Effectiveness of Conservative Treatments in Positional Plagiocephaly in Infants: A Systematic Review

Objective: The objective of this study is to analyze conservative treatments implemented to manage positional plagiocephaly in infants. Methods: This is a systematic review conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, performed in the Medline (PubMed), Scopus, Web of Science, and Cochrane databases. Articles were selected according to the eligibility criteria, regarding the effectiveness of conservative treatments in positional plagiocephaly in infants, published in the last 10 years with a score ≥3 in the PEDro Scale. Results: A total of 318 articles were identified and 9 of them were finally selected. Conclusions: Physical therapy treatment is considered as the first line of intervention in plagiocephaly with non-synostotic asymmetries and manual therapy is the method that obtains the best results within this intervention. In cases of moderate or severe plagiocephaly, helmet therapy can be an effective second-line intervention; however, the best way to prevent this condition is through counseling of parents or caregivers, and early treatment is essential for optimal therapeutic outcomes. The review was registered in PROSPERO (CDR42022306466).


Introduction
The shape of an infant's head is among the primary factors that prompt medical consultation [1]. Although the etiology and management of these deformities is diverse, some head shape alterations require surgical treatment, such as the premature fusion of cranial sutures (craniosynostosis). Positional plagiocephaly (PP) is not associated with synostotic problems; it is the flattening of one side of the head produced by an external force continuously applied [2]. Such deformity occurs mainly during the first months after birth, and is majorly affected by the head's positioning [3]. When a flattening of the skull occurs, the natural tendency of the head turns to this side, pulled by gravity [4]. Plagiocephalic infants exhibit flattening on one side of the back of their head, known as unilateral occipital flattening, accompanied by a bulging on the opposite side of the occiput, referred to as contralateral occipital bulging [5]. During growth, malformations can continue to develop, and the degree of remaining malformation appears to be linked to the quantity of synostotic sutures that are affected [6]. Infants with more severe plagiocephaly

Design
Results are reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [22,23]. The protocol was registered in an international registry for systematic reviews (PROSPERO): CRD42022306466.
A systematic electronic search was performed between September 2022 and January 2023 in the following databases: Medline (PubMed), Scopus, Web of Science, and Cochrane. The aim was to identify studies reporting outcomes on positional plagiocephaly and physical therapy. The summary for the search strategy can be found in Table 1.

Eligibility Criteria
The authors agreed to conduct the search strategy using the PICOS approach (Population, Intervention, Control, Outcomes, and Study design) [24]. Search strategies included DeCS and MeSH terms. The inclusion criteria employed in this systematic review were designed to ensure the selection of relevant studies that addressed the research question while maintaining a balance between comprehensiveness and feasibility. Therefore, the review focused on (1) experimental studies involving patients diagnosed with positional plagiocephaly, that (2) included in their intervention a conservative treatment option. Additionally, (3) only studies published in the English language were included to facilitate accurate data extraction and analysis, and (4) studies published within the last 10 years (2013-2023) were included to provide an up-to-date assessment of the literature and consider recent advancements. To avoid duplication, duplicate papers and multiple reports from the same study with the same outcomes were excluded from the final selection. By adhering to these predefined criteria and employing rigorous search strategies, we aimed to ensure the inclusion of relevant and high-quality studies in our review. This approach has enabled the establishment of systematic reviews, randomized controlled trials, and meta-analyses. It also facilitated critical reasoning on different issues [24], and the formulation of the following question of what was the evidence for conservative treatment of plagiocephaly in infants.

Data Extraction
Two authors independently (MM and MB) screened titles and abstracts of all identified records. Differences between researchers were resolved through discussion and mediation by a third researcher (IEP). A standard format was used to assess for inclusion. The first author, publication year, article type, design of the included studies, number of included studies or any disagreements either at this stage or further on in the process were settled by mediation through a third author, as well as study population, interventions under study, outcome measures, main results, and the authors' conclusions.

Outcomes
Anthropometric assessments and clinical results were registered, including the Cranial Index (CI) [21,25], Cranial Vault Asymmetry Index (CVAI) [19,20,[25][26][27][28], the Index of Oblique Diameter Difference (ODDI) [28], and the Posterior Cranial Asymmetry Index (PCAI) [26]. Ratings of deformation were made on the following scale: 0 = none, Children 2023, 10, 1184 4 of 15 1 = mild, 2 = moderate, and 3 = severe by using a scale based on a measure described by Branch et al. [29], the Alberta Infant Motor Scale (AIMS) for the assessment of gross motor development [30], Maximal Cranial Circumference (MCC), Ear Deviation Index (EDI), and Visual Analogue Scale (VAS) in order to assess the perception of the change in head shape, and the Infant Toddler Quality of Life Questionnaire.

Methodological Quality Assessment
The methodological quality of the included randomized controlled trial studies was evaluated using PEDro scale. The PEDro scale (ranged from 0-10) is based on the Delphi list developed by Verhagen et al. [31,32]. Studies scoring 9-10 points on the PEDro scale are considered to have Excellent methodological quality. Studies with a score between 6 and 8 have a Good methodological quality, between 4 and 5 have a Fair methodological quality, and studies scoring below 4 points are considered to have a Poor methodological quality. One author extracted data and a second author checked it. Any disagreements were resolved by consensus and mediation from a third author.

Risk of Bias Assessment
Two independent reviewers assessed each article for potential sources of bias. Each item was rated as having "high risk", "low risk", or "unclear risk" of bias. To further validate the results, a sensitivity analysis was conducted to examine the impact of including or excluding studies with a high risk of bias on the primary outcomes [33].

Study Selection
The initial search in the databases yielded a total of 318 articles from Medline (PubMed), SCOPUS, Web of Science, and the Cochrane Library.
An initial screening produced 168 articles after duplicates were removed (n = 149). Subsequently, titles and abstracts were screened for eligibility by two independent authors. A total of 137 studies were removed for not focusing on the topic (n = 64), not providing relevant information (n = 53), being case reports (n = 4), commentaries (n = 2), or not meeting the eligibility criteria (n = 14). The remaining 31 studies were screened for fulltext review by two independent authors, who registered reasons for exclusion. After this process, 22 studies were excluded due to their population. Finally, nine articles were assigned to two different examiners who assessed them independently [20,21,[24][25][26][27][34][35][36]. The different phases of the review are illustrated in Figure 1.

Quality of Included Studies
The results for the assessment of the quality of the included studies are presented in Table 2. One studies received a score of two, one study scored six points, one study scored seven points, and, finally, two studies scored nine points.  [36] x x x x --x x x x x 8/10 Pastor-Pons I et al. [21] x x -x --x x x x x 7/10 Pastor-Pons I et al. [25] x x -x ---x x x x 6/10 Kunz F et al. [26] x - Criterion in the PEDro scale: 1 = eligibility criteria; 2 = random allocation of subjects; 3 = allocation concealed: 4 = baseline comparability of important measures; 5 = blinding of subjects; 6 = blinding of therapists; 7 = blinding of assessors; 8 = measures obtained for >85% subjects; 9 = intention to treat analysis; 10 = between-group statistical comparisons; 11 = point measures and measures of variability. * Does not contribute to the total PEDro score. A score of 'x indicates that the criterion is met while a score of '-' indicates that the criterion is not met.

Quality of Included Studies
The results for the assessment of the quality of the included studies are presented in Table 2. One studies received a score of two, one study scored six points, one study scored seven points, and, finally, two studies scored nine points.

Risk of Bias Assessment
Results for the risk of bias assessment are shown in Figure 2. Seven important aspects that could affect the bias of the study, including randomization, treatment allocation concealment, blinding of participants and researchers, outcome assessment blinding, completeness of outcome data, selective reporting, and other sources of bias, were assessed. The score was marked as "Low Risk" (represented by "+"), "High Risk" (represented by "−"), or "Unclear Risk" (represented by "?") for each criterion. In case of any discrepancy, a third reviewer was consulted for resolution. that could affect the bias of the study, including randomization, treatment allocation concealment, blinding of participants and researchers, outcome assessment blinding, completeness of outcome data, selective reporting, and other sources of bias, were assessed. The score was marked as "Low Risk" (represented by "+"), "High Risk" (represented by "−"), or "Unclear Risk" (represented by "?") for each criterion. In case of any discrepancy, a third reviewer was consulted for resolution.

Main Findings
The characteristics of the included studies are shown in Table 3. A total of 5051 patients with PP were included in this review, varying sample sizes in range from n = 24 [28] up to n = 4378 [27] participants.
Cabrera-Martos I et al. [35] based their intervention on a conservative approach including positional changes and the use of an orthotic helmet. Pastor-Pons I et al. [21] implemented manual therapy and an educational program for caregivers. Van Wijk et al.

Main Findings
The characteristics of the included studies are shown in Table 3. A total of 5051 patients with PP were included in this review, varying sample sizes in range from n = 24 [28] up to n = 4378 [27] participants.
Cabrera-Martos I et al. [35] based their intervention on a conservative approach including positional changes and the use of an orthotic helmet. Pastor-Pons I et al. [21] implemented manual therapy and an educational program for caregivers. Van Wijk et al. [36] compared a helmet therapy with the natural progression of cranial asymmetry without intervention. Kuntz et al. [26] divided participants into two groups, one receiving helmet therapy and the other group without it. Seruya et al. [34] treated patients with helmet therapy. Gonzalez Santos et al. [20] implemented helmet therapy or physical therapy. Di Chiara et al. [28] assessed the change in anthropometric measures pre-and post-pediatric physical therapy. Finally, Steinberg J et al. [27] implemented either conservative management or helmet therapy.

Manual Therapy Techniques
Pastor-Pons et al. [21] implemented an upper cervical spine protocol mobilizing cranial structures to restore ROM. The AROM right rotation improvement was significantly larger in the intervention group than in the control group, 13.4 ± 9.1 • and −1.6 ± 9.5 • (p = 0.000). At baseline, the right AROM was significantly lower in the intervention group. The total cervical rotation AROM increased in both groups. The intervention group improved more than the control group, 29.7 ± 18.4 • and 6.1 ± 17.7 • (p = 0.001), respectively [21].
Cabrera-Martos I et al. [30] focused on reducing the biomechanical overload by functionally improving the movement of the joints, mainly the spheno-occipital, the atlantooccipital synchondrosis, and the sacrum. Over time, a progressive improvement in deformity level was noted in all the treated infants, indicating a lesser degree of observable deformity as assessed with the Argenta scale. The asymmetry at the end of the treatment was minimal, with a score of 0 or 1. Duration of treatment was also significantly shorter (p < 0.001) in the intervention group (109.84 ± 14.45 days) compared to the control group (148.65 ± 11.53 days). Additionally, motor behavior was within the normal range (scores above the 16th percentile of the AIMS) in every participant.
The results of the study by Chiara et al. [28] showed improvements in the change in four of the anthropometric measures, performed pre-and post-physical therapy program, being greater in younger children and in the most severe presentations (p < 0.05 or p < 0.01).
Pastor-Pons et al. [21] used a 10-session program consisting of manual therapy and a caregiver education program aimed at reshaping cranial deformation. CVAI presented a greater decrease in the intervention group (3.72 ± 1.40%) compared with the results of the control group, 0.34 ± 1.72% (p = 0.000). CI did not present significant differences between groups. Furthermore, a significant increase in cranial length was found in the intervention group (7.57 ± 2.33 cm) in contrast with the control group (4.25 ± 2.47 cm) (p = 0.001).
Pastor-Pons et al. [25] also showed that, after intervention, the pediatric integrative manual therapy group presented a significant increase in rotation (29.68 ± 18.41 • ) than the control group (caregivers receiving an evidence-based educational physical therapy program) (6.13 ± 17.69 • ) (p = 0.001). No statistically significant differences were found, although both groups improved neuromotor development.

Helmet Therapy
Van Wijk et al. [36] compared natural evolution in cranial deformation with helmet therapy. For plagiocephaly and brachycephaly, the change score was equal between both groups, with a mean difference of −0.2 (95% confidence interval −1.6 to 1.2, p = 0.80) and 0.2 (−1.7 to 2.2, p = 0.81), respectively. A total of 10 out of 39 (26%) participants in the helmet therapy group achieved full recovery, as well as 9 out of 40 (23%) participants in the natural evolution group (odds ratio 1.2, 95% confidence interval 0.4 to 3.3, p = 0.74).
Kunz F et al. [26] showed that the largest reduction in head asymmetry was observed in the intervention group when comparing the changes in the symmetry-related variables in all of the three groups (∆T1−T3).
Seruya M et al. [34] divided patients into seven groups based on their age at the start of treatment. Significant differences were found between groups when assessing the final transcranial difference (p < 0.05). The transcranial difference median rate of change ranged from 0.41 to 0.93 mm/week. Age at treatment baseline was negatively related to the rate of change in transcranial difference (r = −0.88, p < 0.05). At the end of the treatment, cranial symmetry had improved in all groups.
Steinberg J et al. [27] achieved a complete correction in 92.8% of participants. A total of 77.1% of the conservatively managed participants achieved complete correction with repositioning therapy. A subset of participants were transitioned with helmets (crossover group) because they failed to improve. The remaining 7.1% ultimately failed to achieve complete correction with continued conservative therapy. Complete correction was achieved in 95.0% of these 1531 total participants who underwent helmet therapy. There were no differences in outcomes between crossover patients who transitioned to helmet therapy after a mean of 4.1 ± 1.4 months of conservative therapy and those who received helmet therapy as first line treatment (96.1% versus 94.4%; p = 0.375).
The results in Gonzalez-Santos et al. [20] indicated that the initial CVAI for the entire sample was 10.69% (SD = 5.58), with a CVAI of 9.62% (SD = 5.59) for the group with helmet therapy and 11.59% (SD = 5.51) for the group with physical therapy treatment (p = 0.228). Upon final evaluation, the CVAI dropped to 4.07% (SD = 2.26) in the cranial helmet group and 5.85% (SD = 3.60) in the physical therapy group. No significant statistical differences were found between groups (p = 0.70). RCT 34 neurologically healthy subjects aged less than 28 weeks old with a difference of at least 5 mm between cranial diagonal diameters To assess how effective it is to incorporate manual therapy techniques specific for pediatrics, to a caregiver education program in anthropometric cranial measurements and the subjective parental perception of the cranial shape change in infants with PP.
IG: manual therapy plus a caregiver education program.
CG: education program exclusively.
Cranial shape was evaluated using CI and CVAI. Parental perception of change was assessed using a visual analogue scale.
CVAI presented a greater decrease in IG group compared with the CG. CI did not present significant differences between groups. Manual therapy led to a more positive parental perception of cranial changes No adverse effects were reported.
Pastor-Pons I et al. 2021 [25] RCT 34 neurologically healthy subjects aged less than 28 weeks old with a difference of at least 5 mm between cranial diagonal diameters To analyze the effect of manual therapy on the active cervical rotation and in the neuromotor development in a sample of children with PP.
IG: educational approach and specific protocol based on pediatric integrative manual therapy for 10 weeks.
CG: educational approach, therapeutic exercise to reduce preference of position and for motor development.
CI, CVAI, neuromotor development: evaluated using AIMS, Cervical AROM to each side (registered by a photographic image from above).
Incorporating manual therapy into a caregiver education program is linked to an improved outcome regarding neck mobility in PP. No outcome differences in neuromotor development were shown No adverse effects were reported.  The results indicated that both therapies (CHT and PT) led to improvements in cranial deformity, with no statistically significant differences between both treatments. Despite these findings, the authors suggest using a combination of both techniques, starting with PT, and supplementing it with CHT for patients with a higher CVAI.

Discussion
This systematic review gives an overview of all previously published studies for conservative treatments in PP, and highlights the paucity of studies in the literature on the optimal techniques for treating PP. The degree of correction in PP is influenced by age and the type of treatment [37]. Being aware of the recommendations to diagnose and manage PP is determinant in healthcare providers [38]. The program for educating caregivers comprised a series of recommendations based on the literature and included suggestions for motor, sensory, and repositioning stimulation of non-preferred sides and prone positions. Parents received guidance from a physical therapist specialized in pediatrics and were given an informative booklet containing basic guidelines [20,[39][40][41]. The related literature also emphasizes the significance of early screening and provides prevention techniques such as head repositioning and positioning the infant in alternating right/left supine positions, especially during the initial 2-8 weeks of life when the skull is most vulnerable to external forces [40]. It is generally accepted that conservative therapy, including repositioning and physical therapy, is appropriate as an initial treatment, and that cranial orthotics should only be considered if no improvement is seen [39,42,43].
The Congress of Neurological Surgeons Systematic Review indicated that physical therapy is a more effective approach than educational strategies for repositioning in PP [43]. The American Association of Pediatrics discourages the use of positioning pillows in an infant's sleep environment; therefore, the Plagiocephaly Guidelines Committee recommends the use of physical therapy over positioning devices [44].
In conservative management strategies, how severe the deformity is measured by cranial ratio and diagonal difference, torticollis that persists over 6 months, and a delay in neuromuscular development were risk factors, along with age and the level of compliance [22]. Physical therapy should be considered as the first line of intervention for any non-synostotic asymmetries, no matter their severity or first referral age [28,39]. Manipulative treatment is beneficial as it acknowledges the significance of managing the body as a single functional unit, promoting homeostatic processes [36]; the sooner it is applied, the more effective it is. Early strategies both increase the efficacy of the treatment and reduce the worsening rate [28]. Adding manual therapy to the usual management plan leads to a shorter treatment period for infants with a severe plagiocephaly, considered as non-synostotic [36]. Treatments with functional manual therapy manage to improve the asymmetries presented by children younger than 6.5 months old with PP [45].
Helmet therapy is critically questioned with regard to cost-effectiveness and possible commercial involvements [46]. Benefits for children with severe PP are widely accepted [47][48][49]. It is considered, but not validated, that an infant's cranial deformity cannot be corrected with helmet therapy after 1 year. The literature on the efficacy of helmet therapy for PP suffers from limited study power, subjective outcome measures, and variations in the duration of helmet use and patient compliance. Therefore, the question of how the correction rate is affected by the age of helmet treatment initiation and treatment efficacy in older children remains unclear [35]. Guidelines suggest the use of cranial orthotic helmets for cases of moderate to severe plagiocephaly that present at a later stage of age and for infants with persistent moderate to severe plagiocephaly after a course of conservative treatment (repositioning and/or physical therapy). Tamber et al. [41] indicated that there is a considerable body of non-randomized evidence that shows more significant and faster improvement of cranial asymmetry in infants with PP treated with a helmet than with conservative therapy, especially if the asymmetry is severe, and indicated that helmet therapy is applied during the appropriate period of infancy. However, van Cruchten et al. [44] argued that a combination of physical therapy and helmet therapy provides long-term beneficial results. Generally, infants with more severe deformities and those who begin using helmets early in infancy tend to achieve better correction, and in some cases, even normalization of head shape [39]. To estimate the link between the rate of correction and age at initiation of helmet therapy for deformational plagiocephaly, Seruya et al. [34] showed that with increasing infant age, the success rate of plagiocephaly correction with helmet therapy decreases after 32 weeks, and the rate of improvement slows down and becomes relatively stable. However, improvement can still be attained in infants who are older than 12 months of age [34]. Several studies claim to demonstrate that head orthosis therapy in patients with PP leads to significantly better long-term outcomes compared to active repositioning or only physical therapy [26,[50][51][52]. Even after the completion of head orthosis therapy, residual cranial asymmetries continue to improve over time. The results match with those of Kim MJ et al. [53], where patients with PP had a higher risk of developing lateral crossbites, with the likelihood being greater on the side opposite to the posterior flattening. In patients with PP who do not receive head orthosis therapy, facial asymmetries are more commonly observed. The results of the study of Gonzalez Santos et al. [20] showed that in both treatment groups, the CHT group and PT group, the infants showed a progressive improvement in their performance indexes over the 5-month period between the first and the last assessments. Additionally, results showed no statistically significant variations between the different treatment groups. Kunz et al. [26] discussed that the use of a head orthosis is a suitable option for infants with PP when it comes to reducing cranial asymmetry and diminishing developing facial asymmetries. Despite that, based on the similar outcomes between the natural progression of skull deformation and helmet therapy, combined with the high incidence of adverse effects and the high cost of the latter, Van Wijk, B et al. [36] favored against the use of helmets as a standard treatment for moderate to severe cranial asymmetry in healthy infants. Some authors consider the use of cranial orthotic molding helmets to be appropriate because they achieve complete correction in 95.0% of patients, with no difference in outcome between patients who received helmet therapy after failure of conservative therapy compared to those who received helmets as initial treatment [27,54].
As for the aesthetic deficits, the literature shows that in non-operated patients these can be significant [55]; however, even in infants treated at a very young age, many authors state the possible risk of malformation. Moreover, severe residual deformities are directly related to the age at which the infant is managed [56]. Early surgical treatment does not definitively ensure aesthetic and functional results. Primary surgery should be postponed in infants affected by anterior PP without signs of cranial hypertension, until their bone growth is completed, between 5 and 7 years old, so that it will be possible to achieve an optimal aesthetic result after a single surgical intervention [6].
Studies suggest that the cognitive abilities of children treated for PP with or without physical therapy or helmet therapy are not altered in their growth (2-7 years old) [57].
Current treatments for infants with PP are usually effective in children without complications [58], although not all infants get better [59]. It is difficult to determine the gold standard therapy to achieve better results due to the lack of standardized measurement systems, and the scarce quality of the scientific literature. However, parental counseling, correct decubitus position, and manual treatment are considered useful and low-cost interventions for families [60].
Previous reviews [10,14,16,60] have addressed causes, prevalence, risk factors, diagnosis, and the management of plagiocephaly. De Bock et al. [10] showed the existence of conflicting evidence that makes it challenging to identify potential risk factors, and Bialocerkowski et al. [14] presented the high heterogeneity found regarding prevalence rates in the existing literature, outlining the presence of conflicting evidence that is proof of the need to develop systematic reviews such as the one conducted in this study. Furthermore, Ellwood et al. [60] presented results regarding the management of PP that are in line with the ones of this review, showing considerable evidence to use manual therapy in favor of helmet therapy.
This study is not exempt from limitations. A potential publication bias could have been incurred in this study due to the limited number of resources accessed during the systematic review process. Additionally, language bias may have been introduced in this study due to the inclusion of only studies published in the English language. The decision to include studies solely in English was made based on resource constraints and the assumption that English language publications are more widely accessible and representative of the available evidence. Future reviews could consider including studies in multiple languages to minimize language bias and enhance the generalizability of findings. The current review underscores the need for further research in this field. More studies comparing different treatment modalities, evaluating long-term outcomes, and assessing cost-effectiveness are warranted. Critically evaluating the existing evidence, addressing limitations, and identifying future research directions will contribute to the ongoing development of evidence-based management strategies for infants with PP.

Conclusions
For any non-synostotic asymmetry, a pediatric physical therapy program should be considered as the first-line intervention. Among physical therapy methods, manual therapy has been shown to produce the best results, particularly when combined with counseling for parents or caregivers, which can lead to even greater benefits. Repositioning therapy is the main preventive measure against cranial deformities. It is suggested that for infants who have moderate to severe plagiocephaly that presents itself at a later stage, or for those who still have persistent moderate to severe plagiocephaly even after undergoing conservative treatments, helmet therapy is a recommended solution.
Orthotic treatment for children can be initiated after six months of age, but starting treatment at a later age may result in a lower therapeutic success. Surgical intervention may be necessary if there are aesthetic or functional issues that do not improve with other treatments. The age of initiation of treatment should be early, as this will result in greater efficacy and a lower rate of worsening. More research is needed on physiotherapy treatment and its results.