Headache in Patients with Cervical Spondylotic Myelopathy.

Purpose: The anatomical mechanisms of cervicogenic headache caused by upper cervical lesions have been reported. However, the pathomechanisms of headache caused by lower cervical spine disorders remain unknown. The purpose of the current study was to clarify the prevalence and pathogenesis of headaches in patients with cervical spondylotic myelopathy (CSM). Methods: In this retrospective study, a questionnaire regarding preoperative and postoperative symptoms was sent to 147 patients with CSM who were surgically treated in our hospital during the previous 10 years. All of the surgical procedures were decompression surgeries between the C3 and C7 levels. Data from 74 patients (50.3%) were available for analysis. Subjects were divided into four groups according to the presence or absence of preoperative and postoperative headache. The severity of pain, severity of neuropathic pain symptoms, depression, severity of myelopathy, and quality of life (QOL) were also evaluated using questionnaires. The scores of these questionnaires were then compared between the four groups. Kruskal-Wallis tests with Dunn-Bonferroni post hoc tests were used for comparisons. Results: Of the patients with CSM, 31% had headaches preoperatively, and 43% of these headaches disappeared postoperatively. Type 4 (preoperative headache-positive/postoperative headache-positive) patients had more severe pain and neuropathic pain symptoms and lower QOL scores compared with type 1 (preoperative headache-negative/postoperative headache-negative) patients. Conclusions: Approximately one-third of all patients with CSM had headaches preoperatively. Headache in patients with CSM may be neuropathic pain. A proportion of headaches in patients with CSM can be treated by decompression surgery.

Abdominal oblique muscle injury at its junction with the thoracolumbar fascia in a high school baseball player presenting with unilateral low back pain.

Abdominal oblique muscle injury is characterized by acute pain and localized tenderness over the lateral trunk. This injury is particularly common among throwing athletes, and usually presents as anterolateral abdominal wall pain. Imaging evidence is scarce in regard to whether oblique muscle injury at its junction with the thoracolumbar fascia can instead present with low back pain. A high school baseball player with unilateral low back pain was referred to us with a different diagnosis.　Careful palpation and magnetic resonance imaging guided our care, and the patient returned to high-level competition after 7 weeks of conservative treatment, with no report of recurrence in the subsequent 12 months. Oblique muscle injury at its junction with the thoracolumbar fascia should be added to the differential diagnosis for throwing athletes with unilateral low back pain following a torque movement.

Exposure-response analysis of drug-induced QT interval prolongation in telemetered monkeys for translational prediction to human.

INTRODUCTION: The preclinical in vivo assay for QT prolongation is critical for predicting torsadogenic risk, but still difficult to extrapolate to humans. This study ran preclinical tests in cynomolgus monkeys on seven QT reference drugs containing the drugs used in the IQ-CSRC clinical trial and applied exposure-response (ER) analysis to the data to investigate the potential for translational information on the QT effect. METHODS: In each of six participating facilities in the J-ICET project, telemetered monkeys were monitored for 24 h following administration of vehicle or 3 doses of test drugs, and pharmacokinetic profiles at the same doses were evaluated separately. An individual rate-corrected QT interval (QTca) was derived and the vehicle-adjusted change in QTca from baseline (∆∆QTca) was calculated. Then the relationship of concentration to QT effect was evaluated by ER analysis. RESULTS: For QT-positive drugs in the IQ-CSRC study (dofetilide, dolasetron, moxifloxacin, ondansetron, and quinine) and levofloxacin, the slope of the total concentration-QTca effect was significantly positive, and the QT-prolonging effect, taken as the upper bound of the confidence interval for predicted ∆∆QTca, was confirmed to exceed 10 ms. The ER slope of the negative drug levocetirizine was not significantly positive and the QTca effect was below 10 ms at observed peak exposure. DISCUSSION: Preclinical QT assessment in cynomolgus monkeys combined with ER analysis could identify the small QT effect induced by several QT drugs consistently with the outcomes in humans. Thus, the ER method should be regarded as useful for translational prediction of QT effects in humans.

Four-year follow-up of pregnancy-associated osteoporosis: a case report.

A 22-year-old woman presented with complaints of severe pain in a wide region of the thoracolumbar spine. She developed severe pain in the thoracolumbar spine region 2 months after her first delivery and was referred 1 month later. A lateral thoracic X-ray showed depressed degenerative vertebrae (T7, T9). One month after the initial examination, thoracic sagittal magnetic resonance imaging showed low intensity areas on T1-weighted imaging and iso-high intensity areas on T2-weighted imaging at T5, 7, 8, 9 and 11. Bone mineral density measured by ultrasound was low (%YAM 76%). The bone metabolic markers were high, suggesting accelerated osteoclast activity. These findings prompted a diagnosis of pregnancy-associated osteoporosis. She was asked to stop breastfeeding and to wear a lumbar brace, and treatment with nutritional calcium, activated vitamin D3, and risedronate sodium was started. Her low back pain almost disappeared after treatment. Bone metabolic markers showed normalization 8 months after the initial examination. Risedronate sodium was stopped 2 years and 2 months after the initial examination. Teriparatide treatment was started because her bone mineral density remained low; however, the osteoblast marker P1NP was not increased 5 months after the start of teriparatide treatment.

Influence of pre-laminated material on shock absorption ability in specially designed mouthguard with hard insert and space.

PURPOSE: We have developed a new type of laminated mouthguard, the Hard & Space mouthguard, which incorporates a hard material insert and a space to prevent contact between the mouthguard and the buccal surfaces of the teeth. The purpose of this study was to investigate the effect of this new design on shock absorption. METHODS: Three types of mouthguard (a conventional laminated EVA mouthguard and two 3-layer type "Hard & Space" mouthguards made of 1.8-mm or 3.0-mm thick pre-laminated material (Konbiplast) and EVA with a 1.0-mm space) were impacted. Shock absorption was measured by means of a pendulum type steel ball impact testing machine at impact distances of 10, 20, and 30 cm and a dental study model with strain gauges attached to the lingual surfaces and an accelerometer fixed to the maxilla. RESULTS: Distortion of the impacted tooth and acceleration of the model were significantly reduced by all types of mouthguard at all 3 impact distances. The effect of the mouthguard was remarkable in terms of tooth distortion: both thicknesses of Hard & Space mouthguard showed more than 90% shock absorption, compared with only approximately 55-78% with an EVA mouthguard. Furthermore, shock absorption with the thicker 3.0-mm Hard & Space mouthguard reached more than 95% at the highest impact power. CONCLUSION: Within the limitations of this laboratory study, Hard & Space mouthguards showed significantly greater buffer capacity than a conventional EVA mouthguard in terms of tooth distortion at the 3 impact powers tested.

Are all mouthguards the same and safe to use? Part 2. The influence of anterior occlusion against a direct impact on maxillary incisors.

The purpose of this study was to clarify the influence anterior occlusion, of mouthguards, has on protecting against a direct collision to the maxillary anterior teeth. In other words, the support mandibular dentition has when wearing a mouthguard. Two types of mouthguards were used for this study, one with an appropriate anterior occlusion or a mouthguard with positive anterior occlusion (MGAO+) and another which was a single-layer mouthguard lacking the same occlusion or a mouthguard with negative anterior occlusion (MGAO-) but with the same thickness on the buccal side. The instruments used for testing were a pendulum-type impact device with two interchangeable impact objects (a steel ball and a baseball), with a plastic jaw model having artificial teeth. Four testing conditions were observed: one with the jaw open without a mouthguard (Open NoMG), the second with the jaw clenching (loaded with 30 kg weight) without a mouthguard (Clench. NoMG), the third with the jaw clenching with MGAO- (Clench. MGAO-) and the last with the jaw clenching with MGAO+ (Clench. MGAO+). The results are as follows: both types of mouthguards showed the effects in reducing the distortion of the teeth. However, the effect was significantly obvious (steel ball = about 57% shock absorption ability, baseball = about 26%) in the mouthguard with anterior occlusion or support by lower dentition through mouthguard (Clench. MGAO+) than Clench. MGAO-. Thus, the influence of anterior occlusion of mouthguards or the support of mandibular dentition through wearing a mouthguard (MGAO+) is indispensable in reducing the impact force and tooth distortion. The results of this research should further contribute to the establishment of guidelines for safer mouthguards.

Does hard insertion and space improve shock absorption ability of mouthguard?

Mouthguards are expected to reduce sports-related orofacial injuries. Numerous studies have been conduced to improve the shock absorption ability of mouthguards using air cells, sorbothane, metal wire, or hard material insertion. Most of these were shown to be effective; however, the result of each study has not been applied to clinical use. The aim of this study was to develop mouthguards that have sufficient prevention ability and ease of clinical application with focus on a hard insertion and space. Ethylene vinyl acetate (EVA) mouthguard blank used was Drufosoft and the acrylic resin was Biolon (Dreve-Dentamid GMBH, Unna, Germany). Three types of mouthguard samples tested were constructed by means of a Dreve Drufomat (Type SO, Dreve-Dentamid) air pressure machine: the first was a conventional laminated type of EVA mouthguard material; the second was a three layer type with acrylic resin inner layer (hard-insertion); the third was the same as the second but with space that does not come into contact with tooth surfaces (hard + space). As a control, without any mouthguard condition (NOMG) was measured. A pendulum type impact testing machine with interchangeable impact object (steel ball and baseball) and dental study model (D17FE-NC.7PS, Nissin, Tokyo, Japan) with the strain gages (KFG-1-120-D171-11N30C2: Kyowa, Tokyo, Japan) applied to teeth and the accelerometer to the dentition (AS-A YG-2768 100G, Kyowa) were used to measure transmitted forces. Statistical analysis (anova, P < 0.01) showed significant differences among four conditions of NOMG and three different mouthguards in both objects and sensor. About acceleration: in a steel ball which was a harder impact object, shock absorption ability of about 40% was shown with conventional EVA and hard-insertion and about 50% with hard + space. In a baseball that was softer compared with steel ball, a decrease rate is smaller, reduction (EVA = approximately 4%, hard-insertion = approximately 12%, hard + space = approximately 25%) was admitted in the similar order. A significant difference was found with all the combinations except for between EVA and hard-insertion with steel ball (Tukey test). About distortion: both buccal and lingual, distortions had become small in order of EVA, hard-insertion, and hard + space, too. The decrease rate is larger than acceleration, EVA = approximately 47%, hard-insertion = 80% or more, and hard +space = approximately 98%, in steel ball. EVA = approximately 30%, hard-insertion = approximately 75%, and hard + space = approximately 98% in baseball. And a significant difference was found with all the combinations (Tukey test). Especially, hard + space has decreased the distortion of teeth up to several percentages. Acceleration of the maxilla and distortions of the tooth became significantly smaller when wearing any type of mouthguard, in both impact objects. But the effect of mouthguard was clearer in the distortion of the tooth and with steel ball. Considering the differences of mouthguards, the hard-insertion and the hard + space had significantly greater buffer capacity than conventional EVA. Furthermore, hard + space shows quite high shock absorption ability in the tooth distortion. Namely, hard + space has decreased the distortion of teeth up to several percentages in both impact objects.

[Questionnaire survey of dentists who made their own mouthguards].

PURPOSE: Most of the mouthguards on the market are inferior in fit and occlusion related to feeling and injury prevention capacity. Therefore, it is necessary to use appropriate custom-made mouth-guards. This research aimed to obtain data for the selection, improvement, and spread of mouthguards in the future. A questionnaire survey of dentists who had made four kinds of mouthguard was conducted in a mouthguard seminar. METHODS: The questionnaire survey concerning "feeling", "difficulty of production", and "selection when considering use and spread" was done for four kinds of mouthguard. The evaluations were made using a ten-point method with the Kruskal-Wallis test and Mann-Whitney U-test. RESULTS: Concerning the feeling: The laminated mouthguard was evaluated the highest, followed in order by improvement type, vacuum, and boil & bite. Concerning the production: The evaluation differed from other questionnaire items. No significant difference was found among all four kinds of mouthguard, so there was no difference in the fabrication difficulty. Concerning the selection and spread: The evaluation was almost the same as for the feeling. The laminated mouthguard was assessed to be the best mouthguard. CONCLUSIONS: The boil & bite mouthguard which is widespread was evaluated the lowest in all items except production. Therefore, it is necessary to encourage players to use an appropriate custom-made type in view of safety, wearing feeling, and dental occlusion.

[Mouthguard effect of tooth distortion during clenching].

PURPOSE: A mouthguard can protect stomatognathic systems from traumatic damage. However, severe occlusal wear of teeth and loss of teeth have often been found in players clinically. These problems might originate in strong clenching during sports. Although it is thought that a mouthguard may be effective for these types of clenching, the relation between mouthguards and clenching has not been sufficiently examined. In this study, the effect of a mouthguard (Drufosoft 3mm, EVA) on tooth distortion caused by clenching was measured and examined at three different clenching strengths. METHODS: As a test tooth, a lower first molar was selected. A strain gauge applied to the outer surface of the buccal cusp was used to measure the distortion. A muscle balance monitor (GC) was used to regulate clenching strengths (10, 50, and 100%). The maximum-effort clenching without a mouthguard was assumed to be the 100% clenching strength. Measurements were conducted with or without mouthguard. A maximum value during clenching was assumed to be date of distortion by using analytical software AcquKnowledge (BIOPAC System Inc.). Statistical analysis software SPSS (SPSS Japan Inc.) was used for the Mann-Whitney test. RESULTS: 1. The tooth distortion by clenching, regardless of the presence of the mouthguard, increased as clenching power strengthened, from 10, 50 to 100%. 2. The tooth distortion, regardless of strength of clenching, was decreased by wearing the mouthguard in all subjects. At 50 and 100% clenching, it was decreased significantly by the mouthguard in all subjects. CONCLUSIONS: Mouthguards decreaseed the tooth distortion caused by clenching. Therefore, a mouthguard may prevent not only traumatic injuries in contact sports but also damage to teeth and periodontal tissues and so on, which occur due to frequent strong clenching in many sports.

Can mouthguards prevent mandibular bone fractures and concussions? A laboratory study with an artificial skull model.

Some sports' accidents are responsible for inflicting traumatic brain injuries and mandibular bone fractures when impacts occur to the chin. It is often thought that mouth guards can prevent many of these injuries. However, such assertions may be insufficient without adequate research. It is therefore necessary to establish a systematic method of investigation to solve this problem. In the present laboratory study, tests were performed using pendulum impact equipment and an artificial skull model connected to strain gages and accelerometers to simulate and measure the surface distortions related to bone deformation or fractures and the acceleration of the head related to concussions. As impacts, direct blows to the mandibular undersurface were applied. As a result, wearing a mouth guard decreased (P < 0.01) the distortion to the mandibular bone and the acceleration of the head significantly compared with not wearing a mouth guard (54.7%: to the mandible -- measured at a total of three different points, 18.5%: to the head measured at a total of three different points). Within the limits of this study, the following conclusions were drawn: The present measuring system in this study was able to evaluate the distortion to the mandibular and the acceleration of the head from the direct blow to the mandibular undersurface. Mouth guards can reduce distortion to the mandibular and the acceleration of the head from the same blow. So mouth guards might have the possibility to prevent mandibular bone fractures and concussions. However, further well-designed and exhaustive studies are vital to show that mouth guards reduce the incidence of concussions and mandibular bone fractures.