Beta-blocker migraine prophylaxis affects the excitability of the visual cortex as revealed by transcranial magnetic stimulation.

The objective of this study is to assess effects of beta-blocker migraine prophylaxis on cortical excitability determined by transcranial magnetic stimulation (TMS). Phosphene and motor thresholds (PT, MT) were investigated in 29 patients with migraine, in 15 of them prior to and following preventive medication with metoprolol and in 14 patients without prophylaxis. Following prophylaxis headache frequency significantly decreased (p = 0.005) and mean PT were significantly increased (51.5 ± 7.5 vs. 63.6 ± 8.4%) compared to patients without preventive treatment (53.7 ± 5.3 vs. 52.3 ± 6.3%; p = 0.040). Mean MT did not significantly differ either between groups or due to treatment. In the group of all patients, a significant inverse correlation between headache frequency and the level of PT was found (R = -0.629; p < 0.01). There was, however, no significant correlation in the subgroups of patients. We conclude that (a) clinical efficacy of beta-blocker treatment in migraine could be (at least partly) linked to its ability to modulate the excitability of the visual cortex and (b) the PT determined by TMS appears suitable to assess the effects of prophylaxis on cortical excitability in the individual patient. This may be useful in clinical trials investigating migraine preventive drugs.

Age-related reduction in visually evoked cerebral blood flow responses.

The influence of aging on photoreactive flow changes in the posterior cerebral artery (PCA) was investigated in 38 healthy volunteers aged 20-81 years. Mean blood flow velocity (MBFV) was measured at rest and during 10-Hz photic stimulation by transcranial Doppler sonography. The amplitude of the evoked flow response significantly decreased with age (r = -0.39; P < 0.001). In a group of elderly subjects (60-81 years), the evoked blood flow velocity increase was 10.8 +/- 2.7%, which is less than in young subjects aged 20-39 years (14.7 +/- 4.3%; P = 0.001). We conclude that normal aging affects photoreactive flow changes in the occipital lobe. This may limit the application of functional imaging studies based on measurements of blood flow changes in the elderly.

Long-term reorganization of motor cortex outputs after arm amputation.

OBJECTIVE: To investigate the reorganization of the corticospinal system long after arm amputation at different levels. METHODS: Focal transcranial magnetic stimulation (TMS) was performed in 15 patients 21 to 65 years after arm amputation at the level of the forearm, upper arm, or shoulder. Cortically elicited electromyographic responses were investigated in muscles immediately proximal to the stump. TMS was performed on a skull surface grid overlying the motor cortex. The response threshold, number of effective stimulation sites, and the sum of the amplitudes elicited at these sites were evaluated for slightly contracted muscles. RESULTS: Seven of eight patients with forearm amputation had larger stimulation effects in the biceps supplied by the motor cortex contralateral to amputation, as indicated by variable patterns of lowered response thresholds, increased response amplitudes, or increased numbers of effective stimulation sites. In seven patients with a more proximal amputation, the motor responses were investigated in the deltoid and trapezoid muscle. In only two of them, the motor cortex contralateral to amputation showed an increased excitability. Three patients presented with a higher excitability of the motor cortex contralateral to the intact arm and two with a balanced type of excitability. CONCLUSION: Reorganization of the motor system can be present more than 20 years after amputation. Furthermore, differential patterns of reorganized corticospinal output were found for different stump muscles, which might be due to varying amounts of ipsilateral corticospinal projections.

MRI study of human brain exposed to high-dose repetitive magnetic stimulation of visual cortex.

T1-, T2-, and diffusion-weighted MRI was used to determine whether repetitive transcranial magnetic stimulation (rTMS) affects the blood-brain barrier or induces localized brain edema. In 11 healthy individuals, 1,200 to 3,800 stimuli were applied over the visual cortex of one hemisphere in series of 5-, 10-, or 20-Hz stimulus trains. MRI performed 6 minutes to 6 hours after rTMS did not show pathologic changes in conventional MRI sequences, after application of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), or by determining apparent diffusion coefficients.

Morphology of acallosal brains as assessed by MRI in six patients leading a normal daily life.

The pattern of anatomical features of the brain revealed by magnetic resonance imaging (MRI) is described in six patients incidentally identified as having acallosal brains. The complex of morphological features associated with complete agenesis of the corpus callosum included lateral displacement of slitlike anterior horns of the lateral ventricles (bullhorn-like shape), dilatation of the posterior horns of the lateral ventricles, absence of the septum pellucidum, lateral displacement of the cingulate gyri, complete separation of fornices and the presence of the anterior commissure and longitudinal callosal bundles (Probst's bundles). No compensatory enlargement of the anterior commissure was seen in the patients. The planimetrically measured cross-sectional areas of the anterior commissures were between 2.0 and 4.2 mm2 (mean 3.1) (in ten normal subjects they were 4.5, SD 0.4; range 3.8-5.2 mm2) and were reduced in four and normal in two patients. Inconstant morphological features were an absence of the posterior commissure and a radial pattern of the sulci and gyri on the medial aspect of the hemispheres. Conventional clinical testing revealed no abnormalities except a slight impairment of walking heel-to-toe in two patients. None of the patients had subjective restrictions of activities of daily life, which shows the efficacy of unknown compensatory processes.

Abnormal postexcitatory and interhemispheric motor cortex inhibition in writer's cramp.

Focal transcranial magnetic stimulation (TMS) of the motor cortex was used to study excitatory and inhibitory stimulation effects in 25 patients with writer's cramp and 25 healthy volunteers. We investigated excitatory and inhibitory corticospinally mediated motor effects in muscles contralateral to the stimulation side as well as interhemispheric inhibition of tonic motor activity in muscles ipsilateral to stimulation. Motor evoked potentials (MEPs) were recorded from both first dorsal interosseus muscles. Motor thresholds at rest and amplitudes and latencies of MEPs obtained during maximal contraction were always bilaterally normal. The duration of postexcitatory inhibition was significantly shortened (168+/-55 vs. 198+/-39 ms in normal subjects, P=0.001) and the duration of interhemispheric inhibition prolonged (30.3+/-6.6 vs. 26+/-3.9 ms in normal subjects, P < 0.001). Both observations would be compatible with a decreased inhibition of corticospinal and transcallosal outputs of the motor cortex. The results were not influenced by fatigue effects. Abnormal motor cortex inhibition seems to be a generalized phenomenon in writer's cramp since it was detected in both hemispheres and during a simple isometric motor task which did not evoke dystonic symptoms.

Influence of pulse configuration and direction of coil current on excitatory effects of magnetic motor cortex and nerve stimulation.

UNLABELLED: This paper describes the influence of pulse configuration and current direction on the excitation of the hand-associated motor cortex and the median nerve by magnetic stimulation. Monophasic and biphasic current pulses with the same peak rise time of 80 micros and a maximum rate of current change (dI/dt) were discharged through an eight-shaped coil of the stimulator used (Dantec MagPro). Two current directions with opposite orientation in the coil axis were studied. FINDINGS: (1) for both, cortex and nerve stimulation, biphasic stimuli were more effective and elicited compound muscle action potentials (CMAPs) with lower thresholds and larger amplitudes. (2) Using biphasic pulses the direction of the currents in the first phase of the pulse did not influence the CMAP amplitude. (3) Using monophasic pulses induced currents oriented postero-anteriorly in the motor cortex or orthodromically along the nerve axis elicited larger CMAPs than currents in the opposite orientation. (4) Pulse configuration did not influence the CMAP-latencies and by this the stimulation site (cortex, nerve). CONCLUSION: Monophasic stimuli are useful to investigate excitation effects which are dependent on the current direction. The application of biphasic stimuli with their stronger excitation effects might be advantageous when patients with high cortical thresholds or deep lying nerves shall be investigated.

MRI study of human brain exposed to weak direct current stimulation of the frontal cortex.

OBJECTIVE: To determine whether weak transcranial direct current stimulation (tDCS), which is an interesting new tool inducing prolonged cortical excitability shifts in humans, induces brain edema, disturbance of the blood-brain barrier or structural alterations of the brain detectable by magnetic resonance imaging (MRI). METHODS: In 10 healthy individuals, tDCS, which is known to alter cortical excitability for about 1 h, was applied over motor and pre-frontal cortices. contrast-enhanced t1-, t2-, and diffusion-weighted mri was performed immediately before, 30 and 60 min after tdcs. RESULTS: MRI performed 30 and 60 min after tDCS did not show pathological signal alterations in pre- and post-contrast-enhanced T1-weighted and diffusion-weighted MR sequences. CONCLUSIONS: tDCS protocols which are known to result in cortical excitability changes persisting for an hour after stimulation do not induce brain edema or alterations of the blood-brain barrier or cerebral tissue detectable by MRI. SIGNIFICANCE: These results deliver further evidence for the safety of the currently applied tDCS protocols in humans.

Bilateral borderzone brain infarctions in association with heroin abuse.

A 25-year-old drug abuser who developed an unusual pattern of cerebral ischemic lesions is presented. Cerebral magnetic resonance imaging revealed bilateral borderzone infarctions which were attributed to a heroin-associated vasculitis of the basal cerebral arteries. Under probatory corticosteroid medication the mild neurological deficits completely disappeared.

Influence of transcranial magnetic stimulation on pupil size.

In 22 healthy subjects, painless repetitive transcranial magnetic stimulation (rTMS) was used to investigate the role of the cortex in the regulation of pupil size and the influence of TMS on the central autonomic nervous system. RTMS was performed over three brain regions of each hemisphere (frontal, central, parieto-occipital), over cervical nerve roots and in front of the ear (sham stimulation) while the size of the pupil was measured by infrared oculography. rTMS always elicited a dilatation of both pupils, with its maximum after approximately 1.5 s and without significant R-L difference in latency or amplitude of pupillary response. No differential effects were observed for stimulation over different cortex regions of one hemisphere, but stimulation over the right central region evoked a larger dilatation of the pupil than stimulation over the left. Pupillary dilatation was larger for cervical nerve root stimulation (+13.2+/-8.3% (S.D.) of baseline) than for suprathreshold cortex stimulation (+8.4+/-4.5%, five 10-Hz stimuli). Pupillary dilatation in response to magnetic cortex stimulation appears to reflect a mainly unspecific activation of the sympathetic system rather than an activation of a cortical pupillomotor centre. Sympathetic activation following rTMS of the cortex does not limit its experimental and therapeutic application.

Evaluation of cortical excitability by motor and phosphene thresholds in transcranial magnetic stimulation.

Motor threshold (MT), as determined by transcranial magnetic stimulation (TMS), is used as a parameter of cortex excitability. In TMS with single or repetitive pulses, stimulus intensities in general are referred to the individual MT, although it is unclear whether MT also reflects the excitability of nonmotor cortical areas such as the visual cortex. Visual cortex excitability can be assessed by thresholds for eliciting phosphenes (phosphene threshold, PT) following TMS over the occipital cortex. The question of a different efficacy of TMS pulses in distinct cortical areas was approached by comparing motor and phosphene thresholds using single-pulse TMS applied to the primary motor and visual cortex. The aim of the study was to clarify, whether MT and PT correlate with each other and whether MT possibly serves as a reasonable measure for the excitability of the visual cortex. In 32 healthy volunteers, TMS with biphasic single pulses was applied over the motor and visual cortex with a figure of eight-shaped coil connected to a Dantec MagPro stimulator. MT and PT were individually measured (percent of maximal stimulator output). Mean PT (61.4+/-11.7%) was significantly higher than mean MT (39.4+/-5.9%) (p=0.01). MT and PT did not correlate significantly (r=0.29, p>0.1). These findings suggest that the MT does not reflect the excitability of the visual cortex. Regarding excitatory effects, the efficacy of TMS may be different over the motor and visual cortex, likely related to a different excitability of these cortical areas. This should be considered in planning and execution of TMS studies of nonmotor cortical areas.

Normal cerebral hemodynamic response to orthostasis in Parkinson's disease.

In patients with Idiopathic Parkinson's Disease (IPD) without a history of syncope the cardiovascular and cerebrovascular response to orthostatic stress was studied to search for subclinical impairment of autoregulatory mechanisms. Fifteen patients with IPD and 15 healthy age-matched controls were studied at rest and during head-up tilt (HUT). Heart rate, mean arterial blood pressure (MAP) and mean blood flow velocity (MBFV) in the middle cerebral artery were measured simultaneously. Changes of MAP and MBFV and the relationship between both were assessed. During HUT, heart rate increased less in patients than in healthy subjects (16.3% versus 24.2%, p=0.03). In the first minute of orthostasis MAP decreased more in patients than in healthy subjects (-4.0% versus -0.6%, p=0.04). MAP reached the pre-tilt values within 2 min in healthy subjects and 5 min in patients. Cerebral blood flow velocities fell to a similar degree and with similar time characteristics in patients and controls (-15.4% versus -16.7%, p=0.3). In both groups, patients and controls, changes of MAP did not correlate with changes of MBFV. It can be concluded that in IPD patients without symptoms of orthostatic dysregulation the autonomic circulatory control is impaired while the cerebral hemodynamic regulation during orthostasis is unaffected.

[Magnetic resonance imaging of hemorrhagic transformation in ischemic posterior infarction]. / Kernspintomographische Untersuchung der hämorrhagischen Transformation ischämischer Posteriorinfarkte.

PURPOSE: To describe the incidence, time course, and clinical correlates of hemorrhagic transformation (HT) of ischemic stroke in the posterior cerebral artery territory. METHODS: Within 42 months 48 patients with 52 occipital lobe infarctions were examined by T1- and T2-weighted MR imaging. The extent and distribution of secondary hemorrhage were analysed at different intervals after stroke. Volume of ischemic and hemorrhagic infarction was measured planimetrically. RESULTS: HT was observed in 71% of the infarcts between the 5th day and up to 1 year after stroke. HT was most frequently (88%) observed in the 2nd and 3rd month. HT was present in 55% of small infarcts (< 10 cm3), in 88% of medium size (10-50 cm3), and in all large (> 50 cm3) infarcts. In 92% HT presented with petechial bleedings within the cortex (64%) or less frequently (28%) in subcortical structures. The latter types of HT showed no progression and did not increase the clinical deficits. Space-occupying bleedings occurred in only two large defects. CONCLUSIONS: In ischemic posterior infarction, HT can frequently be detected within the first three months after stroke and is predominantly of the petechial type and seems not to be relevant with regard to clinical deficits.

Transient visual blurring, retro-orbital pain and repetitive involuntary movements in unilateral carotid artery occlusion.

An 83-year-old man presented with episodes of right sided retro-orbital pain, visual disturbance, involuntary jerks of his left arm and less frequently his left leg. The symptoms could be triggered by exercise, heat or cough. EEG recordings revealed no epileptic discharges. Duplex ultrasonography showed an occlusion of the right internal carotid artery. Blood flow velocity in the right middle cerebral artery was reduced and vasomotor reactivity to hypercapnia was absent. Reduction of his antihypertensive medication rendered the patient asymptomatic. The combination of transient visual blurring, retro-orbital pain and contralateral limb shaking can be an unusual manifestation of carotid occlusive disease. In such a case, the symptoms may be managed successfully by the elevation of blood pressure.

School and nursing service managers' ability to hold their own amidst daily demands.

Improving quality of life itself subsumes the experience, maintenance, and continuous enhancement of physical and psychological health. It is therefore important for the physical and psychological health of school and nursing service managers that they are able to hold their own successfully, both personally and professionally. Bearing this in mind, the question of the extent to which school and nursing service managers succeed in holding their own (coping) successfully remains. Does their profession (field of work) influence school and nursing service managers' personal beliefs, perceptions of their coping ability amidst daily demands and their use of different types of coping strategies. The purpose of this research project was to address these issues. An empirical investigation was undertaken with reference to a theoretical framework to assess school and nursing service managers' personal beliefs, perceptions of their coping ability amidst daily demands and the coping strategies they use. Consecutive factor analytical procedures, item analyses, Hotelling T2-tests and Student t-tests were conducted on the data. The results of the analyses indicated, inter alia, that nursing service managers and, especially school managers, do not quite perceive themselves capable enough to cope with interpersonal demands. School managers find it significantly more difficult than nursing service managers to cope with demands arising from professional and personal relationships.

Application of transcutaneous oxygen measurement in podiatric surgery.

A practical, noninvasive method of determining the actual physiological state of tissue being examined is presented. The measuring of actual oxygen tension in the skin capillary bed enables the podiatric physician to assess peripheral vascular status. Healing predictability to a tissue area may also be evaluated.

An unclassified fracture of the talus.

The following is a case report detailing what appears to be a previously unreported and unclassified osteochondral fracture of the posterior talar facet. This case report will detail the diagnosis and treatment of the fracture, as well as provide a brief history of previously reported osteochondral lesions involving the talus. The authors suggest a new classification method for these types of fractures.

CT and MRI in severe hypophosphataemia with central nervous system involvement.

We report a 38-year-old woman with extreme hypophosphataemia in whom CT and MRI disclosed bilateral lesions within the basal ganglia, thalamus and occipital lobes. After adequate substitution of phosphate the lesions grossly resolved and the patient recovered. This case is the first to demonstrate that profound changes of serum phosphate may be associated with reversible brain lesions.

[Effect of drug-induced vasodilatation of basal brain arteries with nitroglycerin on blood flow velocity and volume flow in the middle cerebral artery]. / Einfluss medikamentöser Dilatation basaler Hirnarterien mittels Nitroglyzerin auf Strömungsgeschwindigkeit und Volumenfluss in der A. cerebri media.

AIM: The Müller-Casty flow index (FI) is recommended for use in transcranial Doppler sonography (TCD) to measure relative changes in volume flow. We examined the ability of the FI to assess the volume flow during diameter changes of basal cerebral arteries. METHOD: Nitroglycerin (NTG) was used to induce dilation of basal cerebral arteries without affecting cerebral blood flow. Transverse and sagittal sections of the middle cerebral artery (MCA) were obtained by magnetic resonance imaging (MRI) and blood flow velocities in the MCA were measured by TCD. The FI was calculated by multiplying Doppler shift frequency and signal power. RESULTS: NTG induced an increase of MCA-diameter in MRI. The mean FI remained approximately constant (-2.6 +/- 6%), while the mean blood flow velocity dropped significantly (-15 +/- 6%). CONCLUSION: The FI can be used to estimate volume flow in basal cerebral arteries even in case of diameter change.