Normative Reference Value for Tactile Localization Acuity among School-going Children: A Normative Research.

BACKGROUND AND AIM: Tactile localization (TL) is one of the standard assessments to be performed under combined cortical sensory assessment. TL is the ability to locate the point of sensory contact and surprisingly, till date there is no normal reference available for estimating TL. Hence, there is a need to calculate the normative reference of TL among school-going children aged between 8 and 13 years.
MATERIALS AND METHODS: A total of 365 healthy school-going children aged between 8 and 13 years were included in this cross-sectional observational study. Children with any neurological condition and other conditions, which prevent them from taking part in the study were excluded. The sample was recruited by stratified random sampling method from the recognized schools in Ambala district, Haryana, India. After the anthropometric measurements, TL acuity was established by point-to-point tactile localization (PPTL) technique. In this technique, the children were asked to relocate the point of contact made by the investigator over identified 15 areas, and after that the distance between the point of contact made by the principal investigator and the relocation point made by the children is measured in centimeters (cm). The mean of three readings were used to estimate TL acuity. RESULT: TL acuity ranges from 0.9 (0.5, 1.5) cm in little finger of palm to 1.5 (1.0, 2.5) cm in middle of posterior arm. TL acuity increases with increasing age. There exist no significant (P ≥ 0.05) difference in the normative reference value between male and female among the identified 15 areas.
CONCLUSION: Normative reference values of TL acuity have been established among school-going children between 8 and 13 years. Copyright:

INTRODUCTION

Sensory system plays a vital role in day-to-day life.[1] The sensations can be divided into three types, superficial sensation, deep sensation, and combined cortical sensation (CCS). Barognosis, stereognosis, graphesthesia, two-point discrimination, and tactile localization (TL) are the sensory subtype of CCS. TL is the ability to locate the point of sensory contact.[2] TL forms a part of functions of parietal lobe of the brain. When a person is able to identify normal touch sensation, then it is considered as tactile recognition, and when a person may be unable to recognize normal touch sensation, then it is considered as tactile agnosia.[3] TL helps to protect our body from harmful sensory stimulation.[4] It is an important sensory assessment in case of rehabilitation following hand injuries, plastic surgery, parietal lobe disorders, infantile hemiplegia, childhood stroke, burn and skin graft.

Paucity of literature is observed related to TL. To the best of our knowledge, there is only one literature available, related to the estimation of TL acuity in hand and digits, which is published in 2013 by Yoshioka et al.[5] They had studied the somatosensory perception of TL stimuli and examined TL in children, adolescents, adults, and person with William syndrome.[5] Till date, there is no normal reference value available to estimate TL among schoolchildren aged between 8 and 13 years. Therefore, we have assessed the normative reference value for TL among the school-going children.

MATERIALS AND METHODS

This study was performed on primary and middle school–going children. The trial was registered under ClinicalTrials.gov, NCT03546712 on June 06, 2018, with universal trial number (UTN) U1111-1214–2489 under World Health Organization (WHO), International Clinical Trials Registry Platform. The study was ethically approved by institutional ethics committee of Maharishi Markandeshwar (Deemed to be University), Mullana, Haryana, India, with unique reference number MMDU/IEC/1188, dated June 12, 2018. The study was completed in accordance with the principles of the Declaration of Helsinki (Revised, 2013) and National Ethical Guidelines for Biomedical Research involving Children by Indian Council for Medical Research (ICMR, 2017).[6] The study was performed between September 2018, and March 2019.

The school-going children aged between 8 and 13 years were recruited by stratified random sampling method from the recognized private and government schools in Ambala district, Haryana. Final sample size was considered based on unpublished pilot study, which recommended at least 20 children in each age-group.[7] We have used stratified random sampling to minimize selection bias and strengthen the research methodology adopted.[8] For this study, 365 healthy school-going children were recruited from the age-group between 8 and 13 years. Children with known history of neurological condition, skin rashes, and other conditions, which prevent them from taking part in the study were excluded. As there was no risk associated with the study, written consent was waived but oral assent was obtained from the children before their recruitment.[6] Anthropometric measurements were performed either in the playground, home, classroom, or in sports rooms, during physical education at each school. Body weight was measured with calibrated weighing machine after removing shoes, and weight was recorded in kilograms (kg) (rounded off to nearest 0.5kg). Height was measured in centimeters (cm) without shoes with the help of measuring tape pasted on a wall, children were asked to stand against the wall with feet close together and facing forward (rounded off to nearest 0.5 cm). TL was performed on children by point-to-point tactile localization (PPTL) technique. The procedure was explained to the children and made sure that they understood before the commencement of test. According to this, the children were asked to relocate the point of contact on upper extremity made by the investigator with black marker on nondominant hand [Figure 1] of the recruited children and they were asked to relocate with red color marker on the dominant hand [Figure 2]. During the above procedure, recruited school-going children were asked to close their eyes.

Figure 1

PPTL marked by principal investigator on the nondominant hand of children

Figure 2

PPTL marked by children

For performing TL acuity by the PPTL technique, 15 areas were identified as described in previous research.[9] These 15 areas covered all dermatomes of the upper limb. Fifteen areas included in the study were little finger of palm (LFP), middle finger of the palm (MFP), thumb of palm (TP), first dorsal interosseous (FDI), mid last part of the forearm (MLF), medial forearm (MF), medial side of the forearm (MSF), the lower part of the arm (LPA), middle of posterior arm (MPA), lateral upper arm (LUA), lower medial arm (LMA), middle arm (MA), the median upper arm (MUA), lower side of arm (LSA), and upper side of the arm (USA). Children were asked to relocate point on the nondominant hand with the help of red pen marker on those identified 15 areas located by the principal investigator. The pen marker used in this study was nontoxic and used daily by the school-going children, hence it is not harmful, not new to them, and easy to handle them. The distance between black point marked by the principal investigator and red point marked by children with performing PPTL technique was noted in cm for TL acuity. The mean values of the three readings in 15 areas were used for estimating the normative reference value of TL by performing PPTL technique.

Data analysis: For estimating the normality, Kolmogorov–Smirnov normality verification test was used as the sample size was greater than 50 (n = 365). As the data do not follow normal distribution, descriptive statistics was expressed in median and interquartile range (IQR) with range. Statistical test of significance between genders was estimated by Mann–Whitney U test. For all the statistical analysis, the level of significance was defined as P < 0.05. The data were recorded using the statistical software, the Statistical Package for Social Sciences, SPSS, version 16.0 for Windows 7 Ultimate edition (IBM SPSS V-20 for Windows, Armonk, New York).

RESULTS

From screening of 565 school-going children, a total of 365 school-going children were included in the study. Among them, 207 children were male and 158 children were female. Demographic data of the recruited school-going children were displayed in Table 1 as median (IQR). Table 2 shows Mean [(95% confidence interval (CI)], median (IQR) and rage of TL in each 15 areas of school-going children aged between 8 and 13 years. Table 3 shows median (IQR) in each 15 areas between male and female; the significant difference between them was established by Mann–Whitney U test. The result shows that TL acuity increases with increasing age; minimum TL acuity was 0.1 cm and maximum TL acuity was 7.0 cm. No significant difference (P value ≥ 0.05) was observed between male and female in each identified 15 areas.

Table 1

Demographic dimensions of the school-going children recruited (n = 365)

Demographic dimensions	Median (IQR)
Age (year)	10 (9, 12)
Height (cm)	136.2 (127, 144)
Weight (kg)	30 (24, 38)
BMI (kg/cm2)	16 (14, 18)

BMI = body mass index, IQR = interquartile range

Table 2

Normative reference score of tactile localization (TL) on upper limb among children aged between eight and 13 years (n = 365)

Areas	Mean (95% CI)	Median (IQR)	Range
LFP (cm)	1.1 (1.0 - 1.2)	0.9 (0.5, 1.5)	(0.1 - 6.5)
MFP (cm)	1.1 (1.0 - 1.2)	0.9 (0.5, 1.5)	(0.1 - 5.5)
TP (cm)	1.0 (0.9 - 1.1)	1.0 (0.5, 1.4)	(0.1 - 6.5)
FDI (cm)	1.0 (0.9 - 1.1)	1.0 (0.5, 1.5)	(0.1 - 5.0)
MLF (cm)	1.4 (1.3 - 1.5)	1.0 (0.9, 2.0)	(0.1 - 6.3)
MF (cm)	1.4 (1.3, 1.5)	1.0 (0.9, 2.0)	(0.1 - 5.0)
MSF (cm)	1.5 (1.4 - 1.6)	1.2 (1.0, 2.0)	(0.1 - 6.5)
LPA (cm)	1.6 (1.4 - 1.7)	1.5 (1.0, 2.0)	(0.1 - 6.5)
MPA (cm)	1.7 (1.6 - 1.8)	1.5 (1.0, 2.5)	(0.1 - 6.0)
LUA (cm)	1.5 (1.4 - 1.6)	1.5 (1.0, 2.0)	(0.1 - 6.0)
LMA (cm)	1.3 (1.3 - 1.4)	1.3 (1.0, 2.0)	(0.1 - 4.0)
MA (cm)	1.5 (1.4 - 1.6)	1.5 (1.0, 2.0)	(0.2 - 6.5)
MUA (cm)	1.5 (1.4 - 1.6)	1.5 (1.0, 2.0)	(0.1 - 6.0)
LSA (cm)	1.4 (1.4 - 1.5)	1.5 (0.9, 2.0)	(0.1 - 7.0)
USA (cm)	1.4 (1.3 - 1.5)	1.5 (1.0, 1.5)	(0.1 - 6.0)

Note: LFP = Little finger of palm, MFP = Middle finger of palm, TP = Thumb of palm, FDI = First dorsal interosseous, MLF = Mid last part of the forearm, MF = Medial forearm, MSF = Medial side of the forearm, LPA = Lower part of arm, MPA = Middle of posterior arm, LUA = Lateral upper arm, LMA = Lower medial arm, MA = Middle arm, MUA = Median upper arm, LSA = Lower side of arm, USA = Upper side of arm, CI = confidence interval, IQR = inter quartile range, cm = centimeter

Table 3

Comparison between the male and female median value with interquartile range of TL on upper limb (n = 365)

Areas	Male	Female	P value#
LFP (cm)	1.0 (0.5, 1.5)	1.0 (0.5, 1.4)	0.68
MFP (cm)	0.9 (0.9, 1.5)	1.0 (0.5, 1.5)	0.81
TP (cm)	1.0 (0.5, 1.2)	1.0 (0.5, 1.0)	0.57
FDI (cm)	1.0 (0.5, 1.5)	1.0 (0.5, 1.3)	0.84
MLF (cm)	1.3 (1.0, 2.0)	1.2 (0.9, 2.0)	0.68
MF (cm)	1.0 (0.9, 2.0)	1.5 (1.0, 2.0)	0.52
MSF (cm)	1.2 (1.0, 2.0)	1.5 (0.9, 2.0)	0.53
LPA (cm)	1.5 (1.0, 2.0)	1.5 (1.0, 2.0)	0.41
MPA (cm)	1.5 (1.0, 2.5)	1.5 (1.0, 2.5)	0.78
LUA (cm)	1.5 (1.0, 2.0)	1.5 (0.9, 2.0)	0.84
LMA (cm)	1.0 (1.0, 2.0)	1.5 (1.0, 2.0)	0.05
MA (cm)	1.5 (1.0, 2.0)	1.5 (0.9, 2.0)	0.19
MUA (cm)	1.5 (1.0, 2.0)	1.5 (1.0, 2.0)	0.75
LSA (cm)	1.5 (0.9, 2.0)	1.5 (1.0, 2.0)	0.64
USA (cm)	1.3 (0.9, 1.5)	1.5 (1.0, 1.5)	0.18

Note: LFP = Little finger of palm, MFP = Middle finger of palm, TP = Thumb of palm, FDI = First dorsal interosseous, MLF = Mid last part of the forearm, MF = Medial forearm, MSF = Medial side of the forearm, LPA = Lower part of arm, MPA = Middle of posterior arm, LUA = Lateral upper arm, LMA = Lower medial arm, MA = Middle arm, MUA = Median upper arm, LSA = Lower side of arm, USA = Upper side of arm, CI = confidence interval, IQR = inter quartile range, cm = centimeter

#Mann–Whitney U test

DISCUSSION

The study aimed to define the normative reference value of TL acuity on upper limb among the primary and middle school–going children aged between 8 and 13 years. Acuity of TL was performed by PPTL, which consists of two color pen markers; one is red color used by children and the other is black color used by principal investigator. This examination performed on school-going children (PPTL technique) is not time-consuming, as it took approximately 5min for each child to complete the procedure. Demonstration of the procedure was done by the principal investigator well in advance to make sure that the children understood the procedure before the study. Instruction regarding PPTL procedure was given clearly to the school-going children in their understandable lay language. For estimating the TL acuity on upper limb, 15 areas were identified, which are supplied by musculocutaneous, axillary, radial, median, and ulnar nerve, these nerves supply in the arm, forearm, and palm. Fifteen areas included LFP supplied by ulnar nerve, MFP supplied by median nerve, TP supplied by radial nerve, FDI supplied by median nerve, MLF supplied by radial nerve, MF supplied by radial nerve, MSF supplied by ulnar nerve, the LPA radial nerve, MPA supplied by radial nerve, LUA supplied by musculocutaneous nerve, LMA supplied by musculocutaneous nerve, MA supplied by musculocutaneous and axillary nerve, MUA supplied by musculocutaneous nerve, LSA supplied by musculocutaneous nerve, and USA supplied by axillary and musculocutaneous nerve.[9] Thus, the major dermatomes of upper limb were covered by assessing TL acuity performed in these 15 areas.[10]

TL acuity increases gradually in typically developing primary and middle school–going children in the age group between 8 and 13 years. We included upper limb of the children because of increased chances of injury in upper limb than lower limb among the school-going children. We took nondominant hand in upper limb to perform PPTL. Previous article represented that tactile acuity on the neck region with the validity and reliability. They performed four tests, which were two-point discrimination, TL, graphesthesia, and point to point. They reported that two-point discrimination showed excellent test–retest reliability (ICC = 0.85, standard error of the mean [SEM] = 3.7mm), point to point and TL test showed good reliability (ICC = 0.50, SEM = 2.8mm; ICC = 0.60, SEM = 8.8mm, respectively), and graphesthesia showed fair reliability (ICC = 0.48, SEM = 1.9mm). In estimating TL acuity, they found three tests to be significant, and after localization training, they found changes in tactile acuity.[11]

In this study, a total of 365 children participated, and among them, 207 children were male and 158 children were female. As the data did not follow normal distribution of TL acuity on 15 areas, the descriptive statistics was expressed in median with IQR and mean with 95% confidence interval (CI) for each 15 areas among schoolchildren between 8 and 13 years. We compared TL acuity in each 15 areas between male and female. Minimum mean value of TL acuity was 1.0 cm from TP and FDI, and maximum mean value of TL acuity was 1.7 cm from MPA. No significant difference (P value ≥ 0.05) exists between male and female in identified 15 areas. Limitations of the study were unavoidable human error while using measuring tape and reliability of TL depends on the perception of children. The strength of this study was that the recruited school-going children from different geographical locations, which help in greater extrapolation, and minimal time was required to perform TL. Further, the study could be extended in estimating normative reference value of TL in lower limb, children aged less than 8 years and greater than 13 years and among patients with neurological disorders.

The clinical significance of this study was that the normative reference value for TL acuity among school-going children could act as the benchmark in comparing with the children with parietal lobe disorders. The reference norms could be used as the prognostic indicator in case of rehabilitation following hand injuries, plastic surgery, parietal lobe disorders, infantile hemiplegia, childhood stroke, burn and skin graft among children. To the best of our knowledge, this is the first study of its kind, which is available to determine the normative reference value for TL acuity among school-going children.

CONCLUSION

TL acuity reference value among school-going children aged between 8 and 13 years has been reported.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This study was supported by the PG Dissertation Grant, MMDU/2017/18177009, of Maharishi Markandeshwar (Deemed to be University).

Conflicts of interest

There are no conflicts of interest.