Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application. An updated report from an I.F.C.N. Committee

These guidelines provide an up-date of previous IFCN report on “Non-invasive electrical and magnetic stimulation of the brain, spinal cord and roots: basic principles and procedures for routine clinical application” (Rossini et al., 1994). A new Committee, composed of international experts, some of whom were in the panel of the 1994 “Report”, was selected to produce a current state-of-the-art review of non-invasive stimulation both for clinical application and research in neuroscience.

Since 1994, the international scientific community has seen a rapid increase in non-invasive brain stimulation in studying cognition, brain–behavior relationship and pathophysiology of various neurologic and psychiatric disorders. New paradigms of stimulation and new techniques have been developed. Furthermore, a large number of studies and clinical trials have demonstrated potential therapeutic applications of non-invasive brain stimulation, especially for TMS. Recent guidelines can be found in the literature covering specific aspects of non-invasive brain stimulation, such as safety (Rossi et al., 2009), methodology (Groppa et al., 2012) and therapeutic applications (Lefaucheur et al., 2014).

This up-dated review covers theoretical, physiological and practical aspects of non-invasive stimulation of brain, spinal cord, nerve roots and peripheral nerves in the light of more updated knowledge, and include some recent extensions and developments.

A practical guide to diagnostic transcranial magnetic stimulation: report of an IFCN committee

Transcranial magnetic stimulation (TMS) is an established neurophysiological tool to examine the integrity of the fast-conducting corticomotor pathways in a wide range of diseases associated with motor dysfunction. This includes but is not limited to patients with multiple sclerosis, amyotrophic lateral sclerosis, stroke, movement disorders, disorders affecting the spinal cord, facial and other cranial nerves. These guidelines cover practical aspects of TMS in a clinical setting. We first discuss the technical and physiological aspects of TMS that are relevant for the diagnostic use of TMS. We then lay out the general principles that apply to a standardized clinical examination of the fast-conducting corticomotor pathways with single-pulse TMS. This is followed by a detailed description of how to examine corticomotor conduction to the hand, leg, trunk and facial muscles in patients. Additional sections cover safety issues, the triple stimulation technique, and neuropediatric aspects of TMS.

Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines

Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears to be safe. No serious adverse events (SAEs) have been reported so far in over 18,000 sessions administered to healthy subjects, neurological and psychiatric patients, as summarized here. Moderate adverse events (AEs), as defined by the necessity to intervene, are rare, and include skin burns with tDCS due to suboptimal electrode-skin contact. Very rarely mania or hypomania was induced in patients with depression (11 documented cases), yet a causal relationship is difficult to prove because of the low incidence rate and limited numbers of subjects in controlled trials. Mild AEs (MAEs) include headache and fatigue following stimulation as well as prickling and burning sensations occurring during tDCS at peak-to-baseline intensities of 1-2mA and during tACS at higher peak-to-peak intensities above 2mA. The prevalence of published AEs is different in studies specifically assessing AEs vs. those not assessing them, being higher in the former. AEs are frequently reported by individuals receiving placebo stimulation. The profile of AEs in terms of frequency, magnitude and type is comparable in healthy and clinical populations, and this is also the case for more vulnerable populations, such as children, elderly persons, or pregnant women. Combined interventions (e.g., co-application of drugs, electrophysiological measurements, neuroimaging) were not associated with further safety issues. Safety is established for low-intensity 'conventional' TES defined as <4mA, up to 60min duration per day. Animal studies and modeling evidence indicate that brain injury could occur at predicted current densities in the brain of 6.3-13A/m2 that are over an order of magnitude above those produced by tDCS in humans. Using AC stimulation fewer AEs were reported compared to DC. In specific paradigms with amplitudes of up to 10mA, frequencies in the kHz range appear to be safe. In this paper we provide structured interviews and recommend their use in future controlled studies, in particular when trying to extend the parameters applied. We also discuss recent regulatory issues, reporting practices and ethical issues. These recommendations achieved consensus in a meeting, which took place in Göttingen, Germany, on September 6-7, 2016 and were refined thereafter by email correspondence.

Percutaneous RF interstitial thermal ablation in the treatment of hepatic cancer

OBJECTIVE

The aim of this study was to evaluate the usefulness of RF interstitial thermal ablation for treating hepatic cancer.

SUBJECTS AND METHODS

Fifty patients, 39 who had 41 hepatocellular carcinoma nodules and 11 who had 13 hepatic metastatic nodules, underwent RF interstitial thermal ablation. In all but one, a thermal necrosis volume greater than the tumoral nodule volume was created to obtain total tumor destruction. One large tumor was treated for debulking purposes.

RESULTS

Hepatocellular carcinoma nodule destruction was achieved in a mean of 3.3 sessions of RF interstitial thermal ablation. During a mean follow-up of 22.6 months (range, 3-66 months), 16 (41%) of 39 patients had recurrences; two (5%) of these patients showed local recurrences and the remaining 14 (36%) had new lesions. Nine of these 16 patients underwent further RF interstitial thermal ablation that proved effective. RF interstitial thermal ablation was also successfully repeated in four patients who had a second recurrence. With RF interstitial thermal ablation, we treated 54 hepatocellular carcinoma nodules in 39 patients. Eleven (28%) of the 39 patients died: five from hepatic failure due to advanced cancer and six from causes other than cancer. Autopsy was performed on three patients who died from causes other than cancer, one had had two new courses of RF interstitial thermal ablation for two new lesions. Gross examination failed to detect two treated tumor nodules; histologic examination of three other treated tumor nodules showed total necrosis in two nodules and a 3-mm focus of viable cancer cells in the other nodule. Cumulative survival curves showed the median survival time to be 44 months. The survival rate for the first year was 0.94, 0.86 for the second year, 0.68 for the third year, and 0.40 for the fourth and fifth years. In the patients treated for metastatic nodules, posttreatment imaging studies showed necrosis that varied from 80% to 100% in all cases. Pathologic studies performed on two patients who underwent surgery after RF interstitial thermal ablation showed 100% necrosis in one case and 80% necrosis in the other.

CONCLUSION

RF interstitial thermal ablation is a useful percutaneous treatment for hepatic cancer.

Descriptive epidemiology of sarcomas in Europe: report from the RARECARE project

Sarcomas are a heterogeneous group of malignant neoplasms arising from mesenchymal cells which encompass dozens of histological types and can occur in virtually any anatomic site. They form one of the principal groups of rare cancers in Europe as defined in the RARECARE project. We analysed 45,568 incident cases diagnosed during 1995-2002 and registered by 76 population-based cancer registries. Total crude incidence was 5.6 per 100,000 per year with an estimated 27,908 new cases per year in the EU27 countries, of which 84% were soft tissue sarcomas and 14% were bone sarcomas. Gastrointestinal stromal tumours (GIST) were only widely recognised as an entity in the late 1990s and consequently were under-registered. Their true incidence is believed to be about 1.5 per 100,000. Age-standardised incidence of soft tissue sarcomas ranged from 3.3 per 100,000 in Eastern Europe to 4.7 per 100,000 in Northern Europe. About 280,000 persons were estimated to be alive at the beginning of 2003 with a past diagnosis of sarcoma, of which 83% were soft tissue sarcomas and 16% were bone sarcomas. Five-year relative survival for 2000-2002 by the period was 58% for soft tissue sarcomas and 62% for bone sarcomas. The diversity and rarity of sarcomas combined with the quite large number of people affected by them mean that they provide a classic example of the importance of networking in diagnosis, therapy and research for rare cancers.

Percutaneous treatment of small hepatic tumors by an expandable RF needle electrode

OBJECTIVE

The aim of this study was to evaluate the usefulness of expandable RF needle electrodes in the treatment of hepatic cancer.

SUBJECTS AND METHODS

Thirty-seven patients, 23 of whom had 26 hepatocellular carcinoma nodules and 14 of whom had 19 hepatic metastatic nodules, underwent treatment by RF interstitial thermal ablation with expandable needle electrodes. Forty-five tumor nodules were treated in 64 RF interstitial thermal ablation sessions with 83 needle electrode insertions. The mean diameter of the tumor nodules was 2.5 cm (range, 1.1-3.5 cm). Immediate posttreatment tumor necrosis was evaluated by dynamic CT in all cases. Two patients with hepatocellular carcinoma and three patients with metastases underwent surgical resection 20-60 days after RF treatment. The remaining 32 patients were followed up clinically.

RESULTS

The mean number of RF interstitial thermal ablation sessions to complete tumor nodule treatment was 1.4. Mean number of needle electrode insertions was 1.8. No complications were observed. Posttreatment dynamic CT showed a completely nonenhancing area in the site of the treated tumor in 44 of 45 cases. The remaining patient with metastatic disease had persistent enhancing tissue. Histology showed complete necrosis in four treated tumor nodules and residual viable cancer in one. Twenty-one patients with hepatocellular carcinoma were followed up for 6-19 months (mean, 10 months). Of these patients, six showed recurrences and 15 remained apparently disease-free. Two patients died, one from advanced cancer and one from other causes. Eleven patients with hepatic metastases were followed up for 7-20 months (mean, 12 months). Of these patients, nine showed recurrent disease and only two remained apparently disease-free. Two patients died from disseminated disease.

CONCLUSION

RF interstitial thermal ablation of hepatic tumor by expandable needle electrodes is a safe and effective technique. Local ablation of tumors not exceeding 3.5 cm in diameter is achieved in a short time without complications.

A stellar relic from the early Milky Way

The chemical composition of the most metal-deficient stars largely reflects the composition of the gas from which they formed. These old stars provide crucial clues to the star formation history and the synthesis of chemical elements in the early Universe. They are the local relics of epochs otherwise observable only at very high redshifts; if totally metal-free ('population III') stars could be found, this would allow the direct study of the pristine gas from the Big Bang. Earlier searches for such stars found none with an iron abundance less than 1/10,000 that of the Sun, leading to the suggestion that low-mass stars could form from clouds above a critical iron abundance. Here we report the discovery of a low-mass star with an iron abundance as low as 1/200,000 of the solar value. This discovery suggests that population III stars could still exist--that is, that the first generation of stars also contained long-lived low-mass objects. The previous failure to find them may be an observational selection effect.

Percutaneous radio-frequency thermal ablation of nonresectable hepatocellular carcinoma after occlusion of tumor blood supply

PURPOSE

To evaluate the usefulness of percutaneous radio-frequency (RF) thermal ablation of nonresectable hepatocellular carcinoma (HCC) after occlusion of the tumor arterial supply.

MATERIALS AND METHODS

Sixty-two patients with cirrhosis and biopsy-proved HCC underwent RF ablation after interruption of the tumor arterial supply by means of occlusion of either the hepatic artery with a balloon catheter (40 patients) or the feeding arteries with gelatin sponge particles (22 patients).

RESULTS

After a single RF procedure in 56 patients and after two procedures in six patients, spiral computed tomography (CT) demonstrated a nonenhancing area corresponding in shape to the previously identified HCC, which was suggestive of complete necrosis. No major complications occurred. Two patients subsequently underwent surgical resection; the remaining 60 patients were followed up with spiral CT. During a mean follow-up of 12.1 months, 11 HCC nodules showed areas of local progression; 49 were identified as nonenhancing areas with a 40%-75% reduction in maximum diameter. The 1-year estimate of failure risk was 19% for local recurrence and 45% for overall intrahepatic recurrence. The estimated 1-year survival was 87%. Histopathologic analysis of one autopsy and two surgical specimens revealed more than 90% necrosis in one specimen and 100% necrosis in two.

CONCLUSION

HCC nodules 3.5-8.5 cm in diameter can be ablated in one or two RF sessions after occlusion of the tumor arterial supply.

Fertility and obstetric outcome after laparoscopic myomectomy of large myomata: a randomized comparison with abdominal myomectomy

The purpose of this study was to compare, in infertile patients, the efficacy of laparoscopic myomectomy versus abdominal myomectomy, in restoring fertility and to evaluate the obstetric outcomes. Between January 1993 and January 1998, 131 patients of reproductive age, with anamnesis of infertility, underwent myomectomy because of the presence of at least one large myoma (diameter greater than or = 5 cm). Patients were randomly selected for treatment by laparotomy (n = 65) or laparoscopy (n = 66). The two groups were homogeneous for number, size and position of large myomata. Significant differences were found in the post-operative outcome: febrile morbidity (> 38 degrees C) was more frequent in the abdominal than in the laparoscopic group (26.2 versus 12.1%; P < 0.05). Laparotomy caused a more pronounced haemoglobin drop (2.17 +/- 1.57 versus 1.33 +/- 1.23; P < 0.001); three patients received a blood transfusion after laparotomy and none after laparoscopy. The post-operative hospital stay was shorter in the laparoscopic group (142.80 +/- 34.60 versus 75.61 +/- 37.09 h; P < 0.001). No significant differences were found between the two groups as concerns pregnancy rate (55.9% after laparotomy, 53.6% after laparoscopy), abortion rate (12.1 versus 20%), preterm delivery (7.4 versus 5%) and the use of Caesarean section (77.8 versus 65%). No case of uterine rupture during pregnancy or labour was observed.

Hepatitis C virus genotypes and risk of hepatocellular carcinoma in cirrhosis: a prospective study

A prospective study was performed to establish whether infection with specific hepatitis C virus (HCV) genotypes was associated with an increased risk of development of hepatocellular carcinoma (HCC) in cirrhosis. A cohort of 163 consecutive hepatitis C virus antibody (anti-HCV)-positive cirrhotic patients was prospectively evaluated for the development of HCC at 6-month intervals by ultrasound (US) scan and alpha-fetoprotein (AFP) concentration. HCV genotypes were determined according to Okamoto. Risk factors associated with cancer development were analyzed by univariate and multivariate statistics. At enrollment, 101 patients (62%) were infected with type 1b, 48 (29.5%) were infected with type 2a/c, 2 (1.2%) were infected with type 3a, 1 (0.6%) was infected with type 1a, 3 (1.8%) had a mixed-type infection, and, in 8 patients (4.9%), genotype could not be assigned. After a 5- to 7-year follow-up (median, 68 months), HCC developed in 22 of the patients, 19 infected with type 1b and 3 with type 2a/c (P < .005). Moreover, HCC developed more frequently in males (P < .01), patients with excessive alcohol intake (P < .01), those over 60 years of age (P < .02), and in patients who did not receive interferon treatment (P < .02). Multivariate analysis showed that type 1b was the most important risk factor associated with tumor development (odds ratio 6.14, 1.77-21.37 95% confidence interval). Other independent risk factors were older age and male sex. Cirrhotic patients infected with HCV type 1b carry a significantly higher risk of developing HCC than patients infected by other HCV types. The latter may require a less intensive clinical surveillance for the early detection of neoplasia.

Heterocyclic amine content in beef cooked by different methods to varying degrees of doneness and gravy made from meat drippings

Meats cooked at high temperatures sometimes contain heterocyclic amines (HCAs) that are known mutagens and animal carcinogens, but their carcinogenic potential in humans has not been established. To investigate the association between HCAs and cancer, sources of exposure to these compounds need to be determined. Beef is the most frequently consumed meat in the United States and for this study we determined HCA values in beef samples cooked in ways to represent US cooking practices, the results of which can be used in epidemiological studies to estimate HCA exposure from dietary questionnaires. We measured five HCAs [2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)] in different types of cooked beef using solid-phase extraction and HPLC. Steak and hamburger patties were pan-fried, oven-broiled, and grilled/barbecued to four levels of doneness (rare, medium, well done or very well done), while beef roasts were oven cooked to three levels of doneness (rare, medium or well done). The measured values of the specific HCAs varied with the cut of beef, cooking method, and doneness level. In general, MeIQx content increased with doneness under each cooking condition for steak and hamburger patties, up to 8.2 ng/g. PhIP was the predominant HCA produced in steak (1.9 to 30 ng/g), but was formed only in very well done fried or grilled hamburger. DiMeIQx was found in trace levels in pan-fried steaks only, while IQ and MeIQ were not detectable in any of the samples. Roast beef did not contain any of the HCAs, but the gravy made from the drippings from well done roasts had 2 ng/g of PhIP and 7 ng/g of MeIQx. Epidemiological studies need to consider the type of meat, cooking method and degree of doneness/surface browning in survey questions to adequately assess an individual's exposure to HCAs.

Brain temperature, body core temperature, and intracranial pressure in acute cerebral damage

OBJECTIVES

To assess the frequency of hyperthermia in a population of acute neurosurgical patients; to assess the relation between brain temperature (ICT) and core temperature (Tc); to investigate the effect of changes in brain temperature on intracranial pressure (ICP).

METHODS

The study involved 20 patients (10 severe head injury, eight subarachnoid haemorrhage, two neoplasms) with median Glasgow coma score (GCS) 6. ICP and ICT were monitored by an intraventricular catheter coupled with a thermistor. Internal Tc was measured in the pulmonary artery by a Swan-Ganz catheter.

RESULTS

Mean ICT was 38.4 (SD 0.8) and mean Tc 38.1 (SD 0.8) degrees C; 73% of ICT and 57.5% of Tc measurements were > or =38 degrees C. The mean difference between ICT and Tc was 0.3 (SD 0.3) degrees C (range -0.7 to 2.3 degrees C) (p=0. 0001). Only in 12% of patients was Tc higher than ICT. The main reason for the differences between ICT and Tc was body core temperature: the difference between ICT and Tc increased significantly with body core temperature and fell significantly when this was lowered. The mean gradient between ICT and Tc was 0.16 (SD 0.31) degrees C before febrile episodes (ICT being higher than Tc), and 0.41 (SD 0.38) degrees C at the febrile peak (p<0.05). When changes in temperature were considered, ICT had a profound influence on ICP. Increases in ICT were associated with a significant rise in ICP, from 14.9 (SD 7.9) to 22 (SD 10.4) mm Hg (p<0.05). As the fever ebbed there was a significant decrease in ICP, from 17.5 (SD 8.62) to 16 (SD 7.76) mm Hg (p=0.02).

CONCLUSIONS

Fever is extremely frequent during acute cerebral damage and ICT is significantly higher than Tc. Moreover, Tc may underestimate ICT during the phases when temperature has the most impact on the intracranial system because of the close association between increases in ICT and ICP.

Prefrontal [correction of Prefontal] cortex in long-term memory: an "interference" approach using magnetic stimulation

Neuroimaging has consistently shown engagement of the prefrontal cortex during episodic memory tasks, but the functional relevance of this metabolic/hemodynamic activation in memory processing is still to be determined. We used repetitive transcranial magnetic stimulation (rTMS) to transiently interfere with either left or right prefrontal brain activity during the encoding or retrieval of pictures showing complex scenes. We found that the right dorsolateral prefrontal cortex (DLPFC) was crucial for the retrieval of the encoded pictorial information, whereas the left DLPFC was involved in encoding operations. This 'interference' approach allowed us to establish whether a cortical area activated by a memory task actually contributes to behavioral performance.

Corticospinal excitability modulation to hand muscles during movement imagery

Motor evoked potentials (MEPs) to magnetic transcranial stimulation (TCS) were recorded from right abductor digiti minimi (ADM) and first dorsal interosseous (FDI) muscles, sharing the same peripheral innervation but engaged in two different motor demands. In seven healthy and trained subjects, the latencies, amplitudes and variability of MEPs were investigated under the following, randomly intermingled, conditions: full muscular and mental relaxation; mental simulation of selective index finger or little finger abduction; mental non-motor activity (arithmetical calculation); and real motor task (little and index finger abduction). The whole procedure was performed by continuous audiovisual monitoring of electromyographic 'silence' in the tested muscles. The maximal facilitatory effects (= latency shortening and amplitude increase) on MEPs were induced by the real motor task. An amplitude potentiation of MEPs in both tested muscles was present during non-motor mental activity, in comparison to basal values. A further amplitude potentiation, without latency shifts, was confined to the muscle acting as 'prime mover' for the mentally simulated movement, according to the motor program dispatched but not executed by the subject. Similar results were also found in the F-wave, showing that mental simulation affects spinal motoneuronal excitability as well, although -- due to the lack of MEP and F-wave latency shift -- the main effect takes place at cortical level. The study shows that movement imagery can focus specific facilitation on the prime-mover muscle for the mentally simulated movement. This is mainly evident on FDI muscle, which controls fingers (i.e. the index) with highly corticalized motor representation.

Correlation between B-RAFV600E mutation and clinico-pathologic parameters in papillary thyroid carcinoma: data from a multicentric Italian study and review of the literature

Recently, a somatic point mutation of the B-RAF gene (V600E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence variable among different series. Since discordant data on the clinico-pathologic features of B-RAF mutated PTC are present in the literature, the aim of the present co-operative study was to establish the prevalence of this genetic alteration and to perform a genotype-phenotype correlation in a large cohort of patients with PTC. To this purpose, a series of 260 sporadic PTCs with different histological variants were included in the study. The mutational analysis of the B-RAF gene was performed either by RT-PCR followed by single-stranded conformational polymorphism or by PCR and direct sequencing. Statistical analyses were obtained by means of chi2/Fisher's exact test and t-test. Overall, a heterozygous T > A transversion at nucleotide 1799 (V600E) was found in 99 out of 260 PTCs (38%). According to the histological type of the tumor, the B-RAF (V600E) mutation was present in 48.3% of cases of classic PTCs (85 out of 176), in 17.6% (nine out of 51) of follicular variants of PTCs, in 21.7% (five out of 23) in other PTC variants and in none of the ten poorly differentiated tumors. B-RAF (V600E) was significantly associated with the classic variant of PTC (P = 0.0001) and with an older age at diagnosis (P = 0.01). No statistically significant correlation was found among the presence of B-RAF (V600E) and gender, tumor node metastasis (TNM), multicentricity of the tumor, stage at diagnosis and outcome. In conclusion, the present study reports the prevalence of B-RAF (V600E) (38%) in the largest series of sporadic PTCs, including 260 cases from three different Italian referring centers. This prevalence is similar to that calculated by pooling together all data previously reported, 39.6% (759 out of 1914 cases), thus indicating that the prevalence of this genetic event lies around 38-40%. Furthermore, B-RAF (V600E) was confirmed to be associated with the papillary growth pattern, but not with poorer differentiated PTC variants. A significant association of B-RAF mutation was also found with an older age at diagnosis, the mutation being very rare in childhood and adolescent PTCs. Finally, no correlation was found with a poorer prognosis and a worse outcome after a median follow-up of 72 months.

Correlation of tumor size and survival in patients with stage IA non-small cell lung cancer

OBJECTIVE

The purpose of this study was to determine the relationship between tumor size and survival in patients with stage IA non-small cell lung cancer (non-small cell lung cancer; ie, lesions < 3 cm).

METHOD

Five hundred ten patients with pathologic stage IA (T1N0M0) non-small cell lung cancer were identified from our tumor registry over an 18-year period (from 1981 to 1999). There were 285 men and 225 women, with a mean age of 63 years (range, 31 to 90 years). The Cox proportional model was used to examine the effect on survival. Tumor size was incorporated into the model as a linear effect and as categorical variables. The Kaplan-Meier product limit estimator was used to graphically display the relationship between the tumor size and survival.

RESULTS

The Cox proportional hazards model did not show a statistically significant relationship between tumor size and survival (p = 0.701) as a linear effect. Tumor size was then categorized into quartiles, and again there was no statistically significant difference in survival between groups (p = 0.597). Tumor size was also categorized into deciles, and there was no statistical relationship between tumor size and survival (p = 0.674).

CONCLUSIONS

This study confirms stratifying patients with stage IA non-small cell lung cancer in the same TNM classification, given no apparent difference in survival. Unfortunately, these data caution that improved small nodule detection with screening CT may not significantly improve lung cancer mortality. The appropriate prospective randomized trial appears warranted.

Thermal Lesions Induced by 480 KHz Localized Current Field in Guinea Pig and Pig Liver

We evaluated the type, dimension and histopathological evolution of thermal lesions induced in guinea pig and pig liver by radiofrequency electrode needles at various temperatures for different exposure times. The greatest useful necrosis volume was induced by a needle of 1.1 mm diameter and exposed tip 10 mm long at 90 °C and 120 seconds exposure time. It was an ellipsoid with the biggest diameter of about 14 mm diameter and length of about 18 mm. It seems possible that liver tumors of not more than 20 mm diameter in patients without surgical prospects could be destroyed, ultrasonography guiding the needle into the tumor and using the temperature and exposure time mentioned above.

Somatosensory processing during movement observation in humans

OBJECTIVES

A neural system matching action observation and execution seems to operate in the human brain, but its possible role in processing sensory inputs reaching the cortex during movement observation is unknown.

METHODS

We investigated somatosensory evoked potentials (SEPs), somatosensory evoked fields (SEFs) and the temporal spectral evolution of the brain rhythms (approximately 10 and approximately 20 Hz) following electrical stimulation of the right median nerve in 15 healthy subjects, during the following randomly intermingled conditions: a pure cognitive/attentive task (mental calculation); the observation of a motoric act (repetitive grasping) with low cognitive content ('Obs-grasp'); and the observation of a complex motoric act (finger movement sequence), that the subject had to recognize later on, therefore reflecting an adjunctive cognitive task ('Obs-seq'). These conditions were compared with an absence of tasks ('Relax') and actual motor performance.

RESULTS

The post-stimulus rebound of the approximately 20 Hz beta magnetoencephalographic rhythm was reduced during movement observation, in spite of little changes in the approximately 10 Hz rhythm. Novel findings were: selective amplitude increase of the pre-central N(30) SEP component during both 'Obs-grasp' and 'Obs-seq', as opposed to the 'gating effect' (i.e. amplitude decrease of the N(30)) occurring during movement execution. The strength increase of the 30 ms SEF cortical source significantly correlated with the decrease of the approximately 20 Hz post-stimulus rebound, suggesting a similar pre-central origin.

CONCLUSIONS

Changes took place regardless of either the complexity or the cognitive content of the observed movement, being related exclusively with the motoric content of the action. It is hypothesized that the frontal 'mirror neurons' system, known to directly facilitate motor output during observation of actions, may also modulate those somatosensory inputs which are directed to pre-central areas. These changes are evident even in the very first phases (i.e. few tens of milliseconds) of the sensory processing.

Clinical applications of motor evoked potentials

Magnetic stimulation of brain and spinal roots provides a non-invasive evaluation of nervous propagation as well as of motor cortex excitability in healthy subjects and in patients affected by neurological diseases (i.e. multiple sclerosis, stroke, Parkinson's disease, myelopathies etc.). Motor areas can be reliably mapped and short- and long-term 'plastic' changes of neural connections can be studied and monitored over time. By evaluating excitatory and inhibitory phenomena following transcranial stimuli, the mechanisms of action of different drugs, including antiepileptics, can be studied. Moreover, transcranial stimulation of non-motor brain areas represents a probe for the evaluation of lateralized hemispheric properties connected with higher cortical functions. Recent studies suggest a therapeutic role of repetitive magnetic stimulation in psychiatric disorders.

Complications of ultrasonically guided fine-needle abdominal biopsy. Results of a multicenter Italian study and review of the literature. The Cooperative Italian Study Group

This report describes the complications following 10,766 ultrasonically guided fine-needle biopsies performed from 1979 to 1987 in 33 Italian echographic units. The mortality was 0.018%: the two reported deaths were due to hemoperitoneum and occurred in patients with hepatocellular carcinoma arising in a cirrhotic liver. Twenty patients (0.18%) had major complications. This series confirms that abdominal biopsy with fine needles is safe, even though our death rate was higher than in previous reports. Among the other nine fatalities following fine-needle abdominal biopsy reported in the literature, seven were secondary to hemorrhage. The biopsy of pancreatic carcinoma was more dangerous for needle-tract seeding (five of eight reported cases, including one in our series).

Repetitive transcranial magnetic stimulation of the motor cortex ameliorates spasticity in multiple sclerosis

OBJECTIVE

To investigate whether repetitive transcranial magnetic stimulation (rTMS) can modify spasticity.

METHODS

We used high-frequency (5 Hz) and low-frequency (1 Hz) rTMS protocols in 19 remitting patients with relapsing-remitting multiple sclerosis and lower limb spasticity.

RESULTS

A single session of 1 Hz rTMS over the leg primary motor cortex increased H/M amplitude ratio of the soleus H reflex, a reliable neurophysiologic measure of stretch reflex. Five hertz rTMS decreased H/M amplitude ratio of the soleus H reflex and increased corticospinal excitability. Single sessions did not induce any effect on spasticity. A significant improvement of lower limb spasticity was observed when rTMS applications were repeated during a 2-week period. Clinical improvement was long-lasting (at least 7 days after the end of treatment) when the patients underwent 5 Hz rTMS treatment during a 2-week protocol. No effect was obtained after a 2-week sham stimulation.

CONCLUSIONS

Repetitive transcranial magnetic stimulation may improve spasticity in multiple sclerosis.

Characterization of chitosan hydrochloride-mucin interaction by means of viscosimetric and turbidimetric measurements

In the present work the interaction between chitosan hydrochloride (HCS) and two different types of mucin - one obtained from bovine submaxillary glands and the other from porcine stomach - was investigated. Two hydration media were tested: distilled water and 0. 1 M HCl. Intrinsic viscosity, which provides information about polymeric chain conformation, was assessed in both media for HCS and bovine submaxillary mucin. Changes in the specific viscosity of HCS-mucin mixtures were observed as a function of the polymer:mucin weight ratio. The formation of interaction products was indicated by a minimum in the specific viscosity. Such a minimum occurred at different polymer:mucin weight ratios depending on the hydration medium and mucin type. This suggested a different stoichiometry of interaction. Turbidimetric measurements were also effected in order to evidentiate the eventual precipitation of the polymer-mucin interaction products. While in distilled water the precipitation of the interaction product did occur, in acidic medium, although a minimum in specific viscosity was observed, no precipitate was formed. The two techniques employed, viscosimetric and turbidimetric, allowed us to investigate for both mucins the influence of hydration medium on the formation of the HCS-mucin interaction products and to conclude that a slightly acid-neutral pH favours the interaction between HCS and mucins.