Challenges in evaluating the oculomotor function in individuals with Rett syndrome using electronystagmography

Background

Rett syndrome (RTT) is a neurological disorder characterized by a broad spectrum of symptoms. Communication is a major area of difficulty. Use of eye tracking technology offers a potentially effective method of communication when underpinned by intact oculomotor function. In this study, oculomotor function was assessed using electronystagmography (ENG). However, challenges were encountered when examining individuals with RTT.

Development of lymphoproliferative disorder of granular lymphocytes in association with hairy cell leukemia

Lymphoproliferative disorder of granular lymphocytes (LDGL) is a low grade T-cell disease characterized by clonal expansion of large granular lymphocytes of either T cell or natural killer (NK) cell lineage that express the cytotoxic T-cell/NK cell antigens CD16, CD56 and/or CD57. LDGL has been described in association with other malignancies, leading to theories of a common abnormal stem cell as well as development of the LDGL as an immune response to a primary tumor. We have studied 32 patients with hairy cell leukemia (HCL). In 15 patients (47%) we detected an increase in cells expressing cytotoxic T-cell/NK cell antigens. In 10(31%) patients these cells were of T cell lineage, while 5 patients (16%) had increased NK-cells. T cell clonality was detected by PCR in all cases with increased cytotoxic T-cells in which adequate DNA was obtained from peripheral blood. Since in 2 patients the LDGL was not present at diagnosis but developed during follow up, our data suggests that clonal LDGL may develop in response to the HCL. The significance of LDGL in the setting of HCL and flow cytometric evaluation of HCL versus LDGL will be discussed.     

Performance of 225 Dutch school children on Rey's Auditory Verbal Learning Test (AVLT): parallel test-retest reliabilities with an interval of 3 months and normative data.

Performance on Dutch adaptations of Rey's AVLT was examined in a sample of 225 6- to 12-year-old Dutch school children, selected to be representative of the general population. With an interval of 3 months, they were tested twice, using two out of three test forms which proved to be parallel. No test-retest practice effects were apparent. Age had a considerable impact on test performance. Measured imperfectly, socioeconomic background and intellectual level had some additional influence, as did the examiner who administered the tests. Boys made more errors than girls. Normative data corresponded well with those collected in a smaller Australian sample, suggesting usefulness outside The Netherlands. With a parallel test-retest reliability of.70, which was reduced to.59 when the influence of age was taken into account, the most reliable AVLT measure was the total number of words correctly recalled over the five learning trials. On the basis of reliability data, implications for the clinical use of the AVLT are discussed.     

An implantable biotelemetry transmitter for six differential signals

An implantable transmitter for six differential input signals and two reference signals is described. The reference signals provide for synchronising the demultiplexer in the receiver, for automatic amplitude and zero-level calibration of the received signals, and for automatic frequency control of the receiver. A magnetically operated switch allows the transmitter to be turned off during idle periods. The battery life allows 200 h of operation during a period of many months. Signals up to 30 mV peak-to-peak and 0 to 100 Hz can be transmitted.     

Discrimination in Nursing

Discrimination in the health sector is disturbing as it violates the basic principles articulated by care providers. As disturbing is the discrimination reported in the nursing profession itself. Below, the issues behind the eight factors that generate discrimination. Awareness of such harmful—and often painful—practices is the first step in addressing the problem and planning future action     

CT study of craniovertebral rotation in whiplash injury

The present study investigates the diagnostic value of rotatory computed tomography (CT) examinations in normal subjects and patients with whiplash associated disorders (WAD), with the aim of reproducing earlier findings of rotatory CT studies. Forty-seven WAD patients with persistent complaints after a rear-end collision (non-cranial contact acceleration/deceleration trauma) were enrolled in this study. To guarantee a maximally homogeneous study population, only WAD patients with a marked passive cervical retroflexion restriction were included. Transversal CT slices in left and right rotation were made for all cervical levels (the skull included). CT slices in neutral position were used to reconstruct partially depicted vertebrae. Absolute rotatory values were estimated according the method of Penning and Dvorak. For all levels the relative rotatory (RR) value was calculated by dividing absolute rotation values of a particular cervical level by the corresponding total cervical rotation. The measuring error was estimated by comparing the findings of two separately performed measuring procedures. Two age groups of WAD patients were formed. A younger group was matched for age with 26 normal healthy volunteers (the original data of an earlier study). The use of neutral CT slices for reconstruction of a partially depicted cervical vertebra resulted in a measurement error of 1.9 degrees at the level of C0/C1 (occiput/atlas) and 3.5 degrees at C1/C2. Suspected hypermobility as defined by Dvorak was rare in our WAD patients (6.4% C0/C1 and 10.6% C1/C2). RR values at C0/C1 were significantly larger in 79% of the WAD patients. Discriminant analysis of the RR values showed 80% correctly classified WAD patients. Only 11.5% of the normal subjects were classified as false-positive. Since no hypermobility was found at C1/C2, a traumatic lesion of the alar ligaments is less likely. It was concluded that the use of absolute rotation values in rotatory CT scan procedures has a low diagnostic value in WAD patients. Excessive RR values were only found at C0/C1. A traumatic lesion of the ligaments at C0/C1, which prevent vertical translation of the skull with regard to the atlas, is hypothesised. The results of the discriminant analysis of the RR values make this method applicable for the individual WAD patient in daily practice.     

In vitro torsion-induced stress distribution changes in porcine intervertebral discs.

STUDY DESIGN: A cadaveric porcine spine motion segment experiment was conducted. OBJECTIVE: To test the hypothesis that small vertebral rotations cause increased stress in the anulus while decreasing stress in the nucleus through stiffening of the anulus. SUMMARY OF BACKGROUND DATA: Stress profiles of the intervertebral disc reportedly depend on degeneration grade and external loading. Increased stress in the anulus was found during asymmetric loading. In addition, depressurization of the nucleus combined with an instantaneous disc height increase was found when small (<2 degrees ) axial vertebral rotations were applied. METHODS: Seven lumbar porcine cadaveric motion segments consisting of two vertebrae and the intervening disc with ligaments were loaded in the neutral position with 340 N of compression. Stress profiles were obtained in the neutral position, then after 0.5 degrees and 1 degrees axial rotation of the bottom vertebral body. The distribution of compressive stress in the disc matrix was measured by pulling a miniature pressure transducer through the disc along a straight path in the midfrontal plane. Stress profiles were measured in vertical (0 degrees ) and horizontal (90 degrees ) orientation. RESULTS: Deformation of the anulus by small axial rotations of the lower vertebra instantaneously decreased the horizontally and vertically measured stress in the nucleus while increasing stress in the anulus. A 1-hour period of creep loading decreased the stresses in the nucleus and the anulus 20% to 30%, depending on the orientation, but the effect of an increasing stress in the anular region after axial rotation persisted. CONCLUSIONS: The compressive Young's modulus of the composite anulus tissue increases instantaneously when small axial rotations are applied to porcine spine motion segments. This is accompanied by decreased stress in the nucleus pulposus, increased stress in the anulus fibrosus, changes in the stress profile superimposed on and independent of prolonged viscoelastic creep and dehydration, and changes in stress distribution independent of horizontal and vertical orientation.     

Cervical myogenic potentials and controlled postural responses elicited by a prototype vestibular implant

Gaze stabilization and postural control are two key functions of the vestibular system. In consequence, oscillopsia and chronic imbalance are the two main complaints of patients presenting with a severe bilateral vestibular function loss. The vestibular implant is emerging as a promising treatment for this group of patients whose quality of life is significantly impaired. Although the final aim of the vestibular implant should be to restore vestibular function as a whole, until now the research has focused mainly on the restoration of the vestibulo-ocular reflex to improve gaze stabilization. In this study, we aimed to explore whether the vestibulo-collic and vestibulo-spinal pathways could be activated and controlled with the electrical stimuli provided by our vestibular implant prototype. This was first explored and demonstrated with recordings of electrically elicited cervical vestibular evoked myogenic potentials (ecVEMPs). ecVEMPs with characteristics similar to the classical acoustically elicited cervical vestibular evoked myogenic potentials (cVEMPs) were successfully evoked in five out of the eight tested patients. Amplitudes of the electrically elicited N–P complex varied, ranging from 44 to 120 µV. Mean latencies of the N and P waves were of 9.71(± 1.17) ms and 17.24 ms (± 1.74), respectively. We also evaluated the possibility of generating controlled postural responses using a stepping test. Here, we showed that controlled and consistent whole-body postural responses can be effectively obtained with rapid changes in the “baseline” (constant rate and amplitude) electrical activity delivered by the vestibular implant in two out of the three tested subjects. Furthermore, obtained amplitude of body rotations was significantly correlated with the intensity of stimulation and direction of body rotations correlated with the side of the delivered stimulus (implanted side). Altogether, these data suggest that the vestibular implant could also be used to improve postural control in patients with bilateral vestibulopathy.

     

Vibrotactile feedback improves balance and mobility in patients with severe bilateral vestibular loss

The impact of vibrotactile feedback of the gravity vector, provided by a “balance” belt worn around the waist, was evaluated in 39 patients with a severe bilateral vestibular loss, confirmed by extensive laboratory testing and suffering from a low quality of life, mainly due to imbalance. The mobility and balance score (MBS) of all patients prior to the use of the belt was equal or less than 5 out of a scale of 10. Thirty-one out of the 39 patients experienced the effect of the belt on their balance and mobility as positive in a preselection trial of 2 h in the hospital. The 31 positive responders then used the belt for 1 month in daily life. The average MBS increased significantly from 4.2 to 7.9 (paired T test, T = 9.82, p < 0.00001). Twenty-three out of 31 patients reported a benefit ranging from an improvement of 60–200% in their MBS. Eight patients did not experience any benefit. In summary, 23 out of 39 patients with a severe imbalance due to a bilateral vestibular loss experienced a clear benefit of vibrotactile feed = back in daily life. We conclude that vibrotactile feedback via the waist can serve as an effective prothesis for patients with severe bilateral vestibular loss to improve the quality of life.

     

Coordination of leg swing, thorax rotations, and pelvis rotations during gait: the organisation of total body angular momentum

In walking faster than 3 km/h, transverse pelvic rotation lengthens the step ("pelvic step"). It is often assumed that the thorax then starts to counter rotate to limit total body angular momentum around the vertical. But the relative timing of pelvis and thorax rotation during gait is insufficiently understood. The present study aimed at analysing how transverse pelvis and thorax rotations relate to the movements of the upper leg, and how these patterns contribute to total body angular momentum. Nine healthy male volunteers walked on a treadmill at nine different velocities, ranging from 2.0 km/h to 5.2 km/h. Full body kinematics were recorded. Femur-pelvis, pelvis-thorax, and femur-thorax relative phase were calculated, as well as transverse plane angular momentum of all body segments. The shift in pelvis-thorax coordination from in-phase to out of phase with increasing velocity was found to depend on the pelvis beginning to move in-phase with the femur, while the thorax continued to counter rotate with respect to the femur. Moreover, pelvic and thoracic contributions to total body angular momentum were low (less than 10%), while contributions of the legs and arms were much larger (approximately 90%), suggesting that pelvis-thorax coordination is relatively unimportant to the organisation of total body angular momentum. Taken together, these results may imply that our understanding of the pelvic step need to be changed. Moreover, the alterations in pelvis-thorax relative phase that were reported for different locomotor pathologies may depend on different mechanisms.