Enlarged high frequency oscillations of the median nerve somatosensory evoked potential and survival in amyotrophic lateral sclerosis

ObjectiveA large N20 and P25 of the median nerve somatosensory evoked potential (SEP) predicts short survival in amyotrophic lateral sclerosis (ALS). We investigated whether high frequency oscillations (HFOs) over N20 are enlarged and associated with survival in ALS.MethodsA total of 145 patients with ALS and 57 healthy subjects were studied. We recorded the median nerve SEP and measured the onset-to-peak amplitude of N20 (N20o-p), and peak-to-peak amplitude between N20 and P25 (N20p-P25p). We obtained early and late HFO potentials by filtering SEP between 500 and 1 kHz, and measured the peak-to-peak amplitude. We followed up patients until endpoints (death or tracheostomy) and analyzed the relationship between SEP or HFO amplitudes and survival using a Cox analysis.ResultsPatients showed larger N20o-p, N20p-P25p, and early and late HFO amplitudes than the control values. N20p-P25p was associated with survival periods (p = 0.0004), while early and late HFO amplitudes showed no significant association with survival (p = 0.4307, and p = 0.6858, respectively).ConclusionsThe HFO amplitude in ALS is increased, but does not predict survival.SignificanceThe enlarged HFOs in ALS might be a compensatory phenomenon to the hyperexcitability of the sensory cortex pyramidal neurons.     

Gait and plantar sensation changes following massage and textured insole application in patients after anterior cruciate ligament reconstruction

BackgroundGait impairments following anterior cruciate ligament reconstruction (ACLR) may contribute to reinjury or future osteoarthritis development. Recently, plantar cutaneous sensation deficits have been reported post-ACLR. These sensory deficits may influence gait and represent a mechanism through which to improve gait.Research questionCan established sensory interventions change sensation and gait in patients after ACLR and compared to healthy adults?MethodsTwenty-two adults (n = 11 post-ACLR, age:20.5 ± 1.9years, body mass index[BMI]:24.5 ± 3.6 kg/m²; n = 11 healthy, age:20.7 ± 1.4years, BMI:23.3 ± 2.7 kg/m²) completed two sessions separated by 48 h. Gait and plantar cutaneous sensation were assessed pre- and post-intervention (massage or textured insoles). Gait analysis was completed using 3D motion capture at 1.4 m/s ± 5% and standard inverse dynamics analysis. Plantar cutaneous sensation was assessed using Semmes Weinstein Monofilaments with a 4−2-1 stepping algorithm at the plantar aspect of the first metatarsal head, base of the fifth metatarsal, and lateral and medial malleoli. Plantar massage was a 5-minute massage to both feet. Textured insoles (coarse grit sandpaper) were worn while walking. Biomechanical data were assessed via mixed-models, repeated measures ANOVAs and 90 % confidence intervals. Wilcoxon Signed Rank tests and Mann-Whitney U tests evaluated plantar cutaneous sensation within and between groups, respectively.ResultsKnee adduction moment was lower in the ACLR versus the contralateral limb pre-massage. The vGRF was lower during the first half of stance but greater during the second half of stance in the ACLR versus the control group post-massage. Massage improved ACLR limb sensation over the first metatarsal head (P = 0.042) and medial malleolus (P = 0.027). Textured insole application improved ACLR limb sensation over the first (P = 0.043) and fifth (P = 0.027) metatarsals and medial malleolus (P = 0.028).SignificancePlantar massage and textured insoles improved plantar cutaneous sensation in the ACLR limb. Neither intervention influenced gait. Improving plantar sensation may be beneficial for patients after ACLR; however, sensory interventions to improve gait are necessary.     

A modality-specific somatosensory evoked potential test protocol for clinical evaluation: A feasibility study

ObjectiveWe aimed to establish an objective neurophysiological test protocol that can be used to assess the somatosensory nervous system.MethodsIn order to assess most fiber subtypes of the somatosensory nervous system, repetitive stimuli of seven different modalities (touch, vibration, pinprick, cold, contact heat, laser, and warmth) were synchronized with the electroencephalogram (EEG) and applied on the cheek and dorsum of the hand and dorsum of the foot in 21 healthy subjects and three polyneuropathy (PNP) patients. Latencies and amplitudes of the modalities were assessed and compared. Patients received quantitative sensory testing (QST) as reference.ResultsWe found reproducible evoked potentials recordings for touch, vibration, pinprick, contact-heat, and laser stimuli. The recording of warm-evoked potentials was challenging in young healthy subjects and not applicable in patients. Latencies were shortest within Aβ-fiber-mediated signals and longest within C-fibers. The test protocol detected function loss within the Aβ-fiber and Aδ-fiber-range in PNP patients. This function loss corresponded with QST findings.ConclusionIn this pilot study, we developed a neurophysiological test protocol that can specifically assess most of the somatosensory modalities. Despite technical challenges, initial patient data appear promising regarding a possible future clinical application.SignificanceEstablished and custom-made stimulators were combined to assess different fiber subtypes of the somatosensory nervous system using modality-specific evoked potentials.     

(Re)organisation of the somatosensory system after early brain lesion: A lateralization index fMRI study

ObjectiveTo evaluate the relationship between neural (re)organization of the somatosensory cortex and impairment of sensory function (2-point discrimination [2PD]) in individuals with unilateral cerebral palsy.MethodsWe included 21 individuals with unilateral cerebral palsy. 2PD thresholds were evaluated on thumb pads, and activation of the somatosensory cortex was recorded by functional MRI (fMRI) during passive movements of the affected hand. A lateralization index (LI) was calculated for the primary sensory (S1) and secondary sensory (S2) cortices and the correlation between the LI and 2PD thresholds was analysed.ResultsWe found a significant negative correlation between the 2PD thresholds and the S2 LI (r = −0.5, one-tailed P-value = 0.01) and a trend towards a negative correlation with the S1 LI (r = −0.4, one-tailed P-value = 0.05).ConclusionHigh levels of activation in the contralesional hemisphere were associated with high levels of sensory impairment in individuals with unilateral cerebral palsy. The interhemispheric (re)organization of the somatosensory system may not effectively compensate for somatosensory impairment.     

Diagnostic sensitivity of electrophysiology and ultrasonography in ulnar neuropathies of different severity

ObjectiveTo assess the diagnostic performance of electrophysiology and nerve ultrasound in ulnar neuropathies of varying clinical severity in 135 consecutive patients.MethodsClinical severity of ulnar neuropathy was graded on a 4 point scale from very mild (symptoms only) to severe (marked atrophy of intrinsic hand muscles). Sensitivity and localization ability of electrophysiology and nerve ultrasound were assessed for each point of the scale.ResultsUltrasound had higher sensitivity than electrophysiology in clinically very mild (20% and 3% for ultrasound and electrophysiology, respectively) and mild (62% and 47% for ultrasound and electrophysiology, respectively) neuropathies, had greater localizing ability in axonal ulnar neuropathies, and identified nerve hypermobility.Ultrasound nerve cross-sectional area had strong positive correlation with both clinical and electrophysiological severity scores, but with significant overlap across the severity groups.ConclusionThe diagnostic work-up of ulnar neuropathies was improved by using both electrophysiology and ultrasound at all levels of clinical severity. Ultrasound increased the diagnostic yield in very mild and mild neuropathies, localized all the ulnar neuropathies with abnormal non-localizing electrophysiology and identified nerve hypermobility.SignificanceThis is the first detailed analysis of the diagnostic performance of electrophysiology and ultrasound in ulnar neuropathies of varying severity.     

8—2岁市区学龄儿童感觉统合失调与不良行为及家庭因素调查分析

目的：调查本市区小学儿童感觉统合失调现状与不良行为及家庭因素的关系。方法：用感觉统合诊断量表和自制儿童生长发育调查表对1775名学龄儿童进行心理行为问题调查。结果：感觉统合轻度失调23．4％，重度失调13．5％，男童失调发和率（42．86％）明显高于女童（31．36％）P＜0．0），前庭功能失衡发生率最高（21．30％）；统合失调组儿童不良行为发生率高达64．38％明显高于统合正常组（31．11％）P＜0．01，失调组不良行为各因子的发生率亦明显高于统合正常组P＜0．01；学习能力不足儿童与父母文化程度和不同职业有关P＜0．01。结论：儿童感觉纺合失调现状易成为成人心理障碍的潜在因素，应引起重视。     

How far do patients with sensory ataxia benefit from so-called “proprioceptive rehabilitation”?

A rehabilitation program including foot sensory stimulation, balance and gait training with limited vision was performed in 24 patients with clinically defined sensory ataxia. There were 15 patients with bilateral somatosensory loss related to chronic neuropathy and nine patients with unilateral loss-related to multiple sclerosis. After training, balance control assessed using the Berg Balance Test improved similarly in both groups, and Romberg's sign disappeared in some patients, suggesting an improvement in dynamic balance and in the proprioceptive contribution. Conversely, 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. These results show that ataxic patients can improve their balance with better results in dynamic conditions and that the relative contribution of proprioceptive and visual inputs may depend on the extent of somatosensory loss.     

Regulation of single potassium channels by serotonin in the cell bodies of the tail mechanosensory neurons ofAplysia californica

Sensory neurons in the pleural ganglion ofAplysia mediate the afferent portion of the tail withdrawal reflex. Previous work has shown that in these neurons and in the siphon sensory neurons ofAplysia, serotonin modulates a steady-state non-inactivating potassium current called the S current. Using the technique of patch clamping, we have examined the kinetics of single potassium channels and found that they share the properties of the S potassium channel of the siphon sensory neurons. This channel has an elementary slope conductance of73 ± 9.98pS(x±S.E.M.) and shows Goldman rectification. It is active at the resting potential and does not inactivate with maintained depolarization. Bath application of serotonin in a majority of experiments decreased the functional number of channels in the patch.     

兔坐骨神经挤压伤的MRI与SEP对比研究

目的:探讨磁共振成像和体感诱发电位以及两者结合在坐骨神经急性挤压伤中的诊断价值。方法:24只兔按钳夹力的不同随机分为A、B两组,左后肢为损伤侧,右后肢为对照侧,建立坐骨神经急性挤压伤模型,于伤后1、2、4、8周行MR扫描,同时行双侧体感诱发电位检查。结果:损伤侧24条神经,有23条MR显示异常,诊断正确率95.8%,假阴性率4.17%(1/24);24条损伤侧坐骨神经,有22条SEP显示异常,诊断正确率91.6%,假阴性率8.3%(2/24)。MRI与SEP对神经损伤的正确诊断率无统计学差异(P>0.05)。MRI与SEP结合起来,24条损伤神经均显示异常,诊断正确率100%。结论:MR与SEP检查可无创、准确地判断神经损伤,两者结合可明显提高神经损伤的正确诊断率,重复性好,可作为神经损伤的较好诊断手段。     

Responses of tonically discharging neurons in the monkey striatum to primary rewards delivered during different behavioral states

In the primate striatum, the tonically discharging neurons respond to conditioned stimuli associated with reward. We investigated whether these neurons respond to the reward itself and how changes in the behavioral context in which the reward is delivered might influence their responsiveness. A total of 286 neurons in the caudate nucleus and putamen were studied in two awake macaque monkeys while liquid reward was delivered in three behavioral situations: (1) an instrumental task, in which reward was delivered upon execution of a visually triggered arm movement; (2) a classically conditioned task, in which reward was delivered 1 s after a visual signal; (3) a free reward situation, in which reward was delivered at irregular time intervals outside of any conditioning task. The monkeys′ uncertainty about the time at which reward will be delivered was assessed by monitoring their mouth movements. A larger proportion of neurons responsive to reward was observed in the free reward situation (86%) than in the classically conditioned (57%) and instrumental tasks (37%). Among the neurons tested in all situations (n = 78), 24% responded to reward regardless of the situation and 65% in only one or two situations. Responses selective for one particular situation occurred exclusively in the free reward situation. When the reward was delivered immediately after the visual signal in the classically conditioned task, most of the neurons reduced or completely lost their responses to reward, and other neurons remained responsive. Conversely, neuronal responses invariably persisted when reward was delivered later than 1 s after the visual signal. This is the first report that tonic striatal neurons might display responses directly to primary rewards. The neuronal responses were strongly influenced by the behavioral context in which the animals received the reward. An important factor appears to be the timing of reward. These neurons might therefore contribute to a general aspect of behavioral reactivity of the subject to relevant stimuli. Received: 16 September 1996 / Accepted: 1 April 1997