The impact of laser irradiation on global stability in patients with vertebrobasilar insufficiency: A clinical report

Background

Vertebrobasilar insufficiency (VBI) is often observed in active persons in middle age. The main symptoms of this syndrome are balance disturbances [1]. Very often the patients do not present with any other symptoms except for positional vertigo and dizziness, so the differential diagnosis of its origin is very difficult [2]. Along with balance disturbances, transient focal neurological symptoms are sometimes observed, specific for the brain region supplied by the vertebrobasilar artery (VBA) [3,4]. Mechanical endogenous and exogenous factors, such as muscle tone disturbances, osteoarthrosis [5], herniated cervical disc [6], inflammation, or artheriosclerosis, may cause VBI, due to restriction of blood flow in the VBA [4]. We often observe these symptoms during normal physical activity that particularly involve neck and shoulder movements. There are also descriptions of VBI symptoms associated with neck pain, torticollis, and stiff neck. Occasionally the onset of these symptoms has been reported after improper manipulations of the cervical spine [7].

Terret distinguishes the set of symptoms connected with VBI as follows:

The presence of these symptoms can influence social and occupational life, as well as the quality of life [3,4]. Unfortunately, many of the methods used to control VBI are often ineffective. Sometimes it is necessary to involve an interdisciplinary team, but this is very costly and time-consuming.

Low level laser therapy (LLLT) has gained recently popularity in the treatment of arterial occlusion. LLLT produces non-thermal (bio-stimulating) effects, due to an average power less than 500 mW. The biological effects of laser stimulation are observed at a cellular level, and are thought to stabilize the cell membrane, increase intracellular transport, and release endorphins and many other cytokines. The stimulation of the treated region is reported to cause the expansion of blood vessels and an increased blood flow volume. The increase in blood flow is probably caused by the vasodilator reflex via the central nervous system [8].

Exposure to external laser stimulation in patients with ischemic heart disease produces improved rheology of blood, a protective effect on the erythrocyte membrane [9] and an inhibition of lipid peroxidation [10]. Laser light illumination is also reported to reduce the re-stenosis rate after successful balloon angioplasty with coronary stent implantation [11]. The improvement of microcirculation after biomodulation with LLLT (780 nm) has been demonstrated by magnetic resonance imaging (MRI) [12].

LLLT is reported to enhance vasodilatation, as well as proliferation of microvasculature, and is also thought to increase the level of oxygen content in tissue [13]. Laser irradiation at 810 nm (10, 30 and 110 mW) has also been reported to inhibit the vascular contraction reaction induced by noradrenaline (NA) and phenylephrine (PHE), due to stimulation of nitric oxide release and guanyl cyclase [14]. There have also been reports of intravenous laser blood irradiation used to good effect in body-building athletes [15]. Positive effects have observed during laser therapy of venous ulcers (900 nm diode laser, pulsed) combined with radiofrequency (RF) current [16].

The main goal of our research was to evaluate the impact of LLLT of the vertebral artery bilaterally on VBI symptoms, balance, and global stability using manual tests, the Berg Balance Scale, and a Freeman’s balance platform.

Material and Methods

DEVICE AND PARAMETERS:

A CTL-1100 low power laser was used, with a probe of 810–830 nm, power of 100 mW, and energy density of ED=4 J/cm²; the wave was modulated into a frequency of 6 kHz. The laser probe at the top consisted of a 1 cm² quartz window, and delivered a collateral beam. We have established our own protocol, which involves irradiation with a laser beam at 5 points on the skin along the vertebral artery in the cervical region, bilaterally, using delicate pressure. The irradiation was conducted 10 times: once a day from Monday to Friday for two weeks, with a weekend break. All subjective changes were noted.

STATISTICAL ANALYSIS:

The analysis of results from the De Klyn test before and after therapy was performed with Cochran’s Q test, while the results from the Berg Balance Scale were analyzed by calculating-the Spearman rank correlation coefficient. To evaluate the statistical significance of all three tests, the Friedman test was used, with the level of statistical significance assumed at p<0.05.

Results

DE KLYN’S TEST:

During the test, the patients were asked to answer questions about their symptoms: headache, vertigo, tinnitus and nausea; the occurrence of nystagmus was also noted. We noticed a statistically significant reduction in complaints of headache (p=0.0005), vertigo (p=0.0000) and tinnitus (p=0.0387) after therapy. The results are presented in Figures 3–5.

We did not observed any statistically significant differences in such symptoms as nausea (p=0.8187, n.s.) and nystagmus (p=0.3678, n.s.) caused by head rotation.

BERG BALANCE SCALE:

Statistical analysis of the results from the Berg Balance Scale revealed statistically significant differences in almost all tested features (Table 1).

During the initial and final test, the patients received maximum scores for sitting unsupported and changing of position from sitting to standing. That is why we did not observe any statistically significant changes after treatment, due to the ceiling effect. These tasks were very simple for the patients.

The final evaluation of global stability, conducted on the EasyTech LIBRA® platform, was also analyzed statistically. We took into account the total surface of support, the spread surface of support, the extended time and the time of reaction. We observed a tendency towards improvement in all parameters after ten sessions of laser irradiation, but a statistically significant difference was observed only in the total surface of support (p=0.017) and the spread surface of support for the left foot before and after therapy (p=0.030, p=0.025; Figure 6, Table 2). We did not observe any differences in any parameters when comparing results before and 30 minutes after the first session.

Discussion

Vertebrobasilar insufficiency (VBI) is a condition characterized by insufficient blood supply to the posterior portion of the brain, which is responsible for balance, coordination, vision and other functions [17]. Two-thirds of patients with VBI experience dizziness as the most common symptom. The most frequently reported accompanying symptoms in the studies by Grad and Baloh [18] were visual (diplopia, blindness, hallucinations). These are very alarming symptoms that usually bring the patient to consult a physician.

In differential diagnosis it is important to exclude Meniere’s disease, migraine and labyrinthitis [19], and ischemic heart disease [10]. It is also very important to perform manual tests to check for arterial occlusion or disturbances in blood supply due to osteoarthritis. The most popular instrument used in the diagnosis of VBI is De Klyn’s Test. The Berg Balance Test is often used to evaluate the level of balance disturbances occurring during simple activities of daily living [20]. We also try to evaluate quantitative data pertaining to balance disturbances that occur during posture support on an unstable platform (a Freeman Platform).

The problem of VBI is especially important if the patient is over 55 and has other stroke risk factors. Patients with these symptoms must quit smoking, lower the cholesterol level through diet, and exercise regularly. Drugs are often used to control blood pressure, block platelet function, and lower the cholesterol level. It is also possible to perform endovascular repair. The search is underway for other methods that may be useful in improving blood supply to the posterior regions of the brain.

The basic mechanisms of interactions between different wavelengths and tissues are still not fully understood. LLLT has been proven to accelerate collateral circulation and enhance microcirculation. Steg was the first to study in vitro the influence of argon laser (488–514.5 nm) and power supply below 100 mW on vascular smooth muscle cells (VSMCs) [21]. He noticed that lower doses of power supply (<100 mW) caused vasodilatation, and high doses (>1 W) caused vasoconstriction. Gal studied the influence of excimer laser working in a pulse or constant mode. The laser in pulse mode did not cause any reaction, but in constant mode caused vascular constriction [22]. Maegawa and Toshiyuki demonstrated the influence of infrared laser (830 nm) on vascular smooth muscle cells (VSMCs). They found that laser stimulation can cause major vasodilatation and increased arteriolar blood flow [23]. LLLT induced reduction of [Ca+] in VSMCs and stimulated NO synthase [23]. NO can operate as a free radical or as an activator of guanyl cyclase (GC) [24]. Activation of GC leads to an increased level of cGMP. Some authors decline that the heme included in GC serves as a chromophore absorbing laser and ultraviolet light [22,25]. This consequently leads to an increased cGMP level and vasodilatation of smooth muscle cells. It is still unknown which wavelength is absorbed by these structures. We studied a laser wavelength of 830 nm because of its deep penetration and proven clinical effect. We tried to demonstrate that it penetrates through the skin and reaches the vascular wall, where it initiates biochemical changes.

Many authors have demonstrated the influence of laser stimulation on vasodilatation in vivo. Schaffer et al. irradiated the planta pedis of healthy volunteers [12], Teggi treated patients with Meniere’s disease [26], Hirschl treated patients with Raynaud’s phenomenon [27], and Trelles irradiated leg blood vessels with success [16]. Tullberg exposed the masseter muscle to a gallium-aluminium-arsenide laser because of muscle pain and demonstrated an increase in microcirculation [28]. Raggi used a 630 nm wavelength to irradiate athletes’ legs intravenously [15]. Mahikara irradiated the superficial temporal artery with CO2 laser [8]. He concluded that 10 minutes after stopping irradiation, the diameter and blood flow volume of the artery had increased significantly. He also noticed the same changes on the contralateral side.

Our results with a diode laser at λ=830 nm support these observations. In De Klyn’s test we observed a reduction in such symptoms as headache, vertigo and tinnitus after tens session of irradiation, due to better blood supply to the posterior regions of the brain. We did not observe any statistically significant changes 30 minutes after the first session. There were no changes in the occurrence of nausea or nystagmus.

We also noticed statistically significant improvement in balance tests. Patients performed almost all tasks better after treatment than before, probably due to vasodilatation caused by changes in the vascular wall. 10 days of therapy improved blood circulation in the region of the vestibular nuclei, the cerebellum and the cerebellar peduncle. The better the blood supply, the better the tissue perfusion and nourishment. There were no effects of a single session. In other words, transient vasodilatation is not sufficient to improve balance support. There must be better microcirculation in nerve tissue, causing more permanent changes [29,30]. This is presumably the reason why patients improve in balance tasks after 10 sessions of laser stimulation.

The final evaluation of global stability on the Freeman platform supported the foregoing observations. The patients improved in maintaining global stability on an unstable platform. Such improvement cannot be gained due to transient vasodilatation, but rather thanks to better perfusion of nerve tissue and increased oxygen content.

Conclusions

We can safely conclude that laser stimulation at 830 nm with a power supply of 100 mW can be a successful method in the treatment of patients with vertebrobasilar insufficiency. Our results suggest that the main reason for improvement after 10 days of therapy in global stability and balance, along with reduction of VBI symptoms, is better blood perfusion and an increased level of oxygen in brain tissue. The procedures we used turned out to be very sensitive in the evaluation of VBI symptoms.