Background: Unilateral lambdoid synostosis is considered to be the rarest form of craniosynostosis. Since the introduction of the Sudden Infant Death Syndrome "back to sleep" campaign, the incidence of unilateral lambdoid synostosis was reportedly increasing. This was proven to be false and a consequence of non-specific diagnostic criteria in excluding suture fusion from deformational changes. This, in turn, led to ambiguity in the literature in terms of features and surgical correction in the 1980s to 1990s.
Objective of review: We aimed to navigate the literature for true studies of unilateral lambdoid synostosis and examine the results of their surgical corrections.
Type of review: A systematic review with a defined search strategy.
Search strategy: A search on MEDLINE and Google Scholar using strategy: (Unilateral AND ((lambdoid* AND Synostosis) OR (lambdoid* AND Craniosynostosis) OR (Posterior AND Plagiocephaly)) AND (Surgery).
Evaluation method: Articles were reviewed, and data were compiled into tables for analysis.
Results: Seventeen studies were included in this review. A total of 188 patients with unilateral lambdoid synostosis were identified. No patients had major complications (venous sinus tear, neurologic injury, or cerebrospinal fluid leakage). Facial asymmetry was widely noted, and only limited improvement was achieved postoperatively. Auricular displacement was variable and often persisted despite surgery. Neurodevelopment did not deteriorate postoperatively and even improved in several patients. Endoscopic techniques revealed shorter periods of hospitalization, reduced mean estimated blood loss, and no blood transfusion requirements. The timing of surgery at 6 to 12 months was found to be the optimal balance in preventing deterioration in neurodevelopment and allowing favorable cranial growth and morphology.
Conclusions: The current evidence is difficult to navigate because of deformational plagiocephaly being misdiagnosed as unilateral lambdoid synostosis. Despite this, we present the only systematic review of all truly identifiable cases of unilateral lambdoid synostosis. Long-term quantitative studies are required to assess the benefits of the various surgical procedures.