1,721,125 research outputs found
Clinical and research methods for evaluating cortical excitability
No full textThe evaluation of motor cortical output after transcranial magnetic stimulation (TMS) is a means of investigating how the motor cortex reacts to external stimuli (i.e., a method to assess the excitability of the motor cortex). The recording of the descending volleys at the surface of the spinal cord provides a direct measure of the motor cortical output. However, this approach is highly invasive and can be used only during particular conditions. On the other hand, electromyographic recordings of the motor phenomena induced by TMS provide a completely painless, noninvasive, indirect measure of the cortical output, with these phenomena obviously reflecting the excitability of the spinal motoneurons as well as that of the muscle itself. The authors review how the electromyographic activity induced by TMS can provide valuable information about motor cortical excitability for use in clinical practice and research
Selective facilitation of responses to cortical stimulation of proximal and distal arm muscles by precision tasks in man
No full textSensory and motor evoked potentials in multiple system atrophy: a comparative study with Parkinson's disease
No full textSomatosensory evoked potentials (SEPs) to median nerve stimulation and motor evoked potentials to transcranial magnetic stimulation (TMS) of the motor cortex were studied in 15 patients with multiple system atrophy (MSA) and compared with matched groups of 20 patients with idiopathic Parkinson's disease (PD) and of 20 normal controls (NCs). No SEP latency or amplitude abnormalities were observed, and, in particular, the frontal N30 component was not significantly depressed. No differences in TMS threshold for evoking responses in relaxed or active thenar muscles were observed. The mean central motor conduction time was normal for the biceps brachii and opponens pollicis muscles and prolonged in the MSA group for the tibialis anterior muscle. Recording SEPs is not useful to differentiate MSA from PD, while the presence of central motor conduction abnormalities may bring into question the diagnosis of idiopathic PD
The excitability of the human motor cortex increases during execution and mental imagination of sequential but not repetitive finger movements
No full textMotor potentials (MEPs) evoked by focal (figure-of-eight coil) transcranial magnetic stimulation of the left motor cortex were recorded from the right opponens pollicis (OP) and flexor digitorum superficialis (FDS) of 14 normal subjects during different motor tasks. Changes in motor cortical excitability under behavioural conditions presumably connected with premotor and supplementary motor area (SMA) activation were investigated by comparing the size of the MEPs obtained during: (1) rest, (2) mental calculus, (3) repetitive left thumb-to-index opposition, (4) mental simulation of the same task with the right hand, (5) sequences of left thumb-to-fingers opposition, and (6) mental simulation of the same sequences with the right hand. MEP size significantly increased in both muscles during sequential movements of the left hand and sequence simulation with the right hand, but not during mental calculus or actual or simulated repetitive movements. The H-reflex evoked in the OP and FDS muscles by electrical stimulation of the median nerve (at wrist and elbow, respectively) under the same experimental conditions did not show significant modifications. The increase in MEP size during non-routine actual or imagined sequences of finger movements supports the view that the SMA is activated under these conditions and that it exerts a direct facilitatory influence on the motor cortex
The rationale for motor learning in Parkinson's disease.
No full textParkinson's disease (PD) is a chronic progressive disorder mainly affecting the motor system. PD is only partially controlled by symptomatic dopaminergic treatment. Therefore, motor rehabilitation can be used in PD to reduce complications and to train patients in the use of compensatory movement strategies. Rehabilitative practice is largely dependent on the efficiency of motor learning, i.e. the acquisition of new abilities or the adaptation of pre-existing ones. Although patients with PD are able to improve their motor performance through practice, the amount and persistence of clinical benefit are uncertain. Both ''implicit'' (procedural) and ''explicit'' (declarative) features of motor learning have been extensively investigated in patients with PD using neuropsychological testing, serial reaction time paradigms, and analysis of reaching movements. Evidence from these studies suggests an early impairment of ''explicit'' learning in PD, while ''implicit'' learning is relatively preserved. The consolidation of learned motor tasks is defective in PD and the mechanisms of motor learning seem to be independent from dopamine-replacement therapy. The knowledge of motor learning in PD is critical in designing more effective rehabilitative protocols
Medical treatment of joint prosthesis: indication, opportunities and liability profiles
No full textOrthopaedic specialists should completely and sequentially manage osteoarthritis, from the onset to the prosthesis, with no attitude of resignation, complying with national and international Guidelines (GLs) and abiding by the criteria of appropriateness of drugs, rehabilitation and orthopaedic device prescription, in line with the ethics of the medical profession. The GLs are a paper that rationalises the quantity of existing information for a disease, without abusing the decision of the doctor; a large volume of scientific knowledge is concentrated in a format that is easily accessible to doctors when carrying out their work. The use of drugs has taken on a connotation of a rational and multifactorial choice, rather than an accidental and incremental choice - inspired only by safety, rather than efficacy criteria. The Notes compiled by the Italian Medicines Agency - a legal instrument to define the reimbursability of medicines and, therefore, an instrument for managing pharmaceutical expenditure are, in reality, a means to guarantee the appropriateness of the use of medicines, orienting the therapeutic choices according to established Guidelines. In the specific case of osteoarthritis, the knowledge of the GLs is the most appropriate and complete approach towards the disease, in the context of its pathogenetic complexity in its natural history. Moreover, pharmacological treatment of the subchondral osteometabolic damage becomes necessary when documented by magnetic resonance or a scintigraphy; the bone-related pain cannot be challenged through symptomatic analgesic treatment alone
Isolated Demyelination of Corpus Callosum Following Hypoxia
No full textCorpus callosum includes a large amount of axons with various degrees of myelination, interconnecting cerebral hemispheres. Tumors, demyelinating diseases, infections, trauma and metabolic diseases as well as vascular lesions may affect corpus callosum, often extending to other white matter areas of the brain. We describe the case of a 76 years old male patient with history of arterial hypertension, diabetes mellitus and normal pressure hydrocephalus, developing dysphagia during hospitalization. Ab-ingestis pneumonia
caused brain hypoxia and coma; brain magnetic resonance disclosed isolated demyelination of corpus callosum that was not present before hypoxia. Compared to neurons and astrocytes, oligodendrocytes are reported as particularly sensitive to hypoxia. Respiratory involvement without blood flow impairment could have lead to a prevalent oligodendrocytes damage, resulting in a selective demyelination of corpus callosum. Our patient indeed evolved into persistent vegetative state and died five months after hypoxic episode. This case report could give some insight about in vivo brain susceptibility to hypoxic damage
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