Noninvasive Characterisation of Foot Reflexology Areas by Swept Source-Optical Coherence Tomography in Patients with Low Back Pain

Table 1

Optical and SS-OCT images of lumbar reflexology areas and corresponding pain history.

		Multimodal characteristic features of the lumbar reflexology areas (RAs) and clinical history
Parameters	Gender	Normal reflexology area	Abnormal reflexology areas**
		Pathological grade 0	Pathological grade 1	Pathological grade 2	Pathological grade 3
Optical images	Male
SS-OCT images	Male
Optical images	Female
SS-OCT images	Female
Physical features of RAs	Both Genders	No pigmentation; No tenderness*; 0 < VAS ≤ 0.5	Scattered light pigmentation; Tenderness*; 0.5 < VAS ≤ 3	Continuous brown pigmentation; Tenderness*; 3 < VAS ≤ 6	Continuous dark brown pigmentation; Tenderness*; 6 < VAS ≤ 9
SS-OCT features of skin layers	Both Genders	The skin layers (i.e., epidermis, epidermis-dermis junction, papillary dermis, and reticular dermis) were distinctly visible/separable.	The distinction between the papillary dermis and reticular dermis started defusing.	The basement membrane was not visible distinctly. The papillary dermis and reticular dermis were not separable distinctly.	The well separable layers like epidermis, epidermal and dermal junction, papillary dermis, and reticular dermis lost their distinctness.
Luminosity distribution (ref. Figure 5)	Both Genders	Viable epidermis layers exhibited an increase in intensity gradient starting from the layer adjacent to basal membrane (layer 3) towards Stratum Corneum (layer 1).	Slope of the intensity gradient was less compared to normal skin and maximum luminosity was observed at papillary dermis.	Luminosity variations were identical with skin of grade 1 but were at higher intensity than normal skin as well as that of grade 1.	There was almost uniform luminosity throughout all the layers of epidermis and dermis. Total intensity was higher than all other grades.
Clinical history of the subjects 𝑛 = 21; age group: 24–45 years	𝑛control = 6 (Male : Female = 1 : 1); 𝑛LBP = 15 (male : female = 2 : 3)	No pain; 0 < VAS ≤ 0.5	Occasional mild pain in long (>3 hrs) duration of seating/standing 0.5 < VAS ≤ 3 (0.5 < VAS ≤ 3) and disease duration ≤6 months	Occasional moderate pain; (3 < VAS ≤ 6) and needed rest and 6 months < disease duration < 3 years	Chronic moderate pain; (3 < VAS ≤ 5) and frequently pain became severe 6 < VAS ≤ 9 and needed medical intervention. 3 years < disease duration

The depth of subcutaneous layer for which SS-OCT images were captured was 1.75 mm.
*Tenderness was observed in response to finger pressure (FP) (30 N/cm² < FP < 35 N cm²).
**Tenderness without pigmentation 𝑛% = 41%; tenderness with pigmentation 𝑛% = 59%; pigmentation without tenderness 𝑛% = 0; 𝑃<0.05.
SS-OCT feature-based pathological grades of lumbar reflexology areas: grade 0: normal RAs; grade 1 RAs: early degenerative changes in SS-OCT images; grade 2 RAs: moderately advanced changes in SS-OCT images; grade 3 RAs: advanced changes in SS-OCT images.