Craniofacial Clefts

Congenital craniofacial clefts are distortions of the face and cranium with deficiencies or excesses of tissue that cleave anatomic plans in a linear fashion. Craniofacial clefts exist in varying degrees of severity and in a multitude of patterns. Most craniofacial clefts occur along predictable embryologic lines.

Epidemiology

The precise incidence of craniofacial clefts has not been identified because of their rarity and difficulty in characterized physical findings in mild malformations. The incidence of craniofacial clefts has been estimated to be 1.4-4.9 / 100 000. The intrauterine incidence of facial deformities of any type has been documented to be grater than the incidence at live births. Fetuses of therapeutic abortions between 3-18 weeks of gestation were found to have craniofacial malformation at the rate of 42.5 / 100 000.

Etiology

The majority of craniofacial clefts occur sporadically. However, heredity has a role in the causation of craniofacial clefts in Treacher Collins syndrome and Goldenhar syndrome. Animal and human clinical studies have shown that many environmental factors may contribute to the cause of clefts. Four major categories group these factors;

1. radiation,

2. infection,

3. maternal metabolic imbalance,

4. drugs (anticonvulsants, chemotherapeutics, steroids, tranquilizer, retinoids) and

5. chemicals.

Important aspects of embryologic development of the face take place between 4 and 8 weeks of gestation. During this time, the crown-rump length increases from approximately 3,5 mm to 28 mm. Five prominences (the frontonasal and paired maxillary and mandibular) formed by neural crest migration surround the stomodeum. There is a coordination of cell migration, cellular interaction and apoptosis during a short 4 week period. Failure of this intricate program will result in clefts that usually fall along predictable embryonic lines.

Craniosynostosis

Craniosynostosis is the pathologic condition that results from premature fusion of one or more sutures in the cranial vault, leading to a deformity of the vault and cranial base. The condition may be caused by a genetic disorder, be related to gestational toxic influences, or be a sporadic congenital finding.

When a suture fuses prematurely, the skull and the growing brain beneath the suture are restricted, leading to expansion into regions of the skull with less restriction. This “compensatory” growth of the skull occurs largely in planes parallel to the affected suture, resulting in consistent, recognizable cranial deformities.

The 6 fontanelles present at birth are the anterior, posterior, and paired anterolateral and posterolateral fontanelles. The posterior fontanelle closes first at about 2 months. The anterolateral fontanelles (corresponding to the pterion in the adult) normally close 3 months after birth. The posterolateral fontanelles (corresponding to the asterion in the adult) close at the end of the first year, and the anterior fontanelle, which is the last to close, generally does so by 2 years.

The median frontal, or metopic, suture usually closes by 2-6 years. In 10% of the population it remains open until adulthood, and the frontal sinuses are absent or hypoplastic. The remaining sutures close clinically at 6-12 months but do not ossify completely until after 30 years.

The neurocranium achieves 63% of its ultimate growth by birth, 88% by 1 year, and 95% by 10 years. The neonatal brain doubles in volume by 6 months and triples in volume by 2.5 years. By 16 years, the calvaria achieves its mature size and only changes slightly as the bone thickens and remodels over the following 3-4 years.

Primary and secondary causes

In most patients, craniosynostosis is a primary event and occurs sporadically. While the mechanism of primary craniosynostosis remains to be elucidated, there are many known secondary causes.

Craniosynostosis may be induced through internal and external forces. Prenatal compression of the fetal head is implicated as a cause of craniosynostosis. Internal forces known to cause craniosynostosis include a number of teratogens and diseases. Teratogens implicated in craniosynostosis include;

Maxillofacial Trauma

Initial Management of the Trauma Patient

The initial assessment and management of a patient’s injuries must be completed in an accurate and systematic manner to quickly establish the extent of any injury to vital life-support systems. About

30 % of deaths caused by injury can be prevented when an organized and systematic approach is used

Death from trauma is within seconds or minutes of the injury due to;

1. 1. lacerations of the brain,

2. brainstem,

3. upper spinal cord,

4. heart,

5. aorta, or

6. other large vessels.

First few hours after injury (calls golden hours) is also important for life saving. Death is usually due to;

1. 1. central nervous system (CNS) injury

2. hemorrhage.

Sepsis, multiple organ failure, or pulmonary embolism is another reason of death within days or weeks.

Patients are assessed and treatment priorities are established based on patients’ injuries and the stability of their vital signs. Injuries can be divided into three general categories:

1. severe (airway, inadequate breathing ,hemorrhage, and circulatory system damage or shock)

2. urgent (injuries to the abdomen, orofacial structures, chest, or extremities) and

3. nonurgent (nonurgent injuries account for approximately 80% of all injuries)

Facial Fractures

Etiology: Maxillary fractures often result from high-energy blunt force injury to the facial skeleton. Typical mechanisms of trauma include motor vehicle accidents, altercations, and falls. The patterns of fracture propagation in midface trauma originates from the work of René Le Fort. In 1901. He concluded that predictable patterns of fractures follow certain types of injuries. Three predominant types were described.

LeFort I fractures (horizontal) may result from a force of injury directed low on the maxillary alveolar rim in a downward direction. The fracture extends from the nasal septum to the lateral pyriform rims, travels horizontally above the teeth apices, crosses below the zygomaticomaxillary junction, and traverses the pterygomaxillary junction to interrupt the pterygoid plates .

LeFort II fractures (pyramidal) may result from a blow to the lower or mid maxilla. Such a fracture has a pyramidal shape and extends from the nasal bridge at or below the nasofrontal suture through the frontal processes of the maxilla, inferolaterally through the

lacrimal bones and inferior orbital floor and rim through or near the inferior orbital foramen, and inferiorly through the anterior wall of the maxillary sinus; it then travels under the zygoma, across the pterygomaxillary fissure, and through the pterygoid plates .

LeFort III fractures (craniofacial dysjunctions), may follow impact to the nasal bridge or upper maxilla. These fractures start at the nasofrontal and frontomaxillary sutures and extend posteriorly along the medial wall of the orbit through the nasolacrimal groove and ethmoid bones.

The fracture continues along the floor of the orbit along the inferior orbital fissure and continues superolaterally through the lateral orbital wall, through the zygomaticofrontal junction and the zygomatic arch. Intranasally, a branch of the fracture extends through the base of the perpendicular plate of the ethmoid, through the vomer, and through the interface of the pterygoid plates to the base of the sphenoid .

In most instances, maxillary fractures are a combination of the various Le Fort types. In very high-energy blows, maxillary fractures may be associated with fractures to the mandible, cranium, or both (ie, panfacial).

Physical examination

Evaluation of the maxilla and facial bones should be undertaken only after the patient has been fully stabilized and life-threatening injuries have been addressed. In particular, airway considerations and intracranial injuries must take immediate priority.