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We investigated whether the stimulation frequency (SF), the pain phases, and different diagnoses of trigeminal autonomic cephalalgias (TACs) may influence the habituation to pain. We studied the habituation of the nociceptive blink reflex R2 responses at different SFs (.05, .1, .2, .3, .5, and 1 Hz), in 28 episodic cluster headache (ECH) patients, 16 during and 12 outside the bout; they were compared with 16 episodic paroxysmal hemicrania (EPH) during the bout and 21 healthy subjects. We delivered 26 electrical stimuli and subdivided stimuli 2 to 26 in 5 blocks of 5 responses for each SF. Habituation values for each SF were expressed as the percentages of the mean area value of second through fifth blocks with respect to the first one. A significant lower mean percentage decrease of the R2 area across all blocks was found at .2 to 1 Hz SF during ECH, outside of the ECH, and EPH compared with healthy subjects. We showed a common frequency-dependent deficit of habituation of trigeminal nociceptive responses at higher SFs in ECH and EPH patients, independently from the disease phase. This abnormal temporal pattern of pain processing may suggest a trait-dependent dysfunction of some underlying pain-related subcortical structures, rather than a state-dependent functional abnormality due to the recurrence of the headache attacks during the active period.Perspective: TACs showed a frequency-related defective habituation of nociceptive trigeminal responses at the higher SFs, irrespectively of the diagnosis and/or the disease phase. We showed that the clinical similarities in the different subtypes of TACs are in parallel with a trait-dependent dysfunction in pain processing. [ABSTRACT FROM AUTHOR]

Background The harmony of the human gait was recently found to be related to the golden ratio value (ϕ). The ratio between the duration of the stance and that of the swing phases of a gait cycle was in fact found to be close to ϕ, which implies that, because of the fractal property of autosimilarity of that number, the gait ratios stride/stance, stance/swing, swing/double support, were not significantly different from one another. We studied a group of patients with cerebellar ataxia to investigate how the differences between their gait ratios and the golden ratio are related to efficiency and stability of their gait, assessed by energy expenditure and stride-to-stride variability, respectively. Methods The gait of 28 patients who were affected by degenerative cerebellar ataxia and of 28 healthy controls was studied using a stereophotogrammetric system. The above mentioned gait ratios, the energy expenditure estimated using the pelvis reconstructed method and the gait variability in terms of the stride length were computed, and their relationships were analyzed. Matching procedures have also been used to avoid multicollinearity biases. Findings The gait ratio values of the patients were farther from the controls (and hence from ϕ), even in speed matched conditions ( P = 0.011, Cohen's D = 0.76), but not when the variability and energy expenditure were matched between the two groups (Cohen's D = 0.49). In patients with cerebellar ataxia, the farther the stance-swing ratio was from ϕ, the larger the total mechanical work ( R 2 adj = 0.64). Further, a significant positive correlation was observed between the difference of the gait ratio from the golden ratio and the severity of the disease ( R = 0.421, P = 0.026). Interpretation Harmony of gait appears to be a benchmark of physiological gait leading to physiological energy recovery and gait reliability. Neurorehabilitation of patients with ataxia might benefit from the restoration of harmony of their locomotor patterns. [ABSTRACT FROM AUTHOR]

Objective To explore whether the trigeminocervical reflexes (TCRs) show a reflex receptive field organization in the brainstem. Methods The facial skin of 16 healthy subjects was electrically stimulated at nine sites reflecting the distribution of the three branches of the trigeminal nerve. The reflex-evoked EMG responses were measured bilaterally from the neck muscles and the head and neck kinematic reactions were detected. Results TCRs are site dependent. There was a vertical gradient in the magnitude of the reflex responses. EMG and kinematic reflexes were larger when evoked from ophthalmic and maxillary sites than from mandibular ones. The reflex responses exhibited a crossed right–left behavior. Stimulation of the lateral sites evoked larger reflex responses in the contralateral trapezium muscle as well as head rotation and neck bending away from the stimulated side. Conclusion This modular arrangement of the TCRs seems to be related to withdrawal strategies aimed at protecting the face from injuries, in accordance with the functional role that each group of muscles plays in head and neck motion. Significance It is likely that the CNS may exploit the neck muscle synergies revealed by the painful stimulation of the skin face in order to control the head and neck movements. [ABSTRACT FROM AUTHOR]

Highlights: [•] The cutaneous silent period (CSP) is a spinal noxious inhibitory reflex. [•] Escitalopram shows a selective action in inhibiting serotonin reuptake. [•] Escitalopram increases CSP duration without affecting subjective pain sensation. [•] We provide evidence for monoaminergic system involvement in the generation of CSP. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To investigate the effects of bodyweight unloading on the excitability of the nociceptive withdrawal reflex (NWR) and of its receptive fields organisation during quiet stance in humans. Methods: The NWR was elicited in 14 volunteers by electrical stimulation of the sole of the foot at mid-forefoot, arch, and heel points. Participants stood upright and wore a whole-body harness connected via a rope to a pulley. Data were recorded at 0%, 10%, 25% and 40% of the bodyweight unloading. The root mean square of the EMG activity was measured bilaterally from several lower limb muscles. Kinematics of ankle, knee, and hip were measured bilaterally using goniometers. Results: Two-way ANOVA for repeated measures revealed higher reflex sizes at higher degrees of unloading in the tibialis anterior, soleus, and biceps femoris muscles and in the kinematics of the knee joint of the ipsilateral limb. No interaction between stimulation site and unloading was revealed. Conclusions: Unloading induced a generalised enhancement of NWR excitability without modifying the reflex receptive field organisation. Significance: Our study indicates that bodyweight unloading in general enhances the NWR excitability and suggests that only load-related afferent inputs in concert with joint movements may modify the modular organisation of the NWR. [Copyright &y& Elsevier]

Abstract: Objectives: To investigate the behavior of the nociceptive withdrawal reflex (NWR) in the upper limb during reaching and grasping movements in post-stroke hemiparetic patients. Methods: Eight patients with chronic stroke and moderate motor deficits were included. An optoelectronic motion analysis system integrated with a surface EMG machine was used to record the kinematic and EMG data. The NWR was evoked through a painful electrical stimulation of the index finger during a movement which consisted of reaching out, picking up a cylinder, and returning it to the starting position. Results: We found that: (i) the NWR is extensively rearranged in hemiparetic patients, who were found to present different kinematic and EMG reflex patterns with respect to controls; (ii) patients partially lose the ability to modulate the reflex in the different movement phases; (iii) the impairment of the reflex modulation occurs at single-muscle, single-joint and multi-joint level. Conclusions: Patients with chronic and mild-moderate post-stroke motor deficits lose the ability to modulate the NWR dynamically according to the movement variables at individual as well as at multi-muscle and joint levels. Significance: The central nervous system is unable to use the NWR substrate dynamically and flexibly in order to select the muscle synergies needed to govern the spatio–temporal interaction among joints. [Copyright &y& Elsevier]

Abstract: Objective: Trigemino-cervical reflexes (TCRs) are electromyographic responses induced by electrical stimulation of the trigeminal nerve and recorded in the neck muscles. Trigemino-cervical reflexes are detectable in Parkinson’s disease, whereas they are absent in progressive supranuclear palsy (PSP), an atypical parkinsonism associated with brainstem degeneration. To date, no study has investigated TCRs in multiple system atrophy (MSA), another atypical parkinsonism associated with brainstem involvement, which resembles PSP. Methods: To understand whether TCRs are helpful in differentiating PSP from MSA, we compared the TCRs recorded in 10 PSP patients with those obtained from 10 patients diagnosed as having probable MSA, parkinsonian type (MSA-P). Results: Trigemino-cervical reflexes were not recorded in any of the PSP patients, while they were clearly detectable in all the MSA-P patients. Conclusions: Trigemino-cervical reflex recording is a rapid neurophysiological method, which could assist in the differential diagnosis between PSP and MSA-P. Significance: This study further improves our understanding of the different neuronal functioning of extrapyramidal disorders. TCRs monitoring may be useful to support the diagnosis of atypical parkinsonisms especially when clinical evidence is uncertain. [Copyright &y& Elsevier]

Abstract: We investigated changes in visual cortex excitability by analyzing visual evoked potential (VEP) habituation in healthy subjects during tonic pain evoked by the cold-pressor test (CPT). We tested VEP amplitude habituation (slope of the linear regression line for N1-P1 amplitude from the 1st to 6th block of 100 sweeps) in 19 healthy volunteers during 4 experimental conditions: baseline; no-pain (hand held in warm water, 25°C); pain (hand held in cold water, 2–4°C); and the after-effects of tonic pain. During baseline and no-pain sessions, VEPs habituated normally across the 6 consecutive blocks (mean slope –.28 and –.18%), whereas during pain and its after-effects they failed to decrease (0%, and –.11%). Tonic pain induced by the CPT abolishes normal VEP habituation and the lack of habituation persists after the CPT is stopped. Tonic pain probably abolishes VEP habituation by acting on brainstem neural structures which modulate thalamo-cortical activation thereby changing visual cortex excitability. Perspective: This study shows that tonic pain alters visual cortex excitability, a brain region unrelated to pain processing. These changes probably reflect defensive strategies against pain. Extending the study from healthy volunteers to patients with migraine between attacks would offer the opportunity to investigate visual cortical excitability under conditions when baseline habituation is absent. [Copyright &y& Elsevier]

Total hip replacement with minimally invasive direct anterior approach using the "Smith Petersen" interval is an alternative technique to conventional surgery aimed at preserving the integrity of the muscles around the hip joint. This study aimed to observe hip biomechanics, gait variables, hip muscle activation and locomotor performance during three locomotor tasks (forward, lateral, and backward walking), in subjects who undergo total hip arthroplasty with direct anterior approach. Fourteen patients with primary osteoarthritis who underwent direct anterior approach were included in the study. The optoelectronic 3-D motion analysis system integrated with an electromyography surface device was used to acquire the biomechanics of patients before surgery and at 3 and 6 months post-surgery. Spatio-temporal, dynamic, and hip muscle electromyographic parameters were analyzed and compared whit those of healthy controls. Almost all gait parameters improved after surgery. The majority of gait variables neared to the control group at 6 months, while the hip joint range of motion did not. The abnormally increased activation of the muscles around the hip joint was reduced at 6 months post-surgery during all three locomotor tasks. Conversely, the altered gait phase-related electromyographic pattern did not change after the surgery. Our results indicate that hip and gait function during several locomotor tasks improved after surgery, while simultaneously either preserve or restore the muscle activation around the hip joint. A full biomechanical evaluation of the hip function during locomotion may aid physicians and surgeons in optimizing the management of patients before and after hip replacement surgery. • Patients after hip replacement obtain a series of gait function improvements. • The majority of gait variables normalized in patients at 6 months post-surgery. • The surgery reduce the hyperactivation of the hip muscles around the hip joint. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To describe the temporal, kinetic, kinematic, electromyographic and energetic aspects of gait in Charcot-Marie-Tooth patients with foot drop and plantar flexion failure. Methods: A sample of 21 patients fulfilling clinical, electrodiagnostic and genetic criteria for Charcot-Marie-Tooth disease were evaluated by computerized gait analysis system and compared to a group of matched healthy subjects. Patients were classified as having isolate foot drop (group 1) and association of foot drop and plantar flexion failure (group 2). Results: While it was impossible to detect a reliable gait pattern when the group of patients was considered as a whole and compared to healthy subjects, we observed two distinctive gait patterns when patients were subdivided as group 1 or 2. Group 1 showed a gait pattern with some characteristics of the “steppage pattern”. The complex motor strategy adopted by this group leads to reduce the swing velocity and to preserve the step length in spite of a high energy consumption. Group 2 displayed a “clumsy pattern” characterized by very slow gait with reduced step length, a broader support area and great reduction in the cadence. This group of patients is characterized by a low energy consumption and greater energy recovery, due above all to the primary deficit and the various compensatory mechanisms. Conclusions: Such between-group differences in gait pattern can be related to both primary motor deficits and secondary compensatory mechanisms. Foot drop and plantar flexion failure affect the overall gait strategy in Charcot-Marie-Tooth patients. [Copyright &y& Elsevier]

Abstract: The flexion or flexor reflex (FR) recorded in the lower limbs in humans (LLFR) is a widely investigated neurophysiological tool. It is a polysynaptic and multisegmental spinal response that produces a withdrawal of the stimulated limb and resembles (having several features in common) the hind-paw FR in animals. The FR, in both animals and humans, is mediated by a complex circuitry modulated at spinal and supraspinal level. At rest, the LLFR (usually obtained by stimulating the sural/tibial nerve and by recording from the biceps femoris/tibial anterior muscle) appears as a double burst composed of an early, inconstantly present component, called the RII reflex, and a late, larger and stable component, called the RIII reflex. Numerous studies have shown that the afferents mediating the RII reflex are conveyed by large-diameter, low-threshold, non-nociceptive A-beta fibers, and those mediating the RIII reflex by small-diameter, high-threshold nociceptive A-delta fibers. However, several afferents, including nociceptive and non-nociceptive fibers from skin and muscles, have been found to contribute to LLFR activation. Since the threshold of the RIII reflex has been shown to correspond to the pain threshold and the size of the reflex to be related to the level of pain perception, it has been suggested that the RIII reflex might constitute a useful tool to investigate pain processing at spinal and supraspinal level, pharmacological modulation and pathological pain conditions. As stated in EFNS guidelines, the RIII reflex is the most widely used of all the nociceptive reflexes, and appears to be the most reliable in the assessment of treatment efficacy. However, the RIII reflex use in the clinical evaluation of neuropathic pain is still limited. In addition to its nocifensive function, the LLFR seems to be linked to posture and locomotion. This may be explained by the fact that its neuronal circuitry, made up of a complex pool of interneurons, is interposed in motor control and, during movements, receives both peripheral afferents (flexion reflex afferents, FRAs) and descending commands, forming a multisensorial feedback mechanism and projecting the output to motoneurons. LLFR excitability, mediated by this complex circuitry, is finely modulated in a state- and phase-dependent manner, rather as we observe in the FR in animal models. Several studies have demonstrated that LLFR excitability may be influenced by numerous physiological conditions (menstrual cycle, stress, attention, sleep and so on) and pathological states (spinal lesions, spasticity, Wallenberg''s syndrome, fibromyalgia, headaches and so on). Finally, the LLFR is modulated by several drugs and neurotransmitters. In summary, study of the LLFR in humans has proved to be an interesting functional window onto the spinal and supraspinal mechanisms of pain processing and onto the spinal neural control mechanisms operating during posture and locomotion. [Copyright &y& Elsevier]

Introduction: Electrical stimulation of the supraorbital nerve (SON) induces late reflex responses in the neck muscles; these responses are hypothesised to be polysynaptic reflexes participating in a defensive withdrawal retraction of the head from facial nociceptive stimuli. Such responses may extend to the proximal muscle of the arms.Objective: (1) to investigate reflexes in the upper limb muscles (trigemino-spinal responses, TSR) and their relationship with trigemino-cervical responses (TCR); and (2) to identify the nociceptive component of such reflexes and their functional significance.Methods: Reflex responses were registered from the semispinalis capitis and biceps brachii muscles after electrical stimulation of the SON in 12 healthy subjects. The sensory (ST), painful (PT) and reflex thresholds, the latency and area of the responses, the effect of heterotopic painful stimulation (HTP), the recovery cycle as well as the effect of the expected and unexpected stimuli were measured.Results: Stable reproducible TCR and TSR responses were identified at 2.5±0.4 ×ST, which corresponded exactly to the PT in all the subjects. The TCR and TSR areas were markedly reduced after HTP. The recovery cycle of the TSR area was faster than that of the TCR. Repeated rhythmic stimulation failed to induce progressive reflex suppression.Conclusions: These results confirm the nociceptive nature of the TCR and indicate that the biceps brachii response (TSR) has the same nocifensive significance as the posterior neck muscle responses. TCR and TSR are mediated different polysynaptic pathways The presence of trigemino-cervical-spinal responses in our study clearly indicates that there is a reflex interaction between nociceptive trigeminal afferents and both upper and lower cervical spinal cord motoneurons. [Copyright &y& Elsevier]

Objective To investigate how the nociceptive withdrawal reflex (NWR) is modulated during gait initiation. Methods The NWR was elicited in ten subjects using electrical stimulation at four sites in the right foot during symmetrical stance (50% of body weight on each foot) or while performing the first step during gait initiation: either during heel off (HO, 20% of body load on the starting leg) or heel contact (HC, 80% of body load on the starting leg in the first step). Kinematics and EMG responses from major muscles of the ipsilateral leg were recorded. Results The NWR was modulated by stimulation site in all muscles except Soleus. The NWR responses elicited after stimulation of the arch were significantly larger than those evoked at all other sites in Tibialis Anterior, Rectus Femoris, and Vastus Lateralis. At the hip joint, the largest flexion was obtained during HO, whereas the smallest flexion was observed during HC, both following stimulation on the arch of the foot. Conclusions The NWR responses were modulated to maintain balance and continue the development of the gait initiation process. Significance The NWR modulation followed a functional principle, which might allow a functional use in rehabilitation strategies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Multiple system atrophy subjects showed a facilitated temporal processing of pain. [•] MSA and PD showed a comparable level of facilitation in temporal pain processing. [•] Striatonigral neurodegeneration could favor a facilitated temporal pain processing. [ABSTRACT FROM AUTHOR]

Background: Subjects with transfemoral amputation (TFA) show an asymmetric gait pattern associated with a decreased ability to recover mechanical energy and an increased metabolic cost of walking.Research Question: This study aimed to identify the spatio-temporal and kinematic gait variables correlated with mechanical energy values in subjects with TFA and to observe the ability of the identified parameters to discriminate between TFA and controls according to the type of prosthesis.Methods: The gait of 40 subjects with TFA was evaluated with a motion 3-D optoelectronic system. Nine subjects wore a mechanical prosthesis (TFAm), seventeen a C-Leg prosthesis (TFAc), and fourteen a Genium prosthesis (TFAg). Spatio-temporal and pelvic kinematic parameters were measured. Energy recovery was measured relative to the whole-body center of mass (CoM) kinematics as the fraction of mechanical energy recovered during each walking step (R-step). Correlation tests and multiple linear regression analyses were used to evaluate the correlation and association between kinematic and energy variables, respectively. Receiver operating characteristics curves were plotted to assess the ability of the correlated parameter to distinguish subjects with TFA from controls, and optimal cutoff point values were calculated according to the type of prosthesis.Results: Among the spatio-temporal and kinematic parameters correlated to R-step, only pelvic obliquity of the prosthetic side was significantly associated with R-step. It showed an excellent ability to discriminate between TFA and controls. Furthermore, pelvic obliquity showed an excellent discriminative ability in identifying TFAm and TFAc and a good discriminative ability in identifying TFAg from controls.Significance: Pelvic obliquity plays an important role in energy recovery during gait for subjects using prosthetics. This information might be exploited to monitor the adaptation of subjects with TFA to prosthetic devices, to lower the energetic cost of walking potentially, and to reduce the long-term risks of secondary physical complications in prosthetic users. [ABSTRACT FROM AUTHOR]

To explore the role of strong negative emotions in spinal nociception, we evaluated the effect of fear-relevant videos of small animals on the nociceptive withdrawal reflex (NWR) and reflex-related pain perception in healthy subjects with a specific phobia of small animals. Twenty healthy subjects with a specific phobia of small animals diagnosed according to DSM-V criteria were included in this study. The NWR was evoked in the lower limb by stimulating the sural nerve and recording EMG activity in the biceps femoris. NWR pain-related perception was quantified on an 11-point numerical rating scale (NRS). Subjects were examined during 4 recording sessions. In the baseline session, no images were projected. In the other sessions, the subjects were invited to watch a video containing either neutral or phobic content. To evaluate neurovegetative responses, we measured heart rate using a pulse oximeter during each recording session. A series of clinical rating scales were administered to subjects to evaluate disgust, fear, and anxiety. The NWR amplitude was significantly increased during the phobic video session and was associated with the fear inventory scale scores. Women showed higher NWR amplitude values during the phobic video session and a lower recovery rate during the after-effect video session than did men. The NWR amplitude and related pain perception were dissociated from each other during the phobic video session, as the NRS score remained unchanged while the NWR increased in amplitude. Emotions induced by the viewing of phobic videos seem to enhance the activation of the spinal circuitries involved in nociception and the withdrawal reaction without interfering with pain processing pathways or dissociating the reflex response from related pain perception. This effect appears to differ by sex, as it was more intense and longer lasting in women than in men. Emotions induced by phobic video viewing increase the alertness devoted to the defensive reaction by emphasizing nociceptive responses independently from pain perception. The NWR may represent an interesting tool for exploring the interaction between strong negative emotions and spinal nociception. A better understanding of this mechanism may be a theoretical prerequisite for the optimization of pain management in several chronic pain syndromes. • Emotions induced by the viewing of phobic videos modulate the spinal circuitries involved in nociception. • Phobia-personalized videos induce an increase in NWR response amplitude without influencing related pain ratings. • Women show higher NWR amplitude values than men during the phobic visual stimulation. • NWR may represent a tool for exploring the interaction between strong negative emotions and spinal nociception. [ABSTRACT FROM AUTHOR]

Background The aim of this study was to investigate the lower limb muscle coactivation and its relationship with muscles spasticity, gait performance, and metabolic cost in patients with hereditary spastic paraparesis. Methods Kinematic, kinetic, electromyographic and energetic parameters of 23 patients and 23 controls were evaluated by computerized gait analysis system. We computed ankle and knee antagonist muscle coactivation indexes throughout the gait cycle and during the subphases of gait. Energy consumption and energy recovery were measured as well. In addition to the correlation analysis between coactivation indexes and clinical variables, correlations between coactivation indexes and time–distance, kinematic, kinetic, and energetic parameters were estimated. Findings Increased coactivity indexes of both knee and ankle muscles throughout the gait cycle and during the subphases of gait were observed in patients compared with controls. Energetic parameters were significantly higher in patients than in controls. Both knee and ankle muscle coactivation indexes were positively correlated with knee and ankle spasticity (Ashworth score), respectively. Knee and ankle muscle coactivation indexes were both positively correlated with energy consumption and both negatively correlated with energy recovery. Interpretation Positive correlations between the Ashworth score and lower limb muscle coactivation suggest that abnormal lower limb muscle coactivation in patients with hereditary spastic paraparesis reflects a primary deficit linked to lower limb spasticity. Furthermore, these abnormalities influence the energetic mechanisms during walking. Identifying excessive muscle coactivation may be helpful in individuating the rehabilitative treatments and designing specific orthosis to restrain spasticity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: The aims of this study were to develop a kinematic model of the spine, seen as a continuous deformable body and to identify the smallest set of surface markers allowing adequate measurements of spine motion. The spine is widely considered as a rigid body or as a kinematic chain made up of a smaller number of segments, thereby introducing an approximation. It would be useful to have at our disposal a technique ensuring accurate and repeatable measurement of the shape of the whole spine. Ten healthy subjects underwent a whole-spine radiographic assessment and, simultaneously, an optoelectronic recording. Polynomial interpolations of the vertebral centroids, of the whole set of markers were performed. The similarity of the resulting curves was assessed. Our findings indicate that spine shape can be reproduced by 5th order polynomial interpolation. The best approximating curves are obtained from either 10- or 9-marker sets. Sagittal angles are systematically underestimated. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to shed light on the neurochemical modulatory mechanisms of the noxious spinal inhibitory cutaneous silent period (CSP). We study the effects of 100mg of oral tramadol in 11 healthy volunteers. Tramadol has low affinity for opioid receptors and has the ability to inhibit serotonin and noradrenaline reuptake. We elicited CSPs in the first dorsal interosseus muscle and noxious withdrawal flexor reflexes (NWR) in the right biceps femoris muscle before, 30min and each hour up to the 6th after tramadol. Subjective pain sensation was checked on an 11-point numerical scale. Tramadol increased duration of CSP, and reduced the NWR area under the curve maximally 2h after tramadol and paralleled the reduction of subjective pain perception. We suggest that the monoaminergic action of tramadol reinforces the activity of spinal inhibitory interneurons on α-motoneurons for the hand muscles. [Copyright &y& Elsevier]

Abstract: Objectives: Our study is aimed to evaluate the spinal cord pain processing in Huntington’s disease (HD) by testing both the temporal summation threshold (TST) of the nociceptive withdrawal reflex (NWR) and the functional activity of the diffuse noxious inhibitory control (DNIC) as form of supraspinal control of pain. Methods: We enrolled 19 HD patients and 17 healthy controls. We measured threshold (Th), Area, TST and related psychophysical pain sensations of the NWR, at baseline and during and after activation of the DNIC by means of cold pressor test (CPT) as heterotopic noxious conditioning stimulation. Results: In HD patients we found a significantly higher Th and TST as well as a lower Area when compared to controls. During the CPT, a significant inhibition of reflex and psychophysical pain responses were found in both HD patients and controls when compared to baseline, without differences between the groups in CPT results. Conclusions: Our study demonstrated an abnormal spinal cord pain processing in HD patients. Abnormalities in pain processing are not apparently linked to a dysfunctional DNIC inhibitory projection system in HD patients. Significance: Our findings support the hypothesis that the striatum could play a role in pain modulation and that its atrophy could affect pain processing without change the DNIC efficiency. [Copyright &y& Elsevier]

Abstract: The cutaneous silent period (CSP) is a brief transient suppression of the voluntary muscle contraction that follows a noxious cutaneous nerve stimulation. In this study we investigated the influence of the corticospinal tract on this spinal inhibitory reflex. In patients with pyramidal syndrome and in a group of healthy subjects we delivered painful electrical finger stimulation during sustained contraction of the ipsilateral abductor digiti minimi muscle. The CSP latency and duration and the background electromyographic (EMG) activity were measured and compared between-groups. The compound motor action potential amplitude and F-wave latency were also measured after electrical stimulation of the ulnar nerve at the wrist. The CSP latency was significantly longer in patients than in healthy subjects. None of the other variables differed in patients and healthy subjects. Our findings suggest that corticospinal projections influence the CSP latency probably by modulating the balance of excitability in the underlying circuits. [Copyright &y& Elsevier]

Abstract: Background: The relationship between ankle plantar flexor biomechanical properties and gait pattern following surgery for acute rupture of the Achilles tendon has not yet been fully investigated. Methods: Forty-nine young adults (27 men and 22 women) who underwent surgical repair of a complete Achilles tendon rupture were evaluated at 3, 6, 12 and 24 months by clinical assessment, biomechanical evaluation and gait analysis. Findings: Ankle range of motion, plantar flexor passive stiffness and concentric strength were recovered within 12 months. Gait abnormalities related to these factors took longer to disappear owing to the presence of anomalous muscle patterns. At 24 months, a deficit in calf-muscle eccentric strength was still present, determining adaptive changes in gait strategy that involved ankle motion and coordinated muscular activity. Interpretation: Improvement of gait pattern is slower than recovery of plantar flexor mechanical properties. Persisting mechanical impairment resulting in gait adaptations may be detrimental to the healing structures by increasing stress on the Achilles tendon. Restoration of calf-muscle eccentric strength and coordinated antagonist muscle activity should be key points in postoperative rehabilitation following surgical repair of Achilles tendon rupture. [Copyright &y& Elsevier]

Objective: To evaluate the effect of heterotopic painful stimulation (HPS) on the cutaneous silent period (CSP) and the withdrawal flexor reflex (WFR) in the upper limbs, in an attempt to better identify the nociceptive component of the CSP and its functional relationship with the flexor reflex.Methods: The CSP at different stimulus intensities, the WFR and the H/M ratio were studied in 12 healthy adults. Neurophysiological measurements were recorded in the following 4 conditions: (1) control session; (2) non-painful session (dipping hand in water at 25 °C); (3) painful (cold pressor test, CPT); and (4) after-effect (3–8 min after taking hand out of water at 5–6 °C).Results: During the CPT, the duration of the high-threshold CSP was approximately 23% shorter than the baseline value, the high-threshold CSP latency was approximately 10% longer than the baseline value, and the mean RIII reflex area was approximately 40% smaller than the baseline reflex area (all P<0.05). A significant correlation was found between the percentage decrease in the CSP duration and the WFR area (r=0.61, P<0.05).Conclusions: Our findings indicate that the HPS specifically inhibits both the high-threshold CSP and the WFR, thereby providing further evidence that these cutaneous reflexes are functionally and anatomically related, and that they represent different aspects of a complex nocifensive response. [Copyright &y& Elsevier]