Search results for "Transcranial"
showing 10 items of 413 documents
Involvement of Jugular Valve Insufficiency in Cerebral Venous Air Embolism
2007
Background. Cerebral venous air entrapment is a rare finding on cranial computed tomography (CT) scan. Peripheral air embolism is discussed as a potential cause. However, the mechanism of retrograde passage through internal jugular valves and veins is unclear. Case Report. The case of a patient is reported, who had air entrapment in the left cavernous sinus. Prior to CT scanning, a peripheral intravenous line had been placed. Ultrasound revealed excessive insufficiency of the left internal jugular valve. To further study the mechanism of embolism, an echo contrast agent was injected into the cubital vein. A Valsalva maneuver resulted in retrograde transition of microbubbles across the insuf…
Intravenous recombinant erythropoietin does not lead to an increase in cerebrospinal fluid erythropoietin concentration
2000
No abstract
Cortical stimulation and reflex excitability of spinal cord neurones in man.
1995
The H reflex technique was used to evaluate the influence exerted by cortical conditioning on the excitability of the alpha-motoneurone pool and on IA interneuronal activity (reciprocal inhibition). In ten subjects at absolute rest electrical and magnetic stimulation of the motor cortex was transcranially applied during flexor carpi radialis H reflex eliciting and in conditions of reciprocal inhibition induced by radial nerve stimulation. The time courses showed that at intensities below motor threshold, electrical brain conditioning induced an increase in the amplitude of the test reflex when the cortical shock was given 4 ms after the test H reflex. On the contrary, reciprocal inhibition …
Corticobulbar tract involvement in amyotrophic lateral sclerosis. A transcranial magnetic stimulation study
1998
We investigated corticobulbar tract function by recording from the tongue and orofacial muscles and using transcranial magnetic stimulation (TMS) in 30 patients with amyotrophic lateral sclerosis (ALS) in order to improve the diagnostic yield in the detection of subclinical upper motor neuron (UMN) dysfunction. A UMN lesion was assumed when the peripheral conduction time and amplitude of the M-wave were within normal range and either the response to cortical stimulation was absent, or the central conduction time was delayed (> mean + 2.5 SD). Only two patients showed clinical evidence of UMN involvement in the cranial nerves, while TMS demonstrated corticobulbar tract dysfunction in the oro…
Perceptual and response bias in visuospatial neglect due to frontal and parietal repetitive transcranial magnetic stimulation in normal subjects.
2002
Recently some authors have challenged the conventional association of directional motor neglect with damage of frontal structures, showing that pure sensory perceptual neglect (classically associated with parietal lesion) can follow damage of right frontal cortex. The aim of the present study was to assess the type of defect in visuo-spatial attention consequent upon a virtual frontal or parietal lesion induced by transcranial magnetic stimulation in normal subjects. To this purpose eleven subjects performed a visuo-spatial task requiring judgement about the length of the two segments of asymmetrically bisected horizontal lines, presented for 50 ms on a computer monitor. After each visual s…
Modulation of visual cortex excitability in migraine with aura: effects of valproate therapy.
2009
We explored the effects of valproate treatment on visual cortex excitability changes in migraine with aura patients. Abnormal cortical excitability has been suggested to play an important role in the etiopathogenesis of migraine; in particular, it has been suggested a failure of inhibitory circuits in migraine with aura. Valproate acts as a central GABA agonist and it is reasonable suppose that VPA could modify cortical excitability state. Phosphene threshold (PT) was assessed at baseline and after 1 Hz rTMS before and after one month therapy. We found that low-frequency rTMS in drug-free migraineurs decreased PT, while the treatment with the GABA agonist valproate is able to revert the eff…
Transcranial direct current stimulation over the right DLPFC selectively modulates subprocesses in working memory
2018
Background Working memory, as a complex system, consists of two independent components: manipulation and maintenance process, which are defined as executive control and storage process. Previous studies mainly focused on the overall effect of transcranial direct current stimulation (tDCS) on working memory. However, little has been known about the segregative effects of tDCS on the sub-processes within working memory. Method Transcranial direct current stimulation, as one of the non-invasive brain stimulation techniques, is being widely used to modulate the cortical activation of local brain areas. This study modified a spatial n-back experiment with anodal and cathodal tDCS exertion on th…
Impaired Glutamatergic Neurotransmission in Migraine With Aura? Evidence by an Input-Output Curves Transcranial Magnetic Stimulation Study
2011
(Headache 2011;51:726-733) Objective.— An imbalance between activity of inhibitory and facilitatory intracortical circuits could play a central role in migraine etiology. We used input–output curves to achieve further information about intracortical excitability of motor cortex in migraine with aura. Methods.— Input–output curves were measured in the right abductor pollicis brevis muscle at rest in 12 patients suffering from migraine with aura and 8 healthy subjects. Stimuli were delivered at intensity ranging from 100% to 160% of resting motor threshold with 10-second inter-stimulus intervals. Seven patients were studied before and during treatment with levetiracetam. Results.— Results sho…
Transcranial doppler and near infrared spectroscopy in the perioperative period
2013
Maintenance of adequate blood flow and oxygen to the brain is one of the principal endpoints of all surgery and anesthesia. During operations in general anesthesia, however, the brain is at particular risk for silent ischemia. Despite this risk, the brain still remains one of the last monitored organs in clincial anesthesiology.Transcranial Doppler (TCD) sonography and near-infrared spectroscopy (NIRS) experience a revival as these noninvasive technologies help to detect silent cerebral ischemia. TCD allows for quantification of blood flow velocities in basal intracranial arteries. TCD-derived variables such as the pulsatility index might hint toward diminished cognitive reserve or raised i…
Ultrasonography for evaluation of the carotid artery in head and neck cancer.
1994
The dynamic relationship of lymph node metastases to surrounding vascular structures in the neck is important for preoperative patient assessment. When carotid artery involvement is suspected, this relationship often determines whether or not to operate. In the case of adhesive neck metastases along the internal jugular vein, it becomes possible to predict preoperatively if the integrity of this vein may be preserved. Ultrasonography has the ability to differentiate subtle from gross adherence, or simple compression from vascular invasion. This is done by manually palpating the tumor mass and asking the patient to perform various maneuvers while observing on a monitor the relationship of th…