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PubMed1974

Pharmacology of M & B 18,706, a drug which selectively reduces decerebrate rigidity.

1 (+/-)-10-(3-Dimethylamino-2-methylpropyl)-2-valeroylphenothiazine hydrochloride (M & B 18,706) has been compared with dimethothiazine, chloropromazine, diazepam and baclofen for potency in reducing decerebrate rigidity in the cat and rat and for activity in causing ataxia or sedation.2 When given intravenously M & B 18,706 had seven times the potency of dimethothiazine and one-half the potency of chlorpromazine in reducing the rigidity of the intercollicular decerebrate cat. When administered orally M & B 18,706 and chlorpromazine were equi-potent in reducing rigidity but M & B 18,706 was less effective than chlorpromazine in producing ataxia in this species.3 In the rat, M & B 18,706 had one-quarter the potency of chlorpromazine for reducing decerebrate rigidity but had from 1/20th to 1/200th its potency in tests for sedative or tranquillizing activity.4 M & B 18,706, like dimethothiazine and chlorpromazine, had little effect on the rigidity of ischaemic decerebrate cats and failed to inhibit polysynaptic spinal reflexes.5 M & B 18,706 had intravenous potency comparable to chlorpromazine in reducing the pressor action of noradrenaline in the spinal cat.

Adrenergic alpha-Antagonists↗
PubMed2002

Quantitative analysis of the velocity related pathophysiology of spasticity and rigidity in the elbow flexors.

OBJECTIVE: To quantify velocity dependent and position related properties of increased muscle tone measured during a constant velocity stretch. METHODS: Elbow flexors were vertically stretched under four different velocities (40, 80, 120, and 160 degrees /s) through a 75 degrees range of motion in 12 patients with hemiparesis, 16 with parkinsonism, and 12 normal controls. From reactive torque measurement, a linear second order model was adopted to dissociate velocity dependent viscous and velocity independent elastic components. The averaged speed dependent reflex torque (ASRT)--defined as the deviation of measured torque from baseline torque--was used to quantify the viscous component of hypertonia. Velocity sensitivity of ASRT (VASRT) and segmented ASRT (SASRT), derived from the slope of the regression line among ASRT velocity plots and from segmentations of reactive torque, respectively, were used to differentiate the increased muscle tone of spasticity and rigidity. RESULTS: ASRT and VASRT were significantly higher in both spasticity and rigidity than in normal controls. SASRT analysis showed three different position related patterns among spasticity, rigidity, and normal groups: spasticity showed progressively increasing muscle tension relative to position; rigidity showed increased (relative to the norm) but constant muscle tone over the entire stretch range; the normal control group showed a consistently low reactive torque over the entire range. CONCLUSIONS: Velocity dependence analysis indicates that rigidity and spasticity have approximately equal velocity dependent properties. For differentiating these two types of hypertonia, position dependent properties my be employed.

Adult↗
PubMed1976

Suppression of decerebrate rigidity by phenytoin and chlorpromazine.

In cats decerebrated by a midcollicular section, decerebrate rigidity developed that was not alleviated by phenytoin even in doses as great as 60 mg per kilogram. Chlorpromazine that depresses decerebrate rigidity in a dose-related fashion requires 1.5 to 2.0 mg per kilogram to exhibit an appreciable effect. In the presence of 20 mg per kilogram phenytoin, however, as little as 0.1 mg per kilogram chlorpromazine markedly reduces decerebrate rigidity. This drug combination did not impair neuromuscular transmission nor did it severely impair motor coordination in cats. Although phenytoin depressed muscle spindle discharges, this peripheral suppression was insufficient to abolish the rigidity. Phenytoin with or without chlorpromazine may be of value in suppressing muscle rigidity in some disorders of upper motor neuron lesions.

Animals↗
PubMed1991

Parkinson's disease rigidity: magnetic motor evoked potentials in a small hand muscle.

We studied the EMG potentials evoked in the bilateral first dorsal interosseus muscle by electromagnetic stimulation of the corticomotoneuronal descending system in 10 Parkinson's disease patients and in 10 age- and sex-matched normal controls. We selected patients who did not have tremor but had predominant rigidity with asymmetric body involvement. On the rigid side of the PD patients, the threshold to cortical stimulation was lower than on the contralateral side or than normal values. On average, patients had normal central conduction times, but their motor evoked potentials (MEPs) on the rigid side were larger than those of controls when the cortical stimulus was at rest or during slight tonic contraction of the target muscle. In the latter condition, a silent period shorter than that of controls followed MEPs, whereas the peripheral silent period following ulnar nerve stimulation at the wrist was prolonged. Alpha motor neuron excitability, tested by the F-wave method, was enhanced on the rigid side at rest. In rigidity, spinal motor nuclei may be more responsive than normal to descending inputs from motor cortex, or the entire corticomotoneuron system may prove hyperexcitable under given conditions.

Aged↗
PubMed1997

Truncal rigidity as a result of epidural sufentanil--a case report.

It is well known that intravenous opioids may cause truncal rigidity. To the best of our knowledge truncal rigidity induced by epidural opioid has never been reported. Recently, we came across an accident of truncal rigidity following epidural sufentanil. The victim was a 65-year-old female who received cholecystectomy, choledochotomy, and cholangiography. For post-operative pain control, an epidural catheter was inserted cephalad [corrected] at L1-2 interspace with a length of 4 cm of the catheter retained in the epidural space. The epidural catheter was secured and tested for correct placement with 3 ml of 2% lidocaine with 1:200,000 epinephrine prior to induction of general anesthesia. No opioid was ever given in the operative course. When the patient was fully awake and complained of wound pain in the recovery room 50 mg of sufentanil in 10 ml normal saline was given via the epidural catheter after a negative evacuation test. About one minute after the epidural shot, she was found to lose consciousness without any slightest warning sign. Truncal rigidity and locked jaw that followed entailed respiratory arrest and rapid deterioration of oxygenation which evidenced a life-threatening airway emergency. It spite of our efforts we could not manage to ventilate her with ordinary means. It was not until the administration of 80 mg of succinylcholine and oral endotracheal intubation could an adequate ventilation be reestablished. She regained spontaneous breathing 15 min after the episode but for safety's sake she remained intubated for 6 h until the dissipation of analgesia. Another test dose was attempted, which reconfirmed that the epidural catheter was in proper position. She stayed in the recovery room for 24 h and returned to ward in satisfactory condition. The incidence disclosed that epidural sufentanil even with a dose as small as 50 micrograms could cause truncal rigidity. Thus when epidural sufentanil is applied for post-operative pain control constant vigilance is necessary in order to avoid accident.

Abdomen↗
PubMed1990

Scleral buckling and ocular rigidity. Clinical ramifications.

Ocular rigidity is the change in intraocular pressure produced by an incremental change in intraocular volume. Ocular rigidity was determined in 14 donor eyes by injecting small increments of a balanced salt solution through the limbus, while continually monitoring the intraocular pressure with a transducer. A buckling procedure was then performed in these eyes with the use of various solid silicone or stainless steel encircling elements, and the experiments were repeated. Buckled eyes were significantly less rigid than unbuckled eyes, and eyes with higher buckles were significantly less rigid than those with shallower buckles. The observed changes in rigidity are likely secondary to changes in the shape and stress distribution of the scleral shell and are only to a small degree related to the elasticity of the encircling element. Greater volumes of vitreous substitutes, gases, or antibiotics may be injected into buckled eyes compared with unbuckled eyes before excessive intraocular pressures are reached.

Acetates↗
PubMed2001

Use of rigid and flexible bronchoscopy among pediatric otolaryngologists.

OBJECTIVE: To explore how rigid and flexible bronchoscopy are used in pediatric otolaryngologic practice. DESIGN: Survey. PARTICIPANTS: Members of the American Society of Pediatric Otolaryngology who practice in the United States and Canada and were listed in the membership directory were eligible. Of the 206 members, 24 practicing outside the United States or Canada and 11 without an e-mail address or a fax machine were excluded. Hence, a questionnaire was e-mailed or faxed to 171 pediatric otolaryngologists. MAIN OUTCOME MEASURES: Questions concerned the practice setting, type and number of bronchoscopies, indications, complications, and medicolegal cases. RESULTS: Responses were received from 120 subjects (70.2%), with 3 retired and 2 practicing only otology, leaving 115 respondents who completed at least some of the questionnaire. Rigid and flexible bronchoscopy were performed by 72.7% (56/77) of those in academic settings and by 71.1% (27/38) of those in group or solo practices. In the last 12 months, approximately 10 454 total bronchoscopies were performed, with 2052 flexible and 9117 rigid bronchoscopies. Stridor, suspected foreign body inhalation, and laryngomalacia were the most common indications for bronchoscopy. Of the 83 respondents practicing rigid and flexible bronchoscopy, 25 (30.1%) used both instruments to manage complex or repeated foreign bodies, 25 (30.1%) used both to manage patients with cystic fibrosis, and 15 (18.1%) used both to manage simple foreign bodies. Complications were reported by 15.7% of the respondents, the most common being arrhythmia. Familiarity with a case resulting in medicolegal action was reported by 32.2% of the respondents. CONCLUSIONS: Rigid and flexible bronchoscopy have multiple uses in pediatric otolaryngologic practice. Also, flexible bronchoscopy appears to be emerging as a more frequently used diagnostic and therapeutic tool.

Bronchoscopes↗
PubMed1994

Rigid internal fixation of the sternum in postoperative mediastinitis.

OBJECTIVE: The current standard treatment of mediastinitis following median sternotomy is radical sternal débridement and obliteration of anterior mediastinal dead space with muscle or omental flaps. This report describes and reviews our experiences with a new technique of sternal salvage based on osseous quantitative bacteriologic assessment and rigid fixation in patients with postoperative mediastinitis. DESIGN: A retrospective review of 29 patients treated with sternal rigid internal fixation. SETTING: Two tertiary care academic medical centers in Chicago, Ill, and Ann Arbor, Mich. PATIENTS: Patients with postoperative mediastinitis following median sternotomy who underwent rigid internal fixation of retained sternum. INTERVENTION: Following débridement, quantitative bacteriologic assessment and sternal vascularity were assessed. Sternal segments with good vascularity and in bacteriologic balance were anatomically reduced and rigidly fixed to each other with titanium miniplates in 24 patients with postoperative mediastinitis. Five of the 29 patients, at high risk for mediastinitis, underwent rigid internal fixation immediately after their cardiac procedure. MAIN OUTCOME MEASURES: Resolution of infection, wounds remaining closed, and stable sternums. RESULTS: Bony union was obtained in 27 (93%) of 29 patients. The postoperative hospital stay ranged from 5 to 84 days, with a mean stay of 17 days and a median stay of 7 days. Length of stay was directly related to pulmonary function, which correlated with preoperative intubation status. CONCLUSIONS: Radical sternal débridement may not be necessary in all patients with postoperative mediastinitis following median sternotomy. Sternal salvage can safely and reliably be performed with a combination of clinical assessment of vascularity and osseous quantitative bacteriologic assessment. Anatomic reduction of the viable sternal segments is possible even in severely osteoporotic bone.

Adolescent↗
PubMed1986

A comparison of the 25-cm rigid proctosigmoidoscope with the 65-cm flexible endoscope in the screening of patients for colorectal carcinoma.

A comparison of the rigid with the flexible sigmoidoscope was evaluated in 293 patients as part of a screening project for colorectal cancer at Roswell Park Memorial Institute. Patients with either a positive family history for colorectal cancer, a positive stool guaiac test result, a history of hematochezia, or a change in bowel habits were randomly assigned to either rigid or flexible sigmoidoscopy. The median distance of colon examined with the flexible instrument was significantly greater than with the rigid scope (55 versus 17 cm, respectively). A significantly greater number of malignant and premalignant lesions were found with the flexible instrument than with the rigid scope. It was concluded that the flexible sigmoidoscope is superior to the rigid scope in the process of screening for colorectal lesions.

Adolescent↗
PubMedDate not supplied

Quantitative assessment of nocturnal penile tumescence and rigidity in normal men using a home monitor.

Current methods now permit the measurement of nocturnal penile tumescence and rigidity (NPTR) in men with erectile dysfunction. But the relationship of rigidity to tumescence and the changes in rigidity with age have not been defined in normal men. Accordingly, the authors assessed NPTR in 47 normal men using a portable, take-home monitor (Rigiscan). Penile tumescence time was found to decrease with advancing age (p less than 0.05), whereas the number of erectile episodes and penile rigidity did not significantly change with age for men in the third through sixth decades (p less than 0.05). Using area-under-the-curve as an integrated measure of amplitude and duration, significant correlations between tumescence and rigidity (p less than 0.001), and between tip and base measurements (p less than 0.001) were found. With these normative data, prospective studies should determine the sensitivity and specificity of various NPTR parameters in the diagnosis of erectile dysfunction.

Adult↗
PubMed2005

A variational PDE based level set method for a simultaneous segmentation and non-rigid registration.

A new variational PDE based level set method for a simultaneous image segmentation and non-rigid registration using prior shape and intensity information is presented. The segmentation is obtained by finding a non-rigid registration to the prior shape. The non-rigid registration consists of both a global rigid transformation and a local non-rigid deformation. In this model, a prior shape is used as an initial contour which leads to decrease the numerical calculation time. The model is tested against two chamber end systolic ultrasound images from thirteen human patients. The experimental results provide preliminary evidence of the effectiveness of the model in detecting the boundaries of the incompletely resolved objects which were plagued by noise, dropout, and artifact.

Algorithms↗
PubMed1995

Parkinsonian rigidity, dopa-induced dyskinesia and chorea--dynamic studies on the basal ganglia-thalamocortical motor circuit using PET scan and depth microrecording.

Regional cerebral glucose metabolism (rCMRGlu-18FDG) was measured in 6 cases with rigid type Parkinson's disease (PD) (2 cases with dopa-induced dyskinesia = DID), 6 cases with chorea (Ch), 5 cases with essential tremor (EssT) and 2 cases with normal subjects (N). The effects of L-Dopa on rCMRGlu was studied in 3 cases with PD. With the aid of depth microrecording study, stereotactic pallidotomy was performed in all cases with PD. Thalamotomy was performed in 3 cases with Ch. In the EssT and N group, the metabolic pattern was high in the frontal cortex (FCx) but low in the lenticular nucleus (LN). In contrast, all cases with a rigid type PD showed lower rCMRGlu in FCx (premotor, prefrontal area). However, 4 out of 6 cases were higher in LN than the control group. Administration of L-Dopa shifted rCMRGlu toward the normal pattern in this group. Five out of 6 cases with Ch represented higher rCMRGlu in FCx (3 focal, 2 diffuse) but lower in LN. Moreover, when DID occurred, it showed almost the same pattern as in Ch. Electrophysiological studies showed high background neuronal activity (BNA) in the medial segment of the globus pallidus (GP) but low BNA in the lateral segment of the GP in the rigid type of PD. In cases with Ch, irregular burst discharges were often encountered in ventro-oral thalamus. From these results, the on-going changes of basal ganglia-thalamocortical motor circuit in cases with a rigid type PD, DID and Ch are discussed. The underlying mechanisms of Parkinsonian rigidity was considered to contrast with those of DID and Ch within the same motor circuit.

Antiparkinson Agents↗
PubMed2003

Evaluation of indication-based use of transpedicular instrumentations with different rigidity for lumbar spinal fusion: a prospective pilot study with 3 years of follow-up.

In a prospective cohort study in 94 patients with 3 years' follow-up the efficacy of rigid and semi-rigid transpedicular instrumentation for lumbar spine fusion was evaluated via three established scores. Patient groups were similar in respect of anthropometric data. The indication for using the semi-rigid technique was a fairly stable intraoperative situation; for the more common unstable situations, the rigid technique was chosen. Selecting implant rigidity on these criteria led to results with an improvement rate well within the upper success range reported in the literature. Among people in employment, a lengthy preoperative sick leave was an important predictor for unsatisfactory outcome.

Biomechanical Phenomena↗
PubMed1990

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: rigid versus nonrigid fixation.

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation.

Adolescent↗
PubMed1988

Stability of simultaneous maxillary intrusion and mandibular advancement: a comparison of rigid and nonrigid fixation techniques.

This study examines the short-term stability of bimaxillary surgery following Le Fort I impaction with simultaneous bilateral sagittal split osteotomies and mandibular advancement using two standard techniques of postsurgical fixation. Fifteen adults had skeletal plus dental maxillomandibular fixation, and fifteen adults had rigid internal fixation using bone plates in the maxilla and bicortical bone screws between the proximal and distal segments in the mandible. The group with rigid internal fixation did not undergo maxillomandibular fixation. Radiographic cephalograms were analyzed during the postsurgical period to evaluate skeletal and dental stability. There was no statistical difference in postsurgical stability with rigid internal fixation or skeletal plus dental maxillomandibular fixation other than the vertical position of the maxillary molar; the skeletal plus dental maxillomandibular fixation group had a significant amount of postsurgical intrusion of the maxillary molar when compared with the rigid internal fixation group. Although the other measures showed no statistically significant difference between the experimental groups, the amount of variability in postsurgical stability in the group with skeletal plus dental maxillomandibular fixation was greater than that found in the group with rigid internal fixation.

Bone Plates↗
PubMedDate not supplied

The rigidity of bacterial flagellar filaments and its relation to filament polymorphism.

We determined and correlated the rigidity of Salmonella typhimurium, Escherichia coli, and Rhizobium lupini flagellar filaments representing various structural and polymorphic states (plain, complex, straight, superhelical, and right- and left-handed). Persistence length, from which the filament's rigidity and other parameters (Young's modulus, bending force constant, buckling persistence length, flexural deformation, and flexural time) were derived, was determined from electron micrographs of isolated, negatively stained filaments. Outer diameters and radii of strong intersubunit connectivity were determined from three-dimensional image reconstructions and radial mass density profiles from scanning transmission electron microscopy. All filaments appear to be highly rigid with no evident correlation with their helical sense or superhelicity. The complex filament of R. lupini is rigid to the extent that it becomes brittle. The overall flexibility of the flagellum seems to stem mainly from the hook and not from the filament. Polymorphism is probably related to the propelling properties and hydrodynamic shape of the filament rather than to its rigidity.

Escherichia coli↗
PubMed2006

Ocular rigidity in patients with age-related macular degeneration.

PURPOSE: To compare the ocular rigidity in vivo measurements of patients with age-related macular degeneration (AMD) and control subjects. DESIGN: Prospective comparative clinical study. METHODS: The pressure-volume relation and the ocular rigidity coefficient were compared among 32 patients with AMD (AMD group: 16 with neovascular and 16 with nonneovascular AMD) and 44 age-matched control patients (control group) who underwent operation for cataract. This was achieved by an injection of 200 microl of a balanced salt solution (in steps of 4.5 microl) through the limbus in the anterior chamber, while the intraocular pressure was monitored continually with a transducer, up to the limit of 30 mm Hg. RESULTS: The mean age (AMD group: 69.89 +/- 15.92 years vs control group: 65.28 +/- 12.34 years; P = .195), gender (AMD group: 13 female vs control group: 17 female; P = .513), eye's axial length (AMD group: 23.14 +/- 0.75 mm vs control group: 23.04 +/- 1.16 mm; P = .725) of patients with AMD and the healthy control subjects were comparable. No statistically significant difference in ocular rigidity measurements between patients with AMD and control subjects (AMD group: 0.0142 +/- 0.0077 microl(-1) vs control group: 0.0125 +/- 0.0049 microl(-1); P = .255) was found. When we examined separately the two subgroups of patients with AMD (neovascular and nonneovascular AMD), the average ocular rigidity measurements were higher in patients with neovascular AMD vs both control subjects and patients with nonneovascular AMD (neovascular AMD group: 0.0186 +/- 0.0078 microl(-1) vs control group: 0.0125 +/- 0.0048 microl(-1) [P = .014] vs nonneovascular AMD group: 0.0104 +/- 0.0053 microl(-1) [P = .004]). CONCLUSIONS: Despite the limitations placed by the small sample of the examined cases, patients with neovascular AMD who are treated (with photodynamic therapy) have increased ocular rigidity measurements compared with patients with nonneovascular AMD and control patients.

Aged↗
PubMed2004

Confocal microscopy of the corneas of long-term rigid contact lens wearers.

Slit scanning confocal microscopy (Tomey Confoscan P4) was used to evaluate the central cornea of 22 subjects who had been wearing rigid lenses on a long-term, daily wear basis. Anterior and posterior keratocyte densities appeared unaffected by rigid lens wear (P = 0.10 and 0.34 for anterior and posterior keratocyte densities, respectively). Subjects with a previous history of polymethyl methacrylate (PMMA) lens wear showed a reduction in anterior keratocyte density (AKD) (P < 0.0001) and an increased level of haze in the anterior stroma. This may represent previous hypoxic damage. Endothelial cell density (ECD) was unaffected by rigid lens wear (P = 0.36) although an increase in endothelial polymegethism was evident (P < 0.0001). Subjects who had only worn rigid lenses with no history of PMMA lens wear did not show an increase in endothelial polymegethism (P = 0.10). An increased number of microdot opacities compared to the non-lens wearing eye was apparent (P = 0.05). The number of microdot opacities induced by rigid lenses, as reported in this study, appears to be less than that reported by others in respect of soft lenses.

Journal Article↗