New approach for evaluating the effectiveness of whole-body magnetic field therapy in the rehabilitation of patients with lumbar discectomy

Abstract

OBJECTIVE:

Magnetic field therapy involves the application of low-intensity magnetic fields (1–3.5 mT) to a patient’s whole body. The purpose of this study was to assess the effectiveness of whole-body magnetic field (WBMF) therapy in the early rehabilitation of patients after lumbar discectomy.

METHODS:

A convenience sample of 73 patients who underwent lumbar discectomy within 1 month previously participated in the study. All patients were randomly assigned to one of two groups and received either a course of conventional rehabilitation (control group) or conventional rehabilitation together with 10 sessions of WBMF therapy (WBMF group). Participants were evaluated before and after the rehabilitation course by using the Visual Analog Scale for Pain (VAS) and thermal infrared imaging. The latter was used to detect pathological changes in temperature (hyperthermia and thermal asymmetry) of the surface of the skin overlying the lumbar spine and lower extremities.

RESULTS:

The VAS score of the WBMF group decreased from 6.2 $\pm$ 0.3 cm before to 3.2 $\pm$ 0.2 cm after rehabilitation ( $p<$ 0.01), compared to 6.1 $\pm$ 0.4 cm before to 4.3 $\pm$ 0.2 cm after rehabilitation for the control group ( $p<$ 0.05). Reduction of the area of lumbar hyperthermia was observed in 88% of WBMF and 35% of control group patients.

CONCLUSIONS:

When combined with conventional rehabilitation, WBMF therapy was effective in reducing lumbar pain, temperature, and, possibly, inflammation. Results of this study will be used for designing a large-scale clinical trial.

Keywords

Pulsed magnetic field therapy physical therapy infrared thermography spine pain spine cord injury

1. Introduction

Degeneration or trauma of the lumbar spine frequently lead to intervertebral disc herniation, with subsequent irritation of the spinal nerve roots, localized lumbar and/or referred lower extremity pain, restricted spinal mobility, and reduced quality of life [1]. Lumbar disc herniation accounts for $\sim$ 5% of all low back-related symptoms and often requires medical attention [2]. Herniated discs can be treated noninvasively. However, there is strong evidence in favor of lumbar discectomy surgery over conservative treatment [3]. At present, lumbar discectomy is the most common procedure performed for patients experiencing low back and/or referred leg pain associated with disc herniation worldwide [4].

The purpose of discectomy is to reduce or eliminate excessive compression of the spinal nerve roots by removing herniated or loose intervertebral disc tissues. When successful, surgery provides immediate release, but does not prevent further degeneration or inflammation of the disc or neurophysiological changes in spinal nerve roots. Residual or surgery-induced changes in spinal nerve integrity can lead to interruption of the microcirculatory blood flow, development of intraneural or perineural edema, inflammation, and impairment of axonal transport [5, 6, 7]. Clinically, these conditions are manifested through various lumbar spine-related symptoms, such as acute or subacute pain in the dermatomes, altered temperature and vibration sensations, decreased deep tendon reflexes, and weakness of the muscles innervated by the affected nerves. Localized or radiating low back pain is the most devastating and frequently reported symptom.

Pain after discectomy usually has a mixed character involving several underlying mechanisms. A nociceptive mechanism involves altered sensitivity of C-fibers in the affected disc, surrounding tissues, and spasmodic muscles. Neuropathic pain results from direct or indirect damage to the spinal nerves due to surgery-related microtrauma, postoperative edema, ischemia, and inflammation. Most patients with a long history of postoperative pain develop psychogenic pain symptoms later [8].

Patient rehabilitation in the postoperative period includes pharmacological and physical therapies aimed at reducing inflammation and metabolic disruption, restoring integrity of the compressed and damaged nerves, and strengthening spinal muscles. Applied frequently to a specific body part or focused on a specific syndrome, these rehabilitation procedures can be used to treat localized neuropathic symptoms and microcirculatory abnormalities. However, such syndrome-based approaches are less effective in addressing systemic metabolic impairments, disrupted hemodynamics, and asthenoneurotic impairments. In this regard, postoperative rehabilitation may benefit from inclusion of more system-based therapeutic approaches. One such approach could be the application of low-intensity (1–3.5 mT) magnetic fields to the patient’s whole body.

The physiological effects of applying magnetic fields to the whole body are based on the physical manipulation of charged particles. The magnetic field may interact with unbound (electrons, ions) and bound charged particles (atoms, molecules). This interaction produces changes of the membrane potential, lipid peroxidation, physical and chemical properties of water. Shifting the membrane resting potential may selectively attenuate depolarization of nociceptors and make them less sensitive to stimuli [9]. Magnetic fields can stimulate blood flow through the skin and the subcutaneous and muscular tissues, change the primary mechanisms of homeostasis, and activate nonspecific adaptive immune, nervous, and humoral systems. All of these mechanisms facilitate recovery after discectomy in the affected area of the spine [10]. As evidence, analgesic, anti-inflammatory, immunomodulatory, antioxidative, antiedemic, sedative, and enzyme-stabilizing effects of magnetic field therapies have been observed in several clinical studies [11, 12, 13].

Therapeutic effects of applying magnetic fields to the whole body have been documented in patients with hypertension, type 2 diabetes, brain hypoxia, chronic obstructive pulmonary disease, gynecological conditions, infectious diseases, and nonspecific low back pain [13, 14, 15, 16, 17, 18]. Most related clinical studies were conducted in Europe. In contrast, the application of similar devices in other countries, for example in the USA is restricted by federal regulations. The USA Food and Drug Administration recently reclassified most systems that generate pulsed electromagnetic field (PEMF) as risk level 2 wellness devices and approved their use for some, but not all medical conditions. Post-lumbar discectomy symptoms are not included in the list of approved applications, which may explain the lack of clinical trials in this area of American physical medicine. At the same time, PEMF applications have documented positive effects, and the therapy has the potential to be an effective supplement to treatments of low back pain [19, 20]. Thus, further research in this area of physical medicine is important to expand areas of potential magnetic field therapy applications.

The purpose of the present study was to assess the effectiveness of low-intensity (1–3.5 mT) whole-body magnetic field (WBMF) therapy in the rehabilitation of patients after lumbar discectomy. A principal difference of WBMF from other magnetic therapies is that it generates alternating low-intensity fields that cover all of patient’s body parts. When applied to the whole body, the magnetic field is distinctly inhomogeneous and makes patients more sensitive to its action compared to other magnetic field therapy options. In WBMF therapy, the magnitude of the magnetic field can be modulated during the therapeutic session to promote long-term recovery effects. Finally, magnetic fields delivered at 100 Hz can be synchronized with many other biological rhythms of the body, ranging from cellular metabolism to functions of specific systems or organs. This situation can create additional positive chronobiological effects. Considering all of these features, it has been hypothesized that WBMF therapy can be effective in facilitating recovery after lumbar discectomy.

2. Methods

2.1 Subjects

One hundred and ten individuals after lumbar discectomy were initially recruited and screened for potential enrollment in the study (Fig. 1), and of those 110 recruited, 73 individuals (53 males) met the eligibility criteria. The sample of 73 participants was determined as a minimal number of subjects ( $n=$ 70) to insure at least 80% power at the $p=$ 0.05 level, and to allow a possible 4–5% dropout rate ( $n=$ 3). All participants completed the study protocol and were included in data analysis.

Figure 1.

Flow chart for design of the clinical trial.

Eligibility criteria were a history of lumbar disc herniation, lumbar discectomy performed less than 1 month before study enrollment, and pain or discomfort in lumbar area. Participants were excluded if they had any systemic cardiovascular disease, acute infection, severe somatic pathology, implanted cardiostimulator or analogous device, known psychiatric disorder, or confirmed or suspected pregnancy. Before enrollment, all individuals signed an informed consent form that had been approved by the local ethics committee.

All participants were randomly assigned to one of two treatment groups to receive either a course of conventional rehabilitation (control group), or conventional rehabilitation together with 10 sessions of the WBMF therapy (WBMF group). Randomization was done in blocks with the use of sealed envelopes. The control group included 36 participants (mean $\pm$ standard deviation [SD] age: 45.2 $\pm$ 12.7 years; 27 males; time after discectomy: 16.1 $\pm$ 5.3 days, Table 1). The WBMF group comprised 37 matched individuals (age: 39.9 $\pm$ 9.1; 26 males; time after discectomy: 18.1 $\pm$ 6.2 days). The study was conducted in an inpatient clinical setting.

2.2 Treatments

Participants in both groups received a course of conventional rehabilitation that focused on correcting residual or discectomy-related lumbar spine symptoms. The rehabilitation course followed a standard protocol established in the inpatient clinic, with consideration of each patient’s individual goals and limitations. Rehabilitation included nonsteroidal anti- inflammatory and antispastic drugs, glucocorticoids, nonnarcotic analgesics, and 10 sessions of physical therapy. The goal of the first 1–3 therapeutic sessions was to relieve pain and reduce the inflammatory process. Participants performed respiratory exercises; isometric contract-relax exercises involving the upper and lower back muscles (5–6 sec to contract; then 10 sec to relax; repeated 4–6 times); exercises strengthening abdominal muscles; and gentle soft-tissue mobilization and relaxation of the erector spinae group. All exercises were performed in either prone or supine position. After the acute pain had subsided (beginning with the 7 ${}^{\text{th}}$ –8 ${}^{\text{th}}$ sessions) the physical therapy focused on altering posture and movements to achieve the highest level of functioning. Therapeutic exercises were performed in siting and standing 2–3 times a day, and included isometric contractions of the upper/lower back and abdominal muscles with the use of TeraBands, FitBalls, and other fitness equipment. From minimum to no spine mobilization was allowed during all therapeutic activities. Participants began exercising daily for 30 min, eventually increasing a dosage of exercises up to 1.5 hours a day. Concurrently with the therapeutic exercises, participants received ten 30-min sessions of aquatic therapy, scheduled 4–5 times a week, to reduce stress on the injured spine segments and to allow maximum muscle relaxation.

In addition to a conventional rehabilitation course, the WBMF group received 10 sessions of WBMF therapy, scheduled 4–5 times a week and delivered according to a previously patented protocol (Patent RF. No 2613416 RU, MKI A 61 N 2/04 [21]). The therapy was delivered with the use of the UMTI-3F Kolibri Expert device (Madin, Nizhny Novgorod, Russia), illustrated in Fig. 2. The device consists of a scan bed with three solenoid coils, positioned around the bed and perpendicularly to the transverse axis of the patient’s prone or supine body and inside of the coils. The device generates alternating magnetic fields of low intensity ( $\leqslant$ 3.5 mT) rotating around the body, replicating a “cylinder” pattern and covering all body parts.

Figure 2.

Participant positioned inside of three solenoid coils on the UMTI-3F Kolibri Expert scan bed.

The WBMF therapy was delivered to a patient according to the severity of low back pain. Patients with severe pain received magnetic field applications as follows: 1–2 sessions at 10% of the maximal intensity of magnetic field (3.5 mT) for 15 minutes, 3–5 sessions at 20% of the maximal intensity for 15 minutes, 6–7 sessions at 30% of the maximal intensity for 15 minutes, and 8–10 sessions at 50% of the maximal intensity for 20 minutes. Patients with mild-to-moderate pain followed a slightly different protocol of WBMF therapy, which included: 1–2 sessions at 20% of the maximal intensity for 15 minutes, 3–4 sessions at 30% of the maximal intensity for 15 minutes, 5–6 sessions at 40% of the maximal intensity for 20 minutes, 7–8 sessions at 50% of the maximal intensity for 20 minutes, and 9–10 sessions at 60% of the maximal intensity for 20 minutes. Duration of magnetic field exposure was defined based on previous clinical experiences, which showed that extending the therapy to 25–35 minutes failed to add any significant improvement, whereas a shorter duration of 10–12 minutes was clinically insufficient.

During delivery of the WBMF therapy, all safety precautions were met. Before the session began, participants removed all metallic objects. During the session, they were instructed to stay relaxed and to report any discomfort that they may feel. The experimenter monitored their condition.

2.3 Outcome measures

Regardless of group assignment, each participant was evaluated twice: before the rehabilitation course began (before) and immediately after its completion (after). Participants were evaluated at both time points with two outcome measures: pain and pathological changes in temperature (hyperthermia and thermal asymmetry) of the surface of the skin overlying the lumbar spine and lower extremities.

Pain in the lumbar spine area was measured with the valid and reliable Visual Analog Scale for Pain (VAS [22]). Pain was categorized as mild (VAS score: 1–4 cm), moderate (VAS score: 5–6 cm), or severe (VAS score: 7–10 cm).

Temperature of the skin overlying the lumbar spine and lower extremities was measured with the use of infrared thermography (also known as thermal infrared imaging). Validity of this method as a diagnostic technique has been confirmed in previous works and surgical and neurological practice [23, 24, 25]. Infrared thermography allows the temperature distribution over the target area to be recorded and presented in a pallet format with different colors indicating different temperatures. Figure 3 shows an image of the temperature distribution pattern from one representative participant, in a rainbow format. This method has been shown to be very sensitive to detecting temperature differences with an accuracy of 0.1–0.5 ${}^{\circ}$ C, depending on the model and type of thermograph device and camera resolution. As a diagnostic instrument, infrared thermography is used to detect zones of increased temperature (focal hyperthermia). Focal hyperthermia over the spine is an indicator of muscle spasm, inflammation, or venous insufficiency, while hypothermia of the dermatome is evidence of abnormal regulation of blood vessel tone, intraneural or perineural edema, and impaired nerve conduction.

Figure 3.

Pattern of temperature distribution on the surface of the skin over the lumbar spine (upper panel) and lower extremities (lower panel) in one representative participant before ( $A_{b}$ ) and after ( $A_{a}$ ) a course of rehabilitation.

Infrared thermography was performed with the use of an optical-electronic medical thermograph (IRTIS 2000-ME, IRTIS, Russia). Optical-electronic scanning allows the highest possible resolution. The device operates within a spectral range of 3–5 $\mu$ m, thereby providing the highest possible thermal contrast to visualize and identify focal hyper- and hypothermia. The device measures skin temperature patterns remotely and detects temperature differences with an accuracy of 0.1 ${}^{\circ}$ C. The thermograph used in this study has been effectively tested previously for evaluation and diagnosis in patients with various orthopedic diseases [26, 27]. Obtained infrared thermal images were rendered with the use of Tescan Atlas (Tescan, Czech Republic) and AnalySIS 5.0 (Olympus, Japan) software packages. Accuracy of the images was verified with the Image-Pro Plus 6.0 (Media Cybernetics, USA) package, which also allows rendering. Use of two different rendering techniques ensured a minimal error ( $\leqslant$ 2%, according to Kornfeld). Several outcome parameters were computed from the images to characterize a size of hyperthermic area and a temperature difference between hypermetric and normal areas.

Changes in the size of the hyperthermic area over the lumbar spine ( $D_{\textit{spine}}$ ) and size of the thermal asymmetry area over the lower extremities ( $D_{\textit{legs}}$ ) were calculated according to the equations below.

$\displaystyle D_{\textit{spine}}=(A_{b}-A_{a})/A_{b}*100{\%}$ $\displaystyle D_{\textit{legs}}=(A_{b}-A_{a})/A_{b}*100{\%}$

where $A_{b}$ and $A_{a}$ represent areas of hyperthermia/ thermal asymmetry before and after a rehabilitation course. Hyperthermia for the $D_{\textit{spine}}$ index was defined as a temperature difference of more than $+$ 0.5 ${}^{\circ}$ C compared to the temperature in thoracic spine region. This threshold was set based on previous infrared thermography data collected from healthy individuals and is consistent with other studies [28, 29]. Under the normal condition, there is consistent mild hyperthermia in the lumbar spine, with an average temperature difference of 0.42 $\pm$ 0.03 ${}^{\circ}$ C ( $p<$ 0.02) between the thoracic T6-7 and lumbar L4-5 vertebrae. Lower extremities are thermally symmetrical in healthy individuals. For the $D_{\textit{legs}}$ index, the temperature of the skin surface of the affected leg was compared with the temperature of the skin of the nonaffected leg, defining leg thermal asymmetry. The $D_{\textit{legs}}$ index defined changes in the area of thermal asymmetry over a course of rehabilitation.

Changes in the temperature difference for the lumbar spine ( $D\Delta T_{\textit{spine}}$ ) and lower extremities ( $D\Delta T_{\textit{legs}}$ ) were computed with the equations below.

$\displaystyle D\Delta T_{\textit{spine}}=(\Delta T_{b}-\Delta T_{a})/\Delta T_% {b}*100{\%}$ $\displaystyle D\Delta T_{\textit{legs}}=(\Delta T_{b}-\Delta T_{a})/\Delta T_{% b}*100{\%}$

For the $D\Delta T_{\textit{spine}}$ index, $\Delta T_{b}$ and $\Delta T_{a}$ represent the temperature difference between the T6-7 and L4-5 vertebrae before and after rehabilitation, respectively. For the $D\Delta T_{\textit{legs}}$ index, $\Delta T_{b}$ and $\Delta T_{a}$ were calculated between involved dermatomes of the affected leg and a similar area of the nonaffected leg before and after rehabilitation, respectively.

The STATISTICA 10.0/W RUS software package was used for statistical analysis. The VAS measures were compared by two-way ANOVA, with the following factors: group (WBMF, control) and evaluation time (before, after). The Tukey Honest Significant Difference (HSD) test was used for post-hoc comparisons. A minimum significance level of $p<$ 0.05 was set for all comparisons. Thermal infrared images were analyzed in terms of the distribution of patients in each group, based on their $D_{\textit{spine}}$ , $D_{\textit{legs}}$ , $D\Delta T_{\textit{spine}}$ , and $D\Delta T_{\textit{legs}}$ indices.

3. Results

Participants in both groups were matched at the baseline by age, sex, time of lumbar discectomy, and temperature differences before rehabilitation with no significant between-group differences, as confirmed by an independent t-test (Table 1).

Table 1
Demographic and pre-treatment outcome measures of patients with lumbar discectomy (mean $\pm$ standard deviation) in two experimental groups

Parameter	WBMF group	Control group	t-test
	( $n=$ 37)	( $n=$ 36)
Sex (M/F)	26/11	27/9	$>$ 0.1
Age (yr)	39.9 $\pm$ 9.1	45.2 $\pm$ 12.7	$>$ 0.05
Time after	18.1 $\pm$ 6.2	16.1 $\pm$ 5.3	$>$ 0.1
discectomy (days)
VAS score (cm)	6.2 $\pm$ 0.3	6.1 $\pm$ 0.4	$>$ 0.1
${}^{*}\Delta T_{b}$ for spine ( ${}^{\circ}$ C)	1.23 $\pm$ 0.36	1.16 $\pm$ 0.31	$>$ 0.1
${}^{*}\Delta T_{b}$ for legs ( ${}^{\circ}$ C)	0.98 $\pm$ 0.13	0.98 $\pm$ 0.11	$>$ 0.1

${}^{*}$ – $\Delta T_{b}$ for spine represents the temperature difference between the T6-7 and L4-5 vertebrae; and $\Delta T_{b}$ for legs – the temperature difference between involved dermatomes of the affected leg and a similar area of the nonaffected leg before rehabilitation.

3.1 Pain

All participants reported lumbar spinal symptoms, with pain as the chief complaint. Presence of mild-to-severe pain in the lumbar spine and radiating down to the lower extremity was reported by 100% of WBMF and 94.4% of control group patients. Pain was exacerbated when participants maintained a vertical position for a longer period of time in 83.8% of WBMF and in 86.1% of control group patients. The remaining participants reported feeling pain all of the time. In addition to pain, most patients complained of restricted mobility and flexibility in the lumbar spine, loss of sensitivity in specific dermatomes (81.1% of WBMF and 80.6% of control group patients), lack of motivation and mild depression (70.3% of WBMF and 66.7% of control group patients).

Upon completion of a rehabilitation course, 83.8% of WBMF and 77.8% of control group patients had decreased pain (VAS score decrease $>$ 1.7 cm). The 1.7-cm threshold corresponds to the minimal clinically significant difference established for the VAS at the VIII International Forum on Primary Care Research on Low Back Pain [30]. Pain was significantly decreased, as compared to a pain level before rehabilitation in both groups ( $F_{1,71}=$ 50.3, $p<$ 0.001), with VAS scores decreasing from 6.2 $\pm$ 0.3 to 3.2 $\pm$ 0.2 cm (post-hoc test, $p<$ 0.01) in the WBMF group and from 6.1 $\pm$ 0.4 to 4.3 $\pm$ 0.2 cm in the control group ( $p<$ 0.05, Fig. 4). ANOVA revealed significant between-group differences ( $F_{1,71}=$ 31.9, $p<$ 0.001), with the WBMF group demonstrating greater improvements than the control group (post-hoc test $p<$ 0.001).

Figure 4.

Pain severity based on the VAS scale (mean $\pm$ standard deviation) in participants of the WBMF group and control group, before (dark gray bars) and after (light gray bars) a course of rehabilitation. (*) – Significant difference between groups ( $p<$ 0.05).

Figure 5.

Distribution of participants with mild (white), moderate (light gray), and strong (dark gray) changes in the area of hyperthermia in the lumbar spine ( $D_{\textit{spine}}$ , upper panel) and legs thermal asymmetry area ( $D_{\textit{legs}}$ , lower panel) in the WBMF group (A, C) and control group (B, D).

Figure 6.

Distribution of participants with mild (white), moderate (light gray), and strong (dark gray) changes in the temperature difference in the lumbar spine ( $D\Delta T_{\textit{spine}}$ , upper panel) and legs ( $D\Delta T_{\textit{legs}}$ , lower panel) in the WBMF group (A, C) and control group (B, D).

3.2 Temperature differences

Figure 3 illustrates the change in the temperature distribution pattern after rehabilitation for one representative participant. This participant had a larger area of hyperthermia on the surface of the skin over the lumbar spine and greater thermal asymmetry between the left and right legs before rehabilitation than they did after completion of the course. Similar tendencies towards pathological hyperthermia in the lumbar area and asymmetric distribution of temperatures of the skin overlying the lower extremities were observed in 93.1% of study participants in both groups.

After completion of the rehabilitation course, positive changes were found in both groups. Changes were classified as mild when $D_{\textit{spine}}$ or $D_{\textit{legs}}$ was $\leqslant$ 15%, moderate when $D_{\textit{spine}}$ or $D_{\textit{legs}}$ ranged 16–39%, and strong when $D_{\textit{spine}}$ or $D_{\textit{legs}}$ was $\geqslant$ 40%. Figure 5 shows the distributions of changes of the lumbar hyperthermic area and thermal asymmetry of the lower extremities for participants in each group. Moderate-to-strong changes of lumbar hyperthermia ( $D_{\textit{spine}}$ ; Fig. 5A and B) were observed in 88% of WBMF and 35% of control group patients. Strong changes in $D_{\textit{spine}}$ were seen in 41% of WBMF and only 6% of control group patients. More than half of patients in both groups showed mild positive changes in $D_{\textit{legs}}$ , indicating a decrease in the thermal asymmetry of the lower extremities (Fig. 5C and D). Moderate-to-strong changes in $D_{\textit{legs}}$ were found in 47% of WBMF and 41% of control group patients.

Temperature differences between the lumbar and thoracic spine, as well as between the two legs (according to $D\Delta T_{\textit{spine}}$ and $D\Delta T_{\textit{leg}}$ indices) in both groups are illustrated in Fig. 6. By the end of the rehabilitation course, 53% of WBMF group patients showed strong changes in $D\Delta T_{\textit{spine}}$ , compared to 37% of control group patients (Fig. 6A and B). Twice as many control group patients (21%) as WBMF group patients (10%) showed mild improvements in $D\Delta T_{\textit{spine}}$ . Temperature differences between the lower extremities in terms of $D\Delta T_{\textit{legs}}$ showed moderate-to-strong decreases in 87% of WBMF and 54% of control group patients (Fig. 6C and D).

4. Discussion

The study showed that adding WBMF therapy to a course of conventional rehabilitation facilitated recovery after lumbar discectomy. Patients who received low-intensity magnetic field therapy had greater pain reduction than those in the control group. A larger number of WBMF group participants showed reduced temperature differences and hyperthermic areas of the skin surface over the lumbar spine and affected leg. These results confirm the effectiveness of WBMF therapy in the early ( $<$ 1 month) period after lumbar discectomy.

Reduction of pain is one of the main criteria for effective rehabilitation of patients who undergo lumbar discectomy [31]. Clinically meaningful and significant pain reduction was observed in both groups and in more than 70% of cases. This effect was likely related to the early onset ( $<$ 1 month after surgery) of the course of complex rehabilitation, including carefully selected medication, physical therapy, and hydrotherapy. Upon completion of the rehabilitation course, the WBMF group improved their VAS scores by 45% on average, compared to 30% for the control group.

Substantial differences between groups can be attributed to the effects of low-intensity magnetic fields acting on the whole body. Analgesic mechanisms of magnetic induction may include reduction of the sensitivity of nociceptors due to the diffusion of water molecules in the tissues, blockade of nociceptive afferentation at different levels of processing, and release of endorphins to the blood and cerebrospinal fluid [9, 19, 20]. Magnetic field may regulate blood microcirculation in damaged areas by increasing dominance of the vascular endothelial modulators, while suppressing heart rate and respiratory modulation. Activation of all of these cellular mechanisms may ultimately increase the activity of endothelial cells and elasticity of blood vessels, decrease peripheral vascular resistance, improve blood flow, and reduce venous congestion, thereby facilitating recovery after discectomy.

Effects of WBMF therapy were assessed with the use of infrared thermography, a relatively novel measurement technique in physical medicine and rehabilitation. This method was chosen because it is safe, can be repeated multiple times on the same individual, provides objective information, is sensitive to small changes, has no known adverse effects or contraindications, allows multiple images to be made of different body parts, and can be accurately localized to a target area [25]. By using infrared thermography, pathological hyperthermia in the lumbar spine and thermal asymmetry of the lower extremities were detected in more than 90% of study participants. Presence of hyperthermia was interpreted as a sign of inflammation, muscle spasm, and disrupted nerve conduction at the site of spinal surgery.

After the rehabilitation course, moderate-to-strong reduction of the lumbar area of hyperthermia ( $D_{\textit{spine}}$ ) was observed in a majority (88%) of patients in the WBMF group but only one third of control patients. This finding may suggest a positive therapeutic effect of magnetic field on the muscle tone and inflammation after discectomy. More than half of all patients in both groups showed mild changes in areas of thermal asymmetry of the lower extremities ( $D_{\textit{legs}}$ ), and the difference between groups was minimal. This tendency may be associated with the complexity and duration of spinal nerve root recovery, even when facilitated by a course of complex rehabilitation. Temperature differences between the lower extremities ( $D\Delta T_{\textit{legs}}$ ) showed moderate-to-strong decreases in 87% of WBMF and 54% of control group patients. Taken together, the observed post-rehabilitation decreases in leg areas of hyperthermia and temperature differences provide strong evidence of the effects of WBMF therapy on microcirculatory blood flow, which most likely reduced inflammation and intraneural edema. However, recovery of spinal nerve conduction along the entire zone of innervation clearly requires a longer period of rehabilitation.

5. Conclusion

The present research findings confirm the effectiveness of WBMF in the early ( $<$ 1 month post-surgery) rehabilitation of patients who underwent lumbar discectomy. Incorporating this therapy into rehabilitation may facilitate muscle relaxation, normalize blood microcirculation, and reduce the incidence of inflammation, intraneural edema, and pain. The results are consistent with other works and serve as a starting point for designing large-scale clinical trials comparing the effectiveness of different modes of WBMF and their applications to different groups of patients in different periods of recovery after surgery. Thermal infrared imaging has the potential to be an objective, safe, and sensitive diagnostic technique, detecting even mild abnormalities in the lumbar and lower extremity areas. However, more research is needed to confirm the validity and reliability of this method as a diagnostic and clinical evaluation instrument. The present study did not evaluate short- and long-term retention of the WBMF effects and that was a major limitation of the study. Perhaps this question will be addressed in future clinical trials.

Footnotes

Conflict of interest

None to report.

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New approach for evaluating the effectiveness of whole-body magnetic field therapy in the rehabilitation of patients with lumbar discectomy

Abstract

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Methods

2.1 Subjects

Table 1 Demographic and pre-treatment outcome measures of patients with lumbar discectomy (mean ± standard deviation) in two experimental groups

4. Discussion

5. Conclusion

Footnotes

Conflict of interest

References

Table 1
Demographic and pre-treatment outcome measures of patients with lumbar discectomy (mean $\pm$ standard deviation) in two experimental groups