Sensory recovery 1 year after bridging digital nerve defects with collagen tubes.

Purpose: To investigate digital nerve regeneration following implantation of collagen tubes in a prospective study.

Methods: Forty-five digital nerve defects (≤ 2.6 cm) in the hand were reconstructed in 35 patients (6 female, 29 male; mean age, 47 y).

Altered callosal function in cerebral microangiopathy.

Callosal dysfunction is known to be evident in a variety of neurodegenerative and inflammatory diseases of the central nervous system. Cerebral microangiopathy (CMA) may also affect callosal pathways by chronic demyelination. The aim of the present study was to investigate callosal function with respect to the extent of CMA.

[Neurophysiological investigations of information processing in the somato-sensory system].

The ability of the human hand to perform complex sensorimotor tasks such as tactile exploration and grasping is based on 1. exact encoding of somatosensory information by cutaneous mechanoreceptors, 2. elaborated processing of afferent signals in somatosensory relay stations and cortex fields, 3.

Evaluation of coated oxygenators in cardiopulmonary-bypass systems and their impact on neurocognitive function.

Introduction: Coronary artery bypass graft surgery (CABG) using cardiopulmonary bypass (CPB) is assumed to be associated with a decline of neurocognitive functions. This study was designed to analyse the neurocognitive function of patients with coronary heart disease before and after CABG and to determine possible protective effects of oxygenator surface coating on neurological outcome.

Methods: Forty patients scheduled for selective CABG were prospectively randomized into two groups of 20 patients each according to the type of hollow-fibre membrane oxygenator used.

Paired associative stimulation.

Paired associative stimulation (PAS) refers to a paradigm consisting of slow-rate repetitive low-frequency median nerve stimulation combined with transcranial magnetic stimulation (TMS) over the contralateral motor cortex. This protocol has been shown to induce plastic changes of excitability in the human motor cortex. Its principles of design were shaped after associative long-term potentiation (LTP) in experimental animals, a cellular mechanism likely to be relevant for learning and memory.

Measurements of transcallosally mediated cortical inhibition for differentiating parkinsonian syndromes.

Clinicopathologic evidence suggests differential involvement of cortex and corpus callosum (CC) in various disorders presenting with a parkinsonian syndrome. We tested the hypothesis of whether neurophysiologic and morphometric assessments of CC as surrogate parameters of cortical involvement could be helpful in differential diagnosis of parkinsonian disorders. The integrity of CC was assessed neurophysiologically by measuring the ipsilateral silent period (iSP) evoked by transcranial magnetic stimulation (TMS) in a total of 25 patients with idiopathic parkinsonian syndromes (IPS), corticobasal ganglionic degeneration (CBD), progressive supranuclear palsy (PSP), or multiple system atrophy (MSA).

[Use of botulinum toxin the the treatment of muscle pain].

The analgesic effects of botulinum toxin (BTX) have been discussed controversially due to substantial placebo effects and flaws in the study designs used. Additionally, pathophysiological concepts of pain and the specific analgesic mechanisms of BTX remain largely unclear. Apart from pain reduction through the well-documented effects of BTX at the neuromuscular endplate, additional analgesic mechanisms, including other synaptic and local effects, have been suggested.

Disturbed transcallosally mediated motor inhibition in children with attention deficit hyperactivity disorder (ADHD).

Objective: The aim of this study was to investigate mechanisms of motor-cortical excitability and inhibition which may contribute to motor hyperactivity in children with attention deficit hyperactivity disorder (ADHD).

Methods: Using transcranial magnetic stimulation (TMS), involvement of the motor cortex and the corpus callosum was analysed in 13 children with ADHD and 13 sex- and age-matched controls. Contralateral silent period (cSP) and transcallosally mediated ipsilateral silent period (iSP) were investigated.

Representational cortical plasticity associated with brain tumours: evidence from laser-induced interstitial thermotherapy.

Objectives: To test the hypothesis that cortical plasticity related to destructive tumour growth is functionally relevant. This hypothesis predicts that function is dependent on the intactness of tissue surrounding the tumour.

Material And Methods: Eight patients underwent laser-induced interstitial thermotherapy (LITT) for minimally invasive palliative treatment of brain tumours located in eloquent frontal motor regions including the primary motor cortex.

A temporally asymmetric Hebbian rule governing plasticity in the human motor cortex.

Synaptic plasticity is conspicuously dependent on the temporal order of the pre- and postsynaptic activity. Human motor cortical excitability can be increased by a paired associative stimulation (PAS) protocol. Here we show that it can also be decreased by minimally changing the interval between the two associative stimuli.

Mechanisms of enhancement of human motor cortex excitability induced by interventional paired associative stimulation.

Associative stimulation has been shown to enhance excitability in the human motor cortex (Stefan et al. 2000); however, little is known about the underlying mechanisms. An interventional paired associative stimulation (IPAS) was employed consisting of repetitive application of single afferent electric stimuli, delivered to the right median nerve, paired with single pulse transcranial magnetic stimulation (TMS) over the optimal site for activation of the abductor pollicis brevis muscle (APB) to generate approximately synchronous events in the primary motor cortex.

Dysfunction of transcallosally mediated motor inhibition and callosal morphology in patients with schizophrenia.

Objective: In order to assess the functional integrity of motor pathways through the corpus callosum (CC) in patients with schizophrenia transcallosally mediated inhibition (TI) of voluntary tonic EMG activity of first dorsal interosseus muscle following ipsilateral focal transcranial magnetic stimulation (fTMS) was investigated. In addition thickness and length of CC were calculated.

Method: Twelve patients suffering from schizophrenia and 12 healthy controls were investigated.

Effects of riluzole on cortical excitability in patients with amyotrophic lateral sclerosis.

Using transcranial magnetic stimulation, the effect of riluzole (RLZ) on cortical excitability was studied in patients with amyotrophic lateral sclerosis (ALS). Paired-pulse inhibition (PPI) and paired-pulse facilitation (PPF) were reduced. RLZ partially restored deficient PPI in the first of 4 consecutive 3-month periods of testing, but left PPF unchanged.

Tactile apraxia: unimodal apractic disorder of tactile object exploration associated with parietal lobe lesions.

Tactile apraxia is characterized by an isolated disturbance of hand movements for use of and interaction with an object (transitive movements) in the presence of preserved intransitive movements (movements without use of an object, for example repetitive movements or gestures). It is, however, still unclear whether motor and sensory abnormalities represent causal or associated features of tactile apraxia. To address this question, quantitative kinematic recordings of exploratory finger movements (transitive movements) and rapid alternating finger movements (intransitive movements) were studied in 20 healthy volunteers and 22 patients with focal lesions of the parietal, anterofrontal and motor cortex.

Induction of plasticity in the human motor cortex by paired associative stimulation.

Current models of motor cortical plasticity, developed in studies on experimental animals, emphasize the importance of the conjoint activity of somatosensory afferents and intrinsic motor cortical circuits. The hypothesis that an enduring change in excitability in the cortical output circuitry can be induced in the human motor cortex by a paired-stimulation protocol was tested. Low-frequency median nerve stimulation was paired with transcranial magnetic stimulation (TMS) over the optimal cranial site for stimulating the abductor pollicis brevis muscle (APB).

Cutaneomotor integration in humans is somatotopically organized at various levels of the nervous system and is task dependent.

Integration of tactile afferent signals with motor commands is crucial for the performance of purposeful movements such as during manipulation of an object in the hand. To study the somatotopic organization of sensorimotor integration we applied electrical peripheral conditioning stimuli to a digit located near (homotopic stimulation) or distant from (heterotopic stimulation) relaxed or isometrically contracted intrinsic hand muscles at variable time intervals prior to transcranial magnetic stimulation (TMS). Cutaneous stimulation has previously been shown to modulate the amplitude of the motor evoked potential (MEP) and to shorten the duration of the silent period (SP) evoked by TMS.

Demyelination and axonal degeneration in corpus callosum assessed by analysis of transcallosally mediated inhibition in multiple sclerosis.

Objective: Following focal transcranial magnetic cortex stimulation (fTMS), inhibition of voluntary EMG activity in the ipsilateral first dorsal interosseus (FDI) muscle was studied, in order to assess the functional integrity of the corpus callosum in patients with multiple sclerosis (MS).

Methods And Results: Thirty-four patients suffering from definite MS and 12 healthy, age-matched normal subjects were examined. In mid-sagittal slices, 29 patients showed lesions within the truncus corporis callosi in T2-weighted MRI.

Differential effects on motorcortical inhibition induced by blockade of GABA uptake in humans.

1. Blockade of uptake carriers of gamma-aminobutyric acid (GABA) has been shown to modulate inhibition in cortical slices of experimental animals, although little is known about this mechanism in vivo and, in particular, in humans. 2.

Task-dependent modulation of inhibitory actions within the primary motor cortex.

In 11 healthy subjects motor-evoked potentials (MEPs) and silent periods (SPs) were measured in the right first dorsal interosseus (FDI) and abductor pollicis brevis muscles (APB): (1) when transcranial magnetic cortex stimulation (TMS) was applied at tonic isometric contraction of 20% of maximum force, (2) when TMS was applied during tactile exploration of a small object in the hand, (3) when TMS was applied during visually guided goal-directed isometric ramp and hold finger flexion movements, and (4) when at tonic isometric contraction peripheral electrical stimulation (PES) of the median nerve was delivered at various intervals between PES and TMS. Of the natural motor tasks, duration of SPs of small hand muscles was longest during tactile exploration (APB 205+/-42 ms; FDI 213+/-47 ms). SP duration at tonic isometric contraction amounted to 172+/-35 ms in APB and 178+/-31 ms in FDI, respectively.

Multimodal output mapping of human central motor representation on different spatial scales.

1. Non-invasive mapping by focal transcranial magnetic stimulation (TMS) is frequently used to investigate cortical motor function in the intact and injured human brain. We examined how TMS-derived maps relate to the underlying cortical anatomy and to cortical maps generated by functional imaging studies.

Early-onset multisystem degeneration with central motor, autonomic and optic nerve disturbances: unusual Riley-Day syndrome or new clinical entity?

We report a 21-year-old woman presenting with a slowly progressive tetraparesis, optic nerve atrophy on both sides, and autonomic disturbances since early childhood. The patient has been carefully followed up for 5 years with clinical and ancillary investigations. The results and the time course strongly suggest an underlying degenerative syndrome affecting parts of three major systems: autonomic, motor and visual.

Somatosensory evoked potentials modified by laser-induced lesions of the rat cortex.

The effect of focal application of laser energy on the modification of somatosensory evoked potentials (SEPs) was studied in sensory cortical fields of the rat. This article describes the methodological set-up for recording of SEPs and for determining location and size of the laser-induced lesion. The results show that both the size of the lesion of the somatosensory cortex, and the suppression and time of recovery of cortical SEPs varied depending on the laser energy dose.