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Byline: Pradeep. Kumar, Manya. Prasad, Animesh. Das, Deepti. Vibha, Ajay. Garg, Vinay. Goyal, Achal. Srivastava Background: The recovery of the upper-limb (UL) motor function after ischemic stroke (IS) remains a [...]

Byline: Bablu. Rajak, Meena. Gupta, Dinesh. Bhatia, Arun. Mukherjee Background: Repetitive TMS (rTMS), a non-invasive neuro-stimulation tool based on the principle of electromagnetic induction is recently being employed both for [...]

During the last decades, transcranial magnetic stimulation (TMS) has been used as a noninvasive method to investigate motor cortical reorganization and neuroplasticity in humans after stroke. An increasing number of [...]

ABSTRACT. The contextual interference (CI) effect affirms that learning is enhanced when interference during practice is high, such as when participants practice multiple tasks in a random order. Previous research [...]

It has been shown that the negative gradient of the component of the electric field, called the activating function, contributes to nerve excitation. In this paper, the induced electric field in a 3-D human head model by transcranial magnetic stimulation (TMS) has been calculated by employing the impedance method. The activating functions are then obtained by gradient operations to the three components of the induced electric field. The activating functions are scattered over the different brain tissues. Peaks of the activating functions are presented at the interfaces of the different tissues. The largest values of the activating functions are presented in the cerebral spinal fluid (CSF). Results in this paper will be beneficial to the TMS applications in clinic as well as in the brain research. Index Terms--Activating function, impedance method, transcranial magnetic stimulation.

Byline: Parthasarathy. Thirumala, Jessie. Huang, Indraneel. Brahme, Karthy. Thiagarajan, Hannah. Cheng, Donald. Crammond, Jeffrey. Balzer Objective: To evaluate three commonly used alarm criteria for interpreting the significance and diagnostic value [...]

Byline: Pooja. Mailankody, Pramod. Pal Dystonia is a hyperkinetic movement disorder characterized by co-contraction of agonists and antagonists resulting in abnormal twisting and repetitive movements or postures, or both. Cervical [...]

Studies of semantic dementia and PET neuroimaging investigations suggest that the anterior temporal lobes (ATL) are a critical substrate for semantic representation. In stark contrast, classical neurological models of comprehension do not include ATL, and likewise functional MRI studies often fail to show activations in the ATL, reinforcing the classical view. Using a novel application of low-frequency, repetitive transcranial magnetic stimulation (rTMS) over the ATL, we demonstrate that the behavioral pattern of semantic dementia can be mirrored in neurologically intact participants: Specifically, we show that temporary disruption to neural processing in the ATL produces a selective semantic impairment leading to significant slowing in both picture naming and word comprehension but not to other equally demanding, nonsemantic cognitive tasks. repetitive transcranial magnetic stimulation | semantic cognition | temporal pole

Central thalamic electrical stimulation has been proposed as a method for remediation of acquired cognitive disability. Longstanding experimental and clinical observations indicate a key role for neurons within the central thalamus in maintaining the alert waking state and facilitating attended behaviors. Here, we show that continuous high frequency (100 Hz) electrical stimulation of the central thalamus generates widespread cortical activation of c-fos across all cortical layers and a selective pattern of regulation of zif268 within the supragranular, granular, and infragranular cortical laminae. Significant elevation of both immediate early genes also is seen in the dentate gyrus of the hippocampus. Use of the same stimulation parameters is shown to facilitate untrained goal-directed seeking behavior and object recognition memory in rodents. An overall increase of exploratory motor behaviors and grooming activity also is observed, consistent with a global increase in arousal. Taken together, these studies indicate that electrical stimulation of the central thalamus may enhance cognitive performance through neocortical and hippocampal neuronal activation and specific regulation of gene expression. attention | deep brain stimulation | gene expression | intralaminar thalamus | neuromodulation

Transcranial magnetic stimulation (TMS) is used commonly as both a diagnostic tool and as an alternative to electric shock therapy for the treatment of clinical depression. Among the clinical issues encountered in its use is the mitigation of accompanying pain. The objective becomes one of minimizing the induced surface field while still achieving the target field objective. Three techniques discussed for realizing this end are 1) placing a conducting shield over a portion of the central target region, 2) using supplementary coils of opposite polarity in tandem with the primary field, and 3) opening the core angle to distribute the field. Option (3) shows the greatest promise for reducing the ratio of the maximum surface field to the induced target field Index Terms--Electric field, iron core, magnetic, stimulation, suppression.

Byline: G. W. Thickbroom (1), M. L. Byrnes (1), S. A. Archer (1), A. G. Kermode (1), F. L. Mastaglia (1) Keywords: multiple sclerosis; cortical organisation; transcranial magnetic stimulation Abstract: Our objective was to determine whether there are changes in the corticomotor map for the hand in multiple sclerosis, and whether these changes correlate with indices of motor function and measures of corticomotor conduction or excitability. Transcranial magnetic stimulation (TMS) maps, motor evoked potential (MEP) latency and amplitude, motor threshold and EDSS and Purduepegboard measurements were made in 26 subjects with relapsingremitting multiple sclerosis. Correlations were sought between these measurements using the Pearson product--moment correlation with a level of significance of p = 0.05 (two--tailed). Map displacement was positively correlated with MEP latency (p = 3x10.sup.--4) and EDSS (p = 0.007), and negatively correlated with Purdue score (p = 4x10.sup.--4). Purdue scores correlated with all MEP parameters (latency, p = 4x10.sup.--10 threshold, p = 4x10.sup.--6 amplitude, p = 0.003). We conclude that motor reorganisation is associated with impaired corticomotor conduction and may reflect a process of neural plasticity associated with axonal demyelination in MS. An understanding of motor function in MS should incorporate models of both axonal demyelination and conduction deficits as well as neural plasticity. Author Affiliation: (1) Centre for Neuromuscular and Neurological Disorders M518, University of Western Australia, Queen Elizabeth II Medical Centre, Nedlands (WA) 6009, Australia Article History: Registration Date: 01/01/2005 Received Date: 15/07/2004 Accepted Date: 09/11/2004 Online Date: 06/03/2005

Byline: Abena D. Osei-Lah (1), Kerry R. Mills (1) Keywords: Central motor conduction; MEP latency; transcranial magnetic stimulation; amyotrophic lateral sclerosis; corticospinal tract Abstract: Abstract Evidence of upper motor neuron (UMN) dysfunction is essential in making the diagnosis of amyotrophic lateral sclerosis (ALS). Central motor conduction (CMC) abnormalities detected using transcranial magnetic stimulation (TMS) are presumed to reflect UMN dysfunction. CMC is, however, often normal in patients with classical sporadic ALS. The aim of the study was to determine whether the utility of the CMC measure in ALS could be enhanced. We measured CMC to four pairs of muscles (abductor digiti minimi (ADM), biceps, vastus medialis (VM) and abductor hallucis (AH) in 20 controls and 25 ALS patients. The commonest abnormality detected in the ALS patients was an absent MEP, found in 11 patients (44 %) and in 25 of 200 muscles examined. Studying a minimum of three muscles increased the probability of detecting UMN dysfunction. Weakness in the muscle as well as selecting a distal rather than a proximal muscle was significantly associated with an abnormal CMC. Interside differences in CMC were significantly more pronounced in the patient group. In 30% of patients a significant interside difference in AH CMC time was the sole abnormality, suggesting mild UMN dysfunction on the side with the longer CMC. Author Affiliation: (1) Department of Clinical Neurophysiology, Guy's, King's and St. Thomas' School of Medicine, London, SE5 9RS, UK Article History: Registration Date: 01/01/2004 Received Date: 05/11/2003 Accepted Date: 10/05/2004 Article note: Financial support from the Wellcome Trust is gratefully acknowledged.

Keywords: ischemic stroke; transcranial magnetic stimulation; motor evoked potential; prognosis Abstract: Functional derangements in the brain during the acute period of ischemic hemispheric stroke (IS) were assessed in terms of the severity of the motor neurological deficit in the acute period of IS and neurophysiological measures of motor evoked potentials (MEP) using transcranial magnetic stimulation (TCMS). A total of 52 patients (23 women, 29 men, mean age 58.5 +- 8.7 years) were studied. Patients were divided into two subgroups: group 1 consisted of 29 patients with good functional outcomes from the acute period group 2 consisted of 23 patients with poor functional outcomes. The use of TCMS for recording MEP demonstrated increases in the latency of the M response both after stimulation of the projection of the motor area of the cortex of the lesioned hemisphere and after stimulation of the spinal cord. There were increases in the central motor conduction time (CMCT) in the lesioned hemisphere of the brain and a negative correlation was seen between the severity of the neurological defect and CMCT on the one hand (r = --0.65 to --0.78 p &lt 0.001) and, on the other, the latency of the M response in TCMS of the motor zone of the cortex on the side of the hemispheric stroke (r = --0.65 to --0.79 p &lt 0.001). The increases in the latency of the M response and CMCT have prognostic significance for early assessment of the outcome of IS. Article History: Registration Date: 12/10/2004

Byline: Petr KaAovsky (1), Martin Bares (1), Hana Streitova (1), Hana Klajblova (1), Pavel Daniel (1), Ivan Rektor (1) Keywords: Key words cervical dystonia; cortical excitability; cortical inhibition; somatosensory evoked potentials; transcranial magnetic stimulation Abstract: Cortical excitability and cortico-cortical inhibition were examined in twenty-one patients suffering from idiopathic rotational cervical dystonia. Polymyography of cervical muscles, somatosensory evoked potential recordings, and paired transcranial magnetic stimulation were used to assess the dystonic disorder. The results were compared with those obtained in a group of sixteen healthy age-matched volunteers. Statistically significant differences between the patient group and the control group were found when the amplitude values of the mean P22/N30 component measured at F [3, 4] and C[3, 4]' electrode positions were compared. The mean amplitude of P22/N30 in both of these electrode positions contralaterally to the direction of head deviation was significantly higher in the patient group (p a$? 0.05). The mean side-to-side P22/N30 amplitude ratio was calculated in both groups in the F[3, 4] and C[3, 4]' electrode positions: there was a significant difference between the two groups. The mean ratio (calculated contralaterally/ipsilaterally in the patient group and left/right side in the control group) was significantly higher in the patient group (p a$? 0.05). There were statistically significant differences between the two groups when the mean values of MEP amplitudes following paired stimuli at short and medium interstimulus intervals (ISI)) were compared. The percentage of amplitude reduction registered at short ISI was significantly lower in the patient group when both 3 ms ISI and 5 ms ISI were considered, and when the hemisphere contralateral to the direction of head deviation was stimulated. There was also a difference (with the short ISI) when the hemisphere ipsilateral to the direction of head deviation was stimulated, but this difference was not significant (p &lt 0.5). Almost all of the amplitude changes following the paired stimulus at the longer ISI, i. e. 10, 15, and 20 ms were significantly different when the patient group was compared with control group: when the ipsilateral hemisphere was stimulated, the amplitude of conditioned responses was significantly higher following all three paired stimuli (with 10, 15, and 20 ms ISI) at the p a$? 0.05 significance level when the contralateral hemisphere was stimulated, they were significantly higher following the 10 and 20 ms ISI paired stimuli (significance level p a$? 0.05). The interhemispheric difference in the patient group was significant only for the paired stimuli using 3 and 5 ms (short) ISI and 15 and 20 ms (medium) ISI. There was a significantly decreased inhibition at 3 and 5 ms ISI when the hemisphere contralateral to the direction of head deviation was stimulated, as compared with the hemisphere ipsilateral (p a$? 0.05). Similarly, there was a significantly increased facilitation at 15 and 20 ms when the hemisphere contralateral to the direction of head deviation was stimulated, as compared with the hemisphere ipsilateral (p a$? 0.05). The results indicate that a disorder of both cortical excitability and intracortical inhibition exists in patients with cervical dystonia, and that this disorder is lateralized, i. e. it is located within the hemisphere contralateral to the direction of head deviation. Author Affiliation: (1) 1st Department of Neurology, Masaryk University, St. Anne Hospital, PekaAska 53, 656 91 Brno, Czech Republic. pkanov@med.muni.cz or: petr.kanovsky@fnusa.cz, CZ Article note: Received: 5 March 2002, Received in revised form: 1 August 2002, Accepted: 2 August 2002 Correspondence to Doc. MUDr Petr KaAovsky, CSc.

Byline: Giampietro Zanette (1), Stefano Tamburin (2), Paolo Manganotti (2), Nicola Refatti (1), Antonio Forgione (1), NicolA2 Rizzuto (1) Keywords: Key words amyotrophic lateral sclerosis (ALS); transcranial magnetic stimulation (TMS); intracortical inhibition (ICI); motor cortex hyperexcitability Abstract: 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. Author Affiliation: (1) Dipartimento di Scienze Neurologiche e della Visione, Sezione di Neurologia, Ospedale Policlinico G. B. Rossi, piazzale Scuro, 37134 Verona, Italy. gi.zanette@libero.it, IT (2) Department of Neurological Sciences and Vision, Section of Neurological Rehabilitation, University of Verona, Italy, IT Article note: Received: 10 January 2002, Accepted: 12 July 2002 Correspondence to Giampietro Zanette, MD

Byline: I. A. Solopova (1), O. V. Kazennikov (1), N. V. Deniskina (1), Yu. P. Ivanenko (1), Yu. S. Levik (1) Abstract: The role of supraspinal structures in postural adjustment upon standing on stable and unstable supports was studied in healthy individuals. For this purpose, transcranial magnetic stimulation (TMS) of the motor cortex was used in the region of leg representation. The subject stood with the eyes closed on a firm floor or on an unstable support in the form of a paperweight (20 cm in height, with a base radius of 32 cm) with mobility in the sagittal direction. Electric responses of four muscles--the soleus muscle, the anterior tibial muscle, the femoral biceps muscle, and the femoral rectus muscle--were recorded. It was shown that, in all the muscles, the response to TMS upon standing on an unstable support increased by 1.8--2.7 times as compared with the response upon standing on a firm floor. Since the increase in the tonic activity of the muscles studied was statistically insignificant upon switching over from standing on a firm floor to standing on an unstable support, it is hypothesized that the increase in the amplitude of muscle responses is connected with an increased activity of the supraspinal structures or with an increase in the effectiveness of corticospinal connections. The results are discussed from the point of view of the role of the motor cortex in maintaining balance on an unstable support. Author Affiliation: (1) Institute of Problems of Information Transfer, Russian Academy of Sciences, Bol'shoi Karetnyi per. 19, Moscow, 101447, Russia Article History: Registration Date: 12/10/2004

Byline: R. F. Gimranov (1) Abstract: Since 1985, transcranial magnetic stimulation (TMS) has been widely used for the investigation of different processes in the human central nervous system. We studied the thresholds of the motor-evoked responses (MER) during TMS and their hemispheric differences in healthy subjects and patients with brain tumors of different localization: in the brainstem projection, left and right motor areas, and left frontal-temporal area. The obtained results testify to a lower threshold of MER in healthy subjects during TMS of the dominant hemisphere. In patients with brainstem tumors, there was a decrease in the thresholds of MER during TMS. In patients with tumors in the motor area, the thresholds of MER were increased on the lesion side, whereas in patients with tumors in the left temporal area, the thresholds were significantly decreased during TMS of the lesioned hemisphere. Author Affiliation: (1) Burdenko Institute of Neurosurgery, Russian Academy of Medical Sciences, 4-ya Tverskaya-Yamskaya ul. 16, Moscow, 125047, Russia Article History: Registration Date: 12/10/2004

Byline: Peter P. Urban (1), S. Wicht (1), H. C. Hopf (1) Keywords: Key words Amyotrophic lateral sclerosis; Cortico-bulbar tract; Hypoglossal nerve; Facial nerve; Cortico-spinal tract; Transcranial magnetic stimulation Abstract: Background An upper motor neuron (UMN) lesion in amyotrophic lateral sclerosis (ALS) is often difficult to identify because clinical signs may be discrete or masked by severe simultaneous LMN lesions. We compared the diagnostic sensitivity of transcranial magnetic stimulation (TMS) to cranial muscles and limb muscles in the detection of UMN lesions. Design We investigated corticobulbar and corticospinal tract function to the tongue/orofacial muscles and abductor digiti minimi/tibial anterior muscles with TMS in 51 patients with ALS to compare the diagnostic yield in the detection of UMN dysfunction. An UMN lesion was assumed when the following were found: the peripheral conduction time and amplitude of the M-wave were within the normal range, the response to cortical stimulation was absent, the TMS evoked/M-wave amplitude ratio was reduced, and the central motor conduction time or the interside difference was delayed (&gt mean+2.5 SD). Results On the basis of these criteria a UMN lesion to the orofacial muscles was identified in 24 patients (47 %), to the tongue in 27 (53 %), and to the upper and lower limbs in 13 (25 %) and 22 patients (43 %), respectively. Combined abnormalities from all sites increased the diagnostic yield to 39 patients (76 %). TMS of the limb muscles confirmed a UMN lesion in only 15 (54 %) of the 28 patients with clinically confirmed UMN involvement. This number increased to 23 patients (82 %) if tongue and orofacial muscles were taken into acount. Conclusion Our results indicate the early and in most cases subclinical corticobulbar tract involvement of the central motor pathways to the orofacial muscles and tongue in ALS. TMS of the tongue and orofacial muscles had a higher sensitivity in identifying UMN lesions than that of the upper and lower limbs. Author Affiliation: (1) Neurologische Klinik und Poliklinik, Langenbeckstr. 1, 55101 Mainz, Germany, Tel.: +49-6131/175162, Fax: +49-6131/173271, E-mail: urban@neurologie.klinik.uni-mainz.de, DE Article note: Received: 13 December 2000, Received in revised form: 15 March 2001, Accepted: 1 April 2001

Byline: Hotetsu Shimamoto (1), Katsuyuki Takasaki (2), Minoru Shigemori (2), Toshihiro Imaizumi (3), Mitsuyoshi Ayabe (3), Hiroshi Shoji (3) Keywords: Key words Parkinson's disease; Transcranial magnetic stimulation; Hoehn and Yahr staging; Dopamine; Homovanillic acid Abstract: The therapeutic effect of repetitive transcranial magnetic stimulation (rTMS) on clinical performance was assessed by a double-blind study in 9 patients with Parkinson's disease (PD). Nine other patients underwent sham stimulation as controls. The modified Hoehn and Yahr (H&amp Y) staging scale, the Schwab and England Activities of Daily Living (ADL) scale, and the Unified Parkinson's disease rating scale (UPDRS) were used to assess changes of clinical performance. Patients were assessed prior to and following 2 months of rTMS. In addition, the mechanism of rTMS was investigated by dopamine and homovanillic acid (HVA) in the lumbar cerebrospinal fluid (CSF) of 17 patients before and after therapeutic rTMS for three or four months. rTMS was applied manually to the frontal areas 60 times per session, i. e., 30 times per side using a large circular coil, a pulse intensity of 700 V, and a frequency of 0.2 Hz. Sessions were continued once a week for 2 months. The 9 control patients showed no changes of symptoms between the initial evaluation and that after 2 months of sham rTMS. In contrast, all 9 patients receiving rTMS showed a significant decrease of the modified H&amp Y and UPDRS scores after 2 months, while the Schwab and England ADL Scale scores increased significantly. In the second CSF sample from patients receiving rTMS, HVA showed a significant decrease These results suggest that rTMS is beneficial for the symptoms of Parkinson's disease and that it may act via inhibition of dopaminergic systems. Author Affiliation: (1) Director of Shimamoto Neurosurgical Clinic, Kurume University School of Medicine, 11-18-3-chome Ohgi, Ohnoji-citiy, Fukuoka, 816-0911 Japan, Tel.: +81-92/5 13-05 03, Fax: + 81-92/5 13-05 07, JP (2) Department of Neurosurgery, Kurume University School of Medicine, JP (3) Department of Neurology, Kurume University School of Medicine, JP

Byline: Joachim Liepert (1), Ina Uhde (2), Sylvia Graf (2), Ottmar Leidner (2), Cornelius Weiller (1) Keywords: Key words Stroke; Transcranial magnetic stimulation; Rehabilitation; Forced-use therapy; Plasticity Abstract: Treatment-induced plastic changes were investigated in the brains of stroke patients in the subacute stage of illness. Nine patients participated in 1 week of conventional physiotherapy. In the subsequent week conventional physiotherapy was combined with forced-use therapy. Focal transcranial magnetic stimulation was used to determine the motor output areas of the abductor pollicis brevis muscles prior to the treatment and after the first and after the second week. Motor performance was evaluated using the Nine Hole Peg Test, the Frenchay Arm Test and vigorometry to measure the grip strength. Before treatment the cortical representation area of the paretic hand muscle was significantly smaller than the contralateral side. This difference persisted after the first week of physiotherapy. In contrast, the motor output map in the affected hemisphere was significantly enlarged after forced-use therapy. This increase in motor cortex excitability was accompanied by a significant improvement in dexterity. Across the two treatment weeks the centres of the motor output maps shifted significantly stronger in the affected hemisphere than in unaffected hemisphere, suggesting the recruitment of adjacent brain areas. We conclude that the combination of forced-use therapy and conventional physiotherapy enhances motor cortex excitability and improves motor performance compared to a preceding conventional physiotherapy alone. Due to the small number of patients and the lack of a control group, these results are preliminary observations and require replication in a larger sample. Author Affiliation: (1) Department of Neurology, Friedrich Schiller University, Jena, Germany, DE (2) Department of Neurology, Moritz-Klinik, Bad Klosterlausnitz, Germany, DE Article note: Received: 2 February 2000, Received in revised form: 22 June 2000, Accepted: 20 November 2000

Byline: M. I. Polkey (1), A. Duguet (2), Y. Luo (3), P. D. Hughes (1), N. Hart (1), C.-H. Hamnegard (4), M. Green (1), T. Similowski (2), J. Moxham (3) Keywords: Key words Magnetic stimulation; Phrenic nerves; Diaphragm; Fatigue Abstract: Objective: Anterior magnetic stimulation (aMS) of the phrenic nerves is a new method for the assessment of diaphragm contractility that might have particular applications for the clinical assessment of critically ill patients who are commonly supine. Design: We compared aMS with existing techniques for measurement of diaphragm weakness and fatigue in 10 normal subjects, 27 ambulant patients with suspected diaphragm weakness and 10 critically ill patients. Setting: Laboratory and intensive care unit of two university hospitals. Results: Although aMS was not demonstrably supramaximal in normal subjects, the mean value of twitch transdiaphragmatic pressure (Tw Pdi) obtained at 100 % of stimulator output, 23.7 cm[H.sub.2]O, did not differ significantly from that obtained with bilateral supramaximal electrical stimulation (ES), 24.9 cm[H.sub.2]O, or bilateral anterior magnetic phrenic nerve stimulation (BAMPS), 27.3 cm[H.sub.2]O. A fatiguing protocol produced a 20 % fall in aMS-Tw Pdi and a 19 % fall in BAMPS-Tw Pdi the fall in aMS-Tw Pdi correlated with the fall in BAMPS-Tw Pdi (r .sup.2 = 0.84, p = 0.03) indicating that aMS can detect diaphragm fatigue. In ambulant patients aMS agreed closely with existing measures of diaphragm strength. The maximal sniff Pdi correlated with both the aMS-Tw Pdi (r .sup.2 = 0.60, p < 0.0001) and the BAMPS-Tw Pdi (r .sup.2 = 0.65, p < 0.0001) and the aMS-Tw Pdi was a mean (SD) 2.2 (4.3) cm[H.sub.2]O less than BAMPS-Tw Pdi. In addition, aMS correctly identified diaphragm dysfunction in patients studied on the ICU. Conclusions: We conclude that aMS is of clinical value for the investigation of suspected diaphragm weakness. Author Affiliation: (1) Respiratory Muscle Laboratory, Royal Brompton Hospital, Fulham Rd, London SW3 6NP, UK e-mail: m.polkey@rbh.nthames.nhs.uk Tel. + 44-1 71-3 51 89 39 Fax: + 44-1 71-3 51 80 29, GB (2) Laboratoire de Physiopathologie Respiratoire & Unite de Reanimation, Service de Pneumologie, Groupe Hospitalier Pitie-Salpetriere, Assistance Publique-Hopitaux de Paris and UPRES EA 2379, Universite Paris VI, Paris, France, FR (3) Respiratory Muscle Laboratory, Kings College Hospital, Bessemer Rd, London SE5 9PJ, UK, GB (4) Department of Pulmonary Medicine, Sahlgrenska University Hospital, S-413 45 Goteborg, Sweden, SE Article note: Received: 11 November 1999 Final revision received: 17 April 2000 Accepted: 26 April 2000