Overview
Plagiocephaly is a term used to describe an asymmetric head shape. The word itself comes from the Greek plagios (oblique or slanted) and kephale (head). It is important to identify the type of plagiocephaly which is classified into:
Frontal (anterior) plagiocephaly, caused by unilateral synostosis of the coronal suture
Occipital (posterior) plagiocephaly, caused by unilateral synostosis of the lambdoid suture
Frontal (anterior) plagiocephaly
Causes
This condition occurs with premature closure of one coronal suture on one side of the skull. The resulting deformity does not only affect the skull, but it also results in under development of the ipsilateral frontal bone (forehead), supraorbital ridge (eyebrow) and anterior cranial fossa, giving a flattened appearance. The pathological changes also extend to involve the base of the skull resulting in lower facial deformity. This disorder is not congenital, does not have a genetic basis and is usually not associated with raised intracranial pressure.
Symptoms
A characteristic skull deformity is noted where the frontal bone is depressed on the affected side giving the normal side a false appearance of a bulging forehead. The supraorbital ridge is also underdeveloped and deviated backward and upward and there is a lower face twist causing a “winking” effect. The ipsilateral ear is usually situated more anterior and inferior than normal.
Diagnosis
Radiologically, a characteristic feature of frontal plagiocephaly is that the supraorbital margin sweeps backward and upward in what is described as “harlequin orbit”. The sphenoidal margin is also seen to sweep upward parallel to the supraorbital margin. The ipsilateral coronal suture is prematurely fused and examination of the skull often reveals a palpable ridge overlying that suture.
Treatment
The traditional surgery involves surgical release i.e. reopening of the prematurely fused suture. This is extended down to the base of the skull and the surgery is typically accompanied with reconstructive remodeling of the frontal bone (forehead bone), and the supraorbital ridge (eyebrow portion of eye socket) in order to bring the forehead and eyebrow in a position symmetrical to the unaffected side.
Posterior (occipital) plagiocephaly
Causes
The two predominant causes of posterior plagiocephaly are craniosynostosis (<2%) or positional molding (vast majority) of the lambdoid suture. This results in the flattening of the ipsilateral parietooccipital region.
Positional (deformational) plagiocephaly refers to a misshapen (asymmetrical) shape of the head resulting from external repeated pressure to the same area of the head over a relatively long period of time causing a baby's head shape to be abnormal but with no real fusion of the skull sutures. The condition has become more common since the American Academy of Pediatrics recommended that infants sleep on their backs to reduce the incidence of sudden infant death syndrome (SIDS). Causes of positional plagiocephaly include prematurity, torticollis and cervical spine abnormalities.It is usually managed using non-surgical techniques except in severe persistent cases.
Symptoms
True lambdoid synostosis (posterior plagiocephaly) is a very rare form of craniosynostosis and is commonly mistaken for positional plagiocephaly. In true lambdoid synostosis, the lambdoid suture is fused. This gives the affected side a flattened appearance along the back of the head and when looking down at the patient, the ear on the affected side is pulled back toward the involved suture. The forehead is usually not affected as severely but may appear flattened. In contrast, with positional plagiocephaly, the backside of the head is flat but the ear is pushed forward and the forehead on that same side appears full. Additionally, in deformational plagiocephaly, the skull shape abnormality may not have been present at birth and may improve over time, while in posterior plagiocephaly, due to the true synostosis of the lambdoid suture, the deformity is present at birth and worsens with time. Torticollis, prematurity and cervical spine abnormalities are often suggestive of posterior positional molding.
Diagnosis
Radiographic evaluation of the skull would reveal unilateral premature fusion of the lambdoid suture in posterior plagiocephaly. Examination would reveal a flattening of one occiput with an apparent bulging of the normal side. In positional plagiocephaly, there is no fusion of the lambdoid suture.
Treatment
Surgery is the definitive treatment in posterior plagiocephaly. Traditional surgery involves a lambdoid craniectomy or multiple posterior skull craniectomies to correct the deformity. The occipital bone may be removed, reshaped and replaced.
In positional plagiocephaly, parents should try keeping the baby off the affected side. These positioning maneuvers are more successful when started early. Severe and persistent positional plagiocephaly can be treated with a head band or a helmet that is custom-molded to the baby’s head and designed to apply gentle pressure on selective areas. The helmet is worn 23 hours a day and treatment length varies. Persistent, severe or a cosmetically obvious deformity can be corrected with reconstructive surgery.
Prognosis of Plagiocephaly
Plagiocephaly in itself does not affect brain growth or cause any developmental delays or brain damage to the newborn. The goals of surgery are to release the suture and allow growth of the brain while making the skull symmetrical. Following surgery, frequent medical evaluations are needed to ensure that the skull, facial bones and brain are developing normally.
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