**7. Conclusions**

**6. Interventions to improve balance in patients with peripheral neuropathy**

134 Peripheral Neuropathy - A New Insight into the Mechanism, Evaluation and Management of a Complex Disorder

Richardson et al. (2004) [120], in patients with various forms of peripheral neuropathy, found that the use of a cane, ankle orthoses or touching a wall improved spatial and temporal measures of gait regularity while walking under challenging conditions. Evi‐ dence support that, additional hand contact of external objects may reduce postural instability caused by a deficiency of one or more senses. Contact with support of varying stability may reduce the destabilizing effect of a moving visual scene [121]. In patients with moderate to severe diabetic neuropathy, mechanical noise stimulation may improve

To improve stability in patients with decreased somatosensation, footwear may represent a modifiable factor. The efficacy of certain types of stabilizing reactions may be improved whether incorporating a pressure plantar-based biofeedback system in footwear [123], vibrating shoe insoles [38], or by mechanical facilitation of sensation from the boundaries of the plantar surface of the foot [124]. In patients with Charcot-Marie-Tooth, considering individual sensory and muscular deficits, ankle-foot orthosis prescription, appears relevant

Exercise that improves lower-extremity balance and strength (force-generating capacity) has been shown to be effective in reducing falls in older adults [126]. In patients with clinically defined sensory ataxia due to bilateral chronic neuropathy compared to pa‐ tients with unilateral loss-related to multiple sclerosis, after a rehabilitation program including foot sensory stimulation, balance and gait training with limited vision, balance assessed on a static force platform remained similar in the open-eyes condition and improved in the closed-eyes condition only in patients with unilateral sensory loss, while dynamic balance improved in the two groups, suggesting that the relative contribution of proprioceptive and visual inputs may depend on the extent of somatosensory loss [127]. Guidelines for diabetes management recommend that patients perform at least 30 min of physical activity a day six times a week. Few studies on prevention of diabetic neuropathy through exercise have been reported, even if moderate intensity exercise in patients with type 2 diabetes mellitus has been associated with a decrease in blood glucose [128]. A preliminary controlled study has shown that a 12 week program of *tai chi chuan* exercises may improve

Studies evaluating treatment strategies that could improve balance in diabetic patients with polyneuropathy are also scarce. Although, some interventions including leg strengthening and balance exercises to promote ambulatory physical activity may not decrease fall rates, but neither they increase them; suggesting that physical activity interventions that increase activity probably do not increase the risk of falling in patients with diabetic peripheral neu‐ ropathy [130]. In this group of patients, specific training may improve gait speed, balance,

To determine the effect of a specific exercise regimen on clinical measures of postural stability and confidence in a population with peripheral neuropathy, compared to a control group, ten

peripheral nerve conduction velocities and fasting glucose levels [129].

vibration and tactile perception [122].

for improving balance and gait performance [125].

muscle strength and joint mobility [131].

Postural control can be defined as the control of the body's position in space for the purposes of balance and orientation. Balance is the ability to maintain or return the body's centre of gravity within the limits of stability that are determined by the base of support. Spatial orientation defines our natural ability to maintain our body orientation in relation to the surrounding environment, in static and dynamic conditions.

The representation of the body's static and dynamic geometry may be largely based on muscle proprioceptive inputs that continuously inform the central nervous system about the position of each part of the body in relation to the others. Posture is built up by the sum of several basic mechanisms. First the tone of the muscles gives them a rigidity that helps to maintain the joints in a defined position; the postural tone is added to this basic tonus. Postural fixation maintains the position of one or several joints against an internal force. During movement of one segment of the body, other segments are disturbed, producing instability. Thus the precise movement of distal segments can be realized only by stabilizing more proximal segments.

Postural balance is dependent upon integration of signals from the somatosensory, visual and vestibular systems, to generate motor responses, with cognitive demands that vary according to the task, the age of the individuals and their ability to balance. Descending postural commands are multivariate in nature, and the motion at each joint is affected uniquely by input from multiple sensors.

The proprioceptive system provides information on joint angles, changes in joint angles, joint position and muscle length and tension; while the tactile system is associated mainly with sensations of touch, pressure and vibration.

Visual influence on postural control results from a complex synergy that receives multimodal inputs. Vestibular inputs tonically activate the anti-gravity leg muscles and, during dynamic tasks, vestibular information contributes to head stabilization to enable successful gaze control, providing a stable reference frame from which to generate postural responses.

In order to assess instability or walking difficulty, it is essential to identify the affected movements and circumstances in which they occur (i.e. uneven surfaces, environmental light, activity) as well as any other associated clinical manifestation that could be related

to balance, postural control, motor control, muscular force, movement limitations or sensory deficiency. The clinical evaluation should include neurological examination; special care should be taken to identify visual and vestibular disorders, and to assess static and dynamic postural control and gait. Standardized scales and questionnaires may be helpful to evaluate and to follow-up deficits that may be evident on daily life activities.

**Author details**

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The simplest method to record postural sway uses a force plate to measure the feet centre of pressure on the platform. To modify the somatosensory and visual inputs, moving force platforms and visual surroundings have been designed. Gait analysis may include the measurement of joint kinematics and kinetics, electromyography, oxygen consumption and foot pressures.

Polyneuropathy modify the amount and the quality of the sensorial information that is necessary for motor control, with increased instability during both, upright stance and gait.

Patients with peripheral neuropathy may have decreased stability while standing and when subjected to dynamic balance conditions. During upright stance, compared to healthy subjects, recordings of the centre of pressure in patients with diabetic neuropathy have shown larger sway, as well as increased oscillation at 0.5-1 Hz.

Balance and gait difficulties are the most frequently cited cause of falling in all age and gender groups Epidemiological surveys have established that a reduction of leg proprioception is a risk factor for falls.

Patients with polyneuropathy who have ankle weakness are more likely to experience multiple and injurious falls than are those without specific muscle weakness.

Elderly patients with diabetic peripheral neuropathy are more likely to report an injury during walking or standing, which may be more frequent when walking on irregular surfaces. Among other risk factors, the occurrence of falls may be significantly associated with lower extremity weakness, which can be measured by knee extension, ankle dorsiflexion, and chair stands, visual acuity of less than 6/12, lower extremity impairments and poly-pharmacy, among other factors.

In patients with various forms of peripheral neuropathy, the use of a cane, ankle orthoses or touching a wall improved spatial and temporal measures of gait regularity while walking under challenging conditions. Additional hand contact of external objects may reduce postural instability caused by a deficiency of one or more senses.

Studies evaluating preventive and treatment strategies through excercise that could improve balance in patients with polyneuropathy are scarce. However, evidence support that physical activity interventions that increase activity probably do not increase the risk of falling in patients with diabetic peripheral neuropathy, and in this group of patients, specific training may improve gait speed, balance, muscle strength and joint mobility.
