INTEGRATION OF OSTEOPATHIC PALPATORY EVALUATION AND LASER DISPLACEMENT ANALYSIS FOR THE QUANTITATIVE ASSESSMENT OF FRONTAL BONE MICROMOVEMENTS: A PILOT RETROSPECTIVE OBSERVATIONAL STUDY

G. Barassi¹, C.E. Gallenga², M. Genga³, V. Nobile³, M. Gadaleta¹, G. Putignano⁴, S. Bennani³, M. Supplizi¹, L. Prosperi¹, C. Mincarelli⁵ and M. Panunzio⁶

¹ Center for Physiotherapy, Rehabilitation and Re-Education (Ce.Fi.R.R.), venue “G. d’Annunzio” University of Chieti-Pescara, Chieti, Italy;
² Ophthalmology Clinic Operating Unit, Head & Neck Department, “Arcispedale Sant’An-na” University Hospital, Ferrara, Italy;
³ Cranio Tech Solution S.r.l., Taranto, Italy;
⁴ bioERGOtech Foundation, Taranto, Italy;
⁵ Ophthalmology and Orthoptics Sector, “Stenella” Polyclinic, Pescara, Italy;
⁶ Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy.

*Correspondence to:
Giovanni Barassi,
Center for Physiotherapy, Rehabilitation and Re-Education (Ce.Fi.R.R.),
venue “G. d’Annunzio” University of Chieti-Pescara,
Chieti 66013, Italy.
e-mail: coordftgb@unich.it

Received: 10 June, 2026 Accepted: 30 July, 2026

ISSN 2279-5855 print / 3103-7364 [online] Copyright 2026 © by Biolife Publisher This publication and/or article is for individual use only and may not be further reproduced without written permission from the copyright holder. Unauthorized reproduction may result in financial and other penalties. Disclosure: All authors report no conflicts of interest relevant to this article.

ABSTRACT

Craniosacral Therapy (CST) is a controversial branch of osteopathy based on the manual palpatory perception of Frontal Bone Micromovements (FBMs), which would likely benefit from the objectification of FBMs measurements through dedicated non-invasive optoelectronic devices. A pilot retrospective observational study was conducted, recovering data from 20 volunteers who underwent osteopathic screening. Subjects underwent a multimodal FBMs assessment, exploiting a double palpatory evaluation conducted by expert osteopaths and a Laser Displacement Analysis (LDA) device. Manual assessments were quantified using a dedicated Semi-Quantitative Frontal Bone Micromovements Scale (SQFBMS) considering symmetry, amplitude, quality, and rhythmicity. LDA assessments measured the values of bilateral symmetry (R/L ratio), dominant frequency (f_dom), frequency Spectral Centroid (SC), and Peak-to-Peak amplitude of the movement (P2P). Measured values were then processed to obtain a quantitative and inferential description of the observed FBMs. Observed parameters showed high variability. Most of the subjects presented f_dom values below the typical FBMs frequency range. No significant linear correlation was observed between P2P amplitude and the total SQFBMS score. Conversely, SQFBMS domains showed good inter-operator consistency, although with dissimilar dispersion levels. FBMs represent a complex, nonlinear, and multidimensional system. LDA allows for quantitative objectification of FBMs, while SQFBMS offers a seemingly repeatable assessment across operators, albeit with questionable levels of correlation with LDA. The integration of the two approaches could represent the basis to improve the evaluation practices of facility-specific osteopathic screenings and other clinical fields.

KEYWORDS: Craniosacral massage, skull, frontal bone, biomechanical phenomena, optical imaging, biometry, computer-assisted signal processing

 

INTRODUCTION

 

Originating in the 1940s through the work of William G. Sutherland, Craniosacral Therapy (CST), an approach that falls within the scope of osteopathic manual medicine in the cranial field, is based on the assumption of the existence of a so-called Cranial Rhythmic Impulse (CRI), resulting in Frontal Bone Micromovements (FBMs) (1,2). This theoretical framework posits a subtle, inherent kinesis involving the dura mater, the sacrum, and the cranial bones (3). The practice assumes a physiological synergy between the rhythmic motility of the central nervous system, cerebrospinal fluid dynamics, the flexibility of dural membranes, and the micro-mobility of cranial sutures (3). Consequently, CST practitioners employ manual interventions intended to modulate the FBMs to improve clinical outcomes, though the World Health Organization currently classifies the modality as a form of complementary medicine (4).

Like many complementary medicine approaches, CST is characterized by a controversial bibliographic context: overall, literature has produced studies and reviews that have confirmed or denied the positive effects of this approach (5-8). In this regard, the manual palpatory evaluation element of the presumed FBMs is a complex factor that can influence the quality and reliability of CST interventions both in research and in clinical practice. In fact, even the coherence and reliability of the manual evaluation of possible cranial strain patterns is controversial, with some studies considering it good (9) and others considering it extremely invalid (10). Such controversies could be based on the need to re-establish some paradigms of the original thought of William G. Sutherland, rethinking the concepts with respect to the possibility that the cranial sutures slightly move (particularly in the adult subject) on the basis of real and demonstrable physiological concepts, linked to the expansions and contractions of the cerebro-spinal fluid in conjunction with cardio-respiratory activity (1) and to the capacity of the head muscles to induce skull deflections by virtue of their state of tension-contraction (11). A problematic factor in the manual assessment of the FBMs is its extreme dependence on the subjective perception and manual ability of osteopathic practitioners, a factor that tends to be difficult to modify even with adequate training (12), leading to the need to shift osteopathic assessment towards measurable and quantifiable methods (13).

It follows that an objective instrumental approach to assessing FBMs, precise and sensitive enough to identify positional and mechanical variations in cranial areas, could represent a significant step forward in scientific research and clinical practice in the field of CST and other healthcare disciplines that deal with the cranial district. However, to date, such devices specifically designed to assess cranial bone mechanics are still not widely used and lack scientific literature.

The present study aims to preliminarily evaluate the behavior and reliability of the integration of osteopathic palpatory assessment performed by experienced practitioners and non-invasive laser-based cranial movement assessment for the quantitative evaluation of FBMs in a small cohort of asymptomatic subjects, focused first of all at contextualizing its effectiveness as a method for improving osteopathic evaluation practice that can be implemented in the study venue and eventually exploring its applicability to other healthcare areas.

 

MATERIALS AND METHODS

 

Study Design and Ethics

This research is a pilot retrospective observational study carried out in April 2026 at the “Center for Physiotherapy, Rehabilitation and Re-Education – Ce.Fi.R.R.” located in the facilities of the “Gabriele d’Annunzio” University of Chieti-Pescara in Chieti (Italy). The data were recovered from the evaluation forms completed during multimodal osteopathic CST evaluation screening days held at the study site, free of charge and freely accessible to all subjects who received information about it, initially aimed at intercepting subjects potentially benefiting from osteopathic treatments in the reference territory. This study was performed in accordance with the principles of the Declaration of Helsinki (14). In accordance with the standard operational protocols of the lead institution, informed consent was secured in advance from all participants during their baseline screening assessment. This proactive procurement of consent ensures that subjects are apprised of, and agree to, the utilization of their anonymized clinical data for eventual future investigative purposes, encompassing retrospective cohort analyses. All assessment protocols were non-invasive, non-pharmacological, and conducted in full compliance with national health regulations.

Current national regulatory frameworks for the ethical oversight of retrospective non-pharmacological research remain underdeveloped (15). This ambiguity is specifically pronounced regarding the demarcation of competencies and the precise criteria required for ethics committee approval regarding studies that are non-pharmacological and relevant to institution-specific operational practice. Therefore, given the uncertain regulatory context, in the absence of an ethics committee directly competent for the study, standard ethical approval was waived. However, the study adhered to the UNI EN ISO 9001:2015 quality management standards for observational research, as certified by ACCREDIA, the Italian National Accreditation Body (Certificate No. IT15/0304) (16), as a proactive demonstration of adherence to high standards of methodological rigor. The study was conducted in accordance with the Equator STROBE checklist guidelines, taking into account the points relevant to its single-cohort pilot retrospective design.

 

Study Population and Selection Criteria

The study population consisted of a small cohort of subjects who consecutively presented to the clinical site throughout the indicated osteopathic CST evaluation screening days, which took place respectively on the morning of 10 and 11 April 2026 and the whole day of 17 April 2026. The subjects who voluntarily participated in the osteopathic evaluation campaign were asymptomatic and underwent screening because they were interested in a preventive assessment of their musculoskeletal health, in accordance with current national regulations that identify the osteopath as a healthcare professional who deals with prevention and health maintenance, primarily in the musculoskeletal field.

In line with protocols from the study venue, subjects with significant problematic conditions such as neoplasms, pacemakers/electric implants, infections, severe neurological and cognitive deficits, severe cardiovascular disorders, severe spinal hernias and stenosis, severe osteoporosis, fever, seizures, pregnancy, alcohol/drug abuse, systemic inflammatory musculoskeletal disease, tissue necrosis, thrombosis/phlebitis, blood and clotting disorders, age <18, and presence of red flags and suspicious psycho-physical manifestations were excluded from the screening days and, consequently, from observation.

A total of 5 subjects spontaneously presented themselves for evaluation on April 10, 2026, 3 subjects on April 11, 2026, and 13 subjects on April 17, 2026. However, on the first screening day, 1 of the 5 evaluations performed was not completely recorded due to an inaccuracy in the positioning of the subject during the instrumental assessment. Therefore, this evaluation was not considered for observation purposes, as it was incomplete. In the end, upon application of the aforementioned exclusion criteria, data from an osteopathic evaluation were systematically gathered and subsequently extracted from the assessment records of a total of 20 subjects (13 females, 7 males; mean age 48 ± 22 years).

 

Semi-Quantitative Frontal Bone Micromovements Scale (SQFBMS) Assessment

In the context of the objective of preventively identifying the presence of possible osteopathic dysfunctions in the CST setting in subjects who freely participated in the screening days promoted by the reference institution, the subjects first underwent a double routine manual evaluation, performed independently by two osteopath operators of the study center, with more than 20 years of post-training experience each.

To quantify the parameters of the manual observation describing the FBMs manually perceived by the osteopaths, the two operators both used a Likert-type scale created internally at the institution where the study was conducted and called SQFBMS. The scale is divided into four domains, each with a score between 0 and 3 (from 0 = physiological/optimal condition to 3 = severe alteration). Specifically, the domains evaluated were the following:

• Symmetry (D1): from 0 = symmetrical to 3 = marked asymmetry;
• Amplitude (D2): from 0 = physiological amplitude to 3 = severely reduced amplitude;
• Quality of movement (D3): from 0 = fluid/harmonic movement to 3 = disorganized movement;
• Rhythmicity of movement (D4): from 0 = regular rhythm to 3 = disorganized rhythm.

The scale has an overall score given by the sum of the scores assigned by the osteopath to the individual items, which ranges from 0 to 12 points and quantifies the possible dysfunctionality of FBMs from null to high. This format makes it possible to separate the mechanical components (D1 and D2) from the temporal/physiological ones (D3 and D4), favoring a quantified measurability and long-term remeasurability of parameters generally observed subjectively in osteopathic practice, with a consequent presence of biases potentially limiting the application of the correct treatment (17).

The evaluated subjects considered for observation were positioned on an osteopathic table in a horizontal supine relaxed anatomical position, maintained for the entire duration of the evaluations, which lasted 120 seconds for each operator. The evaluations were conducted under standard conditions in the same room for all subjects. Each operator performed his evaluation sitting behind the evaluated subject, with both hands placed on the frontal bones, with the index fingers in full contact along the metopic suture, which divides the two frontal bones (Fig.1). Hands were parallel to the suture, applying gentle and respectful contact.

 

Fig. 1. Palpation of the frontal bones. (A) Frontal view: both hands are placed on the frontal bones with the index fingers in full contact along the metopic suture, which divides the two frontal bones. Hands are parallel to the suture. (B) Top view: the index fingers are joined along the metopic suture. (C) Lateral view: hands remain parallel to the metopic suture, applying a gentle contact.

 

Laser Displacement Analysis (LDA)

A custom and not commercially available non-contact optical measurement setup based on laser displacement sensing was used to detect micrometric surface oscillations at predefined cranial regions. The system operates on an optical triangulation principle, allowing high-resolution detection without mechanical contact. The optical triangulation laser sensors are characterized by a resolution of 2.5 μm, repeatability of 5 μm, measurement range of ±5 mm, reading distance of 30mm and wavelength of 650 nm (Class 2, power ≤ 1mW). The sensor was mounted on a structure which allowed precise alignment on the frontal measuring point, constant distance maintenance and reduction of angular errors. The acquired signals were subjected to digital filtering, time-domain analysis and spectral analysis using Fast Fourier Transform (FFT), to remove high-frequency noise, isolate physiologically relevant oscillatory components and identify dominant spectral bands. The sampling rate was approximately 250 Hz, with an acquisition duration of 120 seconds per subject. The instrument allows to detect the following characterizing parameters of the structural, dynamic and frequency components of the FBMs:

• Right/Left ratio (R/L ratio): right/left ratio of movement amplitudes, taken as bilateral symmetry index; values = 1 indicate perfect symmetry, < 0.70 left dominance, > 1.30 right dominance (thresholds used for cohort categorization);
• Dominant Frequency (f_dom): value of the signal in Hz obtained by FFT, representative of the prevailing oscillatory component;
• Spectral Centroid (SC): centroid value calculated in Hz within the CRI band (0.08–0.16 Hz) (18), representative of the energy center of gravity of the spectrum in the physiological band of interest.
• Peak to Peak (P2P): amplitude between the peaks of the signal in the time domain, calculated as an average of the left and right amplitudes and measured in μm.

The evaluated subjects considered for observation were positioned on an osteopathic table in the same environment and in the same horizontal supine position as the SQFBMS evaluation, also in this case maintaining a relaxed anatomical position for the entire duration of the LDA evaluation. As a further precaution to protect the eyes against the light emitted by the LDA, during the evaluation the observed subjects wore totally darkening black protective goggles, while the operator who managed the device wore shielding glasses for light at 650nm.

 

Statistical Methods

For each variable, mean and standard deviation (SD), median and interquartile range (IQR), as well as reference range (minimum-maximum) were originally calculated. The normality of the distributions was evaluated by graphical inspection (histograms, boxplots) and symmetry analysis (skewness).

An exploratory analysis was carried out using scatter plots, quadrant distributions and cluster identification, aimed at highlighting nonlinear behaviours, multimodal distributions and non-monotonic relationships.

The correlations between variables of the SQFBMS and LDA assessments were explored by means of Pearson’s correlation coefficient (r). The interpretation of strength was made according to the following criteria: r < 0.3 = weak; 0.3–0.6 = moderate; > 0.6 = strong. Specific emphasis was placed on analyzing the correlations between P2P and the SQFBMS total score.

The comparison between the two operators was conducted by Wilcoxon assay for paired samples, appropriate for ordinal and not normally distributed data. The values of the W statistic, Z value, p-value and effect size effect were reported. Inter-operator reliability was assessed by ICC₃,₁ (Intraclass Correlation Coefficient, Two-way Mixed Effects, Single Measures) tests with 95% confidence interval, calculation of linear weighted kappa (κᵂ) and Bland-Altman analysis with bias calculation and Limits of Agreement (LoA = bias ± 1.96 SDs)

For all the analysis conducted the significance threshold was set at a p-value < 0.05. The calculations were carried out using proprietary statistical software.

 

RESULTS

 

Overview

The analysis of the cohort involved the integration of instrumental data obtained by LDA with the independent manual evaluation of two operators according to SQFBMS assessment.

The results showed non-Gaussian distributions and wide inter-subject variability on all the variables considered. Most of the cohort (65%) showed a f_dom value lower than the classic CRI band (< 0.08 Hz) and 55% showed a lateral dominance above the physiological thresholds.

No significant linear correlation emerged between P2P amplitude and SQFBMS clinical severity, with 50% of subjects placed in a position discordant with respect to the expected direction. Inter-operator assessments showed no statistically significant differences on the Wilcoxon test on any of the four domains (p > 0.05); the concordance analysis confirms a moderate to good reliability (ICC₃,₁ = 0.595 – 0.753; κW = 0.595 – 0.712), with Bland-Altman biases all contained within ± 0.35 points.

 

LDA Symmetry distribution (R/L ratio)

The analysis of the R/L ratio stratifies the 20 subjects into three categories defined a priori (Table I). The values were distributed over an extended range, from a minimum R/L = 0.570 (subject 20) to a maximum R/L = 2.270 (subject 9), with the presence of outliers in both directions of dominance.

 

Table I. LDA Symmetry distribution.

Category	R/L Threshold	n.	%
Left Dominance	< 0.70	4	20
Near-symmetry	0.70 – 1.30	9	45
Right Dominance	> 1.30	7	35
Legend: n. = number of subjects; % = percentage of subjects.

 

Near-symmetry represented the most frequent but not the majority condition: overall, 55% of the sample (11/20) had a lateral dominance above the reference thresholds (Fig.2). In 65% of subjects (13/20) the presence of L/R phase reversal was also observed, indicative of bilateral decoupling of movement.

 

Fig. 2. LDA Symmetry distribution detailed for each subject (P) of the cohort. Subjects who had a bilateral decoupling of movement are graphically marked with the symbol (●).

 

LDA Dominant Frequency (f_dom) and Spectral Centroid (SC) distribution

The analysis of the spectral map showed a marked prevalence of dominant frequency values lower than the classical CRI band (Table II).

 

Table II. LDA Dominant Frequency (f_dom) distribution.

Category	fdom Range (Hz)	n.	%
Below the CRI band	< 0.08	13	65
Within the CRI band	0.08 – 0.16	6	30
Above the CRI band	> 0.16	1	5
Legend: n. = number of subjects; % = percentage of subjects.

 

The analysis of the map identifies distinct overlapping clusters, with n = 9, n = 3, and n = 4 subjects respectively, within which the coexistence of subjects with and without phase reversal was variable (respectively 7+2; 3+0; 1+3) (Fig.3).

 

Fig. 3. LDA f_dom and SC distribution clusters overlapping. Single subjects who had phase reversal are graphically marked with the symbol (●).

 

Correlation between LDA-assessed FBMs amplitude (P2P) and SQFBMS assessment score

The amplitude of motion (P2P) showed a range between about 400 and 3000 μm, with high variability (Fig.4). The wide and uneven distribution suggests the presence of distinct biomechanical subgroups. The high standard deviation from the mean confirms a non-Gaussian distribution and high inter-subject heterogeneity.

The distribution of subjects in the quadrants of relationship between P2P and SQFBMS is shown in Figure 4. 50% of subjects show a discordant behavior between range of motion and clinical severity.

 

Fig. 4. Correlation between LDA-assessed FBMs P2P amplitude and SQFBMS score severity. The data clearly indicate the absence of a significant linear relationship between the two variables, suggesting a non-monotonic and multifactorial behavior of the system.

 

Correlations between SQFBMS domains

The Pearson’s correlation matrix was calculated separately for each operator and in pooled mode (n = 40 observations) (Fig.5). These results suggest that the domains are interconnected but represent distinct aspects of the biomechanical system.

 

Fig. 5. Correlations between SQFBMS domains for each operator and in pooled mode, reporting Pearson’s r and significance p-value.

 

Inferential analysis and inter-operator comparison

The results of Wilcoxon’s test for comparison between operators are shown in Table III. No statistically significant differences were observed for any of the domains (p > 0.05). Inter-operator reliability was moderate to good (ICC₃,₁ between 0.60 and 0.75; κᵂ between 0.60 and 0.71).

 

Table III. Inter-operator comparisons.

Domain	Median Δ	W+	W–	Z	p	Effect Size
D1	0.0	25.0	20.0	0.333	0.739	0.075
D2	0.0	20.0	25.0	-0.312	0.755	0.070
D3	0.0	27.0	9.0	1.414	0.157	0.316
D4	0.0	10.0	45.0	-1.941	0.052	0.434
Legend: Δ = difference; W+/W– = W statistic, Z = Z value; p = p value.

 

DISCUSSION

 

The results of the present study show that the FBMs, evaluated through the integration between the SQFBMS, aimed at quantifying the osteopathic palpatory assessment performed by experienced practitioners, and instrumental LDA, have a complex, non-linear and multidimensional behavior. This evidence is consistent with the nature of low-frequency biological signals, in which mechanical, vascular, respiratory and cerebrospinal fluids components can simultaneously contribute to the signal form (1,11).

A first relevant finding concerns the distribution of the R/L ratio. Most of the subjects are in the range of near-symmetry, but a significant proportion have lateral dominance (20% left; 35% right). This confirms that perfect symmetry of the frontal bone does not necessarily represent the most frequent physiological condition, while a certain functional asymmetry can be considered part of the individual biological variability, as vastly demonstrated in the literature (19). However, the presence of extreme values suggests the usefulness of laser displacement in recognizing asymmetrical patterns worthy of clinical investigation.

The dominant frequency shows a prevalence of values lower than the classic CRI band, defined between 0.08 and 0.16 Hz (18), with 65% of subjects having a f_dom < 0.08 Hz. This finding is particularly important because it suggests that FBMs should not be interpreted as a single, linear rhythm, but as the result of an interaction between multiple physiological components. The discrepancy observed between f_dom and SC within the CRI band in many subjects indicates a distribution of energy over multiple frequency components, compatible with a multifrequency signal.

The relationship between P2P amplitude and clinical SQFBMS score does not show a simple linear pattern (r = 0.09; p = 0.72). The fact that 50% of subjects fall into discordant quadrants indicates that the amplitude of movement alone is not sufficient to describe the perceived FBMs at the palpatory level. A subject may have large P2P excursion detected instrumentally by LDA, but high SQFBMS score, or reduced P2P amplitude with reduced SQFBMS values. This confirms the need for a multidimensional model, in which symmetry, amplitude, quality and rhythmicity must be considered together.

The domain analysis of the SQFBMS reinforces this interpretation. The D3 domain (Quality) is the most stable and consistent, probably because it is more directly associated with the P2P instrumental data. The D2 domain (Amplitude) has moderate-high dispersion, suggesting a more complex clinical component that is more influenced by subjective or functional factors. The D4 domain (Rhythmicity) shows the greatest variability and nonlinear behavior, consistent with the fact that an altered frequency can be clinically relevant both in the direction of slowing down and accelerating compared to the classical CRI band.

The correlations between domains are moderate overall. This aspect is methodologically relevant: the domains of the SQFBMS appear interconnected, but not redundant. In other words, each domain contributes to describing a specific dimension of the biomechanical phenomenon of FBMs. A more detailed analysis of the SQFBMS domains suggests that Quality of Movement (D3) may represent the most coherent and reproducible palpatory parameter, likely because it is less influenced by subjective factors and captures the global organization of the movement rather than its mere magnitude. Symmetry (D1) also appears particularly relevant due to its good reproducibility and its conceptual correspondence with the instrumental R/L ratio, whereas Rhythmicity (D4), despite its physiological interest, emerged as the most variable domain and may require further methodological standardization. Conversely, Amplitude (D2) appears insufficient to describe the phenomenon when considered in isolation, consistently with the absence of a significant correlation between total SQFBMS score and P2P amplitude. Taken together, these findings reinforce the interpretation of FBMs as a multidimensional biomechanical phenomenon that cannot be explained by movement amplitude alone but rather requires the integrated evaluation of symmetry, quality, rhythmicity and frequency-related characteristics. In this perspective, future studies could explore the development of an Integrated CranioWave Index (ICI) combining D3, D1, R/L ratio and dominant frequency, which emerged as the most informative parameters in this pilot sample. This characteristic supports the multidimensional structure of the scale and justifies its use in association with objective instrumental parameters.

Inferential analysis using Wilcoxon tests showed no statistically significant differences between operators for any of the domains. This data supports the reproducibility of the SQFBMS scale and indicates good inter-operator reliability. The borderline value observed for D4 suggests, however, that rhythmicity may represent the most sensitive and complex domain to be evaluated, requiring further methodological standardization. Since the palpatory assessment of rhythmicity also requires prolonged attentional effort over time, it is possible that the individual attention span has conditioned the discordance between the two operators, considering that it is a very variable parameter and that moreover it would seem to have progressively reduced in human beings in recent years (20).

From a technological point of view, the LDA represents an innovative element of the study. The non-contact measurement reduces the risk of mechanical interference with the tissue, which could be conditioned by the pressure imposed by the hands of the osteopathic operator (12) and which could contribute to systematic error and a reduction in agreement in palpatory evaluations, especially of body symmetries and CRI (21,22). In this context, the micrometric resolution of laser sensors makes it possible to detect changes that are difficult to perceive with traditional clinical approaches. The integration between LDA and SQFBMS therefore makes it possible to transform a predominantly qualitative assessment into a quantifiable, reproducible and potentially comparable clinical-instrumental model between studies. It is no coincidence that optoelectronic and 3D scan evaluation technologies, also based on lasers, have become increasingly widespread in the context of the evaluation and measurement of the human body, placing themselves among the gold standards of measurement, especially thanks to optical triangulation techniques (23,24). In fact, the application of reliable, reproducible and objective means of measurement could allow to bypass the problems of bias and unreliability of manual palpatory assessments, especially in the CST field (25).

The possibility of accurately characterizing FBMs, especially by LDA technology, could have important implications even in areas beyond the osteopathic one. For example, the anatomical location of the frontal bone also places it as the roof of the orbit and protector of the frontal sinuses (26). It follows that the evaluation of frontal bone movement patterns could be useful, for example, in ophthalmology, where the relationship between intraocular pressure, cranial liquor pressure and ocular microcirculation also related to the physio-anatomical properties of frontal bone could have implications in the study of glaucoma and neuro-ophthalmologic conditions associated with the mechanical barrier function of frontal bone with respect to the visual apparatus (27); in fact the translaminar cribrosa pressure gradient is supposed to be a potential explanation for glaucomatous optic nerve vulnerability (28). Similarly, in the otorhinolaryngology and traumatology fields, the protective function of the frontal bone with respect to the sinuses could be relevant to the measurement of FBMs in contexts related to direct trauma and maxillofacial injuries (26) or sinusitis (29) and condition related to the presence of air flow in the nasal-turbinate-sinus complex in normal or inflammatory conditions (30).

Overall, the data indicates that FBMs cannot be reduced to a single variable. The combination of amplitude, frequency, symmetry and rhythmicity offers a more complete and physiologically plausible reading. This integrated approach between SQFBMS and LDA could effectively improve the evaluation practice within the study location, representing a first step towards the construction of quantitative biomarkers of cranial biomechanics, which in the future could be extended to other institutions and healthcare areas, with a view to multicentric and multidisciplinary cooperation.

It is important to note that the present study has limitations. Firstly, due to the retrospective design without a priori programmed recruitment of the cohort, the sample is numerically small, being limited to individuals who voluntarily presented for evaluation during the screening days of the study site. In any case, since this is a small-scale study conducted following a screening campaign, the results obtained represent an interesting preliminary starting point for research on this integration of evaluation approaches, although the generalizability of the results is limited and generally confined primarily to monitoring the evaluation practices of the study facility. Secondly, since the data were initially collected for the purpose of mere evaluation of potential patients of osteopathic interest for the institution which collected the observed data, it cannot be excluded that the results, especially of the SQFBMS evaluation, were conditioned by external factors and biases of the operators. However, this aspect has been mitigated by the good routine practice generally implemented in the institution where the data collection took place, aimed at standardizing and objectifying as much as possible the parts of evaluation and treatment of potential patients in terms of timing, physical places and interference between operators. Thirdly, it should be emphasized that the LDA evaluation only detects the spatial positioning of the surfaces of the monitored areas, thus preventing the certain identification of the specific anatomical-physiological source of the recorded signal. Finally, the SQFBMS, while showing good preliminary reliability, is a scale used exclusively as a proactive tool of potential objectification of osteopathic manual assessments conducted in routine operational practice at the institution of reference for the study; therefore, it needs further validation studies on larger samples and with multimodal comparison in order to effectively consider its use in any future large-scale studies on the evaluative integration preliminarily observed in this study. In general, although the results observed in this preliminary evaluation are encouraging and full of insights, particularly for the monitoring and updating of the evaluation practices of the study venue, the small scale and methodological limitations imposed by the study design limit the generalizability of what has been observed; this makes it desirable to carry out new and more in-depth studies on the same topic, which take into consideration multicentric cooperation, larger samples, as well as more rigorous and possibly prospective, randomized and controlled settings, in order to improve the reliability, generalizability and reproducibility of the good but complex results preliminarily observed with the present study.

 

CONCLUSIONS

 

The present study demonstrates that the integrated evaluation of FBMs by SQFBMS and LDA allows an objective and multidimensional characterization of frontal bone biomechanics. The main results indicate that:

• cranial symmetry has high individual variability;
• most subjects show dominant frequencies lower than the typical CRI band;
• P2P amplitude does not correlate linearly with clinical severity given by the SQFBMS score;
• SQFBMS domains are related but not redundant;
• there are no significant differences between the results of manual palpatory evaluations of the operators in all the domains analyzed;
• the inter-operator reliability of the SQFBMS rating is moderate to good.

These elements support the interpretation of FBMs as a complex, nonlinear and multifactorial phenomenon. LDA represents a promising technology for the objectification of FBMs, while SQFBMS provides a useful clinical framework to interpret instrumental data and increase the reliability and quantification of palpatory manual assessments.

The integration between objective measurement and clinical evaluation observed at the study venue could open new perspectives in biomechanical, rehabilitative and organ-specific research, with particular interest in the study of the interactions between skull, orbit, intraocular pressure, cerebrospinal fluids dynamics and ocular and mucus microcirculation in the sinuses.

 

Conflict of interest

The authors declare that they have no conflict of interest.

 

Funding

The study was conducted without external funding.

 

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