Modulation of cortical oscillatory activities induced by varying single-pulse transcranial magnetic stimulation intensity over the left primary motor area: a combined EEG and TMS study

Combined transcranial magnetic stimulation/electroencephalography (TMS/EEG) was used to study the activation and interaction of cortical regions to a variety of focused sub- and suprathreshold magnetic pulses over the left primary motor cortex (M1) in ten healthy subjects. Five single-pulse TMS conditions were performed based on the individual resting motor threshold (RMT): (1) 80%; (2) 100%; (3) 120%; (4) 130%; and (5) sham. Simple self-paced movements of the right first finger were also executed. We evaluated the reactions to magnetic stimulation and movement conditions using event-related power and event-related coherence transformations of alpha and beta rhythms. Event-related power reflected regional oscillatory activity of neural assemblies, while event-related coherence reflected the inter-regional functional coupling of oscillatory neural activity. The event-related power transformation revealed that the magnetic pulse modulated cortical oscillations within the first half second for both frequency ranges. For the alpha rhythm, threshold TMS induced a small decrease in the amplitude of EEG oscillations over the stimulation site, while for both rhythms, a progressive synchronization was observed as the intensity of TMS was increased in both hemispheres. Movement onset produced a greater bilateral decrease of power compared with the effects of a magnetic pulse. The event-related coherence revealed that TMS enhanced the electrode connectivity of both hemispheres. Additionally, it was more enhanced within the first 500 ms following stimulation and was seen only for the alpha frequency rhythm. The increase of functional connectivity between cortical areas was minor for magnetic stimulation conditions compared with that for finger movements. The single-pulse TMS over M1 partially modulated the motor cortex generators of oscillatory activity, while a simple active self-paced movement of the right first finger induced greater cortex activation and coupling between cortical regions. We propose that finger movements impose higher functional demands on the motor system compared to artificial magnetic stimulation. These findings are consistent with the possibility that the human motor system may be based on network-like oscillatory cortical activity and might be modulated by brief electromagnetic sub- and suprathreshold pulses applied to M1, suggesting a phenomenon of resetting.     

The effect of repetitive transcranial magnetic stimulation on motor performance, fatigue and quality of life in amyotrophic lateral sclerosis

BACKGROUND: The treatment of amyotrophic lateral sclerosis (ALS) is still disappointing. Repetitive transcranial magnetic stimulation (rTMS) has been suggested to modify the rate of disease progression in ALS. OBJECTIVE: In a pilot controlled study, we tested the effect of 5-Hz rTMS on motor performance, fatigue and quality of life (QoL) in ALS. METHODS: Ten ALS patients underwent a two-week period of daily active or sham 5-Hz rTMS. Outcome measures were assessed with functional, fatigue and QoL scales. Muscle strength was evaluated with the MRC scale and measured with isometric and isokinetic dynamometer. RESULTS: Significant difference at the end of rTMS treatment was found for QoL, maximum voluntary isometric contraction and isokinetic average power when comparing active vs sham treatment. These changes were transitory and outcome measures were not significant two weeks after discontinuation of rTMS. CONCLUSIONS: Though preliminary, our results suggest that 5-Hz rTMS may improve motor function and QoL in ALS. The present data indicate the need of a double-blind therapeutic trial of rTMS in ALS.     

Wake-up stroke and CT perfusion: effectiveness and safety of reperfusion therapy

Objective

Ischemic stroke is a neuroemergency condition highly treatable with thrombolysis and thrombectomy. Recently, observational studies have brought insights into clinical and imaging characteristics of wake-up stroke, which interested up to 25% of ischemic stroke patients. In clinical practice, wake-up strokes are usually not considered for reperfusion therapy. The aim of this study was to investigate the use CT perfusion imaging in patients with wake-up stroke and to assess the effect of neuroimaging information provided by CT perfusion maps on the efficacy and safety of thrombolysis and thrombectomy.

Patients and method

We studied 22 wake-up stroke (WUS) patients (13F/9M mean age) who underwent reperfusion therapy after the eligibility assessed by the CT perfusion imaging (<?50% core-to-penumbra ratio and negative CT perfusion).

Results

Mean National Institutes of Health Stroke Scale (NIHSS) was 8.1?±?4.9 at admission while 3.3?±?5.1 at discharge, significantly different from admission (p?<?0.001). As many as ten patients had mRS lower than 3 at discharge. Intracranial hemorrhage occurred in five patients and caused symptoms worsening only in two patients (decrease of NIHSS score of 4 points) of which one patient died.

Conclusion

The main finding of this study is that wake-up stroke with adequate selection by CT perfusion may benefit reperfusion treatment.

     

Pedobarometric evaluation of equinus foot disorder after injection of botulinum toxin A in children with cerebral palsy: a pilot study

The purpose of this pilot study was to evaluate the effect of treatment with botulinum toxin A (BTX-A) injections on function in children with cerebral palsy (CP) using pedobarometric data collected in a standing position. Ten children with CP (seven males, three females) participated, five with diplegia and five with hemiplegia. All children exhibited signs of unilateral dynamic equinus foot disorder and were community ambulators. Age range at the time of treatment was 6 to 13 years (mean age 9 y, SD 2.5). A comprehensive clinical examination and a pedobarometric evaluation were performed before and after BTX-A injection. All children received at least one injection in each spastic muscle. BTX-A was given to eight children unilaterally and to two children bilaterally. A maximum dose of 4 to 8 units of BTX-A per kilogram body weight was administered. In comparison with pretreatment values, the pedobarometric evaluation revealed a significant increase in the whole plantar surface area on the affected side (p < 0.05), an increase in the peak pressure value at the hindfoot on the affected side (p < 0.05), and a significant shift in the body centre of mass to the affected limb (p < 0.05) 1 month after treatment with BTX-A. A significant decrease in the peak pressure value at the hindfoot on the unaffected side was also observed. Similarly, a decrease in the modified Ashworth scale and an increase in the range of motion were observed. Thus, BTX-A produces a significant plantar surface modification and a significant shift of the body centre of mass which represents an indirect measure of postural attitude. Pedobarometric evaluation can also be useful in quantifying clinical changes after treatment with BTX-A.     

Motor responses to afferent stimulation in juvenile myoclonic epilepsy

PURPOSE: To document whether the mechanisms responsible for myoclonic jerks in juvenile myoclonic epilepsy (JME) are similar to those causing other forms of myoclonus. METHODS: We studied somatosensory evoked potentials, the conditioning effect of cutaneous afferents on motor potentials evoked by transcranial magnetic stimulation (TMS), and intracortical inhibition and facilitation in response to paired TMS in a group of nine patients with JME and 20 normal controls. RESULTS: Intracortical inhibition was abnormal, whereas cortical somatosensory evoked potentials and TMS conditioned by cutaneous afferents were unaltered in JME patients. CONCLUSIONS: Abnormal processing of cutaneous afferents would not appear to contribute to myoclonus in JME.     

Changes in motor cortex inhibition over time in patients with amyotrophic lateral sclerosis

Abnormal balance between intracortical inhibitory and excitatory mechanisms has been found to contribute to the genesis of motor cortex hyperexcitability in amyotrophic lateral sclerosis (ALS), but data are lacking on the role of these abnormalities in the pathophysiology of the disease. We evaluated the resting motor threshold (RMT), the cortical silent period (CSP) to single-pulse transcranial magnetic stimulation (TMS), early intracortical inhibition (ICI), early intracortical facilitation (ICF) and late ICI to paired-pulse TMS in 40 patients with ALS. These parameters were correlated with disease duration and clinical features. They were also monitored over time in selected patients.The main abnormal TMS findings were: (a). reduced or even absent early and late ICI; six out of 9 patients, with normal early ICI at the first recording, developed abnormal ICI after several months; (b). reduced cortical silent period duration with increasing TMS intensity. ICF and RMT were not affected. Impairment of early and late ICI correlated significantly with disease duration, the diagnostic categories and the clinical evidence of upper motor neuron involvement.The alteration of different cortical inhibitory functions seems to take place with disease progression, rather than being the primary event in the pathogenesis of ALS. The impaired inhibition is considered as being due to both depletion of specific subpopulations of intracortical GABAergic neurons and mechanisms involved in motor cortex reorganization following progressive neuronal loss. Clarification of the importance of these factors in the pathogenesis of the disease may have diagnostic and therapeutic implications.     

Acute myelitis as presenting symptom of HIV-HTLV-1 co-infection

A 21-year-old woman presented with acute-onset spastic paraparesis. The MRI spinal scan revealed a contrast-enhanced T2 hyperintensity between C5–T2. The most common neurotropic pathogens were excluded by first level tests. Under suspicion of an acute immune-mediated myelitis, a corticosteroid therapy was administered. However, a seropositivity for both human immunodeficiency virus (HIV) type 1 and human T-lymphotropic virus (HTLV) subsequently emerged. An antiretroviral therapy was started while steroids discontinued. Patient’s clinical conditions remained unchanged. HIV-HTLV-1 co-infection should be included in the differential diagnosis of any acute myelitis, even in patients with a preserved immune status and no risk factors.     

Autonomic dysfunction in post-COVID patients with and witfhout neurological symptoms: a prospective multidomain observational study

Journal of Neurology - The autonomic nervous system (ANS) can be affected by COVID-19, and dysautonomia may be a possible complication in post-COVID individuals. Orthostatic hypotension (OH) and...     

Assessment of Event-Related EEG Power After Single-Pulse TMS in Unresponsive Wakefulness Syndrome and Minimally Conscious State Patients

In patients without a behavioral response, non-invasive techniques and new methods of data analysis can complement existing diagnostic tools by providing a method for detecting covert signs of residual cognitive function and awareness. The aim of this study was to investigate the brain oscillatory activities synchronized by single-pulse transcranial magnetic stimulation (TMS) delivered over the primary motor area in the time–frequency domain in patients with the unresponsive wakefulness syndrome or in a minimally conscious state as compared to healthy controls. A time–frequency analysis based on the wavelet transform was used to characterize rapid modifications of oscillatory EEG rhythms induced by TMS in patients as compared to healthy controls. The pattern of EEG changes in the patients differed from that of healthy controls. In the controls there was an early synchronization of slow waves immediately followed by a desynchronization of alpha and beta frequency bands over the frontal and centro-parietal electrodes, whereas an opposite early synchronization, particularly over motor areas for alpha and beta and over the frontal and parietal electrodes for beta power, was seen in the patients. In addition, no relevant modification in slow rhythms (delta and theta) after TMS was noted in patients. The clinical impact of these findings could be relevant in neurorehabilitation settings for increasing the awareness of these patients and defining new treatment procedures.