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At least 415 records · Page 23Linked to original sources
PubMed1999

Eye-position dependence of three-dimensional ocular rotation-axis orientation during head impulses in humans.

If horizontal saccades or smooth-pursuit eye movements are made with the line-of-sight at different elevations, the three-dimensional (3D) angular rotation axis of the globe tilts by half the vertical eye eccentricity. This phenomenon is named "half-angle rule" and is a consequence of Listing's law. It was recently found that the ocular rotation axis during the horizontal vestibulo-ocular reflex (VOR) on a turntable also tilts in the direction of the line-of-sight by about a quarter of the eye's vertical eccentricity. This is surprising, since, in a "perfect" VOR, the angular rotation axis of the eye should be independent from the position of the eye to fully compensate for the 3D angular head rotation. We asked whether this quarter-angle strategy is a general property of the VOR or whether the 3D kinematics of ocular movements evoked by vestibular stimulation would be less eye-position dependent at higher stimulus frequencies. Nine healthy subjects were exposed to horizontal head impulses (peak velocity approximately 250 degrees /s). The line-of-sight was systematically changed along the vertical meridian of a tangent screen. Three-dimensional eye and head movements were monitored with dual search coils. The 3D orientation of the angular eye-in-head rotation axis was determined by calculating the average angular velocity vectors of the initial 10 degrees displacements. Then, the difference between the tilt angles of the ocular rotation axis during upward and downward viewing was determined and divided by the difference of vertical eccentricity ("tilt angle coefficient"). Control experiments included horizontal saccades, smooth-pursuit eye movements, and eye movements evoked by slow, passive head rotations at the same vertical eye eccentricities. On average, the ocular rotation axis during horizontal head-impulse testing at different elevations of the line-of-sight was closely aligned with the rotation axis of the head (tilt angle coefficient of pooled abducting and adducting eye movements: 0.11+/-0.17 SD). Values for slow head impulses, however, exceeded somewhat the quarter angle (0.33+/-0.12), while smooth-pursuit movements (0. 50+/-0.09) and saccades (0.44+/-0.11) were closest to the half angle. These results demonstrate that the 3D orientation of the ocular rotation axis during rapid head thrusts is relatively independent of the direction of the line-of-sight and that ocular rotations elicited by head impulses are kinematically different from saccades, despite similar movement dynamics.

Adult↗
PubMed2006

Axis of eye rotation changes with head-pitch orientation during head impulses about earth-vertical.

The goal of this study was to assess how the axis of head rotation, Listing's law, and eye position influence the axis of eye rotation during brief, rapid head rotations. We specifically asked how the axis of eye rotation during the initial angular vestibuloocular reflex (VOR) changed when the pitch orientation of the head relative to Earth-vertical was varied, but the initial position of the eye in the orbit and the orientation of Listing's plane with respect to the head were fixed. We measured three-dimensional eye and head rotation axes in eight normal humans using the search coil technique during head-and-trunk (whole-body) and head-on-trunk (head-only) "impulses" about an Earth-vertical axis. The head was initially oriented at one of five pitch angles (30 degrees nose down, 15 degrees nose down, 0 degrees, 15 degrees nose up, 30 degrees nose up). The fixation target was always aligned with the nasooccipital axis. Whole-body impulses were passive, unpredictable, manual, rotations with peak-amplitude of approximately 20 degrees , peak-velocity of approximately 80 degrees /s, and peak-acceleration of approximately 1000 degrees /s2. Head-only impulses were also passive, unpredictable, manual, rotations with peak-amplitude of approximately 20 degrees , peak-velocity of approximately 150 degrees /s, and peak-acceleration of approximately 3000 degrees /s2. During whole-body impulses, the axis of eye rotation tilted in the same direction, and by an amount proportional (0.51 +/- 0.09), to the starting pitch head orientation (P < 0.05). This proportionality constant decreased slightly to 0.39 +/- 0.08 (P < 0.05) during head-only impulses. Using the head-only impulse data, with the head pitched up, we showed that only 50% of the tilt in the axis of eye rotation could be predicted from vectorial summation of the gains (eye velocity/head velocity) obtained for rotations about the pure yaw and roll head axes. Thus, even when the orientation of Listing's plane and eye position in the orbit are fixed, the axis of eye rotation during the VOR reflects a compromise between the requirements of Listing's law and a perfectly compensatory VOR.

Adult↗
PubMed1995

Relationship of the ipsilateral rotation in night period and striatal dopamine content reduction in unilateral nigrostriatal 6-OHDA lesioned rats.

In order to discriminate well-lesioned rats after unilateral microinjection of 6-OHDA into the nigrostriatal dopamine system, we measured the spontaneous rotation in the night period and calculated the rate of ipsilateral rotation movement. The rate of ipsilateral rotation movement increased along with the total rotation movement. The rats with over 95% of ipsilateral rotation kept the rate relatively constant for 4 weeks after 6-OHDA lesion and showed a significant increase of contralateral rotation (253.2 +/- 37.9) as compared with the rat that had lower than 95% ipsilateral rotation (3.6 +/- 1.4) after the injection of apomorphine (0.25 mg/kg, s.c.). The reduction percentages of striatal DA contents in animals with unilateral rotation over 95% and under 95% to the lesioned side were 97.8 +/- 0.6% and 59.6 +/- 5.8% (P < 0.001), respectively. The rats with over 90% reduction of striatal DA levels corresponded nicely to rats with 95% ipsilateral rotation among rats injected with apomorphine. These results suggested that the evaluation of ipsilateral rotation, taken the level of 95% rotation to the lesioned side as a standard, was able to discriminate well-lesioned rats without apomorphine treatment after unilateral nigrostriatal 6-OHDA application.

Animals↗
PubMed1985

Effect of the dopamine D-1 antagonist SCH 23390 on rotational behaviour induced by apomorphine and pergolide in 6-hydroxy-dopamine denervated rats.

The experiments concerned the effects of the D-1 dopamine antagonist SCH 23390 on the rotational behaviour induced by apomorphine and pergolide in 6-hydroxy-dopamine denervated rats. SCH 23390 dose dependently inhibited the rotational behaviour induced by apomorphine. A significant inhibitory effect was obtained after 0.05 mg/kg s.c. of SCH 23390, which involved a change of the typical two-peak pattern of rotation induced by apomorphine. While the first peak of rotation was not significantly modified, the last peak of rotation induced by apomorphine was inhibited in a dose-dependent manner. No significant inhibition of the total rotation induced by pergolide was observed after SCH 23390 pretreatment. SCH 23390 seemed to enhance the duration of the rotation induced by pergolide, resulting in an increase in the total number of turns. However, the intensity of the maximal peak of rotation induced by pergolide was significantly inhibited after 5.0 mg/kg s.c. of SCH 23390. Comparison of the potency with which SCH 23390 inhibited the apomorphine- and pergolide-induced maximal peaks of rotation reveals that SCH 23390 was approximately 100 times more potent in inhibiting the apomorphine than the pergolide response. The results, compared with those in our previous report, show that the D-2 dopamine antagonist sulpiride was 1000 times more potent in inhibiting the pergolide than the apomorphine rotation. The present results support the hypothesis that apomorphine and pergolide induce rotation in 6-hydroxy-dopamine denervated rats by differential actions on D-1 and D-2 receptor sites.

Animals↗
PubMed1989

The effects of naloxone on body rotation-induced analgesia and anorexia in male mice.

The effects of body rotation in a horizontal plane and the opiate antagonist, naloxone, on the nociceptive responses and the feeding behavior of male mice were examined. In the first experiment the mice were rotated (70 rpm, schedule of 15 sec on; 5 sec off) for 60 minutes or exposed to sham rotation for the same duration. Midway through the rotation or sham procedure the mice were either injected with naloxone (1 mg/kg) or isotonic saline. At the end of the 60-minute treatment period the animals were placed on a warm surface (47.5 degrees C) and their latency to show a foot-licking response was measured. The rotation procedure produced a significant (p less than 0.01) increase in response latency in the saline-injected mice and the naloxone injections blocked this analgesic effect. This finding provides evidence for opioid involvement in the rotation-induced analgesia. In Experiment 2 mice on a food restriction schedule were rotated (70 rpm, 15 sec on; 5 sec off) or sham exposed for 60 minutes. Midway through this treatment period the mice were either injected with naloxone (1 mg/kg) or isotonic saline. Following the treatment period the mice were given access to food for 2 hours. The rotation procedure produced a significant (p less than 0.01) reduction in feeding (anorexia) in the first 30 minutes of food access for the saline-injected mice. Injections of naloxone significantly (p less than 0.05) enhanced the rotation-induced anorexia. These experiments demonstrate that rotation-induced analgesia in mice is blocked by the opiate antagonist, naloxone, whereas rotation-induced anorexia is not.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗
PubMed1984

Responses of medullary reticulospinal neurons to sinusoidal rotation of neck in the decerebrate cat.

The electrical activity of 132 neurons located in the inhibitory area of the medullary reticular formation, namely, in the medial aspects of the nucleus reticularis gigantocellularis, magnocellularis and ventralis has been recorded in precollicular decerebrate cats during sinusoidal displacement of the neck. This was achieved by rotation of the body about the longitudinal axis of the animal, while maintaining the head stationary. In particular, 85 neurons were activated antidromically by stimulation of the spinal cord at T12 and L1, the remaining 47 units were not activated antidromically. Among these reticular neurons tested, 66 out of 85 (i.e. 77.6%) of the neurons that were, and 31 out of 47 (i.e. 66.0%) of the neurons that were not antidromically activated responded to slow neck rotation at the frequency of 0.026 Hz and at the peak amplitude of displacement of 10 degrees. The units influenced by neck rotation showed a periodic modulation of the firing rate in response to sinusoidal stimulation of neck receptors. In particular, 70 of 97 units (i.e. 72.2%) were excited during side-down neck rotation and depressed during side-up rotation, while 19 of 97 units (i.e. 19.6%) showed the opposite pattern. In both instances, the peak of the responses occurred with an average phase lead of +41 degrees for the extreme side-up or side-down neck displacement. The remaining 8 units (i.e. 8.2%) showed a prominent phase shift of the peak of their response relative to neck position. The proportion of units excited during side-down neck rotation were almost equally distributed throughout the whole rostro-caudal extent of the reticular structures explored. Responses to neck rotation were detectable at 0.25 degrees of peak displacement. The gain (imp./s/deg.) and the sensitivity (%/deg., i.e. percentage change of the mean firing rate per degree of displacement) in responses of reticulospinal neurons decreased by increasing the peak amplitude of neck rotation from 1 to 10 degrees at a frequency of 0.026 Hz. Therefore, the system did not behave linearly with respect to amplitude of stimulation. By increasing the frequency of stimulation from 0.008 to 0.32 Hz at the fixed amplitude of 10 degrees, the gain, sensitivity and phase lead of responses increased for frequencies of neck rotation above 0.051 Hz. Reticulospinal neurons may thus monitor changes in neck position as well as in velocity of neck rotation. Responses of reticulospinal neurons to neck rotation are discussed in relation to the responses to the same stimulus recently described of vestibulospinal neurons originating from the lateral vestibular nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

The effect of oblique femoral tunnel placement on rotational constraint of the knee reconstructed using patellar tendon autografts.

PURPOSE: Despite the high long-term success rates of anterior cruciate ligament (ACL) reconstructions, 8% of patients undergoing this primary procedure have recurrent disability and graft failure. Nonanatomic tunnel positioning (primarily of the femoral tunnel) accounts for most of all technical failures. We hypothesized that reconstructions that closely recreate the oblique femoral attachment of the ACL would result in more normal knee rotational stability than more vertical reconstruction. The purpose of this study was to determine whether obliquity of the femoral tunnel in the coronal (frontal) plane has an effect on rotational constraint after ACL reconstruction, as measured by anterior tibial translation, external rotation, and internal rotation. TYPE OF STUDY: Ex vivo biomechanical study. METHODS: Ten matched pairs of fresh-frozen cadaver knees were alternately assigned to a standard or an oblique tunnel position reconstruction. Each knee was tested at 30 degrees and 90 degrees of flexion on a materials testing machine in ACL-intact, ACL-sectioned, and ACL-reconstructed states. A 100-N load was applied at a rate of 10 N/second, and anterior tibial translation was measured. Then 6.5 Nm of torque were applied, and external tibial rotation and internal tibial rotation were measured. The effects of tunnel placement and ligament condition were analyzed with a repeated measures analysis of variance. Significance was set at P < or =.05 (Tukey's test). RESULTS: At 30 degrees of flexion, internal tibial rotation in oblique reconstruction was restored to intact values and was significantly less than the internal tibial rotation values in standard reconstruction. Internal tibial rotation in standard reconstruction was significantly greater than intact values. No significant differences were found between standard and oblique tunnel reconstructions and the respective intact values for the remaining internal tibial rotation and all external tibial rotation tests, regardless of flexion angle. CONCLUSIONS: In our biomechanical model, ACL reconstructions using oblique femoral tunnels restored normal knee kinematics.

Aged↗
PubMed2006

A method for manipulating a movable platform's axes of rotation: a novel use of the CAREN system.

The functionality of movable platforms used in human balance studies is limited as they allow rotations around pre-defined axes, which typically run close to the platform's surface and so cannot be used to directly investigate control mechanisms of proximal joints. A new six degrees of freedom platform (CAREN, Motek, Amsterdam) is now available which in principle could be programmed to rotate around any axis of rotation. The location of the default axes of rotation for this device are not documented and the algorithm to move the axes has not yet been defined. The purpose of this study was to (1) locate the platform's default axes of rotation, (2) implement an algorithm for relocating its axes of rotation and (3) evaluate the algorithm. A simplified method was developed to locate the bounding rectangles within which the default axes of rotations were located. The three axes of rotation were found to be at x=1.13+/-0.69 mm, z=-204.22+/-0.63 mm in the roll plane, y=-2.67+/-0.59 mm, z=-211.38+/-0.63 mm in the pitch plane and x=0.43+/-0.70 mm, y=-4.72+/-0.65 mm in the yaw plane (X: left, Y: rear, Z: up), relative to the centre of its surface, with the maximum bounding rectangle of dimensions 2.50mm by 2.42 mm. Relocation of the platform's axes of rotation was achieved by the use of compensatory corrections, which were determined using a translation algorithm. Evaluation of the algorithm involved pitching the platform around three newly defined axes in the sagittal plane, representing the ankle, knee and hip joints. The platform was able to rotate around the new axes while keeping the instantaneous axes of rotation within bounding rectangles of 1.87 mm x 0.81 mm (ankle), 3.04 mm x 1.23 mm (knee), 3.14 mm x 1.63 mm (hip). The ability to overcome the limitation of other moveable platforms makes the CAREN system a valuable tool in research on the role of individual joints in balance.

Algorithms↗
PubMed2005

Achieving ligament stability and correct rotational alignment of the femur in knee arthroplasty: a study using the Medial Pivot knee.

In a series of 90 Medial Pivot arthroplasties rotational alignment of the femur was achieved by provisionally reconstructing the lateral side of the joint and tensioning the medial side with feeler gauges. Axial CT scans were employed to measure the rotational alignment relative to surgical epicondylar axis. In valgus knees the cutting block was externally rotated to adjust for posterolateral bone loss. The mean rotational alignment of the femur was 0.6 degrees of external rotation (S.D. 1.3, range 3 degrees of ER to 4 degrees of IR). The mean laxity of the medial ligament was 1 mm in flexion (SD 1, range 0-5 mm) and 0.5 mm in flexion (S.D. 0.5, range 0-2 mm) In those knees in which the medial ligament had been released the CT alignment was perfect, but when internally rotated against the hip 3-4 mm of gapping was noted. In valgus knees the mean rotation of the femoral component was 0.8 degrees of internal rotation (S.D. 1.5, range 1 degrees of IR to 4 degrees of ER). In spite of externally rotating the cutting block there was still a tendency to internally rotate the femur in some knees. This simple technique achieves the two goals of ligament stability and correct rotational alignment in a high proportion of cases. It may be applicable to any instrument system which employs posterior referencing.

Arthroplasty, Replacement, Knee↗
PubMed2005

Imagined rotations of self versus objects: an fMRI study.

This study used functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying two types of spatial transformations: imagined object rotations and imagined rotations of the self about an object. Participants viewed depictions of single three-dimensional Shepard--Metzler objects situated within a sphere. A T-shaped prompt appeared outside of the sphere at different locations across trials. In the object rotation task, participants imagined rotating the object so that one of its ends was aligned with the prompt. They then judged whether a textured portion of the object would be visible in its new orientation. In the self rotation task, they imagined rotating themselves to the location of the T-prompt, and then judged whether a textured portion of the object would be visible from the new viewpoint. Activation in both tasks was compared to respective control conditions in which identical judgments were made without rotation. A direct comparison of self and object rotation tasks revealed activation spreading from left premotor to left primary motor (M1) cortex (areas 6/4) for imagined object rotations, but not imagined self rotations. In contrast, the self rotation task activated left supplementary motor area (SMA; area 6). In both transformations, activation also occurred in other regions. These findings provide evidence for multiple spatial-transformation mechanisms within the human cognitive system.

Adult↗
PubMed2006

Asymmetrical perception of body rotation after unilateral injury to human vestibular cortex.

Vestibular information plays a key role in many perceptual and cognitive functions, but surprisingly little is known about how vestibular signals are processed at the cortical level in humans. To address this issue, we tested the ability of two patients, with damage to key components of the vestibular network in either the left or right hemisphere, to perceive passive whole-body rotations (25-125 degrees) about the yaw axis. In both patients, the posterior insula, hippocampus, putamen, and thalamus were extensively damaged. The patients' responses were compared with those of nine age- and sex-matched neurologically intact participants. The body rotations were conducted without vision and the peak angular velocities ranged from 40 degrees to 90 degrees per second. Perceived rotation was assessed by open-loop manual pointing. The right hemisphere patient exhibited poor sensitivity for body rotations toward the contralesional (left) hemispace and generally underestimated the rotations. By contrast, his judgments of rotations toward the ipsilesional (right) hemispace greatly overestimated the physical rotation by 50-70 degrees for all tested magnitudes. The left hemisphere patient's responses were more appropriately scaled for both rotation directions, falling in the low-normal range. These findings suggest that there is some degree of hemispheric specialization in the cortical processing of dynamic head rotations in the yaw plane. In this view, right hemisphere structures play a dominant role, processing rotations in both directions, while left hemisphere structures process rotations only toward the contralesional hemispace.

Analysis of Variance↗
PubMed2004

Effects of rotation on measurement of lower limb alignment for knee osteotomy.

The purposes of this study were to clarify the effects of rotation on two-dimensional measurement of lower limb alignment for knee osteotomy using a three-dimensional method and to determine whether this 3-D simulation method could help with planning of knee osteotomy. We developed computer software to calculate femorotibial angle (FTA) and hip-knee-ankle angle (HKA) and simulate knee osteotomy from a CT-based 3-D bone model of the lower limb. Lower limb rotation on anteroposterior long-standing radiographs was measured by superimposing the 3-D bone models. Changes in alignment with limb rotation were calculated using the software. FTA after virtual closed-wedged osteotomy was measured for a hypothetical case of a rotation error of the osteotomy plane in reattaching the proximal cutting surface to the distal cutting surface. For 31 varus knees in 20 patients with medial compartment arthritis, the mean rotation angle, relative to the epicondylar axis, with variable limb position was 7.4 +/- 3.9 degrees of internal rotation (mean +/- SD), ranging from 8 degrees of external rotation to 14 degrees of internal rotation; the mean changes in FTA and HKA were 3.5 +/- 2.2 degrees (range, 0.4-8.6) and 1.6 +/- 1.3 degrees (range, 0.2-4.9), respectively. The FTA "flexion angle" (lateral view alignment from neutral AP) and the absolute HKA "flexion angle" correlated with the change in FTA and HKA with limb rotation, respectively (FTA, R = 0.999; HKA, R = 0.993). The mean change in FTA after virtual closed-wedged osteotomy was 3.2 degrees for internal and external 10 degrees rotation errors in reattaching the osteotomy plane. Rotation may affect measurement of lower limb alignment for knee osteotomy, and 3-D methods are preferable for surgical planning.

Adult↗
PubMed1995

Head-shake vestibulo-ocular reflex testing: comparison of results with rotational chair testing.

The currently accepted "gold standard" for rotational testing of the vestibulo-ocular reflex uses a servo-controlled chair for sinusoidal whole-body rotation. Previous work in our laboratory has shown good concordance between conventional rotational chair testing and head-on-body (or "head-shake") testing for gain and phase values of the vestibulo-ocular reflex as recorded and analyzed on our rotational chair system's software. In this article we describe results obtained from 10 normal subjects and 20 patients with reduced caloric responses using a portable system being developed in our laboratory that allows an examiner to generate both whole-body and head-on-body rotational stimuli. Test frequencies within the range 0.25 to 1.0 Hz were chosen for comparison with results obtained by conventional rotational chair testing. Visual conditions for all tests included both visually enhanced vestibulo-ocular reflex (real earth-fixed target) and mentally enhanced vestibulo-ocular reflex (imagined earth-fixed target, in darkness or with vision obscured) paradigms. Our results show general agreement between head-shake and rotational chair testing and both manual whole-body rotation and head-shake testing on our portable system for vestibulo-ocular reflex gain and phase testing, with the largest differences noted at 1.0 Hz. Portable rotational testing was well tolerated by young and elderly subjects alike. We expect manual whole-body rotation and head-shake testing will be useful adjuncts for examining vestibulo-ocular reflex function when more formal rotational chair testing is not possible.

Adult↗
PubMed2001

A numerical solution to calculate internal-external rotation at the glenohumeral joint.

OBJECTIVE: To validate the approach of using angular velocity vectors to quantify internal-external rotation of the humerus. DESIGN: An experimental approach was used to compare predictions of internal-external rotation of the humerus based on angular velocity vectors, and known measurements of internal-external rotation. BACKGROUND: A primary concern associated with description of glenohumeral biomechanics is measurement of internal-external rotation of the humerus. Euler angles are often used, yet they do not address problems such as Codman's paradox and 'gimbal lock'. Previous work has presented a technique that uses angular velocity vectors to quantify internal-external rotation instead of Euler angles. This approach is promising with regard to providing an independent measure of internal-external rotation of the humerus, and requires validation for subsequent use on humans. METHODS: A gimbal with three axes of rotation that simulated the rotational d.o.f. of the humerus relative to the glenoid was developed and used to validate the use of angular velocity vectors to quantify internal-external rotation of the humeral shaft portion of the gimbal. RESULTS: Correlations between calculated and measured rotation values revealed R(2) values of 0.99, slopes at diagonal (1.0), and y-intercepts near zero (-0.6 degrees ).Conclusions. The expression developed here is a valid and useful method for measuring motion of the humerus relative to the glenoid. RELEVANCE: Angular velocity vectors can be used to accurately determine internal-external rotation of the humerus relative to the glenoid, and this may be useful for the development of arthrometers to characterize the glenohumeral joint.

Biomechanical Phenomena↗
PubMed2002

Apoptosis in rotator cuff tendonopathy.

The aim of this study was to investigate the involvement of apoptosis (programmed cell death) in the pathogenesis of rotator cuff disorders. The edges of torn supraspinatus rotator cuff tendons were collected from patients with rotator cuff tear (n = 25). Samples of the intra-articular portion of subscapularis tendons were collected from patients without rotator cuff tear as control (n = 6). To minimize individual variance, we also collected six pairs of supraspinatus tendon and subscapularis tendon from six patients with rotator cuff tears. Apoptosis was detected by in situ DNA end labelling assay and DNA laddering assay. Immunohistochemical staining was performed to identify cells undergoing apoptosis. Control subscapularis tendon had normal morphology. Tendon from torn supraspinatus rotator cuff showed significant mucoid degeneration. Within the areas of degeneration, there were large numbers of apoptotic cells. The percentage of apoptotic cells in the degenerative rotator cuff (34%) was significantly higher than that in controls (13%) (p < 0.001). The excessive apoptosis detected in degenerative rotator cuff tissue was confirmed by DNA laddering assays. This is the first report of excessive apoptosis in degenerating rotator cuff tendon. Cells undergoing apoptosis in rotator cuff were mainly fibroblast-like cells. These finding indicate that apoptosis may play an important role in the pathogenesis of rotator cuff degeneration.

Adult↗
PubMedDate not supplied

Relationship between the lateral acromion angle and rotator cuff disease.

One hundred consecutive magnetic resonance imaging (MRI) studies of the shoulder obtained for the purpose of evaluating rotator cuff symptoms were retrospectively reviewed to assess the relationship between acromion morphologic appearance and rotator cuff disease. The studies were reviewed simultaneously by two authors. Each cuff was assigned a tendon grade and an overall cuff score with MRI criteria previously described in the literature. A newly described "lateral acromion angle" was measured from a specified oblique coronal cut on each MRI study and was correlated with the corresponding MRI-determined rotator cuff score and supraspinatus tendon grade. Observed correlations were analyzed by using statistical methods. The average measured lateral acromion angle was 78 degrees, with a range from 64 degrees to 99 degrees. Eight shoulders had angles less than or equal to 70 degrees, and all eight of these patients were found to have full-thickness rotator cuff tears. As the lateral acromion angle decreased, a statistically significant increase in rotator cuff disease was noted (p < 0.0001). A significant correlation between increasing age and rotator cuff disease was also observed (p < 0.0001). Multiple regression analysis confirmed that both the lateral acromion angle and the age of the patient were independent predictors of rotator cuff score. Finally, although a trend was noted suggesting a correlation between acromion type (I--flat, II--curved, and III--hooked) and MRI-determined rotator cuff disease, this trend did not reach statistical significance (p = 0.12). Surgical correlation with MRI rotator cuff findings in 35 patients showed an MRI sensitivity of 100% and specificity of 83%. A statistically significant correlation between the lateral acromion angle and MRI-determined rotator cuff disease has been noted. The described angle may be a useful adjuvant in the evaluation and management of rotator cuff disease.

Acromioclavicular Joint↗
PubMed2004

[Rotational stability of the eye in standard photography].

BACKGROUND: After the implantation of a toric IOL (tIOL), postoperative rotations of more than 30 degrees have been reported. Beyond this scope, we investigated the reproducibility of the eye's orientation (rotation stability) in principle. PATIENTS AND METHODS: The rotational stability of the eye was investigated using standard fundus photographs (telecentric fundus camera, Zeiss, Oberkochen). One hundred eyes of 50 patients (28 females) were photographed in a time interval of more than 6 months twice. With the aid of significant markers on the fundus photograph, the axial position of the eye was defined and the rotational angle between the two slides of one eye was measured. RESULTS: The mean absolute rotational angle was 2.4 +/- 1.7 degrees (range 0 to 7.5 degrees ) in all 100 eyes (2.5 +/- 1.6 degrees right eye, 2.4 +/- 1.7 degrees left eye). Only 6 % of the eyes did not rotate. A range of less than 3 degrees rotation was detected in 52 % of the eyes. A rotation of equal to or more than 3 degrees was noted in 42 %. The patient's age did not influence the amount of globe rotation. In- and excyclorotations showed a coincidental distribution and no side differences. CONCLUSIONS: Seven and a half degrees or 3 degrees tIOL rotation would correspond to a residual astigmatism of 26 % or 10 %. When measuring the marked axis of the tIOL, these results are markedly influenced by head inclination, rotation of the head, incyclorotation or excyclorotation. This is transferable, for example, to autorefractor, corneal topography and sectorial analyses for glaucoma diagnostics.

Eye Movements↗
PubMed1988

Equivalent spatial-rotation deficits in normal aging and Alzheimer's disease.

Two tests of spatial-rotation ability were administered to 17 young normals, 23 aged normals, and 51 patients with diagnoses of Alzheimer's disease (AD). The AD patients consisted of 28 early dementia patients and 23 advanced dementia patients. On a computerized version of the Boston Naming Test, 40 objects were presented for naming, 20 of which were rotated 180 degrees. The subjects' capacity for mental rotation was assessed on the basis of their accuracy of naming of rotated vs. unrotated objects. On Money's Standardized Road Map Test, in which the subject is asked whether turns on a map are to the left or to the right, spatial-rotation ability was assessed on the basis of the subject's left-right orientation on turns with movement away from the subject (requiring no rotation) vs. turns with movement toward the subject (requiring rotation). Performance on both tasks was progressively worse in the young normal, aged normal, early dementia, and advanced dementia groups. Both tasks demonstrated a clear spatial-rotation deficit in the elderly. Although the spatial-rotation effect was superimposed upon deficits in naming and left-right orientation in the demented subjects, the magnitude of the rotation effect did not significantly differ in the aged normal vs. the early dementia group on either task, suggesting that early AD produces no further impairment of spatial-rotation abilities than is produced by normal aging.

Adolescent↗