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Biomedical subjects

E Taub

Publications and source records attributed to E Taub.

At least 55 records · Page 3Linked to original sources
PubMed1999

Posterior circulation aneurysms. Technical strategies based on angiographic anatomical findings and the results of 60 recent consecutive cases.

Ninety-eight patients with aneurysms of the posterior circulation were admitted to our department from 1993 to 1997. Sixty of them underwent microsurgical treatment, mostly in the acute stage of subarachnoid hemorrhage. Peri- and intraoperative management were carried out according to a structured treatment strategy. Special aspects of surgical technique included extradural selective anterior clinoidectomy for basilar head aneurysms, lateral suboccipital craniotomy and partial condylectomy without laminectomy for aneurysms of the vertebral artery or posterior inferior cerebellar artery, and a trans-Sylvian approach, as used in selective amygdalohippocampectomy, for aneurysms of the posterior cerebral artery. A careful angiographic evaluation of the aneurysms in relation to the neighboring important arteries and bony structures was essential for optimal surgical planning. Forty-nine patients (82%) made a good recovery by 3 months after surgery. The mortality was 7%.

Acute Disease↗
PubMed1999

Constraint-Induced Movement Therapy: a new family of techniques with broad application to physical rehabilitation--a clinical review.

A new family of rehabilitation techniques, termed Constraint-Induced Movement Therapy or CI Therapy, has been developed that controlled experiments have shown is effective in producing large improvements in limb use in the real-world environment after cerebrovascular accident (CVA). The signature therapy involves constraining movements of the less-affected arm with a sling for 90% of waking hours for 2 weeks, while intensively training use of the more-affected arm. The common therapeutic factor in all CI Therapy techniques would appear to be inducing concentrated, repetitive practice of use of the more-affected limb. A number of neuroimaging and transcranial magnetic stimulation studies have shown that the massed practice of CI Therapy produces a massive use-dependent cortical reorganization that increases the area of cortex involved in the innervation of movement of the more-affected limb. The CI Therapy approach has been used successfully to date for the upper limb of patients with chronic and subacute CVA and patients with chronic traumatic brain injury and for the lower limb of patients with CVA, incomplete spinal cord injury, and fractured hip. The approach has recently been extended to focal hand dystonia of musicians and possibly phantom limb pain.

Activities of Daily Living↗
PubMed1998

Alteration of digital representations in somatosensory cortex in focal hand dystonia.

Focal hand dystonia involves a loss of motor control of one or more digits; it is associated with the repetitive, synchronous movements of the digits made by musicians over periods of many years. Magnetic source imaging revealed that there is a smaller distance (fusion) between the representations of the digits in somatosensory cortex for the affected hand of dystonic musicians than for the hands of non-musician control subjects. The data suggest that use-dependent susceptibility to digital representation fusion in cortex may be involved in the etiology of focal dystonia. A successful therapy for the condition has been developed based on this consideration.

Adult↗
PubMed1998

Reorganization of auditory cortex in tinnitus.

Magnetic source imaging was used to determine whether tonotopy in auditory cortex of individuals with tinnitus diverges from normative functional organization. Ten tinnitus subjects and 15 healthy controls were exposed to four sets of tones while magnetoencephalographic recordings were obtained from the two cortical hemispheres in sequence. A marked shift of the cortical representation of the tinnitus frequency into an area adjacent to the expected tonotopic location was observed. The Euclidean distance of the tinnitus frequency from the trajectory of the tonotopic map was 5.3 mm (SD = 3.1) compared with a distance of 2.5 mm (SD = 1.3) of a corresponding frequency in the healthy controls (t = 3.13, P < 0.01). In addition, a strong positive correlation was found between the subjective strength of the tinnitus and the amount of cortical reorganization (r = 0.82, P < 0.01). These results demonstrate that tinnitus is related to plastic alterations in auditory cortex. Similarities between these data and the previous demonstrations that phantom limb pain is highly correlated with cortical reorganization suggest that tinnitus may be an auditory phantom phenomenon.

Acoustic Stimulation↗
PubMed1998

Motor cortex plasticity during constraint-induced movement therapy in stroke patients.

Stroke patients in the chronic phase received constraint-induced (CI) movement therapy. The motor cortex was spatially mapped using focal transcranial magnetic stimulation (TMS) before and after 2 weeks of treatment. Motor-output areas of the abductor pollicis brevis muscle, motor evoked potential (MEP) amplitudes and location of centre of gravity (CoG) of motor cortex output were studied. After CI therapy, motor performance improved substantially in all patients. There was also an increase of motor output area size and MEP amplitudes, indicating enhanced neuronal excitability in the damaged hemisphere for the target muscles. The mean centre of gravity of the motor output maps was shifted considerably after the rehabilitation, indicating the recruitment of motor areas adjacent to the original location. Thus, even in chronic stroke patients, reduced motor cortex representations of an affected body part can be enlarged and increased in level of excitability by an effective rehabilitation procedure. The data therefore demonstrate a CNS correlate of therapy-induced recovery of function after nervous system damage in humans.

Brain Mapping↗
PubMed1998

Perceptual correlates of changes in cortical representation of fingers in blind multifinger Braille readers.

The mature mammalian nervous system alters its functional organization in a use-dependent manner. Enhanced stimulation of a body part enlarges its cortical representational zones and may change its topographic order. Little is known about the perceptual and behavioral relevance of these plastic alterations in cortical organization. We used blind Braille readers who use several fingers on each hand and who do so for many hours each day as a model to investigate this issue. Magnetic source imaging indicated that the cortical somatosensory representation of the fingers was frequently topographically disordered in these subjects; in addition, they frequently misperceived which of these fingers was being touched by a light tactile stimulus. In contrast, neither the disordered representation nor mislocalizations were observed in sighted controls. Blind non-teacher Braille readers who used only one finger for reading were not significantly different from the sighted controls. Thus, use-dependent cortical reorganization can be associated with functionally relevant changes in the perceptual and behavioral capacities of the individual.

Adult↗
PubMed1998

Cortical reorganization and phantom phenomena in congenital and traumatic upper-extremity amputees.

The relationship between phantom limb phenomena and cortical reorganization was examined in five subjects with congenital absence of an upper limb and nine traumatic amputees. Neuromagnetic source imaging revealed minimal reorganization of primary somatosensory cortex in the congenital amputees (M=0.69 cm, SD 0.24) and the traumatic amputees without phantom limb pain (M=0.27 cm, SD 0.25); the amputees with phantom limb pain showed massive cortical reorganization (M=2.22 cm, SD 0.78). Phantom limb pain and nonpainful phantom limb phenomena were absent in the congenital amputees. Whereas phantom limb pain was positively related to cortical reorganization (r=0.87), nonpainful phantom phenomena were not significantly correlated with cortical reorganization (r=0.34). Sensory discrimination was normal and mislocalization (referral of stimulation-induced sensation to a phantom limb) was absent in the congenital amputees. The role of peripheral and central factors in the understanding of phantom limb pain and phantom limb phenomena is discussed in view of these findings.

Adult↗
PubMed1998

Thermal and EMG biofeedback learning in nonhuman primates.

Four monkeys were found able to learn to raise and lower hand temperature and to reduce muscle tension to low levels using feedback from the target physiological system. The establishment of this model of biofeedback learning in monkeys enables work on mechanisms mediating the modes of biofeedback most used in clinical practice. Results suggest that biofeedback learning does not need to be mediated by the type of human-specific cognitive strategies employed by humans.

Animals↗
PubMed1998

Plasticity of plasticity? Changes in the pattern of perceptual correlates of reorganization after amputation.

We report a follow-up study on seven arm amputees in whom magnetic source imaging had originally revealed a strong correlation between the amount of cortical invasion of the deafferented cortex and the amount of pain evoked sensation mislocalized to the phantom limb. This re-examination was performed in order to corroborate the phenomenon of mislocalization. On follow-up examination for mislocalization 4 weeks later, a close correlation had remained between the original amount of cortical representational reorganization of the amputation zone (at the first examination) and the number of sites from where painful stimuli evoked sensations referred to the phantom limb, i.e. the amount of perceptual mislocalization, at the second examination. However, contrary to our expectation, the topography of referred sensation had completely changed in every patient. These results suggest that while the overall extent of reorganization is a rather stable phenomenon, the concomitant changes in the pattern of sensory processing are not. This may be due to the fact that alterations of sensory processing are not hardwired, but are rather mediated by an extensive and interconnected neural network with fluctuating synaptic strengths. This mechanism may be of importance for neurological rehabilitation.

Accidents↗
PubMed1998

Aneurysm surgery in the acute stage: results of structured treatment.

To evaluate the results of a structured treatment approach to aneurysm surgery in the acute stage, 150 consecutive patients with aneurysmal subarachnoid hemorrhage were studied, including 46 males and 104 females; World Federation of Neurological Surgeons grade I: 21 cases, II: 65, III: 41, IV: 23; day of operation < or = day 3: 103 cases, < or = day 7: 131. Patients underwent angiography on the day of admission or the next followed by surgery. The lamina terminalis and the membrane of Liliequest were routinely opened at surgery. The aneurysm neck was radically clipped after temporary clipping or trapping of the parent arteries. Intraoperative hemodynamic monitoring was used, and the craniotomies were closed without cisternal, epidural, or subgaleal drains. Nimodipine was given perioperatively (48 mg i.v./day for 10 to 14 days). Cases of symptomatic vasospasm were treated with selective intra-arterial administration of papaverine, sometimes combined with angioplasty. Outcome at discharge and 3 months later is good recovery in 61% and 75%, and death in 6% and 7%. The incidence of symptomatic vasospasm was 17%. Devastating vasospasms were observed in 5%. One-third of patients had mean flow velocities exceeding 120 cm/sec determined by transcranial Doppler sonography between days 4 and 14. Communicating hydrocephalus necessitating ventriculoperitoneal shunt occurred in 9%. Our results clearly show a favorable outcome compared with previous reports, especially with respect to the reduced occurrence of fatal vasospasm, hydrocephalus, and technical insufficiency.

Acute Disease↗
PubMed1997

Effects of regional anesthesia on phantom limb pain are mirrored in changes in cortical reorganization.

The causes underlying phantom limb pain are still unknown. Recent studies on the consequences of nervous system damage in animals and humans reported substantial reorganization of primary somatosensory cortex subsequent to amputation, and one study showed that cortical reorganization is positively correlated with phantom limb pain. This paper examined the hypothesis of a functional relationship between cortical reorganization and phantom limb pain. Neuroelectric source imaging was used to determine changes in cortical reorganization in somatosensory cortex after anesthesia of an amputation stump produced by brachial plexus blockade in six phantom limb pain patients and four pain-free amputees. Three of six phantom limb subjects experienced a virtual elimination of current phantom pain attributable to anesthesia (mean change: 3.8 on an 11-point scale; Z = -1.83; p < 0.05) that was mirrored by a very rapid elimination of cortical reorganization in somatosensory cortex (change = 19.8 mm; t(2) = 5.60; p < 0.05). Cortical reorganization remained unchanged (mean change = 1.6 mm) in three phantom limb pain amputees whose pain was not reduced by brachial plexus blockade and in the phantom pain-free amputation controls. These findings suggest that cortical reorganization and phantom limb pain might have a causal relationship. Methods designed to alter cortical reorganization should be examined for their efficacy in the treatment of phantom limb pain.

Adult↗
PubMed1997

Input-increase and input-decrease types of cortical reorganization after upper extremity amputation in humans.

A plastic remodeling of regions in somatosensory cortex has previously been observed to occur in separate experimental paradigms in response to loss of somatosensory input and to increase in input. In this study, both types of cortical reorganization have been observed to occur concurrently in the same adult human nervous system as a result of a single intervention. Following upper extremity amputation, magnetic source imaging revealed that tactile stimulation of the lip evoked responses not only in the area of the somatosensory cortex corresponding to the face, but also within the cortical region that would normally correspond to the now absent hand. This "invasion" of the cortical amputation zone was accompanied by a significant increase in the size of the representation of the digits of the intact hand, presumably as a result of an increased importance of sensory stimulation consequent to increased dependence on that hand imposed by the loss of the contralateral extremity.

Adolescent↗
PubMed1997

The Arm Motor Ability Test: reliability, validity, and sensitivity to change of an instrument for assessing disabilities in activities of daily living.

OBJECTIVE: To continue and expand determination of the reliability, validity, and sensitivity to change of the Arm Motor Ability Test (AMAT), an instrument for assessing deficits in activities of daily living (ADL). DESIGN: The AMAT was administered twice to patients, with an interest interval of either 1 or 2 weeks, by one of two examiners assigned to patients in counterbalanced order. Patients' interest intervals and scores on the arm portion of the Motricity Index was unknown to the raters. SETTING: A referral inpatient neurological rehabilitation center. PATIENTS: Thirty-three subacute stroke inpatients with moderate to mild upper extremity motor deficit: median Motricity-Index-Arm score = 89, median chronicity = 43d, median age = 66yr; 12 were women. MAIN OUTCOME MEASURE AND RESULTS: The AMAT was developed in 1987, and interrater reliabilities at that time were found to range from .95 to .99. The present values for interrater reliability (2 scales) from videotaped test performance were: kappas = .68 to .77. Spearman correlations = .97 to .99. For performance time, interscorer reliability from videotaped test performance was .99. Homogeneities for the three AMAT measures for the total sample (Cronbach's alpha and split-half reliability) were .93 to .99. The test-retest reliabilities for the total sample were .93 to .99. The correlations to the Motricity-Index-Arm score were .45 to .61. The AMAT detected the difference in change occurring as a result of the passage of 1 versus 2 weeks in these subacute inpatients, presumably as a result of intensive therapy and/or spontaneous recovery, confirming the results of an earlier intervention study. CONCLUSION: The AMAT is an instrument with high interrater reliability, internal consistency, and sensitivity to change, as well as having satisfactory concurrent validity.

Activities of Daily Living↗
PubMed1997

Nonlinear preprocessing in short-range motion.

The phenomenon of non-Fourier motion (visually perceived motion that cannot be explained simply on the basis of the autocorrelation structure of the visual stimulus) is well recognized, and is generally considered to be due to nonlinear preprocessing of the visual stimulus prior to a stage of standard motion analysis. We devised a sequence of novel visual stimuli in which the availability of a motion stimulus depends on the nature of the nonlinear preprocessing: an nth order stimulus Pn will generate a perception of motion if it is preprocessed by a nonlinearity of polynomial order n or greater, but not if preprocessed by a nonlinearity of polynomial order less than n. We found that unambiguous motion direction was perceived for P2, P3, and P4, but not for higher-order stimuli, and we measured the contrast thresholds for direction discrimination with superimposed noise. We found that an asymmetric compressive nonlinearity can, in a unified fashion, account for these results, while a purely quadratic nonlinearity or a rectification of the form T(p) = magnitude of p cannot. We compared velocity discrimination judgements for second-order non-Fourier stimuli (P2) with standard drifting gratings. Although velocity comparisons were veridical, uncertainties were greater for the non-Fourier stimuli. This could be reproduced by substituting a Fourier grating with superimposed noise for the non-Fourier grating. These findings are consistent with a single pathway which processes both Fourier and non-Fourier short-range motion, and are discussed in the context of other investigations which have been interpreted as demonstrating separate pathways.

Adult↗