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PubMed1998

Trunk strength in combined motions of rotation and flexion/extension in normal young adults.

Thirty-eight normal healthy young subjects (14 males, 24 females) with mean ages of 23 years (males) and 21 years (females), performed 36 functional rotational tasks of the trunk. The subject's lower extremities were stabilized in a stabilizing platform, allowing the entire motion of flexion-rotation and extension-rotation to take place in the trunk. Of these tasks, 18 were isometric and the other 18 were isokinetic. The isometric tasks consisted of flexion-rotation and extension-rotation from a 20 degrees, 40 degrees and 60 degrees flexed trunk in 20 degrees, 40 degrees and 60 degrees of axial rotation. The isokinetic activity consisted of flexion-rotation and extension-rotation from upright and flexed postures respectively in 20 degrees, 40 degrees and 60 degrees rotation planes at 15 degrees, 30 degrees and 60 degrees/s angular velocities. The results revealed that the males were significantly stronger than females (p < 0.01) and isometric activities produced significantly greater torque compared to isokinetic efforts (p < 0.01). The degree of trunk flexion was not significant; the angle of rotation, although significant, had only a small effect. The 60 degrees trunk rotation was significantly different from 20 degrees and 40 degrees of trunk rotation. The multiple regressions were all significant (p < 0.01); however, they predicted only 40 to 60% of the variations. Based on the results and analysis, it is suggested that the motion involved rather than the torque may have a consequential effect in the precipitation of back injuries.

Adult↗
PubMed2001

Nitrogen use and carbon sequestered by corn rotations in the northern corn belt, U.S.

Diversified crop rotation may improve production efficiency, reduce fertilizer nitrogen (N) requirements for corn (Zea mays L.), and increase soil carbon (C) storage. Objectives were to determine effect of rotation and fertilizer N on soil C sequestration and N use. An experiment was started in 1990 on a Barnes clay loam (U.S. soil taxonomy: fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, SD. Tillage systems for corn-soybean ( Glycine max [L.] Merr.) rotations were conventional tillage (CS) and ridge tillage (CSr). Rotations under conventional tillage were continuous corn (CC), and a 4-year rotation of corn-soybean-wheat ( Triticum aestivum L.) companion-seeded with alfalfa ( Medicago sativa L.)-alfalfa hay (CSWA). Additional treatments included plots of perennial warm season, cool season, and mixtures of warm and cool season grasses. N treatments for corn were corn fertilized for a grain yield of 8.5 Mg ha(-1) (highN), of 5.3 Mg ha(-1) (midN), and with no N fertilizer (noN). Total (1990-2000) corn grain yield was not different among rotations at 80.8 Mg ha(-1) under highN. Corn yield differences among rotations increased with decreased fertilizer N. Total (1990-2000) corn yields with noN fertilizer were 69 Mg ha-1 under CSWA, 53 Mg ha(-1) under CS, and 35 Mg ha(-1) under CC. Total N attributed to rotations (noN treatments) was 0.68 Mg ha(-1) under CSWA, 0.61 Mg ha(-1) under CS, and 0.28 Mg ha(-1) under CC. Plant carbon return depended on rotation and N. In the past 10 years, total C returned from above- ground biomass was 29.8 Mg ha(-1) under CC with highN, and 12.8 Mg ha(-1) under CSWA with noN. Soil C in the top 15 cm significantly increased (0.7 g kg(-1)) with perennial grass cover, remained unchanged under CSr, and decreased (1.7 g kg(-1)) under CC, CS, and CSWA. C to N ratio significantly narrowed (-0.75) with CSWA and widened (0.72) under grass. Diversified rotations have potential to increase N use efficiency and reduce fertilizer N input for corn. However, within a corn production system using conventional tillage and producing (averaged across rotation and N treatment) about 6.2-Mg ha(-1) corn grain per year, we found no gain in soil C after 10 years regardless of rotation.

Agriculture↗
PubMed1999

First-postgraduate-year resident clinical time use on three specialty rotations.

OBJECTIVE: To compare in-hospital time uses by first-postgraduate-year (PGY1) residents during rotations in emergency medicine (EM), internal medicine (IM), and surgery (S). This article reports the clinical components of residency time use. METHODS: A cross-sectional, observational study of the clinical activities of EM PGY1 residents was performed while the residents were on duty during the three specialty rotations. The activities were recorded by an observer using a log with predetermined categories for clinical activities. A time-blocked, convenience sample of resident shifts was observed for each service rotation. The sample was proportional to the total number of hours for which a PGY1 resident was expected to be in the hospital during a rotation on that service. No attempt was made to sample the same resident at all time periods or on all rotations. Proportions were compared by chi2; alpha = 0.0001. RESULTS: Twelve PGY1 residents were observed for a total of 166 hours on S, 156 hours on IM, and 120 hours on EM. These hourly amounts were representative of a typical two-week span of service on each rotation for the residents. On average, the residents spent 57% of their time on clinical or service-oriented activities. During EM and IM rotations, the residents spent most of their time performing clinical information gathering and engaging in case management and data synthesis (52% of total clinical effort). Within this category, residents on EM were more involved with case discussion and review of ancillary test results than on IM (34% vs 20% of time in this category). Conversely, proportionately less time in this category was devoted to documentation on the EM vs IM rotation (56% vs 80%; p < 0.0001). The greatest opportunity to perform procedures was on the S rotation (31% of total clinical time vs 6% for other specialties; p < 0.0001). CONCLUSION: Awareness of the clinical activities performed on PGY1 rotations can help residency directors anticipate educational needs to balance their residents' experience. Since 29% and 42% of total clinical time on PGY1 EM and IM rotations, respectively, is focused on documentation, efforts to enhance charting skills and efficiency are warranted. Also, efforts to enhance PGY1 procedural experience outside of the S rotation appear warranted.

Adult↗
PubMed2005

New noninvasive method for assessment of left ventricular rotation: speckle tracking echocardiography.

BACKGROUND: Left ventricular (LV) torsion is due to oppositely directed apical and basal rotation and has been proposed as a sensitive marker of LV function. In the present study, we introduce and validate speckle tracking echocardiography (STE) as a method for assessment of LV rotation and torsion. METHODS AND RESULTS: Apical and basal rotation by STE was measured from short-axis images by automatic frame-to-frame tracking of gray-scale speckle patterns. Rotation was calculated as the average angular displacement of 9 regions relative to the center of a best-fit circle through the same regions. As reference methods we used sonomicrometry in anesthetized dogs during baseline, dobutamine infusion, and apical ischemia, and magnetic resonance imaging (MRI) tagging in healthy humans. In dogs, the mean peak apical rotation was -3.7+/-1.2 degrees (+/-SD) and -4.1+/-1.2 degrees, and basal rotation was 1.9+/-1.5 degrees and 2.0+/-1.2 degrees by sonomicrometry and STE, respectively. Rotations by both methods increased (P<0.001) during dobutamine infusion. Apical rotation by both methods decreased during left anterior descending coronary artery occlusion (P<0.007), whereas basal rotation was unchanged. In healthy humans, apical rotation was -11.6+/-3.8 degrees and -10.9+/-3.3 degrees, and basal rotation was 4.8+/-1.7 degrees and 4.6+/-1.3 degrees by MRI tagging and STE, respectively. Torsion measurement by STE showed good correlation and agreement with sonomicrometry (r=0.94, P<0.001) and MRI (r=0.85, P<0.001). CONCLUSIONS: The present study demonstrates that regional LV rotation and torsion can be measured accurately by STE, suggesting a new echocardiographic approach for quantification of LV systolic function.

Animals↗
PubMed2006

Arthroscopic release and latissimus dorsi transfer for shoulder internal rotation contractures and glenohumeral deformity secondary to brachial plexus birth palsy.

BACKGROUND: Internal rotation contractures due to external rotation weakness secondary to brachial plexus birth palsy frequently lead to glenohumeral deformity and impaired shoulder function. Our surgical approach to treat these contractures relies on arthroscopic release for young children (less than three years old) and combines arthroscopic release with latissimus dorsi transfer for older children. We report the results for the first thirty-three children followed for a minimum of two years after such treatment. METHODS: Nineteen children with a mean age of 1.5 years (all younger than three years of age) underwent arthroscopic contracture release as the only primary procedure, and fourteen children with a mean age of 6.7 were also treated with a latissimus dorsi transfer. Passive external rotation with the arm at the side and passive and active elevation were measured for all patients preoperatively. Passive and active external rotation, internal rotation, and elevation were measured for all patients postoperatively. Magnetic resonance imaging was performed preoperatively and postoperatively to evaluate the status of the glenohumeral joint. RESULTS: Preoperative passive external rotation averaged -2 degrees for the children who underwent arthroscopic contracture release only and -24 degrees for those who also were treated with a latissimus dorsi transfer. Arthroscopic release achieved a marked increase in passive external rotation and a centered position of the glenohumeral joint at the time of surgery in all but the oldest child in the series, who had severe deformity. The contracture recurred in four of the younger children who had an isolated release, and this was treated with a repeat arthroscopic release and a secondary latissimus dorsi transfer. None of the children who had a primary latissimus dorsi transfer had recurrence of the contracture. At the time of follow-up, the mean passive external rotation was increased by 67 degrees (p < 0.005) in the fifteen children with a successful arthroscopic release, 81 degrees (p < 0.005) in those treated with a primary latissimus dorsi transfer, and 78 degrees in the four patients who were treated with a late latissimus dorsi transfer because the isolated arthroscopic release failed. The mean active elevation increased 12 degrees , 3 degrees , and 10 degrees , respectively, in the three groups. Internal rotation was not measured consistently preoperatively, but when it had been it was found to have decreased substantially postoperatively. Magnetic resonance imaging performed prior to the surgery showed a pseudoglenoid deformity in eighteen of the children. At two years, magnetic resonance images were available for fifteen of those children, and twelve of the images showed marked remodeling of the deformity. CONCLUSIONS: In children who are younger than three years of age, arthroscopic release effectively restores nearly normal passive external rotation and a centered glenohumeral joint at the time of surgery. In most of these children, external rotation strength is sufficient to maintain this range of motion and to improve glenoid development when preoperative deformity was present. The addition of a latissimus dorsi transfer in older children predictably results in similar improvements. Gains in active elevation are minimal. All children have a loss of internal rotation, which is moderate in most of them but is severe in some.

Arthroscopy↗
PubMed1998

[Digital rotational angiography in the study of vascular diseases: technical note and initial clinical applications].

INTRODUCTION: Digital rotational angiography is a technique characterized by a C-arm acquiring images as it rapidly rotates around the patient. We studied the clinical potentials of this technique in the assessment of vascular diseases of the abdominal aorta and of the carotid, lower limbs and renal arteries. MATERIAL AND METHODS: We examined 108 patients (66 men and 42 women; mean age: 54.3 years, range: 34-69): 42 had vascular diseases in the carotid arteries, 47 in the abdominal aorta and lower limbs and 19 in the renal arteries. All the patients underwent digital rotational and non-rotational angiography and we analyzed the diagnostic yield, amount of contrast agent and the utility of additional views for each technique. All the examinations were reviewed with(out) subtraction, in cine-loop mode and frame by frame, as well as with(out) magnification. Finally, we considered background noise in both rotational and non-rotational images. RESULTS: The diagnostic quality of the digital rotational technique was always the same as or superior to that of the non-rotational technique. The former allows better 3D rendering, especially when viewed in the cine-loop mode; the examination is shorter and less contrast agent is needed. In contrast, image noise was increased, especially in lateral and oblique views. Digital rotational angiography was fairly well tolerated but the long breath-hold required was a problem especially to elderly patients. CONCLUSIONS: Digital rotational angiography is a useful tool to study vascular diseases in the carotid arteries and lower limbs using a lower radiation dose and less contrast agent than non-rotational examinations. As for the abdominal aorta and renal arteries, the rotational technique can be a valid adjunct to the conventional one.

Adult↗
PubMed2002

Preliminary study of a new real-time ultrasound method for measuring spinal and rib rotation in preoperative patients with adolescent idiopathic scoliosis.

A portable ultrasound machine with a linear array transducer was used by one observer (ASK) to evaluate the reproducibility for each of spinal (laminal) rotation and rib rotation in 13 preoperative patients with AIS (thoracic 7, thoracolumbar 6, mean Cobb angle 50 degrees, right 9, left 4, age 15.4 years, girls 10). With the subject in a prone position and her head supported, readings of spinal (laminal) and rib rotations were made directly on the back at 18 and 12 levels respectively. The subject was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). Conclusious. Repositioning the patient significantly alters some single level readings of lam inal rotation and rib rotation. Although the mean average spinal rotation and rib rotation each have acceptable reproducibility, repositioning the patient significantly alters the findings. In the appraisal of surgery by ultrasound the positional change reported here for (I) single level laminal rotation and rib rotation, and (2) mean average rotation imposes caution on the interpretation of the findings. The method enables the axial spine-nh rotation differences to be evaluated which is the subject of a separate paper.

Adolescent↗
PubMed1995

Effect of ACL Reconstruction and Tibial Rotation on Anterior Knee Laxity.

The anterior cruciate ligament (ACL) is the primary restraint to anterior translation of the tibia on the femur. Research suggests that resistance to anterior translation changes as the tibia is rotated internally and externally. This study assessed the degree to which ACL reconstruction and tibial rotation affects anterior knee laxity. Nine subjects with ACL lesions and functional instabilities participated in the study. Subjects were measured 1 to 10 days before surgery and 6 to 8 months after ACL reconstruction using the KT-1000 knee arthrometer. A mechanical leg stabilizer was used to assess anterior translation at 20 degrees of knee flexion in three positions: internal rotation of 15 degrees , neutral, and external rotation of 15 degrees . Subjects were measured at 89 and 67 N of anterior force. Data were analyzed with a three-factor (test x position x force) repeated measures ANOVA. Following surgery, reduction in laxity (mm) for the three positions (internal rotation, neutral, and external rotation) was 1.9, 2.8, and 3.4, respectively, at 89 N and 1.5, 2.0, and 2.6, respectively, at 67 N. The degree of reduction in laxity (presurgery to postsurgery) was dependent upon rotation and force, and was greatest in external rotation and least in internal rotation pre- to postsurgery. We concluded that ACL reconstruction using a patellar tendon graft significantly decreased anterior tibial translation at all three positions, but a greater amount of reduction was observed postsurgically at the externally rotated position. This supports the theory that mechanical blocks and secondary restraints such as a taut mid-third of the iliotibial tract may interfere with clinical laxity tests in some positions of tibial rotation. Fixing the tibia in an externally rotated position may decrease the effect of secondary restraints and improve sensitivity in testing for ACL laxity.

Journal Article↗
PubMed2001

Revision rotator cuff repair: factors influencing results.

BACKGROUND: Revision rotator cuff repair is a surgical challenge, and the results have generally been inferior to those of primary repair. We examined the results of revision rotator cuff repair in a large series of patients and assessed which subgroups of patients had the greatest chance for a satisfactory functional outcome. METHODS: A revision rotator cuff repair was performed in eighty patients after the failure of a previous operative repair. The average age of the patients at the time of the revision was fifty-nine years. Prior to revision, the average pain score was 7.4 points (with 0 points indicating no pain and 10 points, severe pain) and the active range of motion of the shoulder averaged 105 degrees of elevation, 39 degrees of external rotation, and internal rotation to the eleventh thoracic vertebra. All patients underwent repeat repair of the rotator cuff tendons to bone. Additional procedures included revision acromioplasty (fifty-three patients; 66%) and distal clavicular excision (twenty-six patients; 33%), among others. RESULTS: After an average duration of follow-up of forty-nine months, the result was rated as satisfactory (excellent, good, or fair) in fifty-five patients (69%) and as unsatisfactory (poor) in twenty-five (31%). At the time of the latest follow-up, the average pain score had improved to 3.0 points and the active range of motion averaged 130 degrees of elevation, 53 degrees of external rotation, and internal rotation to the tenth thoracic vertebra. Improved results were associated with an intact deltoid origin, good-quality rotator cuff tissue, preoperative active elevation of the arm above the horizontal, and only one prior procedure. All seventeen patients who met all four of these criteria had a satisfactory result. CONCLUSIONS: The results of revision rotator cuff repair are inferior to those of primary repair. While pain relief can be reliably achieved in most patients, the functional results are improved principally in patients with an intact deltoid origin, good-quality rotator cuff tissue, preoperative elevation above the horizontal, and only one prior procedure.

Adult↗
PubMed1995

MR diagnosis of rotator cuff tears of the shoulder: value of using T2-weighted fat-saturated images.

OBJECTIVE: The purpose of this study was to compare the use of fat-saturated T2-weighted spin-echo MR imaging with that of conventional T2-weighted spin-echo MR imaging to detect full- and partial-thickness tears of the rotator cuff of the shoulder, using arthroscopy as the standard for the diagnosis. SUBJECTS AND METHODS: Forty-nine consecutive patients with shoulder pain who had both MR imaging and arthroscopy of their affected shoulders were studied. The study group consisted of 10 patients with full-thickness tears of the rotator cuff, 20 with partial-thickness tears of the rotator cuff, and 19 with intact rotator cuff tendons proved arthroscopically. All patients had T1-weighted, conventional T2-weighted, and fat-saturated T2-weighted MR images obtained in a plane slightly oblique to the coronal plane along the long axis of the supraspinous tendon. The images were divided into two sets, one including both T1-weighted and conventional T2-weighted images, the other including T1-weighted and fat-saturated T2-weighted images. Two musculoskeletal radiologists reviewed each set of MR images in a blinded fashion. The reviewers were asked to decide whether the rotator cuff showed a full-thickness tear, a partial-thickness tear, or no tear on each set of images. In the case of partial-thickness tears, the reviewers were asked to indicate which surface (bursal or joint) of the rotator cuff was affected. These data were correlated with the arthroscopic findings and with each other using McNemar and kappa analysis. RESULTS: Detection of full-thickness tears was excellent for both reviewers using either imaging technique. However, when the fat-saturated technique was used, the sensitivity increased significantly, from 80% to 100%. Detection of partial-thickness tears was poor with conventional spin-echo MR imaging (15%). Although significantly improved when fat saturation was used (35%), detection rates were still lower than rates reported in the literature. Identification of the torn surface of the rotator cuff was correct in 50% of cases in which partial-thickness tears were successfully identified. Fat saturation decreased the specificity of identification of both partial and full-thickness tears of the rotator cuff but significantly increased the specificity with which intact rotator cuffs were identified. CONCLUSION: Use of the fat-saturation technique improved detection of both full-thickness and partial-thickness tears of the rotator cuff on MR images compared with standard spin-echo imaging techniques. Despite this improvement, detection of partial-thickness tears was poor with both techniques. Furthermore, correct identification of which surface of the rotator cuff was torn in patients with partial tears was nearly random.

Adult↗
PubMed1998

The association between irregular greater tuberosities and rotator cuff tears: a sonographic study.

OBJECTIVE: Although an association between irregular greater tuberosities and rotator cuff tears has been suggested, no formal studies have been done. This study was designed to investigate the relationship between greater tuberosity irregularities, rotator cuff tears, and age. SUBJECTS AND METHODS: Sonographic examinations of both shoulders of 77 asymptomatic individuals (154 shoulders) between 30 and 80 years old were performed. The rotator cuffs and greater tuberosities were evaluated. Full- and partial-thickness rotator cuff tears were given equal significance. A two-tailed Fisher's exact test, a Student's t test, and logistic regression analysis were used to analyze the data. RESULTS: Sonography showed the greater tuberosity to be irregular in 36 (90%) of 40 shoulders with a rotator cuff tear. The greater tuberosity was irregular in only 12 (11%) of 114 shoulders without a rotator cuff tear. When the greater tuberosity was irregular, sonography showed 36 (75%) of 48 shoulders to have rotator cuff tears. When the greater tuberosity was normal, 102 (96%) of 106 of the rotator cuffs were normal on sonography. Statistical significance was detected (p < .001) for the association of greater tuberosity irregularity and rotator cuff tear. After accounting for age, a statistically significant association was found (p < .001) between rotator cuff status and greater tuberosity status. CONCLUSION: On sonography, greater tuberosity irregularities are reliable indicators in the assessment of shoulders for rotator cuff tears. In addition, we have shown that greater tuberosity irregularities are not simply related to aging.

Adult↗
PubMedDate not supplied

Standard sonography and arthrosonography in the study of rotator cuff tears.

PURPOSE: The aim of this study was to evaluate the sensitivity of ultrasonography, integrating standard ultrasound and arthrosonography after injecting a saline solution into the glenohumeral cavity in cases of suspected rotator cuff tears. MATERIALS AND METHODS: We prospectively examined 40 patients awaiting shoulder arthroscopy for suspected or diagnosed tears of the rotator cuff. A radiologist, unaware of the pre-operative diagnosis, performed an ultrasound scan on all the patients before and after the injection of saline solution into the glenohumeral cavity. The parameters considered were presence or absence of a rotator cuff injury; type of injury according to Snyder and its extent along the longitudinal and transverse planes; presence or absence of effusion into the articular cavity; subacromial/subdeltoid bursal distension. All the patients underwent arthroscopy either the same day or the day after the ultrasound examination. RESULTS: Standard sonography showed 26 complete rotator cuff tears (type C according to Snyder), 2 partial tears (type B according to Snyder) and 12 intact rotator cuffs. Arthrosonography detected 31 complete rotator cuff tears (type C according to Snyder), 1 partial tear (type B according to Snyder) and 8 intact rotator cuffs.Arthroscopy identified 32 complete rotator cuff tears (type C according to Snyder), 1 partial tear (type B according to Snyder) and 8 intact rotator cuffs. Analysis of the results shows that, taking arthroscopy as the gold standard, the sensitivity of normal sonography is 81.2%, whereas that of arthrosonography is 96.8% (p < 0.05). CONCLUSIONS: On the basis of the data obtained in this study, standard sonography, integrated with the injection of a saline solution into the glenohumeral cavity, considerably increases the diagnostic sensitivity for rotator cuff tears. The authors suggest that arthrosonography can be used in the event of suspected rotator cuff tears, when MRI is contraindicated.

Adult↗
PubMed2000

In vivo technique to quantify the internal-external rotation kinematics of the human glenohumeral joint.

Internal and external rotation of the humerus are often related to instability, injury mechanisms, and surgical and rehabilitation outcomes at the glenohumeral joint. The goal of this study was to develop a technique to quantify the internal-external rotation kinematics of the glenohumeral joint in human subjects, including the rotational range of motion, neutral-zone laxity, and flexibility. For both arms of 10 normal subjects, the rotational range of motion of the humerus was assessed at 45 degrees of abduction with 4 Nm of applied moment to produce internal and external rotations about the long axis. The neutral zone was defined as the portion of the rotational range of motion that occurred between +1 and -1 Nm of applied internal-external rotation torque. The flexibility was determined from the slope of the moment-rotation curve from 1 to 4 Nm of applied moment. The repeatability of the device during two trials on the same day and two trials 1 week apart was determined. There were no significant differences between the two same-day and two across-day trials for each outcome measure. The internal-external rotational range of motion was 139.4 degrees (SD 40.5 degrees). The neutral-zone laxity was 77.8 degrees (SD 46.0 degrees). With a linear approximation, the external rotation flexibility (20.1 degrees/Nm [SD 13.7 degrees/Nm]) was four times greater than the internal rotation flexibility (5.8 degrees/Nm [SD 5.1 degrees/Nm]). The changes in the magnitude of the laxity, the ratio between the laxity and the range of motion, or the values for flexibility determined with this technique could be used to describe joint laxity, surgical outcome, and rehabilitation progress.

Adult↗
PubMed1995

Effect of neck rotation on the timing and pattern of infant tidal breathing.

While neck flexion and extension are known to influence the patency of the upper airway, far less information is available regarding the effects of neck rotation. The effect of neck rotation on respiratory rate (RR), expiratory time (tE), and phase angle (phi) was assessed in 17 healthy infants aged between 1 and 4 months. An inclinometer was used to measure neck rotation and uncalibrated Respiratory inductive Plethysmography to measure the dependent variables while the infants were in natural, quiet sleep. Baseline measurements were made with the head positioned centrally (0 degree rotation); further measurement positions included 30 degrees, 60 degrees, 90 degrees rotation, and repeat measurement at 0 degree (0r degree) in randomized order. Mean RR, tE, and phi were determined for each infant in each position. Using the paired t-test, RR at 0 degree rotation was significantly higher than that at 0r degree rotation (mean difference, 5 bpm; 95% CI, 2.1, 8.1; P = 0.0023); mean tE at 0 degree rotation was significantly shorter than at 0r degree rotation (mean difference, -0.18s; 95% CI, -0.27, -0.07; P = 0.002); whereas phi remained similar (mean difference, 10 degrees; 95% CI, -2.2, 22.3; P = 0.10. These changes probably reflect the slowing of metabolism that occurs after the onset of quiet sleep, and they emphasize the importance of randomization. Measurements at 0r degree were randomized and hence were most likely to reflect the true basal condition of the infant with the head in a neutral position. Consequently, these data, rather than those collected at 0 degree at the onset of quiet sleep, were used for comparisons with all subsequent positional changes. When comparing the positions whose order was randomized, neck rotation did not significantly affect RR (P = 0.445), tE (P = 0.272), or phi (P = 0.169). However, two infants demonstrated marked changes in respiratory pattern with decreases in RR and increases in tE at 90 degrees rotation, suggesting that some infants may be susceptible to obstruction in this position.

Humans↗
PubMed1994

Functional properties of rotation-sensitive neurons in the posterior parietal association cortex of the monkey.

We studied the functional properties of rotation-sensitive (RS) neurons of the posterior parietal association cortex in detail. We classified 58 neurons as RS neurons on the basis of statistical analysis, to indicate that their responses to rotary movement were significantly greater (P < 0.01) than those to linear movement of the same stimulus. We calculated rotation index, 1-(L/R), in 82 cells, where L/R is the ratio of net response to linear movement to that to rotary movement. All the RS neurons had rotation index greater than or equal to 0.3. The recording site of these RS neurons was localized in the posterolateral part of area PG (area 7a of Vogt), on the anterior bank of the caudal superior temporal sulcus (STS), in the region partly overlapping the medial superior temporal (MST) area. We compared the response of RS neurons to rotation with that to shearing movement as well as to linear movement. In the majority of RS neurons the ratio of shearing response to rotation response (S/R) was smaller than the ratio of linear response to rotation response (L/R), indicating that the response to rotation was not due to a simple combination of linear movements in the opposite direction. Most of the RS neurons responded to the rotary movement of a single spot as well as that of a slit, although the response was smaller (average 70%) for the former. Most of the RS neurons had large receptive fields (60-180 degrees in diameter) and their responses were independent of the position within the receptive field. The responses of most RS neurons increased monotonically with the increase in angular velocity and were also dependent on the size of the stimulus, although the rate of increase was small when the length was more than 10 degrees. The majority of RS neurons (37/58) responded better to rotation in depth than to that in the frontoparallel plane. Some of them (12/37) responded to diagonal rotation rather than to sagittal or horizontal rotation. We found that some depth RS neurons showed reversal in the preferred direction when we used a trapezoidal window-like plate as the rotating stimulus in the monocular viewing condition, just as occurs in the case of the Ames window illusion. The response of some RS neurons (5/7) was enhanced by tracking eye movement.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2000

Head elevation reduces head-rotation associated increased ICP in patients with intracranial tumours.

PURPOSE: To quantify the effects of graded head rotation and elevation on intracranial pressure (ICP) in neurosurgical patients, before and after induction of general anesthesia. METHODS: Patients with supratentorial tumours (n=12), scheduled for craniotomy with planned ICP monitoring, underwent baseline ICP measurements awake and supine (0 degrees rotation and elevation). Incremental degrees of head rotation (15 degrees) and of head elevation (10 degrees) were performed independently and in combination. Paired measurements of ICP at all levels of head rotation and elevation were also performed before and after induction of general anesthesia (n=6). RESULTS: The baseline ICP was 12.3 +/- 6.4 mmHg (n=12). Changes of ICP were proportional to the degree of head rotation or elevation. Head rotation of 60 degrees maximally increased ICP to 24.8 +/- 14.3 mmHg (P < 0.05). Head elevation above 20 degrees reduced ICP with a maximal reduction to -0.2 +/- 5.5 mmHg at 40 degrees elevation (P < 0.01). Head elevation to 30 degrees reduced the intracranial hypertension associated with head rotation. No differences were observed between ICP measurements made before or after induction of general anesthesia (n=6). Three patients experienced headache with extreme head rotation (<60 degrees) and intracranial hypertension (ICP > 20 mmHg). CONCLUSION: Head rotation of 60 degrees caused an increase in ICP. Concomitant head elevation to 30 degrees reduced the intracranial hypertension associated with head rotation. Headache with head rotation may provide a useful clinical warning of elevated ICP.

Adult↗
PubMed2005

Orienting eye movements and nystagmus produced by translation while rotating (TWR).

Sinusoidal translation while rotating at constant angular velocity about a vertical axis (translation while rotating, TWR) produces centripetal and translational accelerations along the direction of translation and an orthogonal Coriolis acceleration due to the translation in the rotating frame. Thus, a Coriolis acceleration is produced along the bitemporal axis when oscillating along the naso-occipital axis, and along the naso-occipital axis when oscillating along the bitemporal axis. Together, these components generate an elliptically rotating acceleration vector that revolves around the head in the direction of rotation at the frequency of oscillation. Here we studied the orienting and compensatory responses of rabbits during TWR. Combinations of centripetal and translational accelerations were held constant at 0.5 g, and oscillation frequencies were varied from 0.01-0.33 Hz. The amplitude of the Coriolis acceleration increased with the frequency of translation. Naso-occipital translation caused vergence and pitch at all frequencies and roll at higher frequencies, and bitemporal translation produced roll at all frequencies and vergence and pitch at higher frequencies. The sensitivity of each ocular orienting component to linear acceleration was comparable across the different oscillation frequencies. TWR also induced continuous yaw nystagmus with slow phase velocity in the direction of rotation of the acceleration vector. Thresholds for appearance of nystagmus were 0.05 Hz, corresponding to a Coriolis acceleration of 0.06 g. Mean slow phase velocity for a rotating linear acceleration vector produced by 0.5 g along the translation axis and 0.34 g of Coriolis acceleration along the orthogonal axis were approximately 9 degrees /s. Eye velocities during TWR were similar to those generated by off-vertical axis rotation (OVAR), but were opposite in direction with regard to head rotation, following the direction of the rotating acceleration vector in both paradigms. Both are produced by activation of velocity storage in the vestibular system. One important difference between TWR and OVAR is that the head is always upright with regard to gravity during TWR. We speculate that the brain may use these low amplitude rotating linear accelerations to generate eye velocities that help to orient gaze when making turns during normal locomotion.

Acceleration↗
PubMed1999

Latency of voluntary cancellation of the human vestibulo-ocular reflex during transient yaw rotation.

Volitional suppression of the initial vestibuloocular reflex (VOR) was studied in ten normal humans, aged 29+/-8 years (mean+/-standard deviation, SD), who were rotated about a vertical axis centered between the otoliths. Rotations consisted of steps in acceleration of 2800, 1600, 1000, or 500 degrees/S2 delivered at unpredictable times in unpredictable directions in the horizontal plane. As a test of the VOR, subjects were asked to attend to an earth-fixed target located 500 cm away that was either continuously visible or extinguished immediately before rotation. The gain of the VOR (angular eye velocity/angular head velocity) was 0.78+/-0.01 (mean+/-standard error of the mean, SE) during the period 35-45 ms after the onset of head rotation and 0.952+/-0.005 during the period 125-135 ms after the onset of head rotation. Subsequent rotations were performed during viewing of a target that moved with the head (cancellation). Cancellation was studied under three conditions of target visibility: (1) with the target always visible; (2) with the target always extinguished immediately prior to head rotation; or (3) with the target unpredictably extinguished half of the time immediately before each rotation. Cancellation responses showed individual idiosyncrasies, but certain features were common to most subjects. During cancellation, the VOR response generally differed from the earth-fixed target condition in that there was usually a small decrease in slow-phase VOR gain followed by an oppositely directed saccade. During the highest acceleration (2800 degrees/s2), the latency of the earliest statistically significant gain decrease for cancellation, as compared with the earth-fixed target condition, averaged 48+/-5 ms (mean+/-SE) from the onset of head rotation, although it was significantly shorter in one subject who had an onset at 14+/-2 ms. The latency of cancellation increased as head acceleration decreased such that, for each stimulus, cancellation began when the head was displaced an average of 1.4+/-0.1 degrees (-/+SD). Because VOR cancellation generally occurred before the availability of visual feedback or under conditions when vision was never permitted, it is inferred that cancellation is triggered by a threshold eye position or an estimate of head rotation based on integration of vestibular afferents. Cancellation occurred significantly earlier with a visible target than with an extinguished target only at the lowest peak head acceleration of 500 degrees/s2. Corrective saccades with a visible target occurred later for head accelerations of 500 and 1000 degrees/s2 than for greater head accelerations. Significant effects of target illumination on the latencies of both saccades and cancellation occurred at least 80-90 ms after the onset of head rotation, consistent with the earliest available visual feedback. This longer latency of saccades for visible as compared with extinguished targets may be analogous to a release of fixation, as occurs with express saccades. The latency difference due to target visibility was not related to prediction, since it was unchanged under conditions of random target illumination.

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