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Background: Adaptation to a constant sensory stimulus involves many sites along the path of sensory volleys towards perception. The evaluation of such phenomenon may be of clinical interest. We studied adaptation to a constant temperature stimulus in healthy subjects to set normative data and in patients with sensory polyneuropathy (SPN), as proof of concept. Methods: Twenty‐six healthy subjects and 26 patients with SPN in the context of chemotherapy treatment with oxaliplatin for colon cancer were instructed to express through an electronic VAS system (eVAS); the level of sensation felt when a thermode set at either 39º, 41º, 43º, 45º or 47º was applied to their ventral forearm. Results: The eVAS recordings showed typically an abrupt onset that slowed to approach maximum sensation and continued with a slow decrease indicating adaptation. The time to respond (TR), the velocity of the initial response (VR), the maximum sensation (MA), the time to reach MA (MAt), the onset of adaptation (AO) and the decrease in the sensation level with respect to MA at 30 s after stimulus application (SL30), were dependent on the temperature level in all subjects. However, patients showed significantly delayed TR, slowed VR, decreased MA, delayed AO and reduced SL30, with respect to healthy subjects. Differences were more pronounced at low‐temperature levels, with absent AO in 25 patients versus 2 healthy subjects at temperatures of 39º and 41ºC. Conclusion: The study of adaptation to a constant temperature stimulus can furnish valuable data for the assessment of patients with SPN. Significance: We studied perceptual changes in the intensity of thermoalgesic sensation during 30 s of constant temperature stimulation after an abrupt initial contact in healthy subjects and patients with sensory polyneuropathy. Patients showed delayed time to respond, decreased maximal sensation and reduced adaptation with respect to healthy subjects. Differences were more pronounced at low and intermediate temperatures (39ºC to 43ºC). The method is of easy implementation and shows clinically relevant abnormalities in patients with sensory polyneuropathy. [ABSTRACT FROM AUTHOR]

There has been much debate concerning whether startling sensory stimuli can activate a fast‐neural pathway for movement triggering (StartReact) which is different from that of voluntary movements. Activity in sternocleidomastoid (SCM) electromyogram is suggested to indicate activation of this pathway. We evaluated whether SCM activity can accurately identify trials which may differ in their neurophysiological triggering and assessed the use of cumulative distribution functions (CDFs) of reaction time (RT) data to identify trials with the shortest RTs for analysis. Using recent data sets from the StartReact literature, we examined the relationship between RT and SCM activity. We categorised data into short/longer RT bins using CDFs and used linear mixed‐effects models to compare potential conclusions that can be drawn when categorising data on the basis of RT versus on the basis of SCM activity. The capacity of SCM to predict RT is task‐specific, making it an unreliable indicator of distinct neurophysiological mechanisms. Classification of trials using CDFs is capable of capturing potential task‐ or muscle‐related differences in triggering whilst avoiding the pitfalls of the traditional SCM activity‐based classification method. We conclude that SCM activity is not always evident on trials that show the early triggering of movements seen in the StartReact phenomenon. We further propose that a more comprehensive analysis of data may be achieved through the inclusion of CDF analyses. These findings have implications for future research investigating movement triggering as well as for potential therapeutic applications of StartReact. [ABSTRACT FROM AUTHOR]

A startling auditory stimulus (SAS) induces a reflex response involving, among other reactions, a strong contraction of the orbicularis oculi muscle (OOc) and subsequent eye closure. A SAS also induces the StartReact effect, a significant shortening of reaction time in subjects ready for task execution. We examined the obvious conflict appearing when a StartReact paradigm requires participants with eyes closed to open their eyes to look for a visual target. We recorded OOc EMG activity and eyelid movements in healthy volunteers who were instructed to open their eyes at perception of a somatosensory imperative stimulus (IS) and locate the position of a Libet's clock's hand shown on a computer screen at 80 cm distance. In 6 out of 20 trials, we delivered a SAS simultaneously with the IS. The main outcome measures were reaction time at onset of eyelid movement and the time gap (TG) separating subjective assessment of the clock's hand position from real IS issuing. Control experiments included reaction time to eye closing and target location with eyes open to the same IS. Reaction time was significantly faster in SAS than in noSAS trials and slower for eye opening than for eye closing in both conditions. In the eye‐opening task, TG was significantly shorter in SAS with respect to noSAS trials, despite the presence of the SAS‐related burst in the OOc before EMG cessation. Our results indicate that the StartReact effect speeds up eye opening and location of a target in the visual field despite the startle reaction opposing the task. We expanded our knowledge on the reflex and voluntary control of eyelid movements by showing that the task of eye opening to focus the gaze on a visual target was speeded‐up in the context of a StartReact paradigm, despite the unavoidable stimulus‐generated eye‐closing reflex reaction. In contrast, the presence of the startle reflex tended to delay the assessment of target location in control eyes‐opened conditions, as it made subjects close their eyes. [ABSTRACT FROM AUTHOR]

Objective: To provide a neurophysiological tool for assessing sensorimotor pathways, which may differ for those involving distal muscles in simple tasks from those involving distal muscles in a kinetic chain task, or proximal muscles in both. Methods: We compared latencies and magnitudes of motor responses in a reaction time paradigm in a proximal (biceps brachii, BB) and a distal (first dorsal interosseous, FDI) muscle following electrical stimuli used as imperative signal (IS) delivered to the index finger. These stimuli were applied during different motor tasks: simple tasks involving either one muscle, e.g. flexing the elbow for BB (FLEX), or pinching a pen for FDI (PINCH); combined tasks engaging both muscles by pinching and flexing simultaneously (PINCH-FLEX). Stimuli were of varying intensity and occasionally elicited a startle response, and a StartReact effect. Results: In BB, response latencies decreased gradually and response amplitudes increased progressively with increasing IS intensities for non-startling trials, while for trials containing startle responses, latencies were uniformly shortened and response amplitudes similarly augmented across all IS intensities in both FLEX and PINCH-FLEX. In FDI, response latencies decreased gradually and response amplitudes increased progressively with increasing IS intensities in both PINCH and PINCH-FLEX for non-startling trials, but, unlike in BB for the simple task, in PINCH for trials containing startle responses as well. In PINCH-FLEX, FDI latencies were uniformly shortened and amplitudes similarly increased across all stimulus intensities whenever startle signs were present. Conclusions: Our results suggest the presence of different sensorimotor pathways supporting a dissociation between simple tasks that involve distal upper limb muscles (FDI in PINCH) from simple tasks involving proximal muscles (BB in FLEX), and combined tasks that engage both muscles (FDI and BB in PINCH-FLEX), all in accordance with differential importance in the control of movements by cortical and subcortical structures. Significance: Simple assessment tools may provide useful information regarding the differential involvement of sensorimotor pathways in the control of both simple and combined tasks that engage proximal and distal muscles. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this review was to identify risk factors, prognostic factors, and comorbidities associated with common spinal disorders. Methods: A scoping review of the literature of common spinal disorders was performed through September 2016. To identify search terms, we developed 3 terminology groups for case definitions: 1) spinal pain of unknown origin, 2) spinal syndromes, and 3) spinal pathology. We used a comprehensive strategy to search PubMed for meta-analyses and systematic reviews of case-control studies, cohort studies, and randomized controlled trials for risk and prognostic factors and cross-sectional studies describing associations and comorbidities. Results: Of 3,453 candidate papers, 145 met study criteria and were included in this review. Risk factors were reported for group 1: non-specific low back pain (smoking, overweight/obesity, negative recovery expectations), non-specific neck pain (high job demands, monotonous work); group 2: degenerative spinal disease (workers’ compensation claim, degenerative scoliosis), and group 3: spinal tuberculosis (age, imprisonment, previous history of tuberculosis), spinal cord injury (age, accidental injury), vertebral fracture from osteoporosis (type 1 diabetes, certain medications, smoking), and neural tube defects (folic acid deficit, anti-convulsant medications, chlorine, influenza, maternal obesity). A range of comorbidities was identified for spinal disorders. Conclusion: Many associated factors for common spinal disorders identified in this study are modifiable. The most common spinal disorders are co-morbid with general health conditions, but there is a lack of clarity in the literature differentiating which conditions are merely comorbid versus ones that are risk factors. Modifiable risk factors present opportunities for policy, research, and public health prevention efforts on both the individual patient and community levels. Further research into prevention interventions for spinal disorders is needed to address this gap in the literature. [ABSTRACT FROM AUTHOR]

Purpose. Understanding the presentation of spinal cord injury (SCI) due to tumours considering population distribution and temporal trends is key to managing SCI health services. This study quantified incidence rates, function scores, and trends of SCI due to tumour or metastasis over an 18-year time period in a defined region in Spain. Methods. A retrospective cohort study included in-and outpatients with nontraumatic SCI due to tumour or metastasis admitted to a metropolitan hospital in Spain between 1991 and 2008. Main outcome measures were crude and age- and sex-adjusted incidence rates, tumour location and type, distribution by spinal level, neurological level of injury, and impairment ASIA scores. Results. Primary tumour or metastasis accounted for 32.5% of nontraumatic SCI with an incidence rate of 4.1 per million population. Increasing rates with age and over time were observed. Major pathology groups were intradural-extramedullary masses from which meningiomas and neurinomas accounted for 40%. Lesions were mostly incomplete with predominant ASIA Grade D. Conclusions. Increasing incidence rates of tumour-related SCI over time in the middle-aged and the elderly suggest a growing need for neurooncology health resources in the future. [ABSTRACT FROM AUTHOR]

Passive limb displacement is routinely used to assess muscle tone. If we attempt to quantify muscle stiffness using mechanical devices, it is important to know whether kinematic stimuli are able to trigger startle reactions. Whether kinematic stimuli are able to elicit a startle reflex and to accelerate prepared voluntary movements (StartReact effect) has not been studied extensively to date. Eleven healthy subjects were suspended in an exoskeleton and were exposed to passive left knee flexion (KF) at three intensities, occasionally replaced by fast right KF. Upon perceiving the movement subjects were asked to perform right wrist extension (WE), assessed by extensor carpi radialis (ECR) electromyographic activity. ECR latencies were shortest in fast trials. Startle responses were present in most fast trials, yet being significantly accelerated and larger with right versus left KF, since the former occurred less frequently and thus less expectedly. Startle responses were associated with earlier and larger ECR responses (StartReact effect), with the largest effect again upon right KF. The results provide evidence that kinematic stimuli are able to elicit both startle reflexes and a StartReact effect, which depend on stimulus intensity and anticipation, as well as on the subjects’ preparedness to respond. [ABSTRACT FROM AUTHOR]

A startling auditory stimulus (SAS) causes a faster execution of voluntary actions when applied together with the imperative signal in reaction time tasks (the StartReact effect). However, speeding up reaction time may not be the best strategy in all tasks. After a self-initiated fall, the program for landing has to be time-locked to foot contact to avoid damage, and therefore advanced execution of the program would not be convenient. We examined the effects of SAS on the landing motor program in 8 healthy subjects that were requested to let themselves fall from platforms either 50 or 80 cm high at the perception of a visual imperative signal and land on specific targets. In trials at random, SAS was applied either together with the imperative signal (SASIS) or at an appropriate prelanding time (SASPL). As expected, the latency of takeoff was significantly shortened in SASIS trials. On the contrary, the timing of foot contact was not significantly different for SASPL compared with control trials. No changes were observed in the size of the electromyograph bursts in the two experimental conditions with respect to the control condition. Our results indicate that the landing program after a self-initiated fall may in part be organized at the time of takeoff and involve precise information on timing of muscle activation. Once launched, the program is protected against interferences by external inputs. [ABSTRACT FROM AUTHOR]

We describe a new form of γ-aminobutyric acid (GABA) -mediated regulation of the inactivation and of the recovery from inactivation of the L-type Ca2+ current (ICa) in crayfish muscle. GABA (1 mM) was applied during a 2-min period and the peak ICa was measured using two-electrode voltage-clamp recordings 30 min after returning to the control solution. Prepulse-pulse protocols showed that the GABA-mediated inhibition of ICa decreased (>50%) both with increasing prepulse depolarization and as the delay between prepulse and pulse was reduced. GABA also shifted to depolarized values (>5 mV) the S-shaped plots of the peak ICa evoked by a constant depolarizing pulse as a function of prepulse voltage (i.e., inactivation curves) and accelerated the recovery time from the inactivation evoked by depolarizing prepulses (>35%). The effects outlasted GABA application up to 1 h. The observed changes in inactivation properties may be of functional importance because they indicate that previous depolarization relieves the GABA-induced inhibition of ICa, implying that this long-lasting inhibition is under the regulation of the prepulse potential and the subsequent Ca2+ entry. [ABSTRACT FROM AUTHOR]

Provides information on a study on the videofluoroscopic evaluation of prosthetic fit and residual limbs following transtibial amputation. Methods of the study; Identification of the components of residual limb or socket requiring radiographic markers; Description of residual limb-socket relationships during the gait cycle under fluoroscopy.

Spinal cord injury (SCI) leading to neurological deficits produces long-term effects that persist over a lifetime. Survival analysis of patients with SCI, at individual and population level, is important for public health management and the assessment of treatment achievements. The current study evaluated survival following traumatic and non-traumatic SCI worldwide. A systematic review was conducted, and all included papers were assessed for quality using a purposely designed assessment form. Survival data were presented in Kaplan-Meier curves and compared using the log-rank test. Sixteen studies were included of which 11 concerned traumatic SCI, four non-traumatic SCI, and one both. Crude standard mortality rates (SMRs) revealed that overall mortality in SCI is up to three times higher than in the general population. Survival rates were statistically significantly lower in non-traumatic SCI than in traumatic SCI (log-rank p = 0.000). Age at injury, neurological level, extent of lesion, and year of injury have been described as predictors of survival. Causes of death stem from secondary complications, with failure of the respiratory system being the leading cause. This is the first systematic literature review on survival analysis following SCI worldwide. An increase in survival over time was found. However, the SMRs of individuals with SCI still exceed those of an age-matched non-disabled population, mainly due to secondary complications. Lower survival rates were observed in non-traumatic SCI compared with traumatic SCI.