Cloverleaf Skull

A congenital nonsyndromic abnormality with a characteristic trilobular aspect of the skull.

(Figure)

(Figure)

Kleeblattschädel.

Craniosynostosis occurs in approximately 1:2,100 live births in the general population. Cloverleaf skull (CLS) accounts for less than 1% of cases.

All reported cases have been sporadic.

The abnormally shaped skull is caused by premature ossification of the coronal, sagittal, and lambdoid sutures. The metopic and squamous sutures do not fuse. It has been hypothesized that abnormal development of the periosteal vascular plexus alters the ossification and development of the skull. CLS may occur as an isolated finding, but is more commonly associated with Thanatophoric Dwarfism, Achondrogenesis, and Camptomelic Dysplasia. It is also seen in Acrocephalopolysyndactyly (Carpenter Syndrome), and Acrocephalosyndactyly Syndromes (Apert, Pfeiffer, and Crouzon Syndromes).

Based on the clinical findings of trilobular skull aspect and craniosynostosis in radiologic examinations (conventional radiography, computed tomography scanning, and magnetic resonance imaging).

Neonatal death is frequent. Patients may have mental retardation. On examination, the skull has a trilobed appearance with high forehead, beaked nose, and depressed premaxillary region. Hydrocephalus is common. Raised intracranial pressure is seen in approximately 45% of patients with complex craniosynostoses. Other features involve the eyes (marked proptosis, exophthalmos, corneal ulcerations) and the limbs (elbow ankylosis, dysostosis multiplex, syndactyly of toes and fingers, restricted joint mobility). Abnormal vertebral size has occasionally been reported.

The presence of raised intracranial pressure should be determined. If CLS is part of a syndrome or skeletal dysplasia, the patient should be investigated for features of that condition. Evaluate for difficult airway management.

Patients may have increased intracranial pressure. On the one hand, this situation makes a rapid-sequence induction (increased risk of vomiting) for tracheal intubation with controlled ventilation desirable. On the other hand, maintenance of spontaneous ventilation may be required until the airway has been secured if airway management is expected to be difficult. The final decision depends on the clinical situation. Careful eye protection is required because of increased risk for corneal ulceration secondary to proptosis. Careful intraoperative positioning is needed because of orthopedic features.

Succinylcholine and ketamine should be avoided if possible in the presence of already increased intracranial pressure.

Cloverleaf Skull and Bone Dysplasia: CLS in combination with genital and chest anomalies that could increase respiratory risks.

Kozlowski-Warren-Fisher Syndrome: Lethal form of CLS with genital anomalies and rhizomelic micromelia.

Cloverleaf Skull with Micromelia and Thoracic Dysplasia (Benallegue Lacete Syndrome): A frequently early lethal syndrome caused by respiratory distress as a result of thoracic cage hypoplasia.

Thanatophoric Dwarfism: Results from a sporadic defect in the fibroblast growth factor 3 gene, which is a transmembranous regulator. The disease is lethal usually shortly after birth secondary to respiratory failure (thoracic cage hypoplasia). The incidence is approximately 1:10,000 births, making it the most common lethal bone dysplasia.

Osteoglophonic Dysplasia (Craniofacial Dysostosis with Fibrous Metaphyseal Defects): Short stature and stubby hands. There is acrocephaly and CLS deformities with frontal bossing.

Achondrogenesis: A defect in the development of bone and cartilage. A rare type of dwarfism that usually is fatal at birth or soon thereafter. Very short trunk, arms, legs, and neck. The head appears large in relation to the trunk. Hypoplastic mandibula and narrow chest.

Campomelic Dysplasia (Camptomelic Dysplasia): Autosomal dominant inheritance. Incidence is about 1:2,000,000 live births. Short limb dwarfism with prenatal onset. Large anterior fontanelle, macrocephaly, micrognathia, hearing loss, cleft palate. Congenital heart defects (atrial and ventricular septal defects, tetralogy of Fallot), and respiratory failure because of hypoplastic thoracic cage result in early neonatal death.

Carpenter Syndrome (Acrocephalopolysyndactyly Type II): A condition characterized by craniosynostosis, acrocephaly, facial anomalies and syndactyly. Cardiac malformations have also been described.

Apert Syndrome (Acrocephalosyndactyly Type I): Agenesis or premature closure of the cranial sutures, midface hypoplasia, and symmetrical syndactyly of the hands and feet involving at least the second, third, and fourth digits. Cervical spine fusion is common and almost always involves C5-C6. Numerous facial anomalies and heart defects may be associated.

Pfeiffer Syndrome (Acrocephalosyndactyly type V): Sagittal craniostenosis associated with broad thumbs and toes (mostly second toe), variable maxillary retrusion, and partial soft tissue syndactyly characterize this syndrome. Congenital heart disease is most often present.

Crouzon Syndrome (Acrocephalosyndactyly type II): A form of craniofacial dysostosis similar to Apert syndrome, but without syndactyly. Characteristic features include exophthalmos, maxillary hypoplasia, hypertelorism, and a beaked nose.