Biomedical subjects

O Keren

Publications and source records attributed to O Keren.

At least 19 recordsLinked to original sources

PubMed2005

Benign paroxysmal positional vertigo as the cause of dizziness in patients after severe traumatic brain injury: diagnosis and treatment.

OBJECTIVES: To identify patients with benign paroxysmal positional vertigo (BPPV) among patients with severe traumatic brain injury (TBI) and to evaluate the effectiveness of the Particle Repositioning Maneouvre (PRM). DESIGN AND METHODS: Eighteen months prospective study of 150 consecutive patients with severe TBI referred to an in-patients rehabilitation department. INTERVENTIONS: A structured interview emphasizing the possible presence of vertigo followed by a detailed neuro-otological examination. Patients diagnosed with BPPV were immediately treated with the PRM. MAIN OUTCOMES AND RESULTS: BPPV diagnosis was based on a positive Dix-Hallpike positional test. PRM efficacy was determined by repeating the positional test 1 or 2 weeks after treatment. Twenty out of 150 (13.3%) patients complained about positional vertigo. The diagnosis of BPPV was confirmed in 10 patients. Signs and symptoms were completely relieved in six patients after a single PRM, while the other four patients needed repeated treatment for complete resolution of BPPV. CONCLUSIONS: About half of the patients with severe TBI who complain about positional vertigo suffer from BPPV. These patients can be efficiently treated by physical maneouvres improving the rehabilitation outcome.

Accidents↗

PubMed2005

Heart rate variability (HRV) of patients with traumatic brain injury (TBI) during the post-insult sub-acute period.

OBJECTIVE: To evaluate heart rate variability (HRV) of patients with traumatic brain injury (TBI). METHODS: By a prospective study, the HRV was assessed in 20 patients with TBI during the sub-acute period post-injury (the first test was performed at a mean time post-insult of 38 days) and a matched control. The patients were examined twice, 1 month apart. The assessment included HRV (both in time and frequency domains), GCS, length of coma, brain CT, FIM and FAM. RESULTS: A significant difference was found between patients and controls concerning HRV total power, i.e. frequencies between 0.01-0.6 Hz (high frequency p = 0.003, low frequency p = 0.013, total power p = 0.034) and for standard deviation of RR interval p = 0.011. HRV changes were related more to the timing of the evaluation than to the severity of the brain damage. CONCLUSION: HRV differed of patients with TBI and in the control group. Tendency to HRV normalization changes was detected during the first 3 months after the injury, which suggests recovery of the autonomic nervous system.

Adolescent↗

PubMed2005

Dysfunction of the auditory efferent system in patients with traumatic brain injuries with tinnitus and hyperacusis.

OBJECTIVES: Tinnitus, hyperacusis and difficulty listening in background noise are common symptoms reported by patients with traumatic brain injury (TBI). The aim of this study was to explore the function of the auditory system in TBI patients with and without auditory complaints but having normal pure-tone audiograms. METHODS: The study consisted of 24 TBI patients with and 10 TBI patients without auditory complaints. In addition, 15 normal controls were included in the study. The function of the auditory system was tested by recording transient otoacoustic emissions (TEOAE) during the presentation of increasing levels of white noise in the contralateral ear. RESULTS: Most of the TBI patients with auditory complaints (87%) showed absent or significantly reduced effect of the auditory efferent system as compared with the TBI patients without auditory complaints and to normal controls. However, the global amplitude of the TEOAE was significantly higher in TBI patients with auditory complaints compared to those without. CONCLUSIONS: Due to its role in peripheral and central auditory activity, dysfunction of the efferent system may be at least partially responsible for these auditory complaints. This study underscores the importance of testing and evaluating the functional integrity of the medial efferent system by an objective and non-invasive method in patients with TBI.

Acoustic Stimulation↗

PubMed2005

Cerebral blood flow velocity during postural changes on tilt table in stroke patients.

AIM: The aim of the study is to investigate the correlation between orthostatic hypotension (OH), mean flow velocity (MFV) as measured by transcranial Doppler (TCD) in middle cerebral artery (MCA) bilaterally during tilt table test (TTT) and functional and neurological parameters in acute ischemic stroke patients, undergoing rehabilitation. METHODS: Thirteen patients after first ischemic stroke in the MCA territory and 13 healthy volunteers were examined. TTT was performed with elevating the subject from supine to 80 masculine standing position and back to supine within 10 min. Peripheral blood pressure was measured and monitoring of MFV in MCA of damaged and healthy hemisphere by TCD was performed during the TTT. Patients underwent the test few days after admission to rehabilitation department and were classified into 2 subgroups: those with decrease of systolic blood pressure of at least 20 mm/Hg during the test and those without the OH. RESULTS: Among patients without OH, MFV indexes were almost the same in damaged and healthy MCA and did not changed during the test. Patients with OH symptoms showed significant differences between blood flow velocities in 2 hemispheres in favor of nondamaged size. No association was found between the OH and the severity of functional and neurological status after stroke. CONCLUSIONS: These findings suggest that the appearance of OH after ischemic stroke may be associated with decreased blood flow velocity in damaged MCA at the beginning of rehabilitation treatment, but not with functional and neurological status of the patient.

Aged↗

PubMed2004

Are cannabinoid drugs neurotoxic or neuroprotective?

Chronic exposure to cannabinoids was shown to induce long lasting impairment of learning and memory, which was accompanied by morphological damage to the brain. On the other hand, several studies have shown that cannabinoids can protect from various brain traumas. This enigmatic dualism is explained herein by a comprehensive hypothesis, which is based on our recent in vitro studies and on pharmacokinetic in vivo considerations. The hypothesis predicts that low concentrations of cannabinoids will be neurotoxic while high concentrations of the drugs will protect from neuronal damage, and suggests that chronic administration of cannabinoids will induce neuronal death, while their acute administration will protect the brain. We further propose straight forward experiments, both in vivo (animal models for brain damage) and in vitro (cell death in neuronal cultures) to verify this hypothesis. The outcome of these experiments may have practical applications when considering the use of cannabinoids as therapeutic agents and in evaluating the consequences of their use as recreational drugs.

Apoptosis↗

PubMed2003

A therapeutic splint for hypertonic flexed elbow in upper motor neuron diseased patients.

Change in muscle tonus is characteristic of upper motor neuron disease. Upper limb hypertonus is mostly experienced in the flexor muscles group, causing abnormal fixed flexion of the elbow. This in turn leads to functional impairments in daily life (especially in stability while standing and walking, and in activities such as dressing), often accompanied by chronic pain. Extension of the spastic elbow is therefore a significant target goal of the rehabilitation process of these patients. This study presents the development of a simple, cheap and easy-to-use splint aimed at keeping the elbow extended. The splint is made out of cloth and plastic strips with longitudinal pockets sown into a double layer cloth surface. The splint is then wrapped and tightened around the extended elbow. The splint was applied to 30 patients with hypertonic flexed elbow. Patients were asked to keep the splint wrapped around their elbows between one to five hours a day, for a period of three weeks. They were instructed to shorten the time of use whenever they felt pain, discomfort or extended pressure on the arm. Most of the patients completed the trial as instructed and expressed their wish to carry on using it. The reported "side effects" included discomfort, feeling of pressure at the critical points and difficult self-application of the splint. The final splint model was developed based on this feedback. Its efficacy in keeping the elbow in an extended position, its low cost price and easy use makes this splint a viable and simple tool for the rehabilitation process of upper motor neuron disease patients.

Adolescent↗

PubMed2002

Brain injury-related heterotopic bone formation: treatment strategy and results.

OBJECTIVES: Heterotopic bone formation (HO) is a phenomenon occurring in some neurologically injured patients that can adversely affect their rehabilitation. The current study aimed at evaluating functional results and recurrence rates after recurrence of such lesions. DESIGN: The results of 12 excisions of HO in 9 patients were assessed. A single-dose of 750 cGy delivered 24 hr postoperatively was used in seven of nine patients. RESULTS: One year postintervention, the arc of motion averaged 92.5 degrees in the hips, 66.6 in the knees, and 60 degrees in the elbow. Despite increased uptake on bone scans in all patients, recurrence did not occur in any patient. Ambulation levels improved in four of eight hips. Ease of personal hygiene was improved in all patients, although some patients still require assistance. CONCLUSIONS: Excision of symptomatic HO is recommended if limitation of joint motion seems to hinder the patient's rehabilitation. Some motor control is desirable to achieve significant improvement in the patient's quality of life. Increased uptake on bone scans is not a contraindication to surgical excision of HO, provided the neurologic status is stabilized.

Adult↗

PubMed2001

Divers pathways mediate delta-opioid receptor down regulation within the same cell.

Various mechanisms have been proposed for opioid receptor down regulation in different experimental preparations. The present study was aimed to test whether distinct mechanisms can mediate opioid receptor down regulation within the same cell. For this purpose we transfected HEK-293 cells with rat delta-opioid receptor (DOR). We exposed the cells to the opioid agonist etorphine in the absence or presence of various pharmacological agents and measured the binding of the opioid ligand [(3)H]diprenorphine to either isolated cell membranes or whole cells. We found that internalization of the receptors into the cell was mediated by clathrin coated pits and that the internalized receptors were degraded either in lysosomes or by proteosomes. Down regulation involved phosphorylation and at least two different kinases, a tyrosine kinase (TK) and MAPK kinase (MEK), mediated DOR down regulation in parallel routes. G-protein-coupled receptor kinase (GRK) was found to have only a minor role in DOR down regulation in HEK-293 cells. On the other hand, in N18TG2 cells that endogenously express delta-opioid receptors, GRK was the predominant kinase mediating DOR down regulation, with only a minor role for TK and MEK. We conclude that down regulation can take place via divers pathways within the same cell, and that in different cells down regulation is mediated by different mechanisms, depending on the kinase profile of the cells and the compartmentalization of the receptors within the cells.

Acetylcysteine↗

PubMed2001

Tracheotomy in severe TBI patients: sequelae and relation to vocational outcome.

The aim of the present study was to find the influence of performing tracheotomy on outcome of severe TBI patients. TBI patients, many of them intubated during the very acute phase post-injury, who remain unconscious for more than a few days, undergo tracheotomy to provide a reliable long term artificial airway. Tracheotomy, although being a simple elective surgical procedure, may have a negative influence on the rehabilitation process. Tracheotomy was performed in 25% (n=69) of 277 consecutive severe TBI patients admitted to the rehabilitation department during 3 years. In seven patients (10%), tracheotomy was performed immediately after injury due to cranio-facial trauma, in 18 patients (29%) due to respiratory disturbances, in 42 patients (55%) after prolonged intubation, and in two patients (6%) due to combined problems. Forty-five per cent of patients with tracheotomy suffered from respiratory disturbances and 8.6% from complications of tracheotomy. Longer periods of unconsciousness and mechanical ventilation were significantly associated with respiratory complications (p<0.0001 and p<0.001, respectively). However, presence of tracheotomies per se, did not affect vocational rehabilitation.

Adolescent↗

PubMed2001

Combined motor disturbances following severe traumatic brain injury: an integrative long-term treatment approach.

Patients surviving severe traumatic brain injury (TBI) often suffer from residual impairments in motor control, communication skills, cognition and social behaviour. These distinctly hamper their capability to return to their 'pre-trauma' activity. Comprehensive and integrated rehabilitation programmes initiate, during the acute phase, a prolonged treatment process which starts at the most sophisticated medical systems. There is no clear end point for the treatment of these patients, since the recovery process and the rehabilitation activity may continue for years, even after patients return home to live with their families. The inherent inability to make a firm early prediction regarding outcome of patients and the late appearance of additional symptoms stress the need for a comprehensive close long-term follow-up. The following presentation concerns the description of the treatment strategy and long-term improvement of a 22-year-old male who suffered from very severe TBI. On admission to the emergency room, he was in the decerebrated position and his Glasgow Coma Scale (GCS) was at the lowest (3). The focus of this presentation is on the recovery of motor function. The initial motor disabilities included weakness in all four limbs, in particular left hemiplegia, and right hemiparesis with severe bilateral ataxic elements and a marked tremor of the right arm. Range of motion was limited in hips, and he suffered from stiff trunk and neck. Goals of physiotherapy were directed towards improving range of motion (ROM) and active movement. Casting, use of orthoses, biofeedback, hydrotherapy, hippotherapy, medication and nerve blocks for reducing spasticity were timely applied during the process. The motor improvement in this very severe TBI patient who is now over 3 years post-injury still continues and has a functional meaning. He has succeeded in being able to stand up by himself from a chair and is able to walk unaided and without orthoses for very short distances--up to five steps. He is able to drink soup without assistance and play a few notes on the piano. Marked cognitive improvement occurred as well. It is concluded that motor improvement may be evident over long periods of time and various timely interventions may assist in the process.

Activities of Daily Living↗

PubMed2001

Visual search in peripheral vision: learning effects and set-size dependence.

Feature search for a light bar with one orientation (or color) embedded in an array of bars with a very different orientation (or color) is quick, easy and independent of the number of array elements. In contrast, search for a conjunction target has a linear response time dependence on the number of distractors. Training can improve performance of both these tasks. We report that these properties may not be valid for eccentric stimulus presentation. In general, the two hemifields are not equally suited to search, and training is most effective in the weaker hemifield. In addition, the feature-search independence of set-size may not always be valid for stimulus arrays that are presented peripherally. Subjects were tested on orientation and color feature tasks, and on orientation-color conjunction search with 3 array sizes presented at fixation or eccentrically in the right or left hemifield. During a second testing session, improvement was so much greater for the non-preferred hemifield that sometimes the preference was switched. Surprisingly, preferred hemifield performance actually declined for some subjects. Thus, the hemifield preference effect seems related to competition, and perhaps an automatic attention-directing mechanism. We confirmed the central presentation set-size independence for feature search but found a great difference between large and small arrays when presentation was lateral. There are two sources of this array size effect: 1. Target eccentricity, demonstrated by comparing performance for different target locations with the same array size. 2. Target location uncertainty, seen by comparing performance for different size arrays when the target elements appeared at the same locations. Training also affected the array-size dependence, changing search performance from set-size dependent to independent or vice versa at the point of greatest training effect.

Adult↗

PubMed2001

[Relationship between type and amount of treatment and functional improvement in first-stroke during in-patients rehabilitation].

The effectiveness of ongoing rehabilitation services for post-acute stroke patients is poorly documented. The aim of the present study was describe the relationships between functional status at discharge and intensity of therapies, including occupational therapy, physical therapy, speech therapy and nursing care, during inpatient medical rehabilitation. All patients (30) admitted after a first stroke. The functional status of patients was observed by using the Functional Independence Measure on patient admission to rehabilitation and time per week during the hospitalisation. The neurological status of patients was observed by using the NIH Stroke Scale on patient admission to rehabilitation and at discharge. The study population included 30 patients of average 64.4 years; 60% were men; length of stay was 74 days. Statistical analysis were performed to check for intensity of therapies, discharge motor and cognitive function, the extent to which potential functional gains were achieved. Intensities of physical and speech therapies were not significant predictors of outcomes. Intensity of occupational therapy was significant predictor of outcomes (P = 0.04). We suggest that efficiently staged rehabilitation should vary the intensity and nature of services according to patients functional status, impairments, comorbid conditions and other clinical factors.

Activities of Daily Living↗

PubMed2000

[Botulin toxin for spasticity in spinal cord damage by treating the motor endplate].

Therapeutic injection of botulin toxin is well-recognized for reducing tonus in local dystonia. However, its efficacy in reducing spasticity in spinal cord injuries is still unproven. 4 men and 1 woman (mean age 39 years, range 20-56) with spinal cord injury and debilitating spasticity, and no response to standard treatment for spasticity received injections of botulin, 200-300 U, into 4-8 points in their legs to block muscle-nerve synapses. In all 5 tonus was reduced in the area of the block, while in some it was also reduced in more distal muscles. In 1 there was reduced tonus in both the injected and contralateral leg. The therapeutic effect on tonus persisted for 3 months. In spite of objective improvement in tonus in all 5, only 3 felt subjective improvement, but in none was there improvement on standard functional scaling. We found injection of botulin toxin effective in reducing tonus in the spinal cord-injured, and to some extent in improving subjective feeling of well-being in some of them. Objective measurement might show functional improvement after larger doses of toxin injected into more muscles. This might be necessary because the muscle mass of the legs is large and the intensity of involuntary contraction is especially high in these patients.

Adult↗

PubMed2000

Trans-tibial amputee gait: time-distance parameters and EMG activity.

Gait analysis of trans-tibial (TT) amputees discloses asymmetries in gait parameters between the amputated and sound legs. The present study aimed at outlining differences between both legs with regard to kinematic parameters and activity of the muscles controlling the knees. The gait of 14 traumatic TT amputees, walking at a mean speed of 74.96 m/min, was analysed by means of an electronic walkway, video camera, and portable electromyography system. Results showed differences in kinematic parameters. Step length, step time and swing time were significantly longer, while stance time and single support time were significantly shorter on the amputated side. A significant difference was also found between knee angle in both legs at heel strike. The biceps femoris/vastus medialis ratio in the amputated leg, during the first half of stance phase, was significantly higher when compared to the same muscle ratio in the sound leg. This difference was due to the higher activity of the biceps femoris, almost four times higher than the vastus medialis in the amputated leg. The observed differences in time-distance parameters are due to stiffness of the prosthesis ankle (the SACH foot) that impedes the normal forward advance of the amputated leg during the first half of stance. The higher knee flexion at heel strike is due to the necessary socket alignment. Unlike in the sound leg, the biceps femoris in the amputated leg reaches maximal activity during the first half of stance, cocontracting with the vastus medialis, to support body weight on the amputated leg. The obtained data can serve as a future reference for evaluating the influence of new prosthetic components on the quality of TT amputee's gait.

Adult↗

PubMed1999

Potentiation of transmitter release from NMB human neuroblastoma cells by kappa-opioids is mediated by N-type voltage-dependent calcium channels.

The selective kappa-opioid agonist trans-(+/-)-3, 4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl] benzenacetamidemethansulfonate (U50,488) potentiates both basal and depolarization-evoked [3H]dopamine release from NMB cells. The potentiation of dopamine release by U50,488 is mediated by N-type voltage-dependent calcium channels since it is blocked by omega-conotoxin, and is resistant to pertussis toxin (PTX)-treatment. When the stimulation of release by U50,488 is blocked by the N-channel antagonist omega-conotoxin, an inhibitory effect on dopamine release is revealed, suggesting that stimulatory and inhibitory effects of U50,488 are exerted in parallel.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1999

Incidence of sexual dysfunction in TBI patients during the early post-traumatic in-patient rehabilitation phase.

OBJECTIVE: The aim of the study is to find whether sexuality and intimacy dysfunction are already present at the early rehabilitation phase of TBI patients. METHODS: Forty-four consequent severe TBI patients were studied. The GCS and the duration of unconsciousness determined the initial severity of the injury. Patients' function regarding motor, language, cognition and behaviour were assessed by an interdisciplinary team. Sexuality and intimacy were evaluated by using a special closed questionnaire. RESULTS: Regarding self confidence 81% of patients described themselves as having high or average self confidences; 78% described themselves as having high or average feeling of being sexually appealing; mood level was average or high in 80% of patients. Only 7.7% of patients reported having sexual dysfunction at that phase of rehabilitation. CONCLUSIONS: Sexual dysfunction in Severe TBI patients is uncommon at the early post-traumatic phase. It is suggested that sexual dysfunction appearing during later stages of recovery is most probably related to reactive behavioural changes.

Adolescent↗

PubMed1998

Female TBI patients recover better than males.

The purpose of the present study was to look at possible gender differences in outcome after severe traumatic brain injury. Three hundred and thirty four consecutive patients, 72 females and 262 males, age range 5-65 years, were included in the study. Age range and severity of injury, evaluated by duration of unconsciousness, did not differ between male and female patients. Predicted outcome at the time of discharge from an in-patient rehabilitation programme was evaluated according to work capacity. Female TBI patients had a better predicted outcome (p < 0.015). It is suggested that progesterone, acting as a neuroprotective agent, may explain this difference in outcome.

Adolescent↗

PubMed1998

Event-related potentials as an index of cognitive function during recovery from severe closed head injury.

OBJECTIVE: To evaluate the utility and neuropsychological correlates of serially performed recordings of event-related potentials (ERPs) in patients recovering from a severe closed head injury (CHI). DESIGN: Prospective longitudinal study. SETTING: Brain injury rehabilitation unit based in a national rehabilitation hospital. SUBJECTS: Sixteen patients with severe CHI (significant degree of impaired consciousness greater than 24 hours) subclassified into two severity groups according to initial Glasgow Coma Scale (GCS) score: those with initial GCS score < 9, consistent with a more severe injury; and those with initial GCS score > 8, indicating a less severe injury. METHODS: ERPs were elicited using the standard auditory P300 "oddball" detection paradigm. ERP recordings were carried out three times: 2 months after injury, 1 month later, and 2.5 months or more after the initial study. Parameters analyzed included latencies and amplitudes of the P3, N2, P2, and N1 components of the ERPs. Correlations between changes in these ERP parameters and specific neuropsychological test results were evaluated. RESULTS: Initial P3 latencies in the more severely injured group were significantly longer (P < .05) than those recorded in the less severely injured patients. In subsequent recordings, P3 latency was found to be significantly shorter compared with the initial P3 latency, and the difference in P3 latency between the two patient groups was no longer statistically significant by the time of the third recording. For the group as a whole, P3 latency decreased significantly on each repeated recording. N2 latency was found to be significantly shorter (P < .05) between the first and third recordings. Cognitive performance significantly improved between the first and third recordings. P3 latency shortening was correlated with improvement in neuropsychological test scores for short-term and long-term story recall and for word recall. N2 latency shortening was correlated with improvement in the neuropsychological test scores for word recall only. CONCLUSION: ERP recordings performed in the subacute stage after CHI may assist in evaluating injury severity. Moreover, serially performed recordings of P3 latency may be used as a physiologic index of brain activity that correlates with recovery from CHI.

Adolescent↗