Aase Wagner

A mechanism for increased contractile strength of human pennate muscle in response to strength training: changes in muscle architecture

1 In human pennate muscle, changes in anatomical cross‐sectional area (CSA) or volume caused by training or inactivity may not necessarily reflect the change in physiological CSA, and thereby in maximal contractile force, since a simultaneous change in muscle fibre pennation angle could also occur. 2 Eleven male subjects undertook 14 weeks of heavy‐resistance strength training of the lower limb muscles. Before and after training anatomical CSA and volume of the human quadriceps femoris muscle were assessed by use of magnetic resonance imaging (MRI), muscle fibre pennation angle (θp) was measured in the vastus lateralis (VL) by use of ultrasonography, and muscle fibre CSA (CSAfibre) was obtained by needle biopsy sampling in VL. 3 Anatomical muscle CSA and volume increased with training from 77.5 ± 3.0 to 85.0 ± 2.7 cm2 and 1676 ± 63 to 1841 ± 57 cm3, respectively (±s.e.m.). Furthermore, VL pennation angle increased from 8.0 ± 0.4 to 10.7 ± 0.6 deg and CSAfibre increased from 3754 ± 271 to 4238 ± 202 μm2. Isometric quadriceps strength increased from 282.6 ± 11.7 to 327.0 ± 12.4 N m. 4 A positive relationship was observed between θp and quadriceps volume prior to training (r = 0.622). Multifactor regression analysis revealed a stronger relationship when θp and CSAfibre were combined (R= 0.728). Post‐training increases in CSAfibre were related to the increase in quadriceps volume (r = 0.749). 5 Myosin heavy chain (MHC) isoform distribution (type I and II) remained unaltered with training. 6 VL muscle fibre pennation angle was observed to increase in response to resistance training. This allowed single muscle fibre CSA and maximal contractile strength to increase more (+16 %) than anatomical muscle CSA and volume (+10 %). 7 Collectively, the present data suggest that the morphology, architecture and contractile capacity of human pennate muscle are interrelated, in vivo. This interaction seems to include the specific adaptation responses evoked by intensive resistance training.

Long term adaptation to electrically induced cycle training in severe spinal cord injured individuals

Spinal cord injured (SCI) individuals most often contract their injury at a young age and are deemed to a life of more or less physical inactivity. In addition to the primary implications of the SCI, severe SCI individuals are stigmatized by conditions related to their physically inactive lifestyle. It is unknown if these inactivity related conditions are potentially reversible and the aim of the present study was, therefore, to examine the effect of exercise on SCI individuals. Ten such individuals (six with tetraplegia and four with paraplegia; age 27 – 45 years; time since injury 3 – 23 years) were exercise trained for 1 year using an electrically induced computerized feedback controlled cycle ergometer. They trained for up to three times a week (mean 2.3 times), 30 min on each occasion. The gluteal, hamstring and quadriceps muscles were stimulated via electrodes placed on the skin over their motor points. During the first training bouts, a substantial variation in performance was seen between the subjects. A majority of them were capable of performing 30 min of exercise in the first bout; however, two individuals were only able to perform a few minutes of exercise. After training for 1 year all of the subjects were able to perform 30 min of continuous training and the work output had increased from 4±1 (mean±SE) to 17±2 Kilo Joules per training bout (P<0.05). The maximal oxygen uptake during electrically induced exercise increased from 1.20±0.08 litres per minute measured after a few weeks habituation to the exercise to 1.43±0.09 litres per minute after training for 1 year (P<0.05). Magnetic resonance cross sectional images of the thigh were performed to estimate muscle mass and an increase of 12% (mean, P<0.05) was seen in response to 1 year of training. In biopsies taken before exercise various degrees of atrophy were observed in the individual muscle fibres, a phenomenon that was partially normalized in all subjects after training. The fibre type distribution in skeletal muscles is known to shift towards type IIB fibres (fast twitch, fast fatiguable, glycolytic fibres) within the first 2 years after the spinal cord injury. The muscle in the present investigation contained of 63% myosin heavy chain (MHC) isoform IIB, 33% MHC isoform IIA (fast twitch, fatigue resistant) and less than 5% MHC isoform I (slow twitch) before training. A shift towards more fatigue resistant contractile proteins was found after 1 year of training. The percentage of MHC isoform IIA increased to 61% of all contractile protein and a corresponding decrease to 32% was seen in the fast fatiguable MHC isoform IIB, whereas MHC isoform I only comprised 7% of the total amount of MHC. This shift was accompanied by a doubling of the enzymatic activity of citrate synthase, as an indicator of mitochondrial oxidative capacity. It is concluded that inactivity-associated changes in exercise performance capacity and skeletal muscle occurring in SCI individuals after injury are reversible, even up to over 20 years after the injury. It follows that electrically induced exercise training of the paralysed limbs is an effective rehabilitation tool that should be offered to SCI individuals in the future.

Neurologic Complications of Cerebral Angiography: A retrospective study of complication rate and patient risk factors

Purpose: To evaluate the neurologic complication rate and individual patient risk factors in cerebral angiographies using the digital subtraction angiography (DSA) technique and non-ionic contrast media in a department with many radiologists in training. Material and Methods: A retrospective study of 483 cerebral angiographic examinations in 454 patients was carried out. The following parameters were registered: sex and age of the patient, indication for the angiography, cerebral CT diagnosis, laboratory data, type of anesthesia, type of angiographic procedure, level of training of the angiographer, number of participating angiographers, type of catheters, number of vessels catheterized, number of exposures, use of compression series, total amount of contrast media, diagnosis of the angiogram, complications and duration of complications. Results: The frequency of all neurologic complications was 2.3%, the frequency of persistent neurologic deficits was 0.4%. Non-neurologic complications were observed in 14.7% of the examinations. Of all the parameters studied, the only factor that significantly increased neurologic risk was a normal angiogram, a finding we are inclined to ascribe to chance. Performance of a compression series showed a trend towards increasing the neurologic risk. Conclusion: This study showed a complication rate of persistent neurologic deficits of 0.4% which is in accordance with other recent reports. A compression series should not be performed routinely, but only on special indication. This study confirms the low risk of cerebral angiography when performed in a neuroradiological department using the DSA technique and non-ionic contrast media.

Inter- and Intraobserver Study of Radiographic Assessment of Cemented Total Hip Arthroplasties

Radiographs are commonly used to identify loosened total hip prostheses. Interobserver and intraobserver variation was studied in an attempt to interpret 60 random pairs of radiographs with a time interval of 6 months to 12 years between the radiographs. Each of the four observers evaluated all pairs of radiographs independently, and the evaluations were repeated after 2 to 4 weeks. Each observer classified the femoral stem and the acetabular cup separately as stable or loose. Radiolucent lines of more than 2 mm were recorded. For the acetabular components, any change in inclination or migration was noted, and for the femoral components, subsidence or any change in varus or valgus of the stem was noted. There was considerable disagreement in observations of the acetabular component; agreement by all four observers was obtained in only 34 of 60 cases (57%). For the femoral component, agreement was obtained in 37 cases (62%). The observers agreed two and two (pairwise) on the acetabular component in 70 to 83% of cases and on the femoral component, in 72 to 82% of cases. Intraobserver variation was great with regard to the acetabular component, with kappa values ranging from 0.489 to 0.633. As to the femoral component, kappa values ranged from 0.737 to 0.800. Interpretation of radiographs of artificial hip arthroplasty is difficult, and comparisons between different series of implants should be made by the same person.

Intracranial aneurysm following radiation therapy for medulloblastoma A case report and review of the literature

Radiation-induced intracranial aneurysm formation is a rare but life-threatening condition with a high mortality rate secondary to rupture of the aneurysm. Further-more, this condition can mimic tumour recurrence. Only 10 months after craniospinal radiation therapy for medulloblastoma, a 9-year-old boy developed a subarachnoid haemorrhage secondary to a ruptured saccular aneurysm arising from the distal part of the right anterior cerebral artery. The development of intracranial aneurysms and rupture following radiation damage of the arteries has been reported previously, but in no case as soon as 10 months after radiation therapy. It is important to diagnose these aneurysms as they can be successfully treated.

Diagnostic Imaging in Fracture of Lumbar Vertebral Ring Apophyses

The findings at plain radiography, myelography, CT, and MR imaging in 3 cases of fracture of the lumbar vertebral ring apophysis are presented. Familiarity with this entity is important in evaluating low back pain in children and young adults. Conventional radiographs and/or MR imaging may suggest ring apophysis fracture; CT will confirm and classify the diagnosis.

Hyperplastic Callus Formation in Osteogenesis Imperfecta: A case report

We report a case of bilateral hyperplastic callus formation as a complication of fracture in a patient with osteogenesis imperfecta. The clinical and radiographic findings and the differential diagnosis are discussed.

A prospective comparison of iotrolan and iohexol in lumbar myelography

In a double-blind study 238 patients were examined with lumbar myelography using iotrolan or iohexol in randomized sequence in order to evaluate the image quality, the safety and tolerance of iotrolan by monitoring the adverse effects with special attention to late reactions. There were no serious complications. On the first day 28 patients (24%) had headache after iotrolan and 41 (34%) after iohexol. This difference was not significant, and these frequencies are similar to those found after spinal puncture alone. The second most frequent side effect was neck pain; the duration of neck pain were significantly longer after myelography with iohexol than with iotrolan. There was a significantly higher frequency of adverse effects in females the first 24 hours, but during examination and on days 2 to 4 there were no differences between males and females. Anamnestic information or myelographic diagnosis could not predict which patients would have side effects. The image quality was excellent or good in all examinations but one. It is concluded that iotrolan is a safe contrast medium well suited for lumbar myelography.

Intra-arterial nimodipine for cerebral vasospasm after subarachnoid haemorrhage: Influence on clinical course and predictors of clinical outcome:

Intra-arterial nimodipine (IAN) has shown a promising effect on cerebral vasospasm (CV) after aneurysmal subarachnoid haemorrhage. At our institution, Rigshospitalet, IAN treatment has been used since 2009, but the short- and long-term clinical efficacy of IAN has not yet been assessed. The purpose was to evaluate the efficacy and clinical outcome of IAN treatment of symptomatic CV, and to assess the predictors of clinical outcome. Medical records of 25 patients undergoing a total of 41 IAN treatment sessions were retrospectively reviewed. Data on angiographic results, blood-flow velocities and the clinical condition before and after the IAN treatment were recorded. Predictors of the clinical outcome were assessed with a linear regression model. Positive angiographic response was achieved in 95.1% of 41 IAN treatment sessions. Flow-velocity measurements showed no relationship with angiographic responses of IAN. The immediate clinical improvement was observed in three patients (12%). Five patients (20%) had a favourable outcome at discharge and at three-month follow-up; 10 patients (40%) had a moderate to poor outcome; and the rest (40%) died. Increased number of affected vessels and number of procedures carried out per patient, and a trend toward an increased delay time from symptomatic CV to confirming angiographic CV and thus instituting IAN treatment predicted the poor clinical outcome. IAN treatment appears to be effective in reversing angiographic CV. However, it is not always effective in reversing clinical deterioration, as several other factors including treatment delay affect the clinical course.

Transient global amnesia after cerebral angiography still occurs: Case report and literature review

Transient global amnesia is considered a very rare complication of diagnostic cerebral angiography, and has been reported only in a limited number of case reports more than 15 years ago. We describe a patient experiencing transient global amnesia following cerebral digital subtraction angiography. While the condition by definition is self-limiting, its differential diagnoses may cause severe morbidity and/or mortality if left untreated. It is therefore important to build and maintain awareness of transient global amnesia as a possible complication of cerebral angiography.