Depression of motor cortex excitability by low-frequency transcranial magnetic stimulation

We studied the effects of low-frequency transcranial magnetic stimulation (TMS) on motor cortex excitability in humans. TMS at 0.1 Hz for 1 hour did not change cortical excitability. Stimulation at 0.9 Hz for 15 minutes (810 pulses), similar to the parameters used to induce long-term depression (LTD) in cortical slice preparations and in vivo animal studies, led to a mean decrease in motor evoked potential (MEP) amplitude of 19.5%. The decrease in cortical excitability lasted for at least 15 minutes after the end of the 0.9 Hz stimulation. The mechanism underlying this decrease in excitability may be similar to LTD. TMS-induced reduction of cortical excitability has potential clinical applications in diseases such as epilepsy and myoclonus. Spread of excitation, which may be a warning sign for seizures, occurred in one subject and was not accompanied by increased MEP amplitude, suggesting that spread of excitation and amplitude changes are different phenomena and also indicating the need for adequate monitoring even with stimulations at low frequencies.     

Late responses after transcranial magnetic stimulation in stroke

In addition to early responses after transcranial magnetic stimulation, usually designated as Motor Evoked Potentials (MEP), several late responses have been reported in intervals up to 500 ms following stimulus. Our attention in this work was focused on the response in interval 150-300 ms after stimulus output, which is also designated as S > 150 response. We monitored longitudinally late S > 150 response in group of 19 stroke patient with verified hemispherical ischemic lesion. Our results have shown that the presence of late S > 150 response on the first day after stroke predicts an excellent improvement of clinical deficit and that late S > 150 response is more sensitive to hemispheric lesion than early MEPs. From this point of view, recording of late responses can supplement early MEP recording. Our study demonstrated that supratentorial structures are involved in the origin of the S > 150 response. According to the observation that in some patients a normal early response was present and an S > 150 response was absent on the hemiparetic side, and both responses were present on the unaffected side, we hypothesize that cortical structures play an important role in S > 150 response.     

Corticospinal direct response to transcranial magnetic stimulation in humans

The corticospinal motor evoked potential (MEP) response to transcranial magnetic stimulation of the motor cortex was investigated in comparison with the direct (D) response to electrical stimulation of the exposed motor cortex from the spinal epidural space in 7 neurologically normal patients during brain tumor surgery. The D response during operation was obtained by transcranial magnetic stimulation of the scalp over the areas of the cerebral motor cortex, the hand or arm areas. The magnetic induced D response showed a conduction velocity of 50.5-72.7 m/sec and was resistant to anesthesia and unaffected by muscle relaxants and tolerant to high frequency (500 Hz) paired magnetic stimulus, and the latencies of magnetic MEPs corresponded to those with direct electrical stimulation. Thus, recordings of the D response by transcranial magnetic stimulation are useful for not only identifying the location of the motor cortex during intracranial surgery but also for non-invasive recording of pyramidal tract activity during extracranial surgery under general anesthesia.     

Spatial distribution of corticospinal potentials following transcranial electric and magnetic stimulation in human spinal cord

To search for concomitant anomalies among babies with congenital hypothyroidism, 120 newborn babies with confirmed congenital hypothyroidism were studied at the Veterans General Hospital, Taipei. The incidence of concomitant anomalies was estimated to be 11.67% (14/120). Among these anomalies, cardiac and gastrointestinal systems were the most commonly involved, comprising 35.7% (5/14) and 28.6% (4/14) of all anomalies, respectively. The type (i.e. agenesis, ectopia or eutopic goiter) as well as the severity of hypothyroidism were analyzed between groups of babies with or without concomitant anomalies. No differences existed between the two groups of babies regarding these two aspects.     

Responses of human single motor units to transcranial magnetic stimulation

The authors analyse the results of 51 unicompartmental knee prostheses with 1 to 12 years follow-up (mean follow-up: 5 years). The results were evaluated using the scoring system of the "Knee Group" of the SO.B.C.O.T. (Société Belge de Chirurgie Orthopédique et de Traumatologie). This analysis demonstrates that the quality of the results depends on implant positioning. The authors suggest positioning the tibial implant parallel with the healthy plateau and slightly distal, i.e. to position the tibial implant perpendicular to the epiphyseal axis and not to the mechanical axis, as is systematically done with the usual tibial cutting guides. When this ideal positioning was respected, 77.5% of the patients had a score above 90 points (out of a possible maximum of 100 points) and 12.5% had a score between 75 and 89 points. When this condition was not respected, none of the knees obtained more than 75 points. The difference was statistically significant (p = 0.0001).     

Simultaneous recording of slow brain potentials and transcranial magnetic stimulation of hand area in human motor cortex

We have studied 60 ears initial stage professional acoustic trauma and a hearing loss in the 2,000 and 4,000 frequencies at 30-40 db. We also included in the study 60 normal ears as the control group. In the first group we investigated the recruitment by the SISI test. Watson and Tolan's test, vocal audiometry and Metz's test. Recruitment was considered positive when indicated so by two of four tests. In waves I and V of BERA we have obtained the following results compared to those of the normal ears: Amplitude is similar in both waves, whatever the intensity of the click. Latencies increase with weak clicks, more in wave V, while the become equal with stronger clicks, what means the existence of recruitment. While other tests are not useful or doubtful, BERA are of interest for the study on recruitment in deep hearing loss.     

Multi-modality mapping of motor cortex: comparing echoplanar BOLD fMRI and transcranial magnetic stimulation. Short communication

Multiple non-invasive methods of imaging brain function are now available for presurgical planning and neurobiological research. As these new methods become available, it is important to understand their relative advantages and liabilities, as well as how the information gained compares across different methods. A current and future trend in neurobiological studies as well as presurgical planning is to combine information from different imaging techniques. Multi-modal integration may perhaps give more powerful information than each modality alone, especially when one of the methods is transcranial magnetic stimulation (TMS), with its ability to non-invasively activate the brain. As an initial venture in cross comparing new imaging methods, we performed the following 2 studies, locating motor cortex with echoplanar BOLD fMRI and TMS. The two methods can be readily integrated, with concurring results, although each have important limitations.     

Impaired motor cortex inhibition in patients with amyotrophic lateral sclerosis. Evidence from paired transcranial magnetic stimulation

We investigated 14 patients with amyotrophic lateral sclerosis (ALS) by paired conditioning-test transcranial magnetic stimulation to test the hypothesis that the motor cortex is hyperexcitable in ALS. Intracortical (corticocortical) inhibition was significantly less in the ALS group than in an age-matched healthy control group (85.3 +/- 27.0% versus 45.2 +/- 15.5%, respectively; p < 0.0001). In contrast, intracortical facilitation, motor threshold, and cortical silent period duration in the ALS patients were not different from the control group. We suggest that the selective abnormality of intracortical inhibition is best compatible with an impaired function of inhibitory interneuronal circuits in the motor cortex that in turn renders the corticomotoneuron hyperexcitable.     

Suppression and long latency excitation of single spinal motoneurons by transcranial magnetic stimulation in health, multiple sclerosis, and stroke

Our objective was to identify risk factors for development of immunologically mediated respiratory disease in workers exposed to hexahydrophthalic anhydride. We performed a medical and immunologic survey study of 57 workers in a workplace molding operation utilizing hexahydrophthalic anhydride. The main outcome measurements were the development of a respiratory disease due to specific IgE antibody (asthma and/or rhinitis) or specific IgG antibody (hypersensitivity pneumonitis or hemorrhagic rhinitis). Of the 57 workers, 7 had both IgE- and IgG-mediated disease, whereas 9 had only IgE-mediated disease. Although neither smoking, age, nor race were risk factors for development of immunologically mediated disease, exposure level and specific antibody were. In conclusion, development of immunologically mediated respiratory disease due to hexahydrophthalic anhydride is most closely associated with exposure level and development of specific IgE or IgG antibodies.     

Driving cognitive and motor gains with rehabilitation after brain and spinal cord injury

Hepatic involvement in hereditary hemorrhagic telangiectasia (HHT) is rare. Among local pathologic alterations like fibrosis and cirrhosis, arteriovenous shunts lead to hypercirculatory heart failure and require efficient therapy. Present therapeutic strategies consist of percutaneous selective embolization or complete ligation of the hepatic artery. We describe a 53-year-old woman with HHT in whom percutaneous selective embolization of the left hepatic artery failed because of unfavorable anatomy. Instead of ligation a new method of adjustable banding of the hepatic artery was tested. After small-incision laparotomy an expander prosthesis was put on the proper hepatic artery. By filling the prosthesis via the implanted port system the hepatic perfusion could be reduced under control. This method led to effective reduction of the liver perfusion and heart time volume and to successful treatment of heart failure. The method described is an alternative treatment to ligation of the hepatic artery in cases in which percutaneous embolization failed or is not possible.     

Can muscle models improve FES-assisted walking after spinal cord injury?

A flow cytometric method using anti-parasite antibodies was developed to measure binding of Theileria parva sporozoites to the target bovine lymphocyte membrane. Parasite-host cell interactions could be inhibited by monoclonal antibodies to bovine MHC class I and partially by one of two antibodies to BoCD45R. Proteolysis of the lymphocyte surface removed CD45R but not MHC class I determinants, and enhanced sporozoite binding. These observations support the hypothesis that CD45R and CD45R antibodies may nonspecifically prevent close approximation between sporozoites and lymphocytes. Interestingly, under normal conditions, sporozoites of T. parva did not attach to lymphocytes from goats, but did so when the cells were treated with the protease, suggesting that receptor(s) for T. parva sporozoites might be present on caprine cells but are not easily accessible. These and other results indicate that proteases may be involved in binding and entry of T. parva sporozoites. Electron microscopy revealed that the process of binding and entry of sporozoites into protease-treated goat lymphocytes was very similar to that of the bovine cells. However, schizonts did not develop and lymphocyte proliferation was not induced, indicating that cell entry by sporozoites and cellular transformation are separate processes.     

Basic and acidic fibroblast growth factors protect spinal motor neurones in vivo after experimental spinal cord injury

We studied the effect of a single focal injection of recombinant basic (FGF2) or acidic (FGF1) fibroblast growth factor on the survival of spinal motor neurones at 24 h after a standardized spinal cord contusion injury (SCI) in the rat. Both FGF2 and FGF1 (3 microg), microinjected into the injury site at 5 min post-injury (p.i.), protected at least two functionally important classes of spinal motor neurones, autonomic preganglionic neurones in the intermediolateral (IML) column and somatic motor neurones in the ventral horn (VH). Moreover, there was enhanced choline acetyltransferase (ChAT) immunoreactivity in surviving VH and IML neurones, suggesting an improved functional status. Thus, neurotrophic factors such as FGF2 and FGF1 may contribute to an overall strategy to treat acute SCI and improve recovery of function.     

Rapid-rate transcranial magnetic stimulation of left dorsolateral prefrontal cortex in drug-resistant depression

BACKGROUND: Lesion and neuroimaging studies suggest that left prefrontal lobe dysfunction is pathophysiologically linked to depression. Rapid-rate transcranial magnetic stimulation (rTMS) to prefrontal structures has a lateralised effect on mood in normal volunteers, and several preliminary studies suggest a beneficial effect of rTMS on depression. However, adequately controlled studies have not been conducted. METHODS: We have studied the effects of focal rTMS on the depressive symptoms in 17 patients with medication-resistant depression of psychotic subtype. The study was designed as a multiple cross-over, randomised placebo-controlled trial. Sham rTMS and stimulation of different cortical areas were used as controls. FINDINGS: Left dorsolateral prefrontal cortex rTMS resulted in a significant decrease in scores on the Hamilton depression rating scale HDRS (from 25.2 to 13.8) and the self-rated Beck questionnaire BQ (from 47.9 to 25.7). 11 of the 17 patients showed pronounced improvement that lasted for about 2 weeks after 5 days of daily rTMS sessions. No patient experienced any significant undesirable side-effects. INTERPRETATION: Our findings emphasise the role of the left dorsolateral prefrontal cortex in depression, and suggest that rTMS of the left dorsolateral prefrontal cortex might become a safe, non-convulsive alternative to electroconvulsive treatment in depression.     

Enhancement of human motor cortex inhibition by the dopamine receptor agonist pergolide: evidence from transcranial magnetic stimulation

The autoradiographic method with [L-35S]methionine was used to determine the effects of a 2 h acute immobilization stress followed by a 4 h recovery on local rates of protein synthesis in the adult rat brain. Methionine incorporation into proteins was significantly increased (from 17 to 86%) in 37 out of the 39 analyzed brain structures. These results show that the stress-induced activation of the overall rate of brain protein synthesis may persist for at least 4 h after cessation of the stimulus even though the stress-related physiological variables have returned to basal levels. They suggest that increased protein synthesis may play a key role in the molecular events which lead to the neuronal plastic changes following an acute stress.     

Studies on the corticospinal control of human walking. I. Responses to focal transcranial magnetic stimulation of the motor cortex

Experiments were done to determine the extent to which the corticospinal tract is linked with the segmental motor circuits controlling ankle flexors and extensors during human walking compared with voluntary motor tasks requiring attention to the level of motor activity. The motor cortex was activated transcranially using a focal magnetic stimulation coil. For each subject, the entire input-output (I-O) curve [i.e., the integral of the motor evoked-potential (MEP) versus stimulus strength] was measured during a prescribed tonic voluntary contraction of either the tibialis anterior (TA) or the soleus. Similarly, I-O curves were measured in the early part of the swing phase, or in the early part of the stance phase of walking. The I-O data points were fitted by the Boltzmann sigmoidal function, which accounted for >/=80% of total data variance. There was no statistically significant difference between the I-O curves of the TA measured during voluntary ankle dorsiflexion or during the swing phase of walking, at matched levels of background electromyographic (EMG) activity. Additionally, there was no significant difference in the relation between the coefficient of variation and the amplitude of the MEPs measured in each task, respectively. In comparison, during the stance phase of walking the soleus MEPs were reduced on average by 26% compared with their size during voluntary ankle plantarflexion. Furthermore, during stance the MEPs in the inactive TA were enhanced relative to their size during voluntary ankle plantarflexion and in four of six subjects the TA MEPs were larger than those of the soleus. Finally, stimulation of the motor cortex at various phases of the step cycle did not reset the cycle. The time of the next step occurred at the expected moment, as determined from the phase-resetting curve. One interpretation of this result is that the motor cortex may not be part of the central neural system involved in timing the motor bursts during the step cycle. We suggest that during walking the corticospinal tract is more closely linked with the segmental motor circuits controlling the flexor, TA, than it is with those controlling the extensor, soleus. However, during voluntary tasks requiring attention to the level of motor activity, it is equally linked with the segmental motor circuits of ankle flexors or extensors.     

Changes in mood and hormone levels after rapid-rate transcranial magnetic stimulation (rTMS) of the prefrontal cortex

A person's reality and definition of self are socially constructed; ethnicity is integrally involved in this process. Clinical work is successful if the client constructs a self with a sense of positive self-esteem and empowerment. The profession views social workers' use of self as important in successful clinical work, especially with clients ethnically different from themselves. This article provides a framework adapted from a constructivist perspective for the clinician's skillful use of self in therapeutic discourse. The framework consists of five stances the clinician can use in transcending the discomfort he or she may experience in a cross-cultural clinical situation. Use of these stances facilitates clients' ethnic validation, which is essential to positive therapeutic outcomes. This article uses case examples to illustrate the use of the framework.     

Recovery in rats after spinal cord injury

Previous studies from this laboratory have shown evidence of regeneration of long descending spinal motor tracts in rats after spinal cord transection and treatment to modify the animals' immune response. In this study, less extensive surgical lesions were combined with the most favorable drug treatment (75 mg per kilogram of cyclophosphamide in a single dose) in an effort to improve the prospects for regeneration. Less than complete spinal cord transections in the rat were frequently followed by clinical and electrophysiologic evidence of return of function. Such return of function appears to depend on a reorganization of the nervous system that results in the use of the few remaining fibers to transmit motor information rather than on regeneration. Immunosuppressive treatment had no effect on these results.     

Peculiarity of soleus motor potentials evoked by transcranial magnetic stimulation and electrical stimulation of tibial nerve

Fas (Apo-1/CD95) ligand (FasL) is a cytotoxic molecule used by T lymphocytes and natural killer cells for target-cell killing and by nonmalignant and malignant cells in the suppression of immune responses. In this study, FasL expression in B- and T-cell non-Hodgkin's lymphomas was investigated by paraffin immunohistochemical analysis. FasL expression was found to be weak in nonaggressive lymphomas (chronic lymphocytic leukemia/small lymphocytic lymphoma, lymphoplasmacytoid lymphoma, Grade 1 follicular center cell lymphoma) and mantle cell lymphoma but strong in aggressive B-cell lymphomas (diffuse large B-cell lymphoma, Burkitt's-lymphoma). Precursor B-lymphoblastic lymphomas were more heterogeneous, with expression varying from weak to strong. In T-cell lymphomas (anaplastic large-cell lymphoma; peripheral T-cell lymphoma, unspecified), strong FasL expression was observed. Apparently, FasL expression is not limited to neoplasms derived from T cells or natural killer cells, and it might play a supporting role in the progression of non-Hodgkin's lymphomas.