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Premature closure of the lambdoid skull suture is a rare condition affecting infant head shape. It occurs when the suture at the back of the skull fuses too early, leading to an asymmetrical appearance.
This condition falls under postural head shape abnormalities. Since the American Academy of Pediatrics recommended back sleeping for infants in 1992 to prevent sudden infant death syndrome, more cases of suspected premature suture closure have emerged.
The lambdoid suture is located at the back of the skull. If one side closes prematurely, it can cause one side of the back of the head to appear flat while the other side protrudes. This is often called plagiocephaly or "skew head." In rare instances, both sides may close early. Related premature fusion can also occur in the sagittal suture, known as scaphocephaly, resulting in a very flat back of the head.
This condition is uncommon, affecting about 1 in 100,000 newborns in Western countries.
It can be hard to distinguish from flat head syndrome caused by sleeping positions. To identify it, view the head from above: the ear on the flat side may appear more backward or lower than usual, as the skull's development pulls the ear back. Diagnosis often requires computed tomography scans.
Recent studies have shown that in unilateral cases, the face may show asymmetry, with the ear on the affected side appearing more prominent and the face tilting to the opposite side, forming a C-shape from forehead to chin. This can serve as a diagnostic clue.
Like other forms of craniosynostosis, this condition can affect appearance and potentially increase intracranial pressure. Due to the obvious asymmetry, surgical intervention is typically necessary. Decisions should be made after evaluation by pediatric craniofacial surgeons and neurosurgeons.
If diagnosed early, around 2-4 months of age, endoscopic-assisted craniectomy can be performed through small incisions. However, for asymmetric shapes, craniectomy alone may not suffice, and additional skull reshaping surgery might be needed.
The optimal time for posterior skull reshaping is 9-12 months, when the baby is larger, anesthesia risks are lower, and bone healing is better.
Standardized head shape models for 11-month-old infants are customized to guide surgery, improving precision and speed.
Post-surgery, patients are monitored in a neurosurgery intensive care unit for 1-3 days, then transferred to a general ward, with discharge typically after about a week.
The lambdoid suture's location can restrict cerebellar growth, potentially causing cerebellar herniation in severe cases. This pushes the cerebellum toward the cervical spine, which might not show immediate effects but could lead to spinal fluid buildup, headaches, and walking instability over time.
Pre-operative evaluations include 3D computed tomography and magnetic resonance imaging to check for cerebellar herniation. If present, neurosurgeons address it during surgery.
Though rare at 1 in 100,000, such cases are encountered periodically. Infants often show skewed head and facial asymmetry at birth. Pre-surgery confirmation involves 3D CT scans for diagnosis and planning, plus brain and cervical spine MRIs to assess cerebellar herniation.
Computer simulations help plan ideal post-operative outcomes, as the asymmetrical shape lacks a "normal" reference. Simulations guide but do not replace surgical expertise.
In one instance, decompression for cerebellar herniation was performed concurrently and minimally invasively.