to superimposition of the cervical spine. The flared appearance of the mandi-
Fig. 3. Flaring of the bodies of the mandible as'a result of fractures of the condylar neck. ramus. and symphysis menti (solid arrows). Curved arrows indicate the internal rotation of the mandibular bodies.
ble as a result of facial trauma indicates an unstable, dangerous complex of multiple mandibular fractures which, if not stabilized, can lead to complete airway obstruction and suffocation. Department of Radiology Parkland Memorial Hospital 5323 Harry Hines Blvd. Dallas. Texas 75235
REFERENCES 1. Gray H: Anatomy of the Human Body. Philadelphia, Lea & Febiger, 26th Ed, 1956, P 1263 2. Pendergrass EP, Schaeffer JP: The Head and Neck in Roentgen Diagnosis. Springfield. Thomas, 2d Ed, Vol 1, 1956, P 215 3. Shanks SC, Kerley P: A Textbook of X-Ray Diagnosis. Philadelphia, Saunders, 4th Ed, Vol 1. 1969, P 503
