Proprietà fisiologiche della corteccia motoria facciale nell'uomo: studio dei circuiti intracorticali facilitatori ed inibitori e modulazione della plasticità sinaptica

Physiology of corticofacial motor system and the role of facial intracortical circuits are controversial and neither sensorimotor integration nor LTP-like plasticity has been investigated in these muscles. We investigated properties of motor responses (MEP) evoked by trasncranial magnetic stimulation (TMS) of the facial motor cortex, short interval intracortical inhibition (SICI), intracortical facilitation (ICF), short-afferent inhibition (SAI) and effects of paired associative stimulation (PAS) in relaxed and active depressor angulis oris muscle (DAO). SICI and ICF were tested using paired-pulse TMS. SAI was tested by pairing facial nerve electrical stimulation with TMS of the facial motor cortex. Resting and active MEPs were acquired before and after 0-30 min from PAS delivery. SICI and ICF were significant (p < 0.001) in both relaxed and active DAO. SAI was absent in both resting and active condition, but PAS protocol significantly (p < 0.01) facilitated the resting DAO MEPs at all post-PAS times tested. Data showed that cortico-facial projection is bilateral and symmetric, with a contralateral predominance. SICI and ICF work in the facial motor cortex in both resting and active conditions. In addition, despite SAI appearing to be ineffective in FM, evidence was provided for LTP-like plasticity in the facial area

Withdrawal of mechanical ventilation in amyotrophic lateral sclerosis patients: a multicenter Italian survey

Background: Law 219/2017 was approved in Italy in December 2017, after a years-long debate on the autonomy of healthcare choices. This Law, for the first time in Italian legislation, guarantees the patient's right to request for withdrawal of life-sustaining treatments, including mechanical ventilation (MV). Objective: To investigate the current status of MV withdrawal in amyotrophic lateral sclerosis (ALS) patients in Italy and to assess the impact of Law 219/2017 on this practice. Methods: We conducted a Web-based survey, addressed to Italian neurologists with expertise in ALS care, and members of the Motor Neuron Disease Study Group of the Italian Society of Neurology. Results: Out of 40 ALS Italian centers, 34 (85.0%) responded to the survey. Law 219/2017 was followed by an increasing trend in MV withdrawals, and a significant increase of neurologists involved in this procedure (p 0.004). However, variations across Italian ALS centers were observed, regarding the inconsistent involvement of community health services and palliative care (PC) services, and the intervention and composition of the multidisciplinary team. Conclusions: Law 219/2017 has had a positive impact on the practice of MV withdrawal in ALS patients in Italy. The recent growing public attention on end-of-life care choices, along with the cultural and social changes in Italy, requires further regulatory frameworks that strengthen tools for self-determination, increased investment of resources in community and PC health services, and practical recommendations and guidelines for health workers involved

Sensorimotor interaction and motor learning in facial muscles

Background and aim: Integration of sensory information with motor output is thought to be important in motor learning. In limb muscles, this is studied using the short afferent inhibition (SAI) paradigm, to assess sensorimotor interaction, and paired associative stimulation (PAS), to evaluate LTP-like plasticity. As far as we know, SAI and PAS paradigms have never been used in the territory of the cranial nerves. The present study was aimed at testing in normal subjects whether sensorimotor interaction and LTP-like plasticity can be observed in facial muscles as well as in limb muscles. Methods: Motor evoked potentials (MEPs) were evoked in the depressor angulis oris (DAO) muscle of 7 subjects. MEPs were recorded from the contralateral DAO at rest and during 10% maximal voluntary contraction (active condition). SAI was tested in 5 subjects, by pairing electrical stimulation (ES, intensity 3 times the perceptual threshold) of the facial nerve, with magnetic stimulation (TMS, 120% of motor threshold intensity) of the facial motor cortex. Intervals between ES and TMS were 5, 10, 15, 20, 25 and 30 ms. The LTP-like plasticity protocol (200 pairs of ES and TMS, 20 ms ISI, at 0.25 Hz) was tested in X subjects by evoking twenty MEPs in both resting and active conditions, before and at 0, 20 and 30 min after paired stimulation. Results: Facial nerve stimulation in the SAI paradigm had no significant affect on MEP amplitude, either in the active or in the relaxed DAO muscle. By contrast MEP amplitude at rest showed a trend of facilitation (p &lt; 0,072) after the PAS protocol administration. When tested at rest this effect was observed at baseline and after 10 min. On the contrary MEP amplitude recorded during activity was significantly enhanced at 10 (p &lt; 0,026) and 30 (p &lt; 0,014) minutes after PAS. There was a significant difference between the time course in resting and active conditions (p &lt; 0,019). Conclusions: These data show that there is no short latency afferent inhibition in the facial motor cortex, yet despite this, there is evidence for maintained LTP-like plasticity. Further studies are needed to understand how and why PAS works in facial muscles despite the absence of SAI. A larger sample is also required to confirm the PAS effect on resting DAO MEPs. A second point to be clarified is why the PAS time course at rest is different from that operating during active condition.</br

Transcutaneous trigeminal nerve stimulation induces a long-term depression-like plasticity of the human blink reflex.

The beneficial effects of trigeminal nerve stimulation (TNS) on several neurological disorders are increasingly acknowledged. Hypothesized mechanisms include the modulation of excitability in networks involved by the disease, and its main site of action has been recently reported at brain stem level. Aim of this work was to test whether acute TNS modulates brain stem plasticity using the blink reflex (BR) as a model. The BR was recorded from 20 healthy volunteers before and after 20 min of cyclic transcutaneous TNS delivered bilaterally to the infraorbital nerve. Eleven subjects underwent sham-TNS administration and were compared to the real-TNS group. In 12 subjects, effects of unilateral TNS were tested. The areas of the R1 and R2 components of the BR were recorded before and after 0 (T0), 15 (T15), 30 (T30), and 45 (T45) min from TNS. In three subjects, T60 and T90 time points were also evaluated. Ipsi- and contralateral R2 areas were significantly suppressed after bilateral real-TNS at T15 (p = 0.013), T30 (p = 0.002), and T45 (p = 0.001), while R1 response appeared unaffected. The TNS-induced inhibitory effect on R2 responses lasted up to 60 min. Real- and sham-TNS protocols produced significantly different effects (p = 0.005), with sham-TNS being ineffective at any time point tested. Bilateral TNS was more effective (p = 0.009) than unilateral TNS. Acute TNS induced a bilateral long-lasting inhibition of the R2 component of the BR, which resembles a long-term depression-like effect, providing evidence of brain stem plasticity produced by transcutaneous TNS. These findings add new insight into mechanisms of TNS neuromodulation and into physiopathology of those neurological disorders where clinical benefits of TNS are recognized

Intracortical circuits, sensorimotor integration and plasticity in human motor cortical projections to muscles of the lower face

Previous studies of the cortical control of human facial muscles documented the distribution of corticobulbar projections and the presence of intracortical inhibitory and facilitatory mechanisms. Yet surprisingly, given the importance and precision in control of facial expression, there have been no studies of the afferent modulation of corticobulbar excitability or of the plasticity of synaptic connections in the facial primary motor cortex (face M1). In 25 healthy volunteers, we used standard single- and paired-pulse transcranial magnetic stimulation (TMS) methods to probe motor-evoked potentials (MEPs), short-intracortical inhibition, intracortical facilitation, short-afferent and long-afferent inhibition and paired associative stimulation in relaxed and active depressor anguli oris muscles. Single-pulse TMS evoked bilateral MEPs at rest and during activity that were larger in contralateral muscles, confirming that corticobulbar projection to lower facial muscles is bilateral and asymmetric, with contralateral predominance. Both short-intracortical inhibition and intracortical facilitation were present bilaterally in resting and active conditions. Electrical stimulation of the facial nerve paired with a TMS pulse 5–200 ms later showed no short-afferent inhibition, but long-afferent inhibition was present. Paired associative stimulation tested with an electrical stimulation–TMS interval of 20 ms significantly facilitated MEPs for up to 30 min. The long-term potentiation, evoked for the first time in face M1, demonstrates that excitability of the facial motor cortex is prone to plastic changes after paired associative stimulation. Evaluation of intracortical circuits in both relaxed and active lower facial muscles as well as of plasticity in the facial motor cortex may provide further physiological insight into pathologies affecting the facial motor system

Ultrasound and laser as stand-alone therapies for myofascial trigger points: a randomized, double-blind, placebo-controlled study

Background and Purpose. Ultrasound (US) and low-level laser therapy (LLLT) are commonly employed for myofascial trigger points (MTP) despite lack of evidence for usage as stand-alone treatments. The aim of the study was to determine, on MTP of the upper trapezius muscle (uTM), the effects of US and LLLT per se, as delivered in accordance with the procedures reported by surveys about their usage among physiotherapists. Methods. Design was set as a double-blind, randomized, placebo-controlled study. Sixty participants with at least one active MTP in uTM (28 women and 32 men; mean age 24.5 ± 1.44 years) were recruited and randomly assigned to one out of five groups: active US (n = 12), placebo US (n = 12), active LLLT (n = 11), placebo LLLT (n = 11) and no therapy (control, n = 14). The participants and outcome assessor were blinded to the group assignment and therapy delivered. Three outcome measures were assessed at baseline, after a 2-week treatment and 12 weeks after the end of the intervention (follow-up): pressure pain threshold, subjective pain on a numerical rating scale and muscle extensibility performing a cervical lateral flexion. All subjects assigned to the intervention groups were treated five times weekly for overall 10 treatments given. Two-way ANOVA was used to compare differences before and after intervention and among groups at each time-point. Results. After the 2-week intervention, all groups showed pressure pain threshold, numerical rating scale and cervical lateral flexion significant improvements (p&lt;0.05), which were confirmed at the follow-up. When performing multiple comparisons, controls scored significantly less than both the active therapies and placebos, whereas no differences were detected between active therapies and placebos. Conclusions. Ultrasound and LLLT provided significant improvements in pain and muscle extensibility, which were superior to no therapy but not to placebos, thus raising concerns about the suitability, both economically and ethically, of administering such common physical modalities as stand-alone treatments in active MTP of the uTM.</br