Exoskeleton-assisted gait in chronic stroke: An EMG and functional near-infrared spectroscopy study of muscle activation patterns and prefrontal cortex activity.

OBJECTIVES: Gait impairment dramatically affects stroke patients' functional independence. The Ekso™ is a wearable powered exoskeleton able to improve over-ground gait abilities, but the relationship between the cortical gait control mechanisms and lower limbs kinematics is still unclear. Our aims are: to assess whether the Ekso™ induces an attention-demanding process with prefrontal cortex activation during a gait task; to describe the relationship between the gait-induced muscle activation pattern and the prefrontal cortex activity. METHODS: We enrolled 22 chronic stroke patients and 15 matched controls. We registered prefrontal cortex (PFC) activity with functional Near-Infrared Spectroscopy (fNIRS) and muscle activation with surface-electromyography (sEMG) during an over-ground gait task, performed with and without the Ekso™. RESULTS: We observed prefrontal cortex activation during normal gait and a higher activation during Ekso-assisted walking among stroke patients. Furthermore, we found that muscle hypo-activation and co-activation of non-paretic limb are associated to a high prefrontal metabolism. CONCLUSIONS: Among stroke patients, over-ground gait is an attention-demanding task. Prefrontal activity is modulated both by Ekso-assisted tasks and muscle activation patterns of non-paretic lower limb. Further studies are needed to elucidate if other Ekso™ settings induce different cortical and peripheral effects. SIGNIFICANCE: This is the first study exploring the relationship between central and peripheral mechanisms during an Ekso-assisted gait task.

Technological rehabilitation versus conventional rehabilitation following hip replacement: A prospective controlled study.

BACKGROUND: Among new technological rehabilitation systems, there are proprioceptive platforms. These could be useful to improve static and dynamic balance. OBJECTIVE: To evaluate technological proprioceptive rehabilitation compared to conventional rehabilitation in patients after total hip arthroplasty (THA). METHODS: Sixty-four patients after THA were divided in two groups: a conventional group (CG) and a technological group (TG) treated with proprioceptive platforms. Before (T0) and after 20 sessions (T1), we recorded static and dynamic balance. Clinical and disability scales (Modified Harris Hip Score, Barthel Index, Deambulation Index), pain scales (ID-PAIN, DN4, VAS) and QoL scale (SF-36) were administered to patients during T0 and T1. Mann-Whitney U test was used for stabilometric and dynamic assessments to detect differences between groups of patients and healthy subjects. The Wilcoxon signed-rank test was used for the within-group analysis and the ANCOVA test for the analysis between groups of patients. RESULTS: All scales improved significantly in both groups after treatment (p< 0.05). Static balance improved in both groups, but there were greater improvements in the TG than in the CG. All dynamic balance indexes showed significant improvements only in the TG after treatment. CONCLUSIONS: Both treatments improved the clinical, disability, pain, and QoL scales, as well as static balance, but only proprioceptive technological rehabilitation improved dynamic balance. Rehabilitation through proprioceptive platforms can indeed improve static and dynamic balance, which are both crucial for the patient's safety and autonomy.

Actigraphic measurement of the upper limbs movements in acute stroke patients.

BACKGROUND: Stroke units provide patients with a multiparametric monitoring of vital functions, while no instruments are actually available for a continuous monitoring of patients motor performance. Our aim was to develop an actigraphic index able both to identify the paretic limb and continuously monitor the motor performance of stroke patients in the stroke unit environment. METHODS: Twenty consecutive acute stroke patients (mean age 69.2 years SD 10.1, 8 males and 12 females) and 17 bed-restrained patients (mean age 70.5 years SD 7.3, 7 males and 10 females) hospitalized for orthopedic diseases of the lower limbs, but not experiencing neurological symptoms, were enrolled. This last group represented our control group. The motor activity of arms was recorded for 24 h using two programmable actigraphic systems showing off as wrist-worn watches. The firmware segmented the acquisition in epochs of 1 minute and for each epoch calculates two motor activity indices: MAe1 (Epoch-related Motor Activity index) and MAe2 (Epoch-related Motor Activity index 2). MAe1 is defined as the standard deviation of the acceleration module and MAe2 as the module of the standard deviation of acceleration components. To describe the 24 h motor performance of each limb, we calculated the mean value of MAe1 and MAe2 (respectively MA1_24h and MA2_24h). Then we obtained two Asymmetry Rate Indices: AR1_24h and AR2_24h to show the motor activity prevalence. AR1_24h refers to the asymmetry index between the values of MAe1 of both arms and AR2_24h to MAe2 values. The stroke patients were clinically evaluated by NIHSS at the beginning (NIHSST0) and at the end (NIHSST1) of the 24 h actigraphic recordings. RESULTS: Both MA1_24h and MA2_24h indices were smaller in the paretic than in the unaffected arm (respectively p = 0.004 and p = 0.004). AR2_24h showed a better capability (95% of paretic arms correctly identified, Phi Coefficient: 0.903) to discriminate the laterality of the clinical deficit than AR1_24h (85% of paretic arms correctly identified, Phi Coefficient: 0,698). We also found that AR1_24h did not differ between the two groups of patients while AR2_24h was greater in stroke patients than in controls and positively correlated with NIHSS total scores (r: 0.714, p < 0.001 for NIHSS, IC95%: 0.42-0.90) and with the sub-score relative to the paretic upper limb (r: 0.812, p < 0.001, IC95%: 0.62-0.96). CONCLUSIONS: Our data show that actigraphic monitoring of upper limbs can detect the laterality of the motor deficit and measure the clinical severity. These findings suggest that the above described actigraphic system could implement the existing multiparametric monitoring in stroke units.

Upper limb joint kinematics using wearable magnetic and inertial measurement units: an anatomical calibration procedure based on bony landmark identification.

The estimate of a consistent and clinically meaningful joint kinematics using wearable inertial and magnetic sensors requires a sensor-to-segment coordinate system calibration. State-of-the-art calibration procedures for the upper limb are based on functional movements and/or pre-determined postures, which are difficult to implement in subjects that have impaired mobility or are bedridden in acute units. The aim of this study was to develop and validate an alternative calibration procedure based on the direct identification of palpable anatomical landmarks (ALs) for an inertial and magnetic sensor-based upper limb movement analysis protocol. The proposed calibration procedure provides an estimate of three-dimensional shoulder/elbow angular kinematics and the linear trajectory of the wrist according to the standards proposed by the International Society of Biomechanics. The validity of the method was assessed against a camera-based optoelectronic system during uniaxial joint rotations and a reach-to-grasp task. Joint angular kinematics was found as characterised by a low-biased range of motion (<-2.6°), a low root mean square deviation (RMSD) (<4.4°) and a high waveform similarity coefficient (R2 > 0.995) with respect to the gold standard. Except for the cranio-caudal direction, the linear trajectory of the wrist was characterised by a low-biased range of motion (<11 mm) together with a low RMSD (8 mm) and high waveform similarity (R2 > 0.968). The proposed method enabled the estimation of reliable joint kinematics without requiring any active involvement of the patient during the calibration procedure, complying with the metrological standards and requirements of clinical movement analysis.

Efficacy of end-effector Robot-Assisted Gait Training in subacute stroke patients: Clinical and gait outcomes from a pilot bi-centre study.

BACKGROUND: End-effector robots allow intensive gait training in stroke subjects and promote a successful rehabilitation. A comparison between conventional and end-effector Robot-Assisted Gait Training (RAGT) in subacute stroke patients is needed. OBJECTIVE: To investigate the efficacy of end-effector RAGT in subacute stroke patients. METHODS: Twenty-six subacute stroke patients were divided into two group: 14 patients performed RAGT (RG); 12 patients performed conventional gait training (CG). Clinical assessment and gait analysis were performed at the beginning (T0) and at the end (T1) of the rehabilitation. RESULTS: The RG revealed a significant improvement in body function, activities, participation scales, and in the distance measured with the 6 MWT. The affected lower limb's spasticity significantly decreased at T1. In gait analysis, RG showed significantly increases in many parameters. The CG significantly improved clinical assessments but showed no significant changes in gait parameters. Statistically significant differences between RG and CG were found in MRC-HE, TCT, 10 MWT, 6 MWT, and TUG. No significant difference between groups was registered in gait kinematics. CONCLUSIONS: Both rehabilitation treatments produce promising effects in subacute stroke patients. RAGT device offers a more intensive, controlled, and physiological gait training and significantly improved deambulation.

Acute cerebellar stroke and middle cerebral artery stroke exert distinctive modifications on functional cortical connectivity: A comparative study via EEG graph theory.

OBJECTIVE: We tested whether acute cerebellar stroke may determine changes in brain network architecture as defined by cortical sources of EEG rhythms. METHODS: Graph parameters of 41 consecutive stroke patients (<5 days from the event) were studied using eLORETA EEG sources. Network rearrangements of stroke patients were investigated in delta, alpha 2, beta 2 and gamma bands in comparison with healthy subjects. RESULTS: The delta network remodeling was similar in cerebellar and middle cerebral artery strokes, with a reduction of small-worldness. Beta 2 and gamma small-worldness, in the right hemisphere of patients with cerebellar stroke, increase respect to healthy subjects, while alpha 2 small-worldness increases only among patients with a middle cerebral artery stroke. CONCLUSIONS: The network remodeling characteristics are independent on the size of the ischemic lesion. In the early post-acute stages cerebellar stroke differs from the middle cerebral artery one because it does not cause alpha 2 network remodeling while it determines a high frequency network reorganization in beta 2 and gamma bands with an increase of small-worldness characteristics. SIGNIFICANCE: These findings demonstrate changes in the balance of local segregation and global integration induced by cerebellar acute stroke in high EEG frequency bands. They need to be integrated with appropriate follow-up to explore whether further network changes are attained during post-stroke outcome stabilization.

Walking variations in healthy women wearing high-heeled shoes: Shoe size and heel height effects.

BACKGROUND: The use of high heels is widespread in modern society in professional and social contests. Literature showed that wearing high heels can produce injurious effects on several structures from the toes to the pelvis. No studies considered shoe length as an impacting factor on walking with high heels. RESEARCH QUESTION: The aim of this study is to evaluate walking parameters in young healthy women wearing high heels, considering not only the heel height but also the foot/shoe size. METHODS: We evaluate spatio-temporal, kinematic and kinetic data, collected using a 8-camera motion capture system, in a sample of 21 healthy women in three different walking conditions: 1) barefoot, 2) wearing 12 cm high heel shoes independently from shoe size, and 3) wearing shoes with heel height based on shoe size, keeping the ankles' plantar flexion angle constant. The main outcome measures were: spatio-temporal parameters, gait harmony measurement, range of motion, flexion and extension maximal values, power and moment of lower limb joints. RESULTS: Comparing the three walking conditions, the Mixed Anova test, showed significant differences between both high heeled conditions (variable and constant height) and barefoot in spatio-temporal, kinematic and kinetic parameters. SIGNIFICANCE: Regardless of the shoe size, both heeled conditions presented a similar gait pattern and were responsible for negative effects on walking parameters. Considering our results and the relevance of the heel height, further studies are needed to identify a threshold, over which it is possible to observe that wearing high heels could cause harmful effects, independently from the foot/shoe size.

The impact of strabismus surgery on gait pattern in patients with congenital or starting within one year of age strabismus.

Strabismus is a common visual disorder that negatively affects walking and balance. Therapeutic interventions for strabismus include strabismus surgery. Few studies investigated the relationship between strabismus surgery and postural control while, to the best of our knowledge, none has been conducted to assess the influence of strabismus surgery on gait. Therefore, the aim of this study was to evaluate the locomotion characteristics over patients with congenital or starting within one year of age strabismus, one month and three months after strabismus surgery. We enrolled 17 patients with a number of motor and sensorial features. Patients underwent an orthoptic and ophthalmological evaluation as well as a biomechanical evaluation before (T0) and after strabismus surgery (T1 at 1 month, and T2 at 3 months). We observed, mostly in T2 evaluation, significant improvements in the spatio-temporal parameters, such as cadence, velocity, swing, stance and double support phases, step and stride length. The kinematic results revealed a significant increase in hip ROM, strongly related to the improvement of gait speed. No significant differences has been observed in knee and ankle joint ROM. The kinetic results revealed a significant increase in the maximum moment at the knee and ankle joints associated with an increase in the maximum ankle power. Our findings suggest that the safety and balance control associated with gait improve in patients with strabismus following surgery.

Does First Ray Amputation in Diabetic Patients Influence Gait and Quality of Life?

It has recently been suggested that first ray amputation in diabetic patients with serious foot complications can prolong bipedal ambulatory status, and reduce morbidity and mortality. However, no data are available on gait analysis and quality of life after this procedure. In the present case-control study (6 amputee and 6 nonamputee diabetics, 6 healthy non-diabetic), a sample of amputee diabetic patients were evaluated and compared with a sample of nonamputee diabetic patients and a group of age-matched healthy subjects. Gait biomechanics, quality of life, and pain were evaluated. Compared with the other 2 groups, amputee patients displayed a lower walking speed and greater variability and lower ankle, knee, and hip range of motion values. They also tended to have a more flexed hip profile. Pain and lower quality of life were related to worsening biomechanical data. Our study results have shown that gait biomechanics in diabetic patients with first ray amputation are abnormal, probably owing to the severity of diabetes and the absence of the push-off phase provided by the hallux. Tailored orthotics and rehabilitation programs and a specific pain management program should be considered to improve the gait and quality of life of diabetic patients with first ray amputation.

Trunk-lower limb coordination pattern during gait in patients with ataxia.

OBJECTIVE: Although deficit of coordination between the upper and lower body segments might play an important role in impairing gait and stability in ataxic patients, this deficit has not been investigated in subjects with ataxia so far. To evaluate the coordination between trunk and thigh in a sample of patients with ataxia compared with healthy controls and to correlate the coordination measures with the clinical severity. DESIGN: Prospective observational study. SUBJECTS: Sixteen patients with degenerative cerebellar ataxia and sixteen age- and sex-matched controls were studied. METHODS: We assessed the coordination on the sagittal plane between trunk and thigh, considered as rigid segments, by the continuous relative phase (CRP) method. We used the coefficient of multiple correlation (CMC) to measure the within-subject (CMCWS) variability, and the SARA scale to assess clinical severity. RESULTS: CRP curves are dissimilar between ataxic patients and controls, the former showing a chaotic behavior compared to the well-shaped CRP curves observed in the latter. Trunk-thigh coordination has a higher within-subject variability in ataxic patients (median CMCWS: 0.53 for patients, 0.89 for controls, p<0.001). We also found that the CMCWS of the CRP curves negatively correlates with the gait (ρ: -0.565, p: 0.023) and stance (ρ: -0.567, p: 0.022) sub-scores and the total score of the SARA scale (ρ: -0.711, p: 0.002). CONCLUSIONS: Ataxia shows a deficit of spatio-temporal coordination between trunk and thigh. Such a deficit is correlated with the degree of the clinical impairment indicating an important role of inter-segmental coordination in determining the severity of ataxia.

Balance in subjects with congenital or early onset strabismus: Influence of age.

Few studies have investigated the relationship between strabismus and balance, and those that do exist focused on patients within a limited age range, while no studies on possible age-related changes have yet been conducted. Therefore, the aim of our study was to investigate whether the balance strategies adopted by patients with congenital or early onset strabismus change with age. Forty strabismic patients and 36 healthy subjects were enrolled in the study. Both patients and healthy subjects were divided into three subgroups according to age (children, adolescents, and adults) and underwent a stabilometric evaluation. When we compared the whole group of strabismic patients with the group of healthy subjects, we found that the center of pressure area and the trunk oscillations in the former were significantly different from those in the latter; when we considered the three age groups separately, only values in children with strabismus were different from those in the age-matched control group of healthy subjects. Strabismus was found to affect balance in children by inducing a postural strategy characterized by a reduction in physiological trunk oscillations. Gaining a better insight into postural control in strabismic subjects and its evolution with age may be crucial to improving rehabilitation in such patients and planning tailored rehabilitation treatment.

Muscle focal vibration in healthy subjects: evaluation of the effects on upper limb motor performance measured using a robotic device.

PURPOSE: Muscle vibration is a technique that applies a low-amplitude/high-frequency vibratory stimulus to a specific muscle using a mechanical device. The aim of this study was to evaluate, using robot-based outcomes, the effects of focal muscle vibration, at different frequencies, on the motor performance of the upper limb in healthy subjects. METHODS: Forty-eight volunteer healthy subjects (age: 31 ± 8 years) were enrolled. Subjects were assigned to three different groups: the first group, in which subjects underwent muscle vibration treatment with a frequency of 100 Hz; the second group of subjects underwent the same treatment protocol, but using a frequency of vibration of 200 Hz; finally, the control group did not undergo any treatment. The robot-based evaluation session consisted of visually guided reaching task, performed in the sagittal plane. RESULTS: Our results showed that the vibration treatment improved upper limb motor performance of healthy subjects from the baseline (T0) to 10 days after the end of the treatment (T2), but only the group treated with a frequency of 200 Hz reached statistical significance. Specifically, in this group we found an increase of the number of repetitions (T0: 51.4 ± 22.7; T2: 66.3 ± 11.8), and the smoothness of the movement, as showed by a decrease of the Normalized Jerk (T0: 10.5 ± 2.8; T2: 7.7 ± 0.5). CONCLUSION: The results of our study support the use of focal muscle vibration protocols in healthy subjects, to improve motor performance.

Prefrontal cortex as a compensatory network in ataxic gait: a correlation study between cortical activity and gait parameters.

PURPOSE: To investigate whether prefrontal cortex (PFC) functioning during ataxic gait is linked to compensatory mechanisms or to the typical intra-subject variability of the ataxic gait. METHODS: Nineteen patients with chronic ataxia and fifteen healthy subjects were evaluated. The subjects were requested to walk along a straight distance of 10 meters while PFC oxygenation and gait parameters were assessed. PFC activity was evaluated by NIRO-200 while gait analysis was performed by the SMART-D500. To investigate the intra-subject variability of gait, we calculated the coefficient of multiple correlation (CMC) of the hip, knee and ankle kinematic waveforms furthermore, we evaluated the step width. RESULTS: We observed a positive correlation between PFC bilateral oxygenation changes and the step width (r = 0.54; p = 0.02 for the right PFC, and r = 0.50; p = 0.03 for the left PFC). No correlation was found between PFC activity and CMC of the hip, knee and ankle waveforms. CONCLUSIONS: Our results suggest that PFC activity is linked to gait compensatory mechanisms more than to the variability of the joint kinematic parameters caused by a defective cerebellar control.

Idiopathic inflammatory myopathies evaluated by near-infrared spectroscopy.

INTRODUCTION: In this study we evaluated whether near-infrared spectroscopy (NIRS) can determine the metabolic patterns of dermatomyositis (DM), polymyositis (PM), and inclusion-body myositis (IBM). METHODS: We enrolled 10 consecutive patients affected by DM, 11 by PM, and 9 by IBM, and 3 groups of healthy controls. We measured changes in oxygenated and deoxygenated hemoglobin/myoglobin in the extensor digitorum communis during venous and arterial occlusion testing (VOT) and post-occlusion hyperemia. RESULTS: DM showed lower oxygen consumption (P=0.04) during VOT and reduced oxygen supply after VOT (P=0.04) compared with controls. IBM patients showed higher oxygen consumption (P=0.04) during VOT and higher oxygen supply after VOT (P=0.03) than controls. DM patients showed reduced oxidative metabolism compared with IBM (P=0.001), and an impaired ability to supply oxygen compared with PM (P=0.03) and IBM (P=0.001) patients. CONCLUSIONS: NIRS differentiated samples of DM and IBM patients from controls, but it could not distinguish PM patients from a sample of healthy subjects.

Walking strategies in subjects with congenital or early onset strabismus.

INTRODUCTION: In congenital strabismus, sensory adaptations occur hampering the correct development of normal binocular vision. The aim of this study is to investigate if patients with congenital or early onset exotropic or esotropic strabismus adopt different walking strategies with respect to healthy subjects. Our hypothesis is that the abnormal binocular cooperation, occurring in patients with exotropic or esotropic strabismus, could influence neurosensorial adaptation of the gait pattern. MATERIALS AND METHODS: Twenty-five patients were enrolled: 19 with esotropic (ESO) and 6 with exotropic strabismus (EXO). All patients underwent an ophthalmological and orthoptic evaluation. Biomechanical data were collected using a stereophotogrammetric system and a force platform. Twenty-seven age-matched healthy subjects (HS) were used as controls. RESULTS: The comparison between patients with ESO and patients with EXO strabismus showed that the maximal power at the knee and at the ankle was lower in EXO group (p < 0.01 and p < 0.05, respectively). The step width was statistically different between ESO and EXO groups (p < 0.01), lower in patients with ESO and higher in patients with EXO strabismus when compared with HS (though not statistically significant). The deviation angle values showed a relationship with the step width (at the near fixation p < 0.05) and with the maximal power at the knee and at the ankle (at the far fixation for the knee p < 0.001 and for the ankle p < 0.05; at the near fixation for the knee p < 0.05): in the patients with EXO the increased angle deviation is related to larger step width and to lower power at the knee and at the ankle. In the patients with ESO strabismus this relationship is less robust. DISCUSSION: Patients with EXO and ESO strabismus adopt different strategies to compensate their walking difficulties, and these strategies are likely due to an expanded binocular visual field in patients with EXO and to a reduced visual field in patients with ESO strabismus.

Kinematic analysis of the upper limb motor strategies in stroke patients as a tool towards advanced neurorehabilitation strategies: a preliminary study.

Advanced rehabilitation strategies of the upper limb in stroke patients focus on the recovery of the most important daily activities. In this study we analyzed quantitatively and qualitatively the motor strategies employed by stroke patients when reaching and drinking from a glass. We enrolled 6 hemiparetic poststroke patients and 6 healthy subjects. Motion analysis of the task proposed (reaching for the glass, bringing it to the mouth, and putting it back on the table) with the affected limb was performed. Clinical assessment using the Fugl-Meyer Assessment for Upper Extremity was also included. During the reaching for the glass the patients showed a reduced arm elongation and trunk axial rotation due to motor deficit. For this reason, as observed, they carried out compensatory strategies which included trunk forward displacement and head movements. These preliminary data should be considered to address rehabilitation treatment. Moreover, the kinematic analysis protocol developed might represent an outcome measure of upper limb rehabilitation processes.

fNIRS evaluation during a phonemic verbal task reveals prefrontal hypometabolism in patients affected by myotonic dystrophy type 1.

OBJECTIVE: Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, is characterized by a multisystem involvement. Cognitive involvement predominantly affecting frono-temporal functions is an established clinical feature in this disorder. Brain imaging and metabolic studies showed a predominant involvement of fronto-temporal regions in DM1 patients, yet correlation studies among these findings and neuropsychological data gave contrasting results. In order to contribute to clarify the relationship between the metabolic changes documented in the frontal cortex of DM1 patients and a related cognitive task, we applied the functional near-infrared spectroscopy (fNIRS) during the execution of a phonemic verbal fluency task (pVFT). METHODS: We enrolled 29 consecutive right-handed DM1 patients and 30 controls. A 2-channel fNIRS imaging system was used to investigate changes in oxygenated [O2Hb] and deoxygenated [HHb] hemoglobin concentrations in the prefrontal cortex (PFC) during a pVFT. [O2Hb] and [HHb] baseline-corrected activation values were calculated (respectively [O2Hb]c and [HHb]c). RESULTS: In the control group [O2Hb] significantly increased and [HHb] significantly decreased during the pVFT, in the DM1 group no significant variation was found for both parameters revealing no activation of both PFCs during the task. On the other hand, in the DM1 sample, statistical analysis revealed a direct correlation between [O2Hb]c of the left PFC and the pVFT score, while no correlation was observed in the control group. CONCLUSIONS: Our study reveals that DM1 patients show prefrontal hypometabolism during a specific frontal cognitive task compared to controls. Moreover the rapid temporal discrimination of fNIRS allows revealing the correlation between the PFC hypometabolism and the cognitive performance in DM1 patients. SIGNIFICANCE: fNIRS can be helpful to understand the functional correlates of the frontal cognitive impairment in DM1.

Prefrontal cortex controls human balance during overground ataxic gait.

PURPOSE: 1) to verify if prefrontal cortex (PFC) is activated during over ground walking in ataxic patients, 2) to correlate the clinical parameters of gait with the PFC activation patterns. METHODS: Fourteen patients and 20 healthy subjects were studied. Ataxia was assessed by the Scale for the Assessment and Rating of Ataxia (SARA). A 2-channel near-infrared system was used to investigate the changes in oxygenated ([O2Hb]t) and deoxygenated ([HHb]t) hemoglobin concentrations on the PFC during gait. [O2Hb] baseline-corrected activation values ([O2Hb]c) were calculated by the difference between [O2Hb]t and [O2Hb] during upright posture ([O2Hb]b). RESULTS: [O2Hb]t was increased for both channels (respectively p < 0.01 and p = 0.01) only in the patients. No variation was observed in [HHB]t. The correlation coefficient between [O2Hb]c and the SARA gait score was respectively r: 0.878 (p < 0.01) and r: 0.839 (p < 0.01) for the right and left PFC, between [O2Hb]c and the SARA stance score respectively r: 0.893 (p < 0.01) and r: 0.832 (p < 0.01). CONCLUSIONS: During over ground gait PFC is bilaterally activated in patients with severe chronic ataxia. These findings may be associated with compensatory mechanisms which are involved in severe conditions when other nervous centers controlling balance are functionally not efficient.