Biomedical subjects

Zeev Groswasser

Publications and source records attributed to Zeev Groswasser.

8 recordsLinked to original sources

PubMed2006

Hemispheric visual atentional imbalance in patients with traumatic brain injury.

We find a spatially asymmetric allocation of attention in patients with traumatic brain injury (TBI) despite the lack of obvious asymmetry in neurological indicators. Identification performance was measured for simple spatial patterns presented briefly to a locus 5 degrees into the left or right hemifield, after precuing attention to the same (ipsilateral) or opposite (cross-hemifield) side. Though the cue was non-predictive of target location overall, performance was significantly slower for cross than for ipsilateral trials in both patients and controls. We tested 21 TBI patients without overt focal brain damage and nine control subjects. Only patients demonstrated significantly worse performance for left side presentation in the ipsilateral condition. Furthermore, in the cross-hemifield condition, the left-right difference seen in TBI patients was significantly larger-reflecting a failure in producing a leftward attention shift. Again no significant difference was found in controls. These hemifield effects suggest an asymmetry in the ability of TBI patients in shifting attention to the left hemifield, whether from central fixation or from a cue in the contra-lateral hemifield. The results support basic hypotheses regarding visual attention: Attentional control may be asymmetric and attention may be a distributed, rather than localized cortical function.

Adolescent↗

PubMed2006

Vegetative state.

Nowadays more and more patients survive severe brain injury, whether due to traumatic or other causes, owing to the technological advances in medicine. Added to this is a better understanding of pathophysiologic processes, the quality and availability of emergency medicine, and increased medical knowledge in the field. More patients are regaining consciousness than previously. Recovery of functional ability ranges from those still requiring significant nursing care to those able to function independently in activities of daily living. These changes in the levels of consciousness and function can also occur after very long periods of vegetative state. In our personal experience in the hospital, in 2004, 81% of patients in a post-traumatic vegetative state recovered some level of consciousness.

Electroencephalography↗

PubMed2004

Differential time and related appearance of signs, indicating improvement in the state of consciousness in vegetative state traumatic brain injury (VS-TBI) patients after initiation of dopamine treatment.

OBJECTIVE: The goal of the study was to look for the response of treatment with increasing doses of dopaminergic medication on the recovery of vegetative state patients post-TBI. DESIGN: A prospective study of eight patients aged 25-50 years in vegetative state (VS) of mean duration of 104 days following traumatic brain injury (TBI) was performed by investigating changes of their state of consciousness while they were treated with levodopa/carbidopa. RESULTS: Initial improvement was observed in all patients within a mean of 13 days after onset of treatment. Seven patients recovered consciousness after a mean time of 31 days of treatment. The remaining patient showed only slight improvement to minimally conscious state. The sequence of symptoms leading to recovery was the same in all patients; the first to appear was moving a limb on a request, which appeared at a mean time of 13 days. Gradual increase of dose leads to the appearance of better-organized responses like reacting to more than one command, than opening the mouth and appearance of a reciprocal contact. The only side effect was visual hallucinations in one patient, which disappeared after decreasing the dosage. CONCLUSIONS: Clinical awareness to the structured order of responses and to the effect of dosage can help clinicians in early assessment of response to dopaminergic treatment in VS patients.

Adult↗

PubMed2003

Script memory for typical and atypical actions: controls versus patients with severe closed-head injury.

OBJECTIVE: When typical and atypical information about a situation is presented, the latter is usually better recognized. This phenomenon is referred to as the 'typicality effect'. It is claimed by most theories that typical and atypical information are mediated by automatic and effortful processes, respectively. Previous studies reported that patients with closed-head injury (CHI) are impaired only on memory tasks that required effortful but not automatic processes. Accordingly, it was hypothesized that these patients would not show the typicality effect when presented with scripts composed of typical and atypical actions. METHOD: Twenty-two patients with CHI and 23 matched controls listened to two scripts which consisted of typical and atypical activities. RESULTS: As predicted, the findings of the present study revealed impaired typicality effect for patients with CHI as compared with controls. The advantage of the control group over the CHI group was more pronounced in the recognition of atypical than typical actions. CONCLUSIONS: The results are discussed in terms of the limited attentional capacity or passive learning strategy, characteristic of memory impairment in patients with CHI.

Adolescent↗

PubMed2002

Searching with unilateral neglect.

We address two longstanding conflicts in the visual search and unilateral neglect literature by studying feature and conjunction search performance of neglect patients using laterally presented search arrays. The first issue relates to whether feature search is performed independently of attention, or rather requires "spread attention." If feature search is "preattentive," it should survive neglect. However, we find neglect effects for both feature and conjunction search, suggesting that feature search, too, has an attentional requirement. The second controversy refers to the space- or object-based nature of neglect following unilateral right-hemisphere parietal lobe damage. If neglect were a purely spatial phenomenon, then we would expect no detriment in performance in the right (nonneglect) field, and diminished performance for the whole left (neglect) field. On the other hand, if neglect were purely object-based, we would expect diminished performance on the left side of the search array, irrespective of its location in the visual field. We now demonstrate a combination of strong object-based and space-based neglect effects for conjunction search with laterally placed element arrays, suggesting that these two mechanisms work in tandem.

Adult↗

PubMed2002

Impaired skill learning in patients with severe closed-head injury as demonstrated by the serial reaction time (SRT) task.

A group of 20 patients who sustained closed-head injury (CHI) and a matched control group of 20 individuals were tested on the serial reaction time (SRT) task. Three different sequence-learning measures were generated from the task: two implicit and one explicit. The two implicit sequence-learning measures include: (1) the learning rate on the first five blocks of the repeated sequence, assumed to reflect primarily general reaction time learning, and (2) the difference between the fifth block of the repeated sequence and the sixth block, a random sequence that reflects implicit sequence-specific learning. In addition, an explicit measure of sequence learning was generated. The results indicate that the CHI group was impaired on the explicit measure of sequence learning. The groups did not differ on general reaction time learning, one of the implicit measures of sequence learning. However, the control group was superior to the CHI group in learning the specific sequence repeated in the SRT task. This pattern of results is unique to the CHI group, corresponding with neither that of amnesic patients nor with that of patients with dysfunction of the basal ganglia (i.e., Parkinson's diseases).

Adolescent↗

PubMed2002

Quantitive imaging in late traumatic brain injury. Part I: late imaging parameters in closed and penetrating head injuries.

OBJECTIVE: To ascertain the value of relatively simple quantitative radiologic measurements after head injury. Despite major advances in neuroradiology, analysis and reporting of imaging studies is based primarily on individual subjective and local experience, rather than on reproducible, standardized parameters; reliance on newer technologies can improve care, but also raises diagnostic costs. DESIGN: Blinded, retrospective, quantitative assessment of computerized tomography studies done some 14 years post-injury. OUTCOME MEASURES: Frontal horn width (FHW); septum-caudate distance (SCD); temporal horn width (THW); interuncal distance (IUD); third ventricle width (3VW); ventricular score (VS); sulcal width (SW); gray-white matter discriminability (GWMD) and subjective assessment of atrophy (SAOA). RESULTS: Diffuse and frontal damage was noted in both closed (CHI) and penetrating (PHI) head injury groups. Enlargement of frontal lobe parameters (septum caudate distance and frontal horn width suggest frontal injury in both closed and penetrating traumatic brain injury (TBI). Temporal horn width and inter-uncal distance were related to VS, 3VW and FHW in closed, but not in penetrating head injury. CONCLUSIONS: Simple linear CSF space measurements are correlated with volumetric and parenchymal measures, and can represent valuable and reliable low-cost quantitative measures of long term brain damage after TBI.

Atrophy↗

PubMed2002

Quantitative imaging in late TBI. Part II: cognition and work after closed and penetrating head injury: a report of the Vietnam head injury study.

CONTEXT: Functional outcome in relation to CT findings in traumatic brain injured (TBI) patients is not well established in relation to cognitive and vocational outcome. OBJECTIVE: To investigate the possible correlation between relatively simple quantitative radiological measurements and cognitive and vocational outcome. DESIGN: Retrospective analysis of quantitative assessment of CT studies in relation to post-injury cognitive changes and vocational outcome. SETTING: US Army Medical Centre. PATIENTS: 74 penetrating head injured (PHI) and 37 closed head injured (CHI) Vietnam war veterans. OUTCOME MEASURES: The Armed Forces Qualification Test (AFQT); Disability score; Return to work. RESULTS: Total brain volume loss, third ventricle width (3VW), ventricular score (VS), and septum-caudate distance (SCD) were significantly related to cognitive change and return to work in PHI patients. Volume loss and 3VW were the most valuable radiologic predictors of outcome in multivariate linear and logistic regression models for both CHI and PHI. CONCLUSION: 3VW on late CT scans following traumatic brain injury is a powerful predictor of overall long-term cognitive outcomes and potential for return to work.

Adult↗