Concurrent changes in shortening reaction latency and reaction time of forearm muscles in post-stroke patients.

The objective was to confirm the hypothesis that shortening reaction (ShoRe), normally occurring on forcibly shortening a muscle, is depressed or delayed in post-stroke patients. Eight post-stroke patients and ten age-matched normal subjects had a 50 degrees wrist extension or flexion induced by a torque-motor in the affected and the non-affected upper limb. Patients were instructed either not to intervene or to assist displacement (reaction-time condition, RT). Frequency of occurrence and latency of stretch reflex (SR) and ShoRe, and RTs were measured from the electromyograms (EMG) of wrist flexor (FCR) and extensor (ECR) muscles. SR had higher than normal frequency in both muscles. ShoRe disappeared in ECR on the affected side but had normal frequency in FCR of both sides. ShoRe latency was prolonged in FCR and ECR, in both affected and unaffected sides. RTs were prolonged in both FCR and ECR, in both affected and unaffected sides. Across all patients, RTs and ShoRe latencies in the FCR were correlated. Neither RTs nor ShoRe latencies were correlated to Ashworth score. RTs were inversely correlated to Medical Research Council scores. The decreased and delayed ShoRe in post-stroke patients supports a role for the cortico-spinal pathway in its production or modulation. Monitoring of ShoRe can give insight into the recovery of the descending control of spinal reflexes.

Depression is the main determinant of quality of life in multiple sclerosis: a classification-regression (CART) study.

PURPOSE: Quality of life in multiple sclerosis has been often measured through the SF-36 questionnaire. In this study, validation of the SF-36 summary scores, its 'physical' component, and its 'mental' component was attempted by exploring the joint predictive power of disability (EDSS score), of anxiety and depression (HADS-A and -D scores, respectively), and of disease duration, progression type, age, gender and marital status. METHOD: The sample consisted of 75 patients suffering from multiple sclerosis admitted to an inpatient rehabilitation unit. The interplay between potential predictors was assessed through a particular regression model (classification and regression tree, CART). Two main advantages of this technique are its robustness with respect to distributional assumptions (rarely met by scores coming in from questionnaires) and its sensitivity to high-order interactions, between independent variables, difficult to detect through conventional multiple regression. RESULTS: Predictive variables for physical component of the SF-36 were EDSS and HADS-D (36.8% variance explanation). The only predictive variable for mental component of SF-36 was HADS-D (39.1% variance explanation). CONCLUSION: Results confirm previous findings showing that in patients with multiple sclerosis quality of life is heavily determined by person's mood, whatever his/her neurological or functional severity. The usefulness and validity of the SF-36 as an index representative of quality of life is debatable, as long as depression explains much of its variance. Further refinement of quality of life definition and measurement is worth further psychometric and statistical research.

How does stroke restrict participation in long-term post-stroke survivors?

OBJECTIVE: To explore the factors determining 'restricted participation' in a selected population of long-term post-stroke survivors. MATERIALS AND METHODS: Seventy-three consecutive post-stroke inpatients were scored for mood and restriction in participation by means of self-administered questionnaires, respectively the Hospital Anxiety and Depression Scale (HADS/A; HADS/D) and London Handicap Scale (LHS). Neurological impairment and functional disability were evaluated with the Unified Neurological Stroke Scale (UNSS) and Functional Independence Measure (FIM). RESULTS: Physical independence and occupation were the most severely affected domains on the LHS. UNSS, FIM, HADS/A, HADS/D scores were significant determinants of restriction in participation at univariate analysis performed with each LHS domain. FIM score and emotional status finally emerged as the independent determinants of restricted participation for the LHS domains most related to body function (mobility, physical independence, occupation). Depression was the determinant factor for orientation and social integration. CONCLUSION: Functional disability and mood disorders may independently contribute to the restricted participation of post-stroke patients. Most of the LHS domains remain stable over time.

Are the neurophysiological techniques useful for the diagnosis of diaphragmatic impairment in multiple sclerosis (MS)?

OBJECTIVE: To characterize cortico-diaphragmatic pathway involvement in multiple sclerosis (MS) by means of transcranial magnetic stimulation (TMS), and verify its clinical impact. METHODS: TMS from diaphragm (Dia), and abductor digiti minimi (AbdV degrees ) was performed in 26 MS patients. Phrenic nerve (PN) conduction study was also performed. Expanded disability status scale (EDSS) and fatigue descriptive scale (FDS) were measured. Forced vital capacity (FVC), forced expiratory volume at the first second (FEV1), peak expiratory flow (PEF) were tested: the predicted percentage value (% pred) was considered. RESULTS: Cortical motor evoked potential (Cx-MEP) latency and central motor conduction time (CMCT) were prolonged, respectively, in 31 and 23% of patients from Dia, in 76 and 79% from AbdV degrees. PN-compound motor action potential (CMAP) was normal. EDSS correlated to Cx-MEP from AbdV degrees (P<0.01), and PN-CMAP amplitude (P<0.05), FEV1 % pred (P<0.01), PEF % pred (P<0.01). PN-CMAP amplitude correlated to FVC % pred P=0.05, FEV1 % pred P<0.01, PEF % pred P<0.01. Fatigue was related to AbdV degrees Cx-MEP and CMCT (P<0.05 and P<0.01). CONCLUSIONS: Cortico-diaphragmatic pathway is impaired only in a minority of MS patients. Lack of correlation between TMS findings from Dia and respiratory tests argues against its routinary use to detect subclinical respiratory alterations. Fatigue seems to be related to the motor impairment rather than to respiratory distress.

The shortening reaction of forearm muscles: the influence of central set.

OBJECTIVE: The EMG of the forearm muscles shortened by an imposed wrist joint displacement has been studied at different levels and distribution of background muscle activity and with different instructions to the subjects, in order to test the hypothesis that the recorded EMG response (shortening reaction, ShoRe) could be deliberate in origin. METHODS: Ten normal subjects were examined. A torque motor induced 50 degrees wrist extension or flexion at 500 degrees /s. The subjects were relaxed or exerted a 10% maximal voluntary contraction. They were instructed either not to intervene, or to oppose the displacement, or else to assist it. Several trials were repeated at different initial angles. RESULTS: We found a short-latency reflex (SR) in the stretched muscle, be it flexor or extensor, and a later inconstant ShoRe in the antagonist. ShoRe latency was compatible with that of a reaction time (RT), and was not influenced by the initial wrist angle. When subjects assisted the movement, the EMG burst in the shortening muscle was in every respect a RT; when they opposed the movement, the ShoRe disappeared. There was a strict temporal relationship between SR duration and ShoRe latency. CONCLUSIONS: We suggest that the brain would deliberately trigger the ShoRe on recognizing the displacement direction. The occurrence of such activity in the shortened muscle makes the SR to abruptly stop. The temporal relationship between the duration of the SR and onset of the ShoRe can be an expression of the inhibition on the SR burst by the cortical drive to the antagonist muscle being shortened, possibly through the action of spinal inhibitory interneurones. The ShoRe would complete the movement momentarily braked by the SR and redistribute the muscle tone across antagonists, appropriate for the new muscle length.

Loss of large-diameter spindle afferent fibres is not detrimental to the control of body sway during upright stance: evidence from neuropathy.

Fifteen patients with Charcot-Marie-Tooth type 1A (CMT1A) disease and 46 normal controls were studied. In the patients, leg muscle strength, touch-pressure, vibration and joint position sense were reduced; lower limb tendon reflexes were absent in 12 or markedly decreased. Motor and sensory conduction velocity (CV) of leg nerves was either reduced or not measurable. The Neurological Disability Score and the Neuropathy Score were obtained from clinical and electrophysiological examination, respectively. Tilt of a supporting platform elicited short- (SLR) and medium-latency (MLR) responses to stretch in the foot muscle flexor digitorum brevis (FDB) in controls. In the patients, the former response was absent and the latter delayed. These findings are in keeping with the known loss of large-diameter myelinated fibres, with relative sparing of the smaller fibres. The MLR delay was fully accounted for by the slowed CV of the motor fibres. The MLR afferent time was similar to that in normal subjects. Body sway area (SA) during quiet stance was recorded with eyes open or closed, and with feet apart or together. Under all postural and visual conditions, SA was within normal range in the less severely affected patients, but was moderately increased in the patients with a more severe neuropathy score. Across all patients, no correlation was found between SA and muscle force, motor CV, touch pressure, vibration and joint position sense, considered either separately or as an aggregate. We suggest that: (1) functional integrity of the largest afferent fibres is not necessary for appropriate equilibrium control during quiet stance and (2) any unsteadiness is related to additional functional alterations in smaller fibres, most likely group II spindle afferent fibres.

A PC-1 amino acid variant (K121Q) is associated with faster progression of renal disease in patients with type 1 diabetes and albuminuria.

Insulin resistance characterizes type 1 diabetes in patients with albuminuria. A PC-1 glycoprotein amino acid variant, K121Q, is associated with insulin resistance. We examined the impact of the PC-1 K121Q variant on the rate of decline of the glomerular filtration rate (GFR) by creatinine clearance derived from the Cockroft-Gault formula in 77 type 1 diabetic patients with albuminuria who were followed for an average of 6.5 years (range 2.5-15). Patients carrying the Q allele (n = 22; 20 with KQ and 2 with QQ genotypes) had a faster GFR decline than those patients with the KK genotype (n = 55) (median 7.2 vs. 3.7 ml x min(-1) x year(-1); range 0.16 to 16.6 vs. -3.8 to 16.0 ml x min(-1) x year(-1); P < 0.001). Significantly more patients carrying the Q allele belonged to the highest tertile of GFR decline (odds ratio = 5.7, 95% CI 4.1-7.2, P = 0.02). Levels of blood pressure, HbA1c, and albuminuria were comparable in the two genotype groups. Albuminuria (P = 0.001), mean blood pressure (P = 0.046), and PC-1 genotype (P = 0.036) independently correlated with GFR decline. Because all patients were receiving antihypertensive treatment, the faster GFR decline in the patients carrying the Q allele could be the result of reduced sensitivity to the renoprotective effect of antihypertensive therapy. PC-1 genotyping identifies type 1 diabetic patients with a faster progression of diabetic nephropathy.

Quantitative measures of spasticity in post-stroke patients.

OBJECTIVE: Quantitative evaluation of muscle tone in post-stroke patients; correlation of biomechanical indices with conventional clinical scales and neurophysiological measures; characterization of passive and neural components of muscle tone. METHODS: Mechanical stretches of the wrist flexor muscles of 53 post-stroke patients were imposed by means of a torque motor at constant speed. Patients were clinically studied using the Ashworth scale for spasticity and the Medical Research Council score for residual muscle strength. The neurophysiological measures were Hoffmann reflex latency, Hmax/Mmax ratio, stretch reflex threshold speed (SRTS), stretch reflex (SR) latency and area, passive (ISI) and total (TSI) stiffness indices. RESULTS: Hmax/Mmax ratio, SR area, ISI and TSI values were significantly higher in patients, while SRTS was significantly lower. TSI, SRTS and SR area were highly correlated to the Ashworth score. CONCLUSIONS: This EMG-biomechanical technique allows an objective evaluation of changes in muscle tone in post-stroke patients, providing easily measurable, quantitative indices of muscle stiffness. The linear distribution of these measures is particularly indicated for monitoring changes induced by treatment. The apparatus seems suitable to characterize neural stiffness, while difficulties were found in isolating the passive components, because of the occurrence of tonic EMG activity in most spastic patients.

Motor neuron disease: usefulness of transcranial magnetic stimulation in improving the diagnosis.

Clinical upper motor neuron (UMN) involvement is sometimes difficult to detect in motor neuron disease (MND). For this reason we performed transcranial magnetic stimulation (TMS) to find out whether this technique may be useful in revealing signs of pyramidal tract impairment. Fifty-five MND patients, clinically divided into 22 amyotrophic lateral sclerosis (ALS), 18 ALS with probable UMN signs (ALS-PUMNS), 10 pure lower motor neuron syndrome (LMNS), and 5 progressive bulbar palsy (PBP), underwent standard TMS, recording from abductor digiti minimi and flexor allucis muscles. Prolongation of cortical motor evoked potential (MEP) latency and central conduction time (CCT) and absent MEP were considered as pathologic. ALS-PUMNS and LMNS patients were clinically reclassified after 1 year. TMS was abnormal in 95.4% of ALS, 72.2% of ALS-PUMNS, 50% of LMNS and 20% of PBP. Correlations between TMS parameters and both clinical signs of UMN involvement and disease severity were highly significant. TMS showed a high sensitivity, but lacked specificity. After 1 year, 11 patients among the ALS-PUMNS group were clinically reclassified as definite ALS: all of them had shown TMS abnormalities at the first examination. In conclusion, TMS provides important diagnostic information for an early prediction of ALS in those MND patients presenting with clinically equivocal UMN impairment.

Somatosensory and motor evoked potentials at different stages of recovery from severe traumatic brain injury.

OBJECTIVE: To detect changes of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) at different stages of recovery from severe brain injury and to determine whether they can be used to predict late functional outcome. DESIGN: Correlational study on a prospective cohort. SETTING: Brain injury rehabilitation center. PATIENTS: Twenty-seven consecutively sampled patients with severe traumatic brain injury referred to the inpatient intensive rehabilitation unit of primary care in a university-based system. MAIN OUTCOME MEASURES: (1) Glasgow Outcome Scale, Disability Rating Scale, and Functional Independence Measure; (2) SEPs and MEPs from upper limbs (ULs) and lower limbs (LLs). Outcome was assessed at 6 and 12 months after trauma. Correlations were computed with the nonparametric test of Spearman-Rank. RESULTS: Both SEPs and MEPs showed dynamic changes (p < .02 for N20, p < .05 for N30, P40, and N45), with a trend toward a progressive normalization. N30 was more frequently abnormal than N20. SEPs from LLs were more frequently and more persistently abnormal than those from ULs. Clinical and functional outcome was strongly correlated with the degree of abnormality of SEPs from LLs (p < .002), whereas only mild relationships were found with SEPs from ULs. Both SEPs and MEPs showed a high negative predictive value (83% for N30 and 83% for P40), but only SEPs from LLs also had a high positive predictive value (72% for P40). Sensitivity was 88% both for N30 and P40. Specificity was 50% for N30 and 70% for P40). CONCLUSION: SEPs from LLs can be very useful in monitoring the postacute phase of traumatic brain injury and in identifying patients who require further intensive rehabilitation. MEPs may be of questionable value.

Sympathetic skin response in amyotrophic lateral sclerosis.

OBJECTIVES: The aim of our study was to verify the usefulness of the sympathetic skin response (SSR) as an instrument for assessing autonomic involvement in amyotrophic lateral sclerosis (ALS). MATERIAL AND METHODS: - We studied palmar and plantar SSR in 31 patients with ALS (mean age: 58.4+/-9.3 years); 48 age-matched healthy subjects constituted the control group. RESULTS: Palmar SSR was elicitable in all patients, and its latency and amplitude did not significantly differ from that of the controls. Plantar response was evoked in all but 7 patients. The lack of response was significantly related to the functional disability and duration of the disease. CONCLUSIONS: We conclude that SSR, even the plantar response, cannot be considered a useful tool for detecting early autonomic involvement in ALS.

[Processes of speech production: Analysis of the methods and applications in a group of normal subjects (I)]. / Studio dei Processi di Produzione della Parola: Metodi di Analisi ed Applicazione in un Gruppo di Soggetti Normali (Parte I).

The measurement of reaction times in response to suitable stimuli may provide insight into the separate functional blocks corresponding to diverse speech production mechanisms. The quantitative evaluation of speech motor performance provides useful information for the early detection and long-term monitoring of many neurological diseases. The vocal reaction times (VRTs) technique and its application in the assessment of a group of normal subjects is presented. Speech motor performance and the effect of age were investigated by measuring VRTs and speech duration, in a group of thirty normal subjects divided into three age groups (18-44, 45-59, 60-80). VRTs were measured by using an immediate and delayed reaction stimulation paradigm. Analysis of the acoustic and electromyographic signals indicated that reaction times increased with age in both the immediate and delayed tasks; also the acoustic signal durations increased with age. The analysis of variance showed that the difference between the young and elderly groups was statistically significant. This technique may be considered a useful tool to provide qualitative and quantitative measures of the processes involved in speech production.

Quantitative evaluation of normal muscle tone.

Forty-eight normal subjects were evaluated for the purpose of objectively quantifying muscle tone. Flexor carpi radialis and extensor digitorum communis electromyographic (EMG) activity was simultaneously recorded during wrist movements imposed by a torque motor. Each session was subdivided into three steps: (1) measurement of the 'intrinsic stiffness index' (ISI) at 10 degrees/s; (2) measurement of the 'total stiffness index' (TSI) at 500 degrees/s; (3) evaluation of the stretch reflex threshold speed (SRTS). No stretch reflex (SR) was found in about half of the subjects, even at the highest speed. ISI was higher in males (p < 0.001); significant differences in TSI were found between subjects with SR and those without (p < 0.02); no statistical differences in SRTS were found for either age or gender. ISI, TSI and SRTS, appear to be reliable indices of the range of normal muscle tone for its quantitative assessment.

[Effect of motor neuron density on the curve of motor neuron impoverishment in amyotrophic lateral sclerosis]. / L'effetto densità dei motoneuroni sulla curva di depauperamento motoneuronale nella sclerosi laterale amiotrofica.

We have clinically and electromyographically examined, during a follow-up study, weakened muscles and still clinically normal muscles of 9 patients affected by amyotrophic lateral sclerosis (ALS) and of 3 patients affected by focal benign amyotrophy (FBA). MRC scores corrected with positive semiquantitative evaluations of the number of giant motor unit (MU) action potentials and with negative evaluations of the number of fasciculations and fibrillations potentials have been found to linearly correlate with the percentage of the residual MUs calculated from the mean amplitude and the spike number during maximal voluntary contraction. A main finding is that the loss of MUs slows down in the last 10 months of the disease. It follows that after a phase when the pathological process was accelerated by the toxic effect due to the abnormally high concentration of glutamate released by dead motoneurons, the residual cells because of the decreased motoneuronal density are less exposed to the possible neurotoxic damage.

Decreased heart rate variability in amyotrophic lateral sclerosis.

Autoregressive spectral analysis of heart rate variability (HRV) was performed in 29 patients with amyotrophic lateral sclerosis (ALS) and 33 age-matched healthy subjects to evaluate the involvement of the autonomic nervous system. HRV analysis provides a means to recognize low (LF) and high (HF) frequency components, respectively mediated by sympathetic and parasympathetic heart control. An increase in the mean heart rate at rest (P < 0.001), a decrease in standard deviation of R-R interval as well as in PNN50 (P < 0.001), and an increase in the LF/HF component ratio (P < 0.01) were found in the ALS patients, indicating a vagal-sympathetic imbalance. These alterations were not related to the clinical features and to the duration of the disease. Our results suggest a subclinical involvement of the autonomic nervous system in ALS, particularly affecting parasympathetic cardiovascular control.

[Abdominal propriospinal myoclonus of unknown etiology]. / Myoclonies propriospinales abdominales d'étiologie inconnue.

We report the case of a 77-year-old woman with a two-year history of abdominal non rhythmic myoclonus. Neurological examination was normal. Bursts of myoclonic activity were recorded from the rectus abdominis muscle and then from the external oblique muscle after a delay of 40 ms. Magnetic resonance imaging of dorsal spine revealed T7-T8 and T9-T10 disc protrusions without root compression. Electroencephalography, back-averaging-EEG, brain computed tomography scan, motor and sensory evoked potentials revealed no abnormality, thus ruling out the possibility that the myoclonic jerks might be of cortical origin. Electromyography of the rectus abdominis and external oblique and of the T7-T8 paraspinal muscles did not show signs of denervation. Therefore a peripheral origin of the myoclonus could be excluded. In our patient the difference in latency of the EMG activity between the external oblique and the rectus abdominis muscles was possibly due to the caudal propagation of the myoclonus by slowly conducting pathways, supporting the hypothesis for its propriospinal origin, even though a known ethiologic factor could not be identified.

Multiparametric quantitative evaluation of the speech production system: a study in normal subjects.

This paper describes a systems architecture developed for the study of the speech production system. The architecture utilizes two personal computers: the "Word-Image Presenter" (WIP) that presents a sequence of words to the subject under examination as visual stimulation, and the "Signal Acquisition System" that controls the WIP, acquires the acoustic signal, the oromandibular electromyographic signals, the kinematic lip and jaw signals and measures reaction times and durations. Thirty normal subjects divided into three age groups (18-44, 45-59, 60-80) underwent examination by means of the described system. During the test a random sequence of two words was presented to the subjects; the protocol consisted of an immediate reading task and two delayed reading tasks with variable foreperiods of 0.1 and 1.5 s for one task and 0.5 and 4 s for the other. The analysis of the resultant acoustic and electromyographic signals indicated that reaction times increased with age in both the immediate and delayed tasks. The analysis of variance showed that the difference between the young and elderly groups was statistically significant. The sample size of the groups, however, is too small to consider these results normative data.