616 Craniosynostosis Craniosynostosis, the premature fusion of one or more cranial sutures, is most frequently described in relation to asymmetry and plagiocephaly, possibly as a result of the over-referral of infants with deformational non-synostotic DP to craniofacial or plastic surgery clinics. Primary craniosynostosis is either simple or compound and part of a genetic syndrome [36]. Premature closing of one lambdoid suture is the most frequently mentioned differ- ential diagnosis of DP [24, 33, 36]. The incidence of this single suture craniosynostosis is rare (1–3 cases to 100,000 newborns) [37, 42] and can be clinically differentiated from DP by four major signs: from the vertex view, a trapezoid head shape can be observed, a palpable unilateral ridge, bulging of the unilateral mastoid, and an asymmetric skull base with tilt to the ipsilateral side [24, 33, 42]. The impact of the premature closure of cranial sutures in complex craniosynostosis is impressive: strong progressive deformation of the skull, risk of increasing intracranial pressure, and developmental problems. When evident, timely surgical intervention is warranted [24, 33, 36, 50, 51]. The following three categories are groups of disorders. Clear incidence rates could not be found. Congenital abnormalities or malformations Musculoskeletal congenital malformations must be consid- ered in an asymmetry that is present immediately after birth [3, 7]. Well-known malformations are those of the spine, such as a Klippel-Feil syndrome, hemi-vertebrae, and a hemi-atlas [22, 38, 64]. Exceptional phenomena are hypoplasia or aplasia of the face, neck, or trunk muscles [2]. Patients may show defects in other systems as well, such as syndactyly, deafness, or a congenital heart disease. The co-incidence of defects may be an important sign of a syndrome. An asymmetric development or posture can be an associated finding in a variety of syndromes and abnormalities. These features are often present immediately after birth, but will not always be discovered until a second stage [64]. Local abnormalities, such as a vascular ring (around the trachea) or tracheomalacia, are occasionally an indirect cause of an asymmetric posture [60]. Disorders in sensory systems In the screening of infants with asymmetry, eye movement and/or vision and hearing disorders must be considered. Infants with congenital nystagmus and restrictive or paralytic strabismus may use anomalous head positions to maximize visual function [26, 47, 63]. No clear incidence rates were found. A predictive factor for an ocular origin of Eur J Pediatr (2008) 167:613–619 torticollis is the family history of ocular problems, in particular, congenital nystagmus. The ocular pathology may be subtle. In case of doubt, infants must be referred to an ophthalmologist [63]. Theoretically, a unilateral hearing disorder can induce a positional preference in young infants. In the literature search, no match was found for hearing loss and torticollis, except in syndromes such as Klippel-Feil or Moebius. A connection between ear malformation and hearing loss is mentioned [23]. Acquired asymmetry, non-musculoskeletal A number of disorders in systems other than the musculoskeletal system can cause a postpartum asymme- try, but the asymmetry is not the only symptom. The disorders have in common that their symptoms are not stable and occur some time after birth. The signs and symptoms can be seen as so-called “red flags” and require immediate medical evaluation. It may be second- ary to a trauma [27] or to inflammatory conditions, such as pharyngitis [8, 13, 29, 55]. Grisel syndrome (a non- traumatic atlanto-axial rotatory subluxation following infections of the upper respiratory tract) is often described, but never under the age of six months [7, 19, 29]. Another cause can be related to the cardio-respiratory or the digestive system, such as Sandifer syndrome (fluctuating asymmetry with abnormal body movements and contor- Table 2 Signs and symptoms of acquired symptomatic asymmetry disorders with a low incidence Signs and symptoms Hints for disorders General history Heavy pain Vomiting/drowsiness Lethargy/irritability Trauma Seizures/convulsions Acute onset Stridor, dyspnea Reflux Fever Specific examination Sunset phenomenon Bulging anterior fontanel Abnormal course Increasing head tilt Recurrent episodes Retro-pharyngeal abscess [13] Increased intracranial pressure [30] Tumor [12, 30], intracranial injury [27] Intracranial injury [27] Epilepsy; increased intracranial pressure; Sandifer syndrome [17] Infection, abscess [13]; Grisel syndrome (>6 months) [29, 55] Vascular ring [60] Sandifer syndrome; pathological gastroesophageal reflux [17] Infection, abscess [13] Increased intracranial pressure Increased intracranial pressure, intracranial injury [27] Infection [13]; tumor [12, 30] Benign paroxysmal torticollis [9, 21]