Restless legs syndrome and post polio syndrome: a case-control study.

BACKGROUND AND PURPOSE: The aim was to investigate the prevalence of restless legs syndrome (RLS), fatigue and daytime sleepiness in a large cohort of patients affected by post polio syndrome (PPS) and their impact on patient health-related quality of life (HRQoL) compared with healthy subjects. METHODS: PPS patients were evaluated by means of the Stanford Sleepiness Scale and the Fatigue Severity Scale (FSS). The Short Form Health Survey (SF-36) questionnaire was utilized to assess HRQoL in PPS. RLS was diagnosed when standard criteria were met. Age and sex matched healthy controls were recruited amongst spouses or friends of PPS subjects. RESULTS: A total of 66 PPS patients and 80 healthy controls were enrolled in the study. A significantly higher prevalence of RLS (P < 0.0005; odds ratio 21.5; 95% confidence interval 8.17-57) was found in PPS patients (PPS/RLS+ 63.6%) than in healthy controls (7.5%). The FSS score was higher in PPS/RLS+ than in PPS/RLS- patients (P = 0.03). A significant decrease of SF-36 scores, including the physical function (P = 0.001), physical role (P = 0.0001) and bodily pain (P = 0.03) domains, was found in PPS/RLS+ versus PPS/RLS- patients. Finally, it was found that PPS/RLS+ showed a significant correlation between International Restless Legs Scale score and FSS (P < 0.0001), as well as between International Restless Legs Scale score and most of the SF-36 items (physical role P = 0.0018, general health P = 0.0009, vitality P = 0.0022, social functioning P = 0.002, role emotional P = 0.0019, and mental health P = 0.0003). CONCLUSION: Our findings demonstrate a high prevalence of RLS in PPS, and that RLS occurrence may significantly influence the HRQoL and fatigue of PPS patients. A hypothetical link between neuroanatomical and inflammatory mechanisms in RLS and PPS is suggested.

Upper motor neuron involvement in X-linked recessive bulbospinal muscular atrophy.

OBJECTIVE: Clinicopathological findings of X-linked recessive bulbospinal muscular atrophy (SBMA) are indicative of lower motor neuron and primary sensory neuron involvement. The aim of our study was to investigate the presence of subclinical upper motor neuron (UMN) dysfunction in this disease. METHODS: Two siblings with clinical presentation, routine electrophysiological tests, histopathological features of muscle and nerve biopsies and genetic testing consistent with diagnosis of SBMA underwent transcranial magnetic stimulation (TMS). The analysed parameters were motor evoked potential (MEP) threshold, silent period (SP) and central motor conduction time. Intracortical inhibition with paired pulses from 1 to 6ms interstimulus intervals (ISIs) was evaluated in the older brother. RESULTS: MEP parameters were significantly altered in limb and cranial muscles and MEP suppression after paired stimulation significantly reduced in the older brother. MEP abnormalities were present in one lower limb, but SP abolished in all limbs, in the younger brother. CONCLUSIONS: Subclinical involvement of UMNs may be present in patients affected by SBMA. This finding suggests that the array of neuronal systems whose function may be affected by the pathogenic process of SBMA is larger than it was considered so far. SIGNIFICANCE: TMS is a sensitive diagnostic tool for the identification of UMN dysfunction and should be included in the diagnostic evaluation of patients with SBMA.

The role of botulinum toxin in the neuro-rehabilitation of young patients with brachial plexus birth palsy.

PURPOSE: To favour the active movements of the shoulder abductor/external rotator, elbow extensor and supinator muscles, through the partial inhibition of the uninvolved antagonistic muscles, in the Brachial Plexus birth Palsy (BPP). METHODS: The type A Botulinum Neuro Toxin (BNT-Dysport, Ipsen) was injected in 50 outpatients (mean age: 4.7 +/- 3.4 years) with BPP according to the criteria: early and current neuro-rehabilitation (Reflex Locomotion-RL), age <14 years, no cognitive impairment. Repeat injections (1.9 +/- 0.8) were performed in 30 patients. RESULTS: The range of active movements increased at the maximal benefit phase, compared to the baseline values (p < 0.05-0.01). The gain of shoulder's abduction was directly related to the youngest age (r = 0.6). An expanded compliance of the injected muscles and a faster response to the RL, in respect to that experienced in the pre-BNT sessions, was detected. The Global Clinical Rating Scale disclosed the temporal profile of the clinical outcome, with step-like increases of the function in 70% of the patients, and a 'plateau' trait in the remaining ones (+29.8 +/- 10.5%). The video-taped recordings showed an improvement in the global movements. CONCLUSIONS: The employment of BNT in the management of young patients with BPP has beneficial effects in the integration of the bodily scheme.

Pharmacologic reversal of cortical hyperexcitability in patients with ALS.

OBJECTIVE: To reverse the profile of abnormal intracortical excitability in patients with ALS by administering drugs that promote GABAergic transmission. BACKGROUND: Transcranial magnetic stimulation (TMS) has revealed abnormalities of cortical inhibition in ALS, a reduction of the silent period, and the absence of intracortical inhibition normally occurring in response to paired TMS. Impaired inhibitory transmission could play a role in the physiopathology of this illness. METHODS: Using paired TMS with conditioning stimuli from 1-to-6-msec-interstimulus intervals, we investigated 16 patients with ALS. The protocol included: (1) the "drug-free" profile of paired TMS; (2) paired TMS 30 minutes after the intake of diazepam (3.5 mg); (3) paired TMS after 3 weeks' treatment with gabapentin (GBP) (600 mg/day) or riluzole (50 mg/twice a day). RESULTS: Intracortical inhibition is lost in patients with ALS, and this abnormal profile is reversed by diazepam or sustained treatment with GBP. We also noted that motor-evoked potential amplitudes to single stimuli increased (p<0.01) after diazepam and GBP. CONCLUSIONS: The demonstration of pharmacologic reversal of hyperexcitability in patients with ALS makes a potentially significant contribution toward understanding the pathophysiology of a disease that has so far eluded an effective cure.

The effect of riluzole in amyotrophic lateral sclerosis: a study with cortical stimulation.

A population of 31 patients with sporadic amyotrophic lateral sclerosis (ALS) was selected for a prospective open study based on treatment with riluzole. A neurophysiological evaluation was performed by means of single and paired transcranial magnetic stimulation (TMS). The examined parameters, excitability threshold, motor evoked potential (MEP) duration, silent period (SP) duration and time course of intracortical inhibition to paired TMS after 6 months treatment, were matched against those recorded from the patients themselves before the beginning of treatment and from 20 (single TMS) or 10 (paired TMS) age-matched control subjects. Normal behaviour of the SP in response to increasing TMS was found in the treated patients; they showed a significant linear correlation between these two parameters (r=0.96) comparable to that calculated for controls (r=0.98), and significantly different with respect to drug-free patients (r=0.8, P=0.014). A significant reduced size of the 'conditioned' MEPs to paired stimulation was documented in the treated patients compared with the untreated patients (P=0.002). Our neurophysiological contribution to the assessment of the effect of riluzole on the motor cortical inhibitory property in ALS may be considered a setting for controlled trials in extended patient series, even in a pre-clinical phase.

The effect of benzodiazepines and flumazenil on motor cortical excitability in the human brain.

In the present study, the effects of benzodiazepines (diazepam) were evaluated in terms of cortical excitability changes, as tested with transcranial magnetic simulation (TMS). In particular, analyzed were drug-induced changes regarding two selected parameters of TMS: (1) the cortical excitability threshold and (2) the silent period duration (SP). For this purpose, we evaluated the effects of long-term therapy with diazepam in the patients affected by anxiety disorders and the changes induced by single oral doses of diazepam in both healthy controls and patients. In addition, we tested cortical excitability changes in two 'extreme conditions' where a considerable concentration of serum benzodiazepine-like activity was reached, as represented by diazepam overdose and idiopathic recurrent stupor (IRS). In both groups of patients, a significant increment of motor threshold was found, while in the overdose patients, the SP was also increased. The administration of flumazenil in these two conditions was followed by a prompt reversal effect, consisting of a return to normal cortical excitability parameters. The long-term usage of diazepam in patients with anxiety disorders is associated with significantly increased threshold; the increased value of these parameters was temporarily further enhanced by the administration of a single oral dose of diazepam, which, in normal control subjects, is not associated with changes of cortical excitability. The results of this study reveal that different physio-pathological conditions induced by the influence of benzodiazepine and its antagonist are reflected in excitability changes which attest to the involvement and modification of cortical GABAergic activity.

Towards a neurophysiological marker of amyotrophic lateral sclerosis as revealed by changes in cortical excitability.

Motor evoked potentials (MEPs) to magnetic trans cranial stimulation (TCS) were recorded in 47 patients with amyotrophic lateral sclerosis (ALS) in order to evaluate both excitability and conductivity changes relating to central motor pathways. The results were compared with those obtained from a control population of 43 subjects, 34 patients with definite multiple sclerosis (MS) and 15 patients with a rigid early from of Parkinson's disease (PD). The excitability threshold to TCS was higher in ALS patients for both upper and lower limbs compared with both controls and PD patients, but lower than that of MS patients. The Silent Period duration (SP (hand recordings): 80.1 ms, SD: 38.5) was significantly shorter in ALS patients than in all the other examined subjects (P < 0.001), nor did it increase proportionally to TCS intensity as with control subjects. The abnormal behavior of the SP appears to be specifically linked to the ALS disease, since it was neither observed in PD patients, nor in those with multiple sclerosis, who, on the contrary, displayed a prolonged mean duration of the SP (161.6 ms, SD 77 vs. 115.7 ms, SD 62 for the control group). Due to the neuronal loss of the largest neurons in ALS, MEP latency, amplitude, duration and the motor central conduction time (CCT) were in different proportion found abnormal. Our study shows how different neurological diseases with central motor involvement share broadly similar MEP abnormalities, but a different involvement of the silent period. We suggest that in ALS patients there may be abnormalities of motor cortical inhibitory mechanisms which are detected with the measurement of the SP. The distinctive 'depression' of this parameter in the case of ALS could be a significant marker for diagnosing this disease.

Distinguishing forms of generalized epilepsy using magnetic brain stimulation.

In this study, we have used paired transcranial stimulation of the motor cortex to test the hypothesis that cortical inhibition is decreased in juvenile myoclonic epilepsy (JME). The double shock technique was adopted here because it offers a means for highlighting abnormal inhibitory mechanisms. From previous experiments performed on healthy subjects, it is known that a magnetic conditioning stimulus, of subthreshold intensity, suppresses the MEP in response to a subsequent suprathreshold stimulus delivered after 1-4 msec. JME patients were selected as a potential contrast with other forms of idiopathic generalized epilepsy, because they complain of myoclonic jerks without loss of consciousness, indicating with certainty a dysfunction of the motor cortex. Two patients with sporadic grand mal and one non-epileptic patient were also investigated. Paired stimulation was produced by a Bi-stim (Magstim) stimulator, with a figure-of-8 coil placed over the hand area of the motor cortex, and a set of interstimulus intervals (ISIs) ranging from 1 to 6 msec was analyzed. In JME patients there were two indications of abnormality with respect to normal subjects and to the other epileptic patients: (1) the absence of MEP suppression to paired stimulation; (2) a progressive amplitude increase of MEPs to the test stimulus alone. In the two patients with the other form of epilepsy the pattern of inhibition was broadly preserved, even though there was some difference from the normal profile. The results suggest that the loss of MEP inhibition can be regarded as a marker of JME.

Magnetic transcranial stimulation in healthy humans: influence on the behavior of upper limb motor units.

Aim of the study was to analyze the characteristics of motor action potentials recruitment during magnetic trans-cranial stimulation (TCS) of the brain. Coaxial needle recordings from hand and upper limb musculature, as well as surface electrodes were employed in 20 healthy controls during magnetic TCS with regular and figure-of-8 coil in different experimental protocols including: (a) simple reaction time paradigm during which TCS at subthreshold intensity for eliciting MEPs in relaxation was delivered at various intervals between the signal to move and the onset of the voluntary EMG burst; (b) suprathreshold TCS was randomly delivered while the subject was voluntarily firing at a regular rate one 'low' and/or 'high threshold' motor unit action potential (MUAP). The pre- and post-TCS MUAPs recruitment as well as their firing rates were compared; (c) recordings with two separate needles picking up individual MUAPs from the same or from two different muscles were obtained in order to test 'synchrony' of MUAP's discharge before and after TCS; (d) the influence of the time-interval separating the last discharged MUAP from TCS was evaluated. (e) differences between simultaneous surface and depth recordings were examined. The following results were obtained. (a) The same low-amplitude MUAP which is first voluntarily recruited at the onset of the EMG burst is the one initially fired by TCS in the pre-movement period. Latency shortenings and amplitude enlargement of surface MEPs were observed with faster reaction times. Such changes were coupled to the recruitment of high-threshold MUAPs being larger in amplitude and briefer in latency than the initial one. (b) When using suprathreshold TCS, MEPs followed by silent periods were found. The SP was followed by a rebound acceleration of the MUAPs firing rate compared with pre-TCS levels. Besides rebound acceleration, new MUAPs of larger amplitude than the original (= pre-stimulus) ones were recruited beyond the voluntary control. This phenomenon-together with longer SPs- was progressively more pronounced with stronger stimuli. (c) TCS was affecting the 'synchrony' of MUAPs. (d) If the latency difference between the last pre-stimulus spike and the TCS was exceeding the half-cycle of the MUAP 'natural' firing, the SP was longer in duration. (e) SPs not preceded by MEPs were clearly present in depth recordings. Surface recordings mainly reflected the behavior of high-threshold and large MUAPs.

Latency jump of "relaxed" versus "contracted" motor evoked potentials as a marker of cortico-spinal maturation.

Magnetic brain stimulation was carried out in 17 children, aged from 2 to 12 years, in order to investigate the latency difference between relaxed and contracted motor evoked potentials (MEPs) as a function of age. While the latency of contracted MEPs increased in a linear fashion with age and body size, the relaxed MEP latency had a much slower "maturation," which gained the adult value at about 10-12 years of age in parallel with the acquisition of manual skills. The age-related variation of this "latency jump" appears to be a specific indicator of maturative phenomena relating to motor systems.

Age-related changes of motor evoked potentials in healthy humans: non-invasive evaluation of central and peripheral motor tracts excitability and conductivity.

A comparative analysis of the corticospinal tract nervous propagation and excitability threshold was carried out in young (25 subjects, age range 16-35 years) and in elderly (40 subjects, 51-86 years) populations of healthy volunteers. Motor evoked potentials (MEPs) were recorded from the hand and foot muscles following transcranial magnetic stimulation (TCS) during complete relaxation and active contraction of the target muscles. Threshold intensities corresponded to the stimulator's output eliciting liminal MEPs in about 50% of stimuli during relaxation. It was found that threshold values of magnetic TCS were significantly higher in the elderly (44 +/- 6.4% vs 39 +/- 3.5% for the hand; 66 +/- 10.1% vs 56 +/- 6.7% for the foot; P < 0.001) than in the young subjects. Moreover, this index progressively increased with age (P < 0.001), whilst the propagation time along the central motor tracts did not parallel such an age-related trend.

Brain excitability and electroencephalographic activation: non-invasive evaluation in healthy humans via transcranial magnetic stimulation.

Excitability changes of the central motor tracts as a function of the electroencephalographic (EEG) characteristics has been investigated in 10 healthy volunteers. Transcranial magnetic stimulation (TCS) was administered to the right motor cortex with an intensity 5-10% above threshold for the elicitation of motor evoked potentials (MEPs) in the left forearm muscles. Simultaneously, the right median nerve was stimulated to provoke an H-reflex in the forearm flexors and EEG activity was recorded from the left hemiscalp. Subjects were completely relaxed and were asked at random either to keep the eyes closed while maintaining mental inactivity (A) or to open their eyes and perform mental arithmetics (B). Latencies and amplitudes of MEPs and H-reflexes were statistically matched with the spectral content of the EEG. In condition A, MEPs of 119 +/- 61 microV, with up to 36% of missing responses and background EEG activity dominated by rhythms in the alpha range were found. In condition B, MEPs of 219 +/- 66 microV (P less than 0.001), with less than 16% of missing responses, 'blocking' of the background alpha rhythms, and a potentiation of the faster ones' relative power were observed. Changes of the H-reflex characteristics were neither statistically significant nor related to MEP amplitude and EEG spectral profile fluctuations.