Heikki Aalto

One-footed and externally disturbed two-footed postural control in patients with chronic low back pain and healthy control subjects. A controlled study with follow-up.

Study Design. A study of postural control during one‐footed and externally disturbed two‐footed stance among healthy control subjects and patients with chronic low back pain at the beginning of a functional back restoration program and 6 months later at follow‐up examination. Objectives. To study postural control cross‐sectionally among control subjects and patients with low back pain, and to evaluate the effects of functional restoration on the postural control parameters in a follow‐up examination. Summary of Background Data. Deficits of motor skills and coordination have been reported in association with musculoskeletal disorders. It has been found that patients with chronic low back pain have impaired psychomotor control, but the impairment is reversible with successful low back rehabilitation. It is insufficiently known how functional activation and intensive physical training affect postural control. Methods. Sixty‐one healthy volunteers (32 men, 29 women) and altogether 99 patients with low back pain participated in the study. Sixty‐eight patients (33 men, 35 women) had moderate and 31 (18 men, 13 women) had severe low back pain. Postural stability was measured with a force platform. In two‐footed stance, vibration stimulation on calf and back muscles was used to disturb the balance. Center point of force‐velocity (cm/sec), average position shift in anteroposterior direction (cm), and maximal position shift in lateral direction (cm) were used as the parameters. Results. Reliability of all tests was acceptable. Center point of force‐velocity was the most sensitive parameter and the one‐footed measurement the most sensitivetest for evaluating postural stability. At the beginning, the patients with severe low back pain had poorer one‐footed postural control compared with the control subjects (P = 0.0003). The subgroup of patients with moderate low back pain participated in the restoration program. The outcome of the restoration program was considered good if the disability because of low back pain (Oswestry index) decreased during the restoration program and poor if the disability increased or did not change. The one‐footed postural stability remained primarily at the same level as the initial results in the control and good outcome groups, but became significantly poorer in the poor outcome group. The difference between poor outcome and control groups was statistically significant (P = 0.04). Conclusions. Impaired postural stability seems to be one factor in multidimensional symptomatology of patients with chronic low back trouble. Postural stability is easily disturbed in case of impairment in strength, coordination, or effective coupling of muscles in the lumbar and pelvic area. Patients with chronic low back pain seem to experience impairment in these functions, which should be taken into consideration when back rehabilitation programs are planned.

Postural Control and Age

We quantified the effect of vision, pressoreceptor function and proprioception on the postural stability at different ages. Altogether 212 healthy volunteers (ages from 6 to 90 years) were examined by using a computerised force platform. The sway velocity (SV) was measured with eyes open and eyes closed during quiet stance on a bare platform and a foam plastic covered surface. In addition, to study the proprioceptive system, pseudorandom vibration perturbation was applied on the calf muscles. The SV showed a U-shaped curve: the children and the oldest swayed most. Equilibrium was most stable around 50 years. The visual system was of most importance for balance control in the old. The children were sensitive of pressoreceptor and proprioceptive perturbation, indicating the importance of these systems for their postural control.

Psychomotor speed and postural control in chronic low back pain patients A controlled follow-up study.

Study Design Psychomotor speed (reaction time) and postural control (center point of force velocity) among healthy control volunteers and patients with chronic low back pain (LBP) were studied at the beginning of an active, functional, restoration back rehabilitation program and 6 months after the program. Objectives To study cross‐sectionally reaction times and center points of force velocity among control volunteers and patients with low back pain, and to evaluate the effects of the restoration on these measures of motor function in a follow‐up examination. Summary of Background Data Deficits of motor skills and of coordination have been reported in association with musculoskeletal disorders, but one can only speculate about an association between proprioceptive dysfunction and low back disorders on the basis of the currently available data. Methods Sixty‐one healthy control volunteers and 99 patients with low back pain‐68 of these patients experienced moderate pain; 31 experienced severe pain‐participated in the study. Reaction times for upper and lower limbs were tested with a system based on a microcomputer. Postural stability was measured with a vertical force platform. Results A consistent trend was found in which patients with low back pain had reaction times slower than those of control volunteers. Men with severe low back pain had significantly longer hand reaction times than men in the control group (P = 0.03). Women with severe low back pain also had poorer postural control than women with moderate low back pain (P = 0.02) and women in the control group (P = 0.04). Functional restoration seemed to have an effect on reaction times. The restoration was considered successful if the condition of a patient with a disability that had resulted from low back pain improved during the follow‐up examination and unsuccessful if the disability worsened. Patients who experienced these results were identified in groups called “good” and “poor,” respectively. Among men, the reaction times improved in the control group and “good” groups, but they became slower in the “poor” group. The difference between “good” and “poor” groups was significant (P = 0.008). Women in the “good” group achieved the most improved reaction times, and the difference between these women and the control women almost reached significance (P = 0.076). Conclusion The results indicate that patients with chronic low back pain have impaired psychomotor speed and, among women, impaired postural control. Psychomotor speed improved during an active, functional, restoration back rehabilitation program.

Subclinical vestibulocerebellar dysfunction in migraine with and without aura

Objective: In patients with migraine, neurotologic symptoms and signs occur commonly. The authors’ aim was to determine whether neurotologic findings are in accordance with the type of migraine and whether test findings differ from those of healthy controls. Methods: The authors examined 36 patients with various types of migraine classified by International Headache Society criteria. Comprehensive neurotologic tests were performed between attacks: video-oculography (VOG), electronystagmography, static posturography, and audiometry on 12 patients with migraine with aura (MA) and 24 patients with migraine without aura (MO). Results were compared to those of test-specific nonmigrainous control groups. Only eight migraineurs (six with MA and two with MO) had vertigo or dizziness. Results: Despite the absence of clinical neurotologic symptoms, most of the patients with migraine (83%) showed abnormalities in at least one of these tests. Both migraine types differed significantly from the control group (in VOG, in saccadic accuracy, and in static posturography). Vestibular findings tended to be more severe in MA than in MO. Conclusions: These data suggest that interictal neurotologic dysfunction in MA and MO share similar features and that the defective oculomotor function is mostly of vestibulocerebellar origin.

Intratympanic gentamicin in Meniere's disease

Ninety-three patients with intractable Menieres disease were treated with gentamicin (Garamycin 40 mg/ml) administered in 1 to 4 transtympanic injections. The patients were tested at frequent intervals and followed up for 2 years. Before treatment all subjects experienced moderate or severe handicap caused by Menieres disease. Two years after the treatment, rotatory vertigo was abolished in 81% of subjects, Tumarkin attacks were cured in 60%, and work capacity was severely reduced in 10% and moderately reduced in 17% of subjects. The outcome of the caloric responses did not correlate with the outcome of the treatment. In logistic regression analysis poor outcome of treatment correlated with Tumarkin attacks (odds ratio 5.5), severity of vertigo (odds ratio 3.8) and gait disorders (odds ratio 2.9). The mean hearing level was significantly affected by the treatment (before, 59.1 dB HL; after, 67.9 dB HL). Ten treated ears became deafened. During follow-up 44 subjects were subjected to retreatment, usually after 6 months. Intratympanic gentamicin treatment is a relatively safe and effective way to treat Menieres disease. The authors recommended starting with 2 injections and renewing the injections if relapse occurs.

Postural Stability in Shooters

Ten competition shooters were tested during simulated race using the force platform technique to investigate the effect of training on postural stability. The shooters were tested at 30-min intervals during a race simulating actual race conditions. Sway velocity was calculated during 27-second periods. The postural stability was evaluated with and without competition clothing. The shooters had significantly better stability than untrained control subjects, when tested without supportive clothing. The competition clothing reduced the sway velocity further both in visual and nonvisual conditions. The Romberg quotient was higher in shooters than in normal controls, indicating that the shooters used to an increased amount proprioceptive and vestibular cues to stabilize their posture. The good postural stability of the shooters apparently results from assiduous training aimed to improve postural stability.

Intratympanic Gentamicin in Bilateral Meniere's Disease

Treatment of bilateral Menieres disease is a delicate task. Streptomycin has demonstrated its ability to successfully control the vertigo attacks, but in some cases it results in oscillopsia and transforms the periodic attacks to permanent instability. If the site of the active labyrinth can be determined, a more specific treatment can be tried. We have treated 14 patients with intractable bilateral Menieres disease with intratympanic gentamicin (Garamycin, 40 mg/ml) administered initially in either 1, 2, 3, or 4 injections. The patients were tested at frequent intervals and followed up for 2 years. The work capacity, severity of vertigo, and gait difficulties were scored before treatment and during each test occasion. The postural stability was evaluated on a force platform and sway velocity was analyzed. Before treatment, moderate or severe reduction of work capacity was experienced by all of the subjects, which correlated to severity of vertigo and gait problems. Two years after treatment, the vertigo attacks were eliminated in 11 subjects and controlled in three subjects. The work capacity of three subjects was still moderately or severely reduced. This reduction depended on gait disturbance and Tumarkin attacks. The average postural stability returned to pretreatment level 2 years after the treatment was begun. The outcome of the caloric responses did not correlate with the outcome of the treatment. Hearing was not significantly affected by the treatment. Intratympanic gentamicin treatment is a relatively safe and effective way to treat bilateral Menieres disease when the symptoms can be localized to one ear.

Postural Stability, Neck Proprioception and Tension Neck

We examined whether tension neck (TN) may due to inadequate proprioceptive and vestibular activation of the cervico-collic reflex (CCR). CCR and vestibulospinal responses (VSRs) were recorded from 106 forest workers by stimulating the neck, lumbar or calf proprioceptors by vibration. The VSRs were recorded with posturography. TN occurred in 27 out of 106 subjects. The subjects with TN (48.5 years) were older than those without TN (43.1). The mean body sway during quiet stance was the same in both groups during the neck stimulation. In subjects with tension neck stimulation of neck or lumbar proprioceptors caused excessive, unpredictable body excursion in the lateral and anteroposterior direction that continued after stimulation. Results from stimulation of lower limb proprioceptors did not significantly differ between the 2 groups. In logistic regression analysis a model to predict TN consisting of perstimulatory postural stability (odds ratio 1.4) and poststimulatory postural stability (odds ratio 1.8) turned out to be statistically significant. The anatomical findings of CCR in the medulla oblongata suggest that neck muscle afferents control the posture and muscle activity of the neck. The erroneus facilitation of proprioception in TN subjects indicate that TN may be raised by inadequate facilitation of CCR.

Tullio Phenomenon and Postural Stability: Experimental Study in Normal Subjects and Patients with Vertigo

The effect of low-frequency sound (LFS) on postural stability was studied in 55 healthy volunteers and in 152 patients with vertigo due to different types of inner ear disease. The sound pressure levels ranged from 130 to 132 dB and were given at frequencies of 25, 50, and 63 Hz. The duration of each stimulation lasted 30 seconds. The postural responses were measured with a force platform. The LFS stimulation improved the postural stability of the healthy subjects through the alerting response. We did not observe any difference in the body sway according to whether the LFS was delivered with monaural or binaural stimulation. Twenty-six percent of the patients with Menieres disease, 40% with chronic otitis media with vertigo, and 26% with vertigo of peripheral origin experienced significant postural instability at least at two of the three test frequencies during stimulation with LFS. The results demonstrate that in subjects with different types of inner ear disease the vestibular system starts to respond to LFS. The activation of vestibulospinal responses by LFS seems to be an expression of the Tullio phenomenon.

Development of virtual reality stimuli for force platform posturography

People relying much on vision in the control of posture are known to have an elevated risk of falling. Dependence on visual control is an important parameter in the diagnosis of balance disorders. We have previously shown that virtual reality (VR) methods can be used to produce visual stimuli that affect balance, but suitable stimuli need to be found. In this study, the effect of six different VR stimuli on the balance of 22 healthy test subjects was evaluated using force platform posturography. We report in more detail and expand the results published earlier. According to the tests two of the stimuli have a significant destabilizing effect on balance. In addition a significant displacement effect on the subjects center of pressure (COP) was found. Thus it is shown that the design of VR stimuli to cause different effects on the control of balance is possible.