Leg muscle recruitment in highly trained cyclists

In this study, we examined patterns of leg muscle recruitment and co-activation, and the relationship between muscle recruitment and cadence, in highly trained cyclists. Electromyographic (EMG) activity of the tibialis anterior, tibialis posterior, peroneus longus, gastrocnemius lateralis and soleus was recorded using intramuscular electrodes, at individual preferred cadence, 57.5, 77.5 and 92.5 rev.min(-1). The influence of electrode type and location on recorded EMG was also investigated using surface and dual intramuscular recordings. Muscle recruitment patterns varied from those previously reported, but there was little variation in muscle recruitment between these highly trained cyclists. The tibialis posterior, peroneus longus and soleus were recruited in a single, short burst of activity during the downstroke. The tibialis anterior and gastrocnemius lateralis were recruited in a biphasic and alternating manner. Contrary to existing hypotheses, our results indicate little co-activation between the tibialis posterior and peroneus longus. Peak EMG amplitude increased linearly with cadence and did not decrease at individual preferred cadence. There was little variation in patterns of muscle recruitment or co-activation with changes in cadence. Intramuscular electrode location had little influence on recorded EMG. There were significant differences between surface and intramuscular recordings from the tibialis anterior and gastrocnemius lateralis, which may explain differences between our findings and those of previous studies.

MR morphometry of posterior tibialis muscle in adult acquired flat foot

We conducted magnetic resonance imaging of the posterior tibial (PT) and flexor digitorum longus (FDL) muscle bellies in 12 patients undergoing surgical treatment for unilateral posterior tibial tendon (PTT) dysfunction. All patients had atrophy of the PT muscle compared to the normal leg (mean 10.7%, p=0.008). In those patients with a complete rupture of PTT there was replacement of the PT muscle by fatty infiltration. Conversely, the FDL muscle showed a compensatory hypertrophy (mean 17.2%, p

Progressive dysgraphia in a case of posterior cortical atrophy

Dysgraphia (agraphia) is a common feature of posterior cortical atrophy (PCA). However, detailed analyses of these spelling and writing impairments are infrequently conducted. LM is a 59-year-old woman with dysgraphia associated with PCA. She presented with a two-year history of decline in her writing and dressmaking skills. A 3D T-1-weighted MRI scan confirmed selective bi-parietal atrophy, with relative sparing of the hippocampi and other cortical regions. Analyses of LM's preserved and impaired spelling abilities indicated mild physical letter distortions and a significant spelling deficit characterised by letter substitutions, insertions, omissions, and transpositions that was systematically sensitive to word length while insensitive to real word versus nonword category, word frequency, regularity, imagery, grammatical class and ambiguity. Our findings suggest a primary graphemic buffer disorder underlies LM's spelling errors, possibly originating from disruption to the operation of a fronto-parietal network implicated in verbal working memory.

A comparison of the lateral and posterior retroperitoneoscopic approach for complete and partial nephroureterectomy in children

Objective To report the comparative results of a selective posterior or lateral retroperitoneoscopic approach (RPA) for nephroureterectomy in children. Patients and methods Following an established experience with RPA, 36 complete and 19 partial nephrouretectomies were prospectively randomized to a posterior and lateral retroperitoneoscopic approach. The patients were aged 4 months to 14 years, with a body weight at operation of 5.7-82 kg. For posterior RPA the child is positioned prone, with three access ports. The operating space was created with balloon dissection and maintained with CO2 insufflation. The child was then rotated 30 degrees with the kidney in the dependent position, and the operator and assistant standing on the affected side. In the lateral approach the child is in the lateral decubitus position with the operator and assistant facing the dorsal aspect of the patient. Results There was no significant difference in operative duration between the lateral and posterior approaches for nephrectomy (65 and 47 min) or partial nephrectomy (85 and 75 min). Two lateral nephrectomies required open conversion (one upper pole and one lower pole). Conclusion The posterior approach gives easy and quick access to the renal pedicle. It is preferable for complete nephrectomy alone and partial or polar excision. In children under 5 years old a near complete ureterectomy can be achieved. The lateral approach creates more inferomedial space, gives better access to ectopic kidneys and allows complete ureterectomy in all cases, Access to the pedicle in the normal position requires more frequent positioning of the kidney. Care must be taken as peritoneal tears are more common.

Posterior leukoencephalopathy following, intrathecal chemotherapy with MRA-documented vasospasm

Posterior leukoencephalopathy syndromes have been reported with hypertension, and immunosuppressive and chemotherapy agents. Cerebral vasospasm on MR angiography (MRA) has been noted in cases due to eclampsia. The authors report a case of Balint syndrome with irreversible posterior leukoencephalopathy on MRI following intrathecal methotrexate and cytarabine. Hypertension was not present. Diffuse, reversible arterial irregularities consistent with vasospasm were present on MRA during the acute illness.

Measurement of muscle contraction with ultrasound imaging

To investigate the ability of ultrasonography to estimate musactivity, we measured architectural parameters (pennation angles, fascicle lengths, and muscle thickness) of several human muscles (tibialis anterior, biceps brachii, brachialis, transversus abdominis, obliquus internus abdominis, and obliquus externus abdominis) during isometric contractions of from 0 to 100% maximal voluntary contraction (MVC). Concurrently, electromyographic (EMG) activity was measured with surface (tibialis anterior only) or fine-wire electrodes. Most architectural parameters changed markedly with contractions up to 30% MVC but changed little at higher levels of contraction. Thus, ultrasound imaging can be used to detect low levels of muscle activity but cannot discriminate between moderate and strong contractions. Ultrasound measures could reliably detect changes in EMG of as little as 4% MVC (biceps muscle thickness), 5% MVC (brachialis muscle thickness), or 9% MVC (tibialis anterior pennation angle). They were generally less sensitive to changes in abdominal muscle activity, but it was possible to reliably detect contractions of 12% MVC in transversus abdominis (muscle length) and 22% MVC in obliquus internus (muscle thickness). Obliquus externus abdominis thickness did not change consistently with muscle contraction, so ultrasound measures of thickness cannot be used to detect activity of this muscle. Ultrasound imaging can thus provide a non-invasive method of detecting isometric muscle contractions of certain individual muscles.

Traumatic tear of tibialis anterior during a Gaelic football game: A case report

Reports of traumatic injury to the anterior lower leg muscles are scarce, with only a handful of reports of traumatic injury to the tibialis anterior. A database search of Medline, Cinhal, and Sports Discus only revealed three such cases, and they did not result from a direct sporting injury. This report documents the case of a traumatic rupture of tibialis anterior muscle in a young female Gaelic football player. It details the surgical repair and management of tibialis anterior muscle and the physiotherapy rehabilitation to full function.

Specialization in pyramidal cell structure in the cingulate cortex of the Chacma baboon (Papio ursinus): An intracellular injection study of the posterior and anterior cingulate gyrus with comparative notes on the macaque and vervet monkeys

This study forms part of an ongoing investigation of pyramidal cell structure in the cingulate cortex of primates. Recently we have demonstrated that layer III pyramidal cells in the anterior cingulate gyrus are considerably larger, more branched and more spinous than those in the posterior cingulate gyrus (areas 24 and 23, respectively) in the macaque and vervet monkeys. Moreover, the extent of the interareal difference in specialization in pyramidal cell structure differed between the two species. These data suggest that pyramidal cell circuitry may have evolved differently in these closely related species. Presently there are too few data to speculate on what is selecting for this specialization in structure. Here we extend the basis for comparison by studying pyramidal cell structure in cingulate gyrus of the Chacma baboon (Papio ursinus). Methodology used here is the same as that for our previous studies: intracellular injection of Lucifer Yellow in flat-mounted cortical slices. We found that pyramidal cells in anterior cingulate gyrus (area 24) were more branched and more spinous than those in posterior cingulate gyrus (area 23). Moreover, the complexity in pyramidal cell structure in both the anterior and posterior cingulate gyrus of the baboon differed to that in the corresponding regions in either the macaque or vervet monkeys. (C) 2005 Elsevier Ireland Ltd. All rights reserved.

The impact of neurodynamic testing on the perception of experimentally induced muscle pain

Neurodynamic tests such as the straight leg raising (SLR) and slump test are frequently used for assessment of mechanosensitivity of neural tissues. However, there is ongoing debate in the literature regarding the contributions of neural and non-neural tissues to the elicited symptoms because many structures are affected by these tests. Sensitizing manoeuvres are limb or spinal movements added to neurodynamic tests, which aim to identify the origin of the symptoms by preferentially loading or unloading neural structures. A prerequisite for the use of sensitizing manoeuvres to identify neural involvement is that the addition of sensitizing manoeuvres has no impact on pain perception when the origin of the pain is non-neural. In this study, experimental muscle pain was induced by injection of hypertonic saline in tibialis anterior or soleus in 25 asymptomatic, naive volunteers. A first experiment investigated the impact of hip adduction, abduction, medial and lateral rotation in the SLR position. In a second experiment, the different stages of the slump test were examined. The intensity and area of experimentally induced muscle pain did not increase when sensitizing manoeuvres were added to the SLR or throughout the successive stages of the slump test. The findings of this study lend support to the validity of the use of sensitizing manoeuvres during neurodynamic testing. (C) 2004 Elsevier Ltd. All rights reserved.

Regional specialization in pyramidal cell structure in the limbic cortex of the vervet monkey (Cercopithecus pygerythrus): an intracellular injection study of the anterior and posterior cingulate gyrus

The pyramidal cell phenotype varies quite dramatically in structure among different cortical areas in the primate brain. Comparative studies in visual cortex, in particular, but also in sensorimotor and prefrontal cortex, reveal systematic trends for pyramidal cell specialization in functionally related cortical areas. Moreover, there are systematic differences in the extent of these trends between different primate species. Recently we demonstrated differences in pyramidal cell structure in the cingulate cortex of the macaque monkey; however, in the absence of other comparative data it remains unknown as to whether the neuronal phenotype differs in cingulate cortex between species. Here we extend the basis for comparison by studying the structure of the basal dendritic trees of layer III pyramidal cells in the posterior and anterior cingulate gyrus of the vervet monkey (Brodmann's areas 23 and 24, respectively). Cells were injected with Lucifer Yellow in flat-mounted cortical slices, and processed for a light-stable DAB reaction product. Size, branching pattern, and spine density of basal dendritic arbors were determined, and somal areas measured. As in the macaque monkey, we found that pyramidal cells in anterior cingulate gyrus (area 24) were more branched and more spinous than those in posterior cingulate gyrus (area 23). In addition, the extent of the difference in pyramidal cell structure between these two cortical regions was less in the vervet monkey than in the macaque monkey.

Surface-active phospholipid (surfactant) in equine tendon and tendon sheath fluid

AIM: To investigate the presence of surface-active phospholipid (SAPL, or surfactant) in equine tendon and tendon sheath fluid. METHODS: The left front flexor tendon and sheath were removed from five Thoroughbred horses. Phospholipid was extracted from tendon sheath fluid using Folch reagent and quantified using spectroscopy. Transmission electron microscopy (TEM) was used to observe the tendon surfaces. RESULTS: The presence of phospholipid (90.6 (SD 4.3) mu g/ml) in tendon sheath fluid, plus the appearance of oligolamellar layers and lamellar bodies on the tendon surface were indicative of SAPL. CONCLUSIONS: Evidence of SAPL was found in equine tendon, and may have a similar lubricating function as reported for synovial joints. CLINICAL RELEVANCE: These findings may have important implications for normal tendon function and possible therapeutic adjuncts for tendon and tendon sheath injuries.