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[Ischemia of the brain stem caused by compression of the vertebral arteries by head rotation--an etiology for SIDS?].

UNLABELLED: Hypoperfusion of the brainstem during head rotation may be a risk factor for the development of SIDS. On this background we established a Doppler sonographic screening programme of the basilar cerebral arteries to evaluate the dependency of blood flow on head and body position. PATIENTS AND METHOD: We investigated 3840 newborns (1872 girls and 1968 boys) with a birth weight of 3399 +/- 497 g and a gestational age of 39.2 +/- 1.4 weeks. The investigations were performed in the neonatal period with an average age of 4.7 +/- 3 days. In all infants blood flow was measured in the basilar artery (BA) in supine position with the head in the midline. From the flow profile peak systolic flow velocity Vs and time average flow velocity TAV were measured. Additionally flow measurements were performed in supine and prone position with rotation of the head to the right and left side. A decrease of blood flow velocities below 50% of the value in neutral position was considered to be abnormal. Retrograde or biophasic flow profiles during rotation were considered to be pathologic. In infants with abnormal or pathologic flow during rotation of the head flow measurements in the vertebral arteries (VA) were additionally performed. Blood flow velocities in the VA were measured in supine and prone position with the head in the midline position and after rotation to the right and to the left. In neutral position unilateral vertebral hypoplasia, aplasia and normal VA were differentiated. The judgement after rotation was performed such as in the BA. RESULTS: In 3807 infants (99.14%) blood flow velocities during head rotation did not decrease below 50% of the value measured in neutral position. In 33 infants (0.86%) a decrease of blood flow velocities below 50% could be found during rotation. In 7 infants (0.18%) a pathologic flow could be found during head rotation. 27 of the 33 infants with abnormal and pathologic blood flow in the BA during rotation showed anatomic abnormalities of the VA. 20 of these infants (61%) had unilateral vertebral hypoplasia (11 right, 9 left side), 7 (21%) had unilateral vertebral aplasia (4 right, 3 left side). 32 of the 33 infants with abnormal flow in the BA showed a decrease of blood flow in the contralateral VA during head rotation. 9 infants had an abnormal, 19 a pathologic flow within the contralateral VA. In 4 infants the corresponding VA could not be measured during head rotation. The decrease of blood flow velocities in the BA during head rotation was caused by compression of the contralateral VA at the craniocervical junction. CONCLUSION: Blood flow within the basilar artery of healthy infants is independent of body position and rotation of the head. A decrease of the flow velocities below 50% during rotation has to be considered as an abnormality. The incidence of pathologic blood flow during head rotation with 1.8@1000 approximates the incidence of SIDS. Hypoperfusion of the brainstem during head rotation may be a risk factor of SIDS.

Blood Flow Velocity↗
PubMed2002

The derotation sign for perioperative diagnosis of significant partial-thickness rotator cuff tears.

PURPOSE: To describe and evaluate a simple perioperative test (the derotation sign) that differentiates significant (grade 3) partial-thickness and small full-thickness rotator cuff tears from insignificant (grades 1 and 2) partial-thickness rotator cuff tears and intact rotator cuffs. TYPE OF STUDY: Sensitivity and specificity study. METHODS: A study was conducted of 123 patients who underwent shoulder arthroscopy for chronic symptomatic rotator cuff disease, each of whom was subjected to a derotation test under general anesthesia. Specifically, the glenohumeral joint was rapidly distended with fluid just before arthroscopy. One of 3 possible observations was made: (1) the arm rotated internally only, (2) the arm initially rotated internally and then externally rotated (positive derotation sign), or (3) the arm did not rotate at all. Arthroscopic findings were then correlated with the derotation test. RESULTS: Forty-one shoulders had no arm rotation on derotation testing; all had rotator cuff tears greater than 2 cm in size. Forty-two shoulders with impingement and no rotator cuff tears, as well as 23 shoulders with grade 1 or grade 2 partial-thickness rotator cuff tears showed internal rotation only. Seventeen shoulders had a positive derotation sign; all of these had either a grade 3 partial-thickness or a small full-thickness (<1 cm) rotator cuff tear. CONCLUSIONS: The derotation test is useful in the perioperative differentiation of functionally intact rotator cuffs from those with significant tears. The derotation sign is specific for the diagnosis of grade 3 partial-thickness and/or small (<1 cm) full-thickness rotator cuff tears.

Adolescent↗
PubMed2003

Vestibular, optokinetic, and cognitive contribution to the guidance of passive self-rotation toward instructed targets.

We ask how vestibular and optokinetic information is combined ("fused") when human subjects who are being passively rotated while viewing a stationary optokinetic pattern try to tell when they have reached a previously instructed angular displacement ("targeting task"). Inevitably such a task entices subjects to also draw on cognitive mechanisms such as past experience and contextual expectations. Specifically, because we used rotations of constant angular velocity, we suspected that they would resort, consciously or unconsciously, to extrapolation strategies even though they had no explicit knowledge of this fact. To study these issues, we presented the following six conditions to subjects standing on a rotatable platform inside an optokinetic drum: V, pure vestibular (passive rotation in darkness); O, pure optokinetic (observer motionless, drum rotating); VO, combined (passive rotation while viewing stationary drum); Oe, optokinetic extrapolation (similar to O, but drum visible only during first 90 degrees of rotation; thereafter subjects extrapolate the further course in their minds); VOe, combined extrapolation (similar to VO, but drum visible only during first 90 degrees ); AI, auditory imagination (rotation presented only metaphorically; observers imagine a drum rotation using the rising pitch of a tone as cue). In all conditions, angular velocities ( v(C)) of 15, 30, or 60 degrees /s were used (randomized presentation), and observers were to indicate when angular displacement (of the self in space or relative to the drum) had reached the instructed magnitude ("desired displacement", D(D); range 90-900 degrees ). Performance was analyzed in terms of the targeting gain ( G(T) = physical displacement at time of subjects' indication / D(D)) and variability (% E(R) = percentage absolute deviation from a subject's mean gain). In all six conditions, the global mean of G(T) (across v(C) and D(D)) was remarkably close to veracity, ranging from 0.95 (V) to 1.06 (O). A more detailed analysis of the gain revealed a trend of G(T) to be larger with fast than with slow rotations, reflecting an underestimation of fast and an overestimation of slow rotation. This effect varied significantly between conditions: it was smallest in VO, had intermediate values with the monomodal conditions V and O, and also with VOe, and was largest in Oe and AI. Variability was similar for all velocities, but depended significantly on the condition: it was smallest in VO, of intermediate magnitude in O, VOe, Oe, and largest in V and AI. Additional experiments with conditions V, O, and VO in which subjects repetitively indicated displacement increments of 90 degrees, up to a subjective displacement of 1080 degrees, yielded similar results and suggest, in addition, that the displacement perceptions measured at the beginning and during later phases of the rotation are correlated. With respect to the displacement perception during optokinetic stimulation, they also show that the gain and its variability are similar whether subjects feel stationary and see a rotating pattern, or feel rotated and see a stationary pattern (circular vection). We conclude that the vestibular and optokinetic information guiding the subjects' navigation toward an instructed target is not fused by straightforward averaging. Rather the subjects' internal velocity representation (which ultimately determines G(T)) appears to be a weighted average of (1) whatever sensory information is available and of (2) a cognitive default value reflecting the subjects' experiences and expectations. The less secure the sensory information (only one source as in V or O, additional degrading as in Oe or AI), the larger the weight of the default value. Vice versa, the better the information (e.g., two independent sources as in VO), the more the actual velocity and not the default value determines displacement perception. Moreover, we suggest that subjects intuitively proceeded from the notion of a constant velocity rotation, and therefore tended to carry on the perception built up during the beghe perception built up during the beginning of a rotation or, in the case of vestibular navigation, to compensate for the decaying vestibular cue by means of an internal recovery mechanism.

Adult↗
PubMed1991

Rotational flexibility of the human knee due to varus/valgus and axial moments in vivo.

Knee ligamentous injuries persist in the sport of Alpine skiing. To better understand the load mechanisms which lead to injury, pure varus/valgus and pure axial moments were applied both singly and in combination to the right knees of six human test subjects. The corresponding relative knee rotations in three degrees of freedom were measured. Knee flexion angles for each test subject were 15 and 60 degrees for the individual moments and 60 degrees for the combination moments. For both knee flexion angles the hip flexion angle was 0 degrees. Leg muscles were quiescent and axial force was minimal during all tests. Tables of data include sample statistics for each of four flexibility parameters in each loading direction. Data were analyzed statistically to test for significant differences in flexibility parameters between the test conditions. In flexing the knee from 15 to 60 degrees, the resulting knee rotations under single moments depended upon flexion angle with varus, valgus, and internal rotations increasing significantly. Also, rotations were different depending on load direction; varus rotation was significantly different and greater than valgus rotation at both flexion angles. Also external rotation was significantly different and greater than internal at 15 degrees flexion, but not at 60 degrees flexion. Coupled rotations under single moments were also observed. Applying pure varus/valgus moments resulted in coupled external/internal rotations which were inconsistent and hence not significant. Applying pure axial moments resulted in consistent and hence significant varus/valgus rotations; an external axial moment induced varus rotation and an internal axial moment induced valgus rotation. For combination moments, varus/valgus rotations decreased significantly from those rotations at similar load levels in the single moment studies. Also, a varus moment significantly increased external rotation and a valgus moment significantly decreased internal rotation. These differences indicate significant interaction between corresponding load combinations. These results suggest that load interaction is a potentially important phenomenon in knee injury mechanics.

Adult↗
PubMed2006

[Impact of the eye's cyclorotation on axial orientation analysis of toric intraocular lenses: recommendations for an optimized evaluation of rotational stability of toric IOLs].

BACKGROUND: After the implantation of toric intraocular lenses (tIOLs) significant postoperative tIOL rotation angles were measured occasionally. We investigated the rotational stability of eyes during standardized photography and recommend two methods for an enhanced evaluation of tIOL rotation. PATIENTS AND METHODS: 1. The cyclorotation of the eye was investigated using standard fundus photography. A sequence of two fundus photographic slides was taken in 550 phakic eyes of 275 consecutive patients with a time interval of at least 6 months. With characteristic markers on the fundus photograph, the axial orientation of the eyes was defined and the cyclorotation between the two slides of each eye was measured. 2. Using bifocal photography (HRA II - Heidelberg Retina Angiograph), a sequence of anterior segment and fundus images was taken considering stable head position in 19 pairs of photographs of eyes with implanted tIOLs. The angle between reference fundus axis and tIOL axis was measured at both time stages (mean: after 3 months). The difference of the angle between bifocal-image samples was defined as the real tIOL rotation angle. 3. Ten pairs of anterior segment photographs of eyes with a tIOL were investigated using the Axenfeld loop analysis. In each photograph, the angle between the axis connecting two Axenfeld loops and the tIOL axis was measured. The difference of two angles of two photographs was defined as the rotational tIOL angle. RESULTS: 1. The mean absolute eye's rotation angle was 2.3 +/- 1.7 degrees (range: 0 to 11.5 degrees) in all 550 eyes. Only 9.1 % of the eyes did not rotate. In 57.3 % of the eyes a rotation of less than 3 degrees and in 33.6 % of more than or equal to 3 degrees was detected. The eye's cyclorotation correlated (p < 0.04) with an age older than 39 years and higher astigmatism (> 1.5 D). Because of the significant amount of spontaneous globe rotation we developed the following enhanced methods to minimize measurement errors of tIOL rotation: 2. Bifocal photography: comparing the 19 HRA anterior segment images, the amount of mean tIOL rotation was 5.4 +/- 4.8 degrees (range: 0 - 20.0 degrees). Using the bifocal photography, the mean tIOL rotation was 1.9 +/- 1.3 degrees (range: 0 - 5.0 degrees). The overestimated rotation of the tIOL (only anterior segment tIOL comparison) correlated with higher amounts of the eye's cyclorotation (r = 0.94; p = 0.01) and higher corneal astigmatism (r = 0.54; p = 0.05). 3. The simultaneous analysis of Axenfeld loops revealed significantly smaller amounts of tIOL rotation (2.3 +/- 2.5 degrees range: 0 - 7.0 degrees ) in 10 pairs of anterior segment photographs in contrast to the single analysis of tIOL axis (5.5 +/- 4.8 degrees range: 1 - 13.0 degrees p = 0.09). A reduction of up to 18.0 degrees tIOL rotation measurement failure was possible in single cases by applying the bifocal photography or simultaneous Axenfeld loop analysis. CONCLUSIONS: Head inclination, head rotation, and incyclo- or excyclorotation of the eye may have a significant impact on the tIOL axis evaluation. Besides the bifocal photography the simultaneous Axenfeld loop analysis could be a promising alternative to the conventional axis evaluation of tIOLs.

Artifacts↗
PubMed2006

Axial rotation of the lumbar spinal motion segments correlated with concordant pain on discography: a preliminary study.

OBJECTIVE: One possible cause of back pain in patients with intervertebral disk degeneration is decreased stability of the motion segment. Axial rotations between lumbar spinal vertebrae can be measured noninvasively with CT. We tested the hypothesis that larger axial rotations are found in motion segments with disks that test positive for concordant pain, which is considered by some investigators to be a reasonable, accurate predictor of spinal instability. SUBJECTS AND METHODS: Between October 2002 and March 2004, all patients undergoing discography were evaluated for inclusion in the study, with the approval of the institutional review board. All patients in whom concordant pain was detected at discography were enrolled in the study. The patients were placed supine in the CT scanner on a table that rotated the pelvis 8 degrees clockwise and then counterclockwise with respect to the thorax. CT images were obtained with the patient in the two positions of rotation. An automated program calculated the amount of rotation between each lumbar vertebra as a result of the table rotations. Rotations were stratified by disk level and by disk classification (concordant pain, nonconcordant pain, no significant pain). RESULTS: We recorded the axial rotations of 94 disks in 16 consecutive patients (10 women, six men; age range, 26-53 years) after two disks were excluded because of a previous fusion. There were 68 normal disks by MRI and discography, six disks with nonconcordant pain, and 20 disks with concordant pain. Rotation averaged 0.6 degrees for the normal disks, 1.4 degrees for disks with nonconcordant pain, and 1.8 degrees for disks with concordant pain. The differences were significant (analysis of variance, p < 0.001). Disks at L3-L4 with concordant pain rotated on average 1.2 degrees , whereas disks classified as normal or nonconcordant pain rotated on average 0.7 degrees (significant at p = 0.005). Disks at L4-L5 with concordant pain rotated on average 1.9 degrees , and those without concordant pain rotated on average 1.4 degrees (significant at p = 0.05). Disks with concordant pain at L5-S1 had an average rotation of 2.2 degrees , whereas disks without concordant pain had an average rotation of 1.5 degrees (marginally significant difference at p = 0.07). CONCLUSION: Concordant pain at discography predicts increased axial rotation at a lumbar disk level.

Adult↗
PubMed1999

Lower restenosis rate with stenting following aggressive versus less aggressive rotational atherectomy.

The present study evaluated the acute and follow-up results of stenting following aggressive rotational atherectomy compared with stenting following less aggressive rotational atherectomy. Recent work has demonstrated that stenting following rotational atherectomy is a promising strategy for complex and calcified lesions. However, there is little information available regarding the optimal procedural technique of rotational atherectomy to be employed before stent implantation. Between May 1995 and February 1997, 162 lesions in 126 patients were stented following rotational atherectomy because of the presence of severe calcification on fluoroscopy or intravascular ultrasound (95%). The lesions were divided as to whether aggressive rotational atherectomy was performed or not. Aggressive rotational atherectomy, defined as the use of a final burr size > or =2.25 mm and/or final burr/vessel ratio > or =0.8, was performed in 56 lesions. A less aggressive rotational atherectomy strategy was performed in 106 lesions. Procedural Q-wave (8.9% vs. 1.9%, P<0.05) and non-Q-wave (11% vs. 1.9%, P<0.05) myocardial infarctions were observed more frequently after aggressive rotational atherectomy; there was no significant difference in the incidence of other procedural complications. Although there was no significant difference in minimal lumen diameter after the procedure (3.11+/-0.68 vs. 2.99+/-0.48 mm, NS), at follow-up a greater minimal lumen diameter was observed in the lesions treated with aggressive rotational atherectomy compared to those treated with less aggressive rotational atherectomy (2.12+/-1.31 vs. 1.56+/-0.89 mm, P<0.01). Restenosis rates were 50.0% in the lesions treated without aggressive rotational atherectomy and 30.9% in those treated with aggressive rotational atherectomy (P<0.05). There was no significant difference in the incidence of restenosis with a focal pattern between the two groups (25.0% vs. 21.4%, NS). In contrast, restenosis with a diffuse pattern was lower in lesions treated with aggressive rotational atherectomy than in those without aggressive rotational atherectomy (9.5% vs. 25.0%, P<0.05). Aggressive rotational atherectomy followed by stenting is a promising strategy to reduce the restenosis rate in calcified lesions. However, the aggressive strategy is associated with an increased risk of procedural myocardial infarction.

Calcinosis↗
PubMed2001

Mental object rotation and the planning of hand movements.

Recently, we showed that the simultaneous execution of rotational hand movements interferes with mental object rotation, provided that the axes of rotation coincide in space. We hypothesized that mental object rotation and the programming of rotational hand movements share a common process presumably involved in action planning. Two experiments are reported here that show that the mere planning of a rotational hand movement is sufficient to cause interference with mental object rotation. Subjects had to plan different spatially directed hand movements that they were asked to execute only after they had solved a mental object rotation task. Experiment 1 showed that mental object rotation was slower if hand movements were planned in a direction opposite to the presumed mental rotation direction, but only if the axes of hand rotation and mental object rotation were parallel in space. Experiment 2 showed that this interference occurred independent of the preparatory hand movements observed in Experiment 1. Thus, it is the planning of hand movements and not their preparation or execution that interferes with mental object rotation. This finding underlines the idea that mental object rotation is an imagined (covert) action, rather than a pure visual-spatial imagery task, and that the interference between mental object rotation and rotational hand movements is an interference between goals of actions.

Adult↗
PubMed1995

[Transtrochanteric rotation osteotomies for osteonecrosis of the femoral head. Apropos of 20 cases].

PURPOSE OF THE STUDY: Twenty consecutive rotation osteotomies for idiopatic necrosis of the femoral head were reviewed with an average follow-up of 6,5 years, in order to evaluate an original technique (which uses a nail plate for rotation and fixation of the fragments), and to determine the middle term results (and therefore indications) of anterior and posterior rotation osteotomies. MATERIALS AND METHODS TECHNIQUE: rotations were achieved by rotating the femoral head with the nail of the nail plate, and without dissection of the posterior vascular bundle. We performed 16 anterior rotation osteotomies (according to Sugioka, with an average rotation of 52 degrees) and 4 posterior rotation osteotomies (described by Kempf, with an average rotation of 77 degrees). Only two patients were lost after 2 years follow-up (with good result), and the radio-clinical outcome of 18 operations at 5 years was known. RESULTS: Global results were : 7 failures, 3 fair and 10 very good or good. In the 4 posterior rotations (Kempf) we achieved 4 very good results, even in Ficats stage 3. In the 16 anterior rotations we could in all cases obtain, on the hip in extension, an almost complete discharge of the necrotic zone, as after osteotomy it was no more in front of the acetabular major bearing zone (defined as an angle of 40 degrees around the apex of the femoral head on the lateral Lequesne view). We obtained 6 good and very good results, 3 fair, and 7 failures requiring a THR. There were 2 factors of poor prognosis : Stage of the necrosis, as we observed 4 failures in the 4 Ficat's stage 3, and only 3 failures in the 12 stage 2. Depth of the necrosis, as we achieved 6 very good and good results and 1 poor in the 7 cases when it was no more than 1/3 of the head diameter. But in the 9 cases where depth was over one third there were 3 fair and 6 poor results. DISCUSSION: Our technique proved to be reliable as it achieved the rotation planned before operation (only one hypo-correction of 15 degrees) and bone fusion, allowing full weight bearing at 3 months in all cases. No extension of the necrotic area was observed. Posterior rotation osteotomy was followed by long term favorable results, may be because it achieves an anatomic discharge of the necrotic zone not only when the hip is in extension, but also when the hip is flexed. Anterior rotation is only recommended when : a rotation not exceeding 60 degrees (therefore without risks for the posterior bundle) allows a discharge of the necrotic zone when the hip is in extension. The necrosis is stage 2. In Stage 3 a progressive arthritis may occur as, in hip flexion, the necrotic sector of the non spherical head comes in front of the acetabular major bearing zone. The depth of the necrosis does not exceed 1/3 of the femoral head, such as in cases of a very large necrosis, mechanical degradation of the non necrotic part of the head may occur, even if discharge of the necrosis is achieved. CONCLUSION: Transtrochanteric rotation osteotomy may delay of a decade or more the occurring of osteoarthritis, if its indications are restricted to patients under 40, suffering from idiopatic necrosis. In our series Sugioka osteotomy gave good results in stage 2 when necrosis depth was no more than 1/3 of the head diameter. Posterior osteotomy allows a better discharge of the necrotic zone and thus may be proposed in less restricted conditions.

Adult↗
PubMed2002

Linearity of canal-otolith interaction during eccentric rotation in humans.

During natural behavior, the head may simultaneously undergo rotation, transduced by the semicircular canals, and translation, transduced by the otolith organs. It has been demonstrated in monkey that the vestibulo-ocular reflexes (VORs) elicited by both endorgans (i.e., the angular and linear VORs, or AVOR and LVOR) sum linearly during combined rotation and translation, but this finding has proven more elusive in humans. To investigate the combined AVOR/LVOR response, six human subjects underwent yaw eccentric rotation at 3 Hz in darkness while displaced from the axis of rotation. Responses to on-center yaw rotation (AVOR alone) and interaural translation (LVOR alone) were also recorded. During eccentric rotation with the subject facing away from the axis of rotation (i.e., nose out), in which a yaw to the right occurs simultaneously with a translation to the right (i.e., translation in phase with rotation), the AVOR and LVOR acted synergistically. Responses were always out of phase with rotation, and became larger in magnitude as vergence increased. For nose-in eccentric rotation, during which translation is out of phase with rotation, the LVOR acted antagonistically to the AVOR. During near viewing, the LVOR often dominated the overall response when eccentricity was sufficiently large, producing eye movements that were in phase with the rotational stimuli. As vergence decreased, the LVOR influence diminished, eventually resulting in responses that were out of phase with rotation at lowest vergence. When the response to pure yaw rotation was vectorially removed from the responses to eccentric rotation, the results proved statistically indistinguishable from the LVOR recorded during interaural translation, suggesting that the ocular response to combined angular and linear motion reflects the linear combination of the AVOR and LVOR.

Adult↗
PubMed1993

Mechanisms of amphetamine-induced rotation in rats with unilateral intrastriatal grafts of embryonic dopaminergic neurons: a pharmacological and biochemical analysis.

Amphetamine induces a pronounced rotation directed ipsilateral to the lesion and lasting about 2 h in rats bearing a unilateral lesion of the nigrostriatal dopaminergic pathway. Implantation of embryonic dopaminergic neurons into the lesioned striatum leads to a compensation of this rotation. However, graft-bearing animals display a strong biphasic contralateral rotation, lasting up to 5 h. To try to ascertain the mechanisms of this anomalous rotation, two separate experiments were performed. First, we tested whether the contralateral rotation presented by the grafted animals could be correlated to the persistence of the lesion-induced decoupling of striatal D1 and D2 receptors. Lesioned and grafted animals were submitted to a series of four amphetamine (5 mg/kg, i.p.) rotation tests. Preceding each test animals received, in a randomized order, one of four of the following treatments: physiological saline, a D1 receptor blocker (SCH-23390, 0.1 mg/kg, s.c.), a D2 receptor blocker (raclopride, 2.5 mg/kg, i.p.) or the combination of the D1 and D2 antagonists. The ipsilateral rotation observed in the lesioned animals was abolished by the separate blockade of both classes of dopamine receptor as well as by their combined blockade. Grafted animals could be separated into two subgroups, based on the effect of the antagonists during the first 2 h of amphetamine-induced rotation. In one subgroup, antagonists had the same effect on the amphetamine-induced contralateral rotation as they did on the ipsilateral rotation displayed by lesioned animals. In this group, D1 and D2 receptors were therefore recoupled by the implant in the lesioned striatum. In the other subgroup, the contralateral rotation could be antagonized only by the combined D1 and D2 blockade, while the separate blockade of D1 or D2 receptors did not decrease or even increased the amphetamine-induced rotation. This indicates that in this group the lesion-induced decoupling of D1 and D2 receptors persisted. Nevertheless, the characteristics of the amphetamine-induced rotation (magnitude, duration) were the same in the two subgroups. Likewise, hypersensitivities of both D1 and D2 receptors were completely abolished by the graft in both subgroups. From this experiment it is concluded that the amphetamine-induced rotation observed in grafted animals is not correlated with the state of coupling of striatal D1 or D2 receptors. In a second experiment, dopamine release was monitored by microdialysis in the graft-bearing and the contralateral normal striatum of awake, behaving animals following the administration of amphetamine to test whether the observed rotation could be explained by a higher than normal dopamine release from the implanted dopaminergic neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Amphetamine↗
PubMed1998

Mental rotation within linguistic and non-linguistic domains in users of American sign language.

American sign language (ASL) uses space itself to encode spatial information. Spatial scenes are most often described from the perspective of the person signing (the 'narrator'), such that the viewer must perform what amounts to a 180 degrees mental rotation to correctly comprehend the description. But scenes can also be described, non-canonically, from the viewer's perspective, in which case no rotation is required. Is mental rotation during sign language processing difficult for ASL signers? Are there differences between linguistic and non-linguistic mental rotation? Experiment 1 required subjects to decide whether a signed description matched a room presented on videotape. Deaf ASL signers were more accurate when viewing scenes described from the narrator's perspective (even though rotation is required) than from the viewer's perspective (no rotation required). In Experiment 2, deaf signers and hearing non-signers viewed videotapes of objects appearing briefly and sequentially on a board marked with an entrance. This board either matched an identical board in front of the subject or was rotated 180 degrees. Subjects were asked to place objects on their board in the orientation and location shown on the video, making the appropriate rotation when required. All subjects were significantly less accurate when rotation was required, but ASL signers performed significantly better than hearing non-signers under rotation. ASL signers were also more accurate in remembering object orientation. Signers then viewed a video in which the same scenes were signed from the two perspectives (i.e. rotation required or no rotation required). In contrast to their performance with real objects, signers did not show the typical mental rotation effect. Males outperformed females on the rotation task with objects, but the superiority disappeared in the linguistic condition. We discuss the nature of the ASL mental rotation transformation, and we conclude that habitual use of ASL can enhance non-linguistic cognitive processes thus providing evidence for (a form of) the linguistic relativity hypothesis.

Adult↗
PubMed1999

In vivo motion analysis of forearm rotation utilizing magnetic resonance imaging.

OBJECTIVE: To analyse in vivo normal forearm rotation utilizing the image processing method on axial magnetic resonance imaging. DESIGN: Rotatory motion and translation of the radius and rotation of the ulna were analysed in vivo, utilizing features of the bone image; axial centre of gravity and axis of the bone. METHODS: Axial magnetic resonance images at the proximal, middle and distal portion of the right forearms of 20 healthy volunteers were examined in five rotational positions, maximum pronation, 45 degrees pronation, neutral, 45 degrees supination and maximum supination. The axis of forearm rotation, the rotation angle of the radius, the rotation of the radius around its axial centre of gravity, and the rotation of the ulna around its axial centre of gravity were calculated on these axial MR images. RESULTS: The radius rotates in a near-circular ellipse around its rotational centre located on a line through the radial head and the ulnar head from maximum supination to 45 degrees pronation. There was discrepancy between the calculated maximum rotational angle of the radius and the pronation-supination angle showed on the goniometer. This discrepancy was due to motion at the radiocarpal, midcarpal and carpometacarpal joints. The rotation of the ulna ranges within 6 degrees. At maximum pronation, there was palmar translation of the radius. CONCLUSIONS: The forearm rotation is not a simple rotatory motion but a complex motion with rotation and translation. The palmar translation of the radius at maximum pronation may be caused by incongruity of the distal radioulnar joint and contraction of the pronator quadratus muscle. RELEVANCE: To date there exist few methods for the accurate and non-invasive assessment for motion analysis of the forearm rotation. Such a technique utilizing magnetic resonance image characteristics is, however, helpful to reveal accurate self- and relative-rotatory motion of both radius and ulna as well as the translation movement on forearm rotation in normal forearm.

Adolescent↗
PubMed1998

Constrained testing conditions affect the axial rotation response of lumbar functional spinal units.

STUDY DESIGN: Human cadaveric spine specimens were tested in axial rotation using constrained and unconstrained methods. OBJECTIVES: To determine the degree to which constrained methods affect the response of the functional spinal unit in axial rotation at lumbar and lumbosacral levels. SUMMARY OF BACKGROUND DATA: A substantial controversy exists in the literature regarding the appropriateness of different testing methods. No study has been found in which the effect of constraint on axial rotation behavior was objectively examined. METHODS: Ten human cadaveric spine specimens (five L3-L4, five L5-S1) were tested in axial rotation, using both constrained and unconstrained methods. In the unconstrained test, pure moments were applied to the upper vertebra, and its complete three-dimensional motion was measured using an optoelectronic camera system. In the constrained test, the specimens were loaded in a fixed-axis servohydraulic test machine individually around five rotational axis positions within the vertebral body, and the rotational motion was measured. RESULTS: The rotational angles in the constrained tests were not different among the five rotational axis positions. However, the maximum rotation from the five axis positions was approximately 40% greater than the minimum rotation, a significant difference. The axial rotational motion of the unconstrained tests was always less than the maximum rotation measured in the constrained test. However, the total rotational angle using the helical axis of motion was not significantly different from the constrained angles. CONCLUSIONS: The large differences between maximum and minimum rotation angles demonstrate that the behavior of the functional spinal unit in axial rotation is sensitive to the axis's position but the location of the axis is not repeatable. This supports the use of unconstrained methods in spinal testing.

Adult↗
PubMed2005

Vertebral rotation and thoracic torsion in adolescent idiopathic scoliosis: what is the best radiographic correlate?

BACKGROUND: As a result of the increased appreciation of the three-dimensional nature of scoliosis and modern spinal instrumentation's improved corrective capabilities, there has been renewed interest in the correction and measurement of vertebral rotation. Computed tomography (CT), the gold standard for accuracy, is limited in its clinical utility owing to cost, radiation exposure, and the effects of postural changes on scoliosis curves and vertebral rotation. Consequently, the Perdriolle and Nash-Moe techniques remain the standard measurements for providing a reasonable estimate of pre- and postoperative vertebral rotation because of their simplicity. However, these techniques have considerable interobserver variability, and pedicle screw instrumentation obscures the landmarks necessary for utilizing these techniques for postoperative vertebral rotation assessment. The purpose of the present study was to assess the utility of alternate radiographic measures to assess vertebral rotation and thoracic torsion when compared with conventional measures on pre- and postoperative radiographs and CT evaluation. METHODS: We reviewed the preoperative, immediate postoperative, and final follow-up radiographs, as well as the pre- and postoperative CT scans, of 19 patients (average age 15 years, 6 months) with Lenke 1 curves (average 55 degrees , range 47-66 degrees ), all treated with anterior spinal fusion. Coronal and sagittal Cobb angles as well as vertebral rotation (Perdriolle and Nash-Moe) at the superior uninstrumented, superior instrumented, apical, inferior instrumented, and inferior uninstrumented vertebrae were measured on all films, and vertebral rotation was assessed on the CT scans by a previously described method. Additionally, several measures of thoracic torsion (as a proxy for vertebral rotation and overall deformity improvement) were assessed. These included the rib-vertebral angle difference (RVAD), apical rib hump prominence (RH), apical vertebral body-rib ratio (AVB-R), and apical rib spread difference (ARSD). RESULTS: The postoperative main thoracic curve averaged 26 degrees (range 16-39 degrees , 52% correction) and 29 degrees (range 22-40 degrees , 47% correction) at final follow-up. For apical derotation, the postoperative CT improved from -11.5 degrees to -6.6 degrees and correlated significantly with the Cobb main thoracic curves (42% correction, r = 0.48, P = 0.003). There was weakly positive, but statistically significant, correlation between the pre- and postoperative CT scans and the corresponding Perdriolle and Nash-Moe measures of segmental rotation (r = 0.32-0.40, all P < 0.0001). The RVAD demonstrated poor correlation with the main thoracic curve values and correction, Perdriolle rotation and correction, and CT rotation and correction (r = -0.22-0.37, all P > 0.20). The apical RH demonstrated good correlation with the main thoracic curve (r = 0.65, P < 0.0001), apical Perdriolle rotation (r = 0.57, P < 0.0001), and CT apical rotation (r = 0.53, P = 0.002). We also found moderate correlation between the AVB-R and the main thoracic Cobb, apical Perdriolle, and CT (r = 0.57, 0.59, and 0.49, respectively; all P < 0.005). Similar relationships were found with the ARSD (r = 0.51, 0.47, and 0.43, respectively; all P < 0.02). CONCLUSIONS: The RH, AVB-R, and the ARSD-measures of thoracic torsion-demonstrated moderate to good overall correlation with the main thoracic curve Cobb angles, apical Perdriolle rotation, and apical CT rotation. These should be useful as clinical measures for assessing three-dimensional deformity correction on plane radiographs, especially for the intraoperative evaluation of vertebral derotation and thoracic symmetry restoration.

Adolescent↗
PubMed1995

Effects of load manipulations, heart rate, and contractility on left ventricular apical rotation. An experimental study in anesthetized dogs.

BACKGROUND: Left ventricular twist or torsion has been defined as the counterclockwise rotation of the ventricular apex with respect to the base during systole. We have recently shown that since base rotation is minimal, measurement of apex rotation reflects the dynamics of left ventricular (LV) twist. Since the mechanisms by which load and contractility affect twist are controversial, we aimed to determine the relation between apex rotation and volume, contractility, and heart rate under conditions in which dimensions and pressures were accurately measured. METHODS AND RESULTS: Using our optical device coupled to the LV apex, apex rotation was recorded simultaneously with LV pressure, ECG, LV segment length, and minor-axis diameters (sonomicrometry) in 12 open-chest dogs. Using vena caval occlusion and volume loading, a linear end-diastolic (ED) relation between apex rotation and LV area index was obtained (slope, 0.61 +/- 0.06 degrees/percent change; intercept, -60.1 +/- 6.2 degrees; n = 10) that differed from the end-systolic (ES) relation (slope, 1.36 +/- 0.27 degree/percent change; intercept, -132.5 +/- 24.9 degrees; P < .005). With changes in contractility, afterload, or heart rate, for both ED and ES the apex rotation-volume points fell within the range of the relations established by changing preload, suggesting that volume is the major determinant of twist. Vena caval occlusion (preload and afterload decrease) caused an increase in amplitude of apex rotation, with maximal apex rotation occurring earlier in ejection. In contrast, acute volume loading (predominant preload increase) caused a small decrease in the amplitude of apex rotation, and twist relaxation was delayed into the isovolumic relaxation period. Likewise, with single-beat aortic occlusion (increased afterload), there was a slight decrease in the amplitude of apex rotation, and maximal apex rotation was delayed into the isovolumic relaxation period. Paired pacing (increased contractility) increased the total amplitude of apex rotation by 42% and caused a delay in untwisting until the end of the isovolumic relaxation period. An increase in heart rate over 150 beats per minute resulted in a significant decrease in the amplitude of apex rotation with a similar delay of twist relaxation into the isovolumic relaxation period. CONCLUSIONS: The effects of load, contractility, and heart rate manipulations on LV twist as measured throughout the cardiac cycle by the optical apex rotation method are manifested by changes in both the amplitude and dynamics of torsion. LV twist at ED and ES is primarily a function of volume; this relation appears to be unaltered by heart rate, afterload, and contractility. Whereas decreased load caused early untwisting, increases in preload, afterload, heart rate, and contractility caused a consistent pattern of delay in twist relaxation.

Anesthesia↗
PubMedDate not supplied

Surgical rotations: the good, the bad, and the ugly.

BACKGROUND: Every surgeon's career begins with a surgical residency. Each residency has dreaded rotations as well as those that seem ideal, but to date, no objective criteria exist to define such rotations. The aim of this study is to establish objective criteria that, when applied to a specific rotation, will define it as a "dream" or a "dreaded" rotation and, in the process, elucidate the good, the bad, and the ugly of surgical rotations in general. METHODS: All 39 residents from a multi-institutional residency program were asked to collaboratively identify the criteria they felt necessary for a dream rotation. Each resident evaluated 16 rotations at 4 hospitals using the identified criteria on a scale of "Inadequate," "Optimal," and "Ideal/Dream Rotation." Residents then gave an overall evaluation of each rotation as a dream rotation on a scale of "No," "For the Most Part," or "Yes." Finally, each resident was asked whether the individual rotations were following ACGME recommendations on duty hours. RESULTS: The best correlations with a dream rotation were: clinical experience - quality and quantity of cases (r = 0.83), operative experience (r = 0.83), patient management responsibilities (r = 0.78), and outpatient office experience (r = 0.77). All p-values were < 0.05. The following correlated less with a dream rotation: conferences (r = 0.56, p < 0.05), medical student experience (r = 0.56, p < 0.05), and hospital facilities (r = 0.28, not significant.). Scut work was the only category for which there was a negative correlation with a dream rotation (r = -0.53, p < 0.05). Eighty-six percent of residents reported compliance with ACGME work hour recommendations, with no apparent correlation with a dream rotation.

Ambulatory Care↗
PubMedDate not supplied

External rotation of the glenohumeral joint: ligament restraints and muscle effects in the neutral and abducted positions.

External rotation of the glenohumeral joint is important in a variety of pathologic states, yet the ligamentous restraints to external rotation have not been thoroughly investigated and the muscle effects have received even less attention. The purpose of this study was to investigate the ligamentous restraints and muscle effects limiting external rotation of the glenohumeral joint in a biomechanical cadaveric model. External rotation torque was applied to the humeri of 15 shoulders mounted in the supine position in a custom fixture while varying rotator cuff and biceps loads in 15 degrees and 60 degrees of glenohumeral abduction. A randomly chosen ligament (coracohumeral ligament [CHL], combined superior and middle glenohumeral ligaments [S+M], anterior band of the inferior glenohumeral ligament [AB], entire inferior glenohumeral ligament [IGHL], or posterior capsule [PC]) was cut, and testing was repeated (n = 3 for each ligament). Torque data were collected every 3 degrees through the entire range of external rotation. Individual muscles were loaded with 22.2 N (designated as a standard state) and were compared with loads of 0, 11.1, and 44.5 N. Alterations in muscle loads were analyzed with a residual maximum likelihood-based repeated-measures model. Ligament effects were analyzed by use of analysis of variance with Tukey correction. In the neutral position, each ligament except the PC significantly affected the torque required for external rotation, with IGHL > CHL > AB > S+M. In this position, loading the subscapularis to 44.5 N significantly increased the torque required to externally rotate the shoulder whereas unloading it significantly decreased the torque required. In the 60 degrees abducted position, each ligament except the PC significantly affected the torque required for external rotation, with IGHL > AB > S+M > CHL. In this position, loading the biceps or subscapularis to 44.5 N significantly increased the torque required to externally rotate the shoulder as rotation increased whereas unloading it significantly decreased the torque required as rotation increased. This work demonstrates that the glenohumeral joint capsule behaves as a cylinder with many regions serving as restraints to external rotation. In addition, the long head of the biceps has an important role as a dynamic restraint to external rotation in the abducted shoulder. This is a new function attributed to the biceps and reinforces the role of external rotation in the generation of biceps and superior labral pathology.

Biomechanical Phenomena↗