Unilateral lambdoidsynostosis (Trigonocephaly)

 Unilateral lambdoid synostosis (Trigonocephaly)
 General about craniosynostosis
 Evaluation of craniosynostosis
Unilateral lambdoid synostosis (Trigonocephaly)

Premature closure of the lambdoid suture leads to:

• Ipsilateral occipital flatness
• Ipsilateral mastoid bulge
• Posterior/inferior displacement of the ear ipsilateral to the suture
• Variable ipsilateral frontal bone retrusion

General about craniosynostosis


Craniosynostosis is the premature closure of one or more cranial vault or cranial base sutures. The prematurely closed suture imposes restrictions to the growth of underlying brain, resulting in compensatory growth and expansion of less restricted areas.



  • Defined inheritance and associated   anomalies
  • Usually involves coronal sutures but may involve any and all sutures
  • Often called craniofacial dysostosis


  • Based on morphology and suture involvement
  • Single suture synostosis or multiple suture synostosis
  • The nonsyndromic craniosynostosis can be further subdivided into symmetrical (bilateral involvement) and asymmetrical (unilateral involvement) craniosynostosis.


Craniosynostosis has been estimated to occur in 1:2000 to 1:2500 births. The distribution between the different synostosis are as follows:

  • Sagittal synostosis 40 – 55 %
  • Coronal synostosis 20 – 25 %
  • Metopic synostosis 5 - 15 %
  • Lambdoid synostosis 0 – 5 %
  • Multiple suture synostosis 5 – 15 %, mainly as a part of a syndrome.

Causes for premature fusion of cranial sutures

Factors associated with nonsyndromic premature fusion of cranial sutures are as follows:

  • Environmental factors
  • Multiple gestation (eg. twins, triplets)
  • Large infant size
  • Abnormal infant position
  • Uterine abnormalities
  • Head constraint
  • Drugs (eg. Nitrofurantoin, Warfarin,
  • Endocrine abnormalities

Functional issues

During the first year of life the brain will triple in size, followed by slower growth until it reaches its full size in the teen age years. Restrictions of this growth may have functional consequences. The most typical ones are listed below.

  • Elevated intracranial pressure (>15-17mm Hg) occurs in approximately 47% of patients with multiple, and in 14% of patients with single suture fusion 
  • Blindness: optic nerve atrophy, corneal exposure
  • Hydrocephalus (mainly for Syndromic patients)
  • Developmental delay
  • Abnormalities of speech and hearing
  • Abnormalities of the ocular axis and adnexa
  • Abnormalities of the airway
  • Malocclusion (Angle class III)
  • The x-ray on the left show the appearance of the "Beaten Copper Cranium" pattern found in a patient with elevated intracranial pressure

The appearance of the "Beaten Copper Cranium" pattern in a CT-scan of a patient with a clover leaf skull deformity.
Evaluation of craniosynostosis

The diagnosis of craniosynostosis is made by physical examination and radiographic analysis.

History of risk factors during pregnancy

  • Multiple gestation (eg. twins, triplets)
  • Large infant size
  • Abnormal infant position
  • Uterine abnormalities
  • Head constraint
  • Maternal smoking
  • Caucasian maternal race
  • Advanced maternal age
  • High altitude
  • Maternal use of nitrofurantoin
  • Paternal occupation (agriculture, forestry)
  • Fertility treatments
  • Endocrine abnormalities
  • Warfarin ingestion

Family history

A positive family history may be found in up to:

  • 2 % of patients with nonsyndromic sagittal suture closure
  • 10 % of patients with nonsyndromic coronal suture closure
  • 10 % of patients with nonsyndromic metopic suture closure
  • 50 % of patients with a syndromic craniosynostosis

Elevated ICP

Elevated ICP occurs in approximately 47% of patients with multiple, and in 14% of patients with single suture fusion. ICP can be recognized clinically by the finding of papilledema on fundoscopic examination and, in later stages, "thumb printing" or the "beaten copper" appearance on plain radiographs of the skull. Headaches, irritability, developmental delays, and sophisticated eye evaluation (visual evoked potentials, colour analysis) may suggest increased ICP.

Respiratory problems

Patients with significant midface retrusion should be evaluated for the presence of sleep apnea and airway compromise. Syndromic patients may also have intrinsic airway anomalies such as tracheal sleeve and laryngomalacia.

Physical examination

Physical examination should include evaluation of:

  • suture ridging
  • sutural patency by manual palpation
  • skull and facial configuration
  • fullness and patency of both the anterior and posterior fontanels
  • the presence of exophthalmos or orbital dystopia
  • eyelid ptosis and strabismus
  • occlusal relationships and dental development
  • the presence of diplopia and papilledema
  • the intracranial pressure

Radiographic assessment

Although plain film radiographs (anteroposterior and lateral skull) may be useful, the gold standard radiographic method is 2D- and 3D-CT-scans.