Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range.

We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, A_{⊥}^{ep}, at five beam energies from 315.1 to 1508.4 MeV and at a scattering angle of 30°<θ<40°. The covered Q^{2} values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c)^{2}. The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-Q^{2} kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and πN inelastic intermediate states, suggests that there are other inelastic intermediate states such as ππN, KΛ, and ηN. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.

[Incidental durotomy: intraoperative aid in ten steps]. / Iatrogene Duraverletzung: intraoperative Hilfe in zehn Schritten.

OBJECTIVE: Management of the intradural structures safely, closure of the dura according to the tear, and minimizing the epidural dead space. INDICATIONS: Incidental durotomy (ID). CONTRAINDICATIONS: None. SURGICAL TECHNIQUE: 1. Bone removal until whole dural tear is visible (if necessary); 2. intradural inspection; 3. reposition the fibers; 4. perform an inside patch (if ID > 5 mm); 5. dural closure; 6. outside patch; 7. Valsalva maneuver; 8. epidural pedicled muscle flap; 9. multilayer wound closure; 10. lumbar drainage of cerebrospinal fluid (if necessary). POSTOPERATIVE MANAGEMENT: Bed rest up to 48 h; analgesics. RESULTS: The intraspinal part of 4020 surgeries performed with the aid of a microscope were evaluated. The overall prevalence of ID was 4.4%. The prevalence was lowest in virgin microdiscectomies (1.7%) and varied from 3.6% in decompression for spinal canal stenosis up to 14.5% in revision procedures. Of the overall 195 IDs, 127 occurred in primary surgeries and 68 in revision surgeries. In 107 primary surgeries, the individual surgical technique (InT) achieved a single stage closure of the ID in 96 procedures (89.7%). Among 20 virgin surgeries, the ten-step technique (10 ST) was successful in all cases (P = 0.21). Among 42 revision procedures following failed attempts to stop the CSF leakage, the InT achieved single-stage closure in 36 procedures (85.7%), whereas after introduction of the 10 ST, closure was successful in all 26 cases (P = 0.03).

[Relevance of spinal navigation in reconstructive surgery of the cervical spine]. / Relevanz der spinalen Navigation in der rekonstruktiven Halswirbelsäulenchirurgie.

BACKGROUND: Spinal navigation has made significant advances in the last two decades. After initial experiences with pedicle screws in the thoracic and lumbar spine, technological improvements have resulted in their increased application in the cervical spine. Instrumentation techniques like cervical pedicle screws, lateral mass screws in C1 and transarticular screws C1/C2 have become standard due to the application of image guidance. TECHNIQUE: Different navigation techniques can be distinguished based on the type of imaging. In the cervical spine, the preoperative computer tomography (CT) scan that requires intraoperative matching is still the standard of care due to the high image quality. 3D fluoroscopy navigation techniques are currently widely used in the lumbar spine, but the reduced image quality obviates the application in the more sophisticated cervical anatomy or the cervicothoracic region. The future availability of intraoperative CT scans (iCT) combines the advantages of high image quality with those of intraoperative image acquisition. This will lead to a wider use of image guidance in the cervical spine and will enable the surgeon to apply minimally invasive techniques with higher accuracy. APPLICATION: The successful application of spinal navigation is based on the technical knowledge of navigation systems and its exercise in daily routine. Only the sufficient experience of the clinical staff makes it possible to standardize operational procedures to increase patient safety, reduce radiation dose and shorten operation time.

[Rheumatoid instability in the cervical spine : Diagnostic and therapeutic strategies]. / Die rheumatische Instabilität der Halswirbelsäule : Diagnostik und therapeutische Strategien.

BACKGROUND: The involvement of the cervical spine in rheumatoid arthritis (RA) continues to be of clinical importance even in this age of biologics. Pathophysiological changes begin with an isolated atlantoaxial subluxation and may progress to a complex craniocervical and subaxial instability. The onset of cervical myelopathy can occur at any time and leads to a deterioration of the prognosis for the patient. THERAPY: Treatment of the rheumatoid cervical spine should be aimed at improvement of the symptoms and prevention of further progress of the disease. In the case of instability, this is only possible by surgical treatment. The increasing usage of biological agents has led to a change in the clinical picture of the cervical involvement in RA patients. There are fewer patients presenting with isolated atlantoaxial instability. In contrast, the number of patients with complex craniocervical and/or subaxial instabilities is increasing. Complex cervical instabilities may require a longer fusion from the occiput to the upper thoracic spine. Modern operative techniques make this complex surgery also possible in severely disabled patients with a high comorbidity.

Open-door laminoplasty : What can the unilateral approach offer?

OBJECTIVE: Multilevel posterior decompression of subaxial cervical spinal canal stenosis through a less-invasive unilateral approach. INDICATIONS: Degenerative cervical myelopathy due to multilevel subaxial spinal canal stenosis. CONTRAINDICATIONS: Cervical kyphosis or instability, bilateral radiculopathy due to foraminal stenosis, involvement of C2 or C7. SURGICAL TECHNIQUE: Unilateral subaxial approach with detachment of muscles only on one side. The ipsilateral laminae C6 to C3 are cut at the laminofacet junction and opened up. The loss of resistance is usually due to a greenstick fracture in the proximity of the contralateral laminofacet junction. The opened laminae are fixed with Z­shaped thin titanium plates. If necessary, the laminoplasty can be combined with a unilateral fixation and fusion by the same approach. POSTOPERATIVE MANAGEMENT: Early mobilization 4-6 h postoperatively. No orthosis necessary. RESULTS: A total of 131 patients (77 men, mean age 67 years) with a multilevel cervical spondylotic myelopathy (CSM) underwent surgery using a posterior approach. In 52 patients (40%), a unilateral approach was performed (laminoplasty: n = 30; laminoplasty/fusion: n = 22). In this group, the mean operation time was less compared with two other techniques (unilateral approach: 110 min; laminectomy/fusion: 150 min; 360° approach: 210 min). The postoperative European myelopathy score (EMS) improved from 12.8 to 15.2. The overall complication rate was 17% (unilateral approach: 9%; laminectomy/fusion: 18%; 360° approach: 27%).

Minimally invasive posterior cervical foraminotomy for treatment of radiculopathy : An effective, time-tested, and cost-efficient motion-preservation technique.

OBJECTIVE: To relieve foraminal root impingement due to lateral soft disc fragments, bony spurs, or other rarer causes. INDICATIONS: Soft disc fragment whose bulk is >2/3 lateral to the lateral border of the thecal sac. Intraforaminal dorsal bony narrowing of the root canal. Intraforaminal synovial cyst, extra/intradural tumor. CONTRAINDICATIONS: Paramedian and median soft/hard disc protrusions. Kyphosis of the index level. SURGICAL TECHNIQUE: Patient prone in reverse Trendelenburg position with the head fixed in a Mayfield clamp. Cervical spine horizontal and approximately 10 cm above the heart. Microscope from skin to skin. Skin incision: 25 mm, about 10 mm off the midline. Microsurgical blunt splitting of the muscle layers along the fiber direction. An expandable tubular retractor or a miniaturized speculum counter retractor, table anchored, is centered on the target lamino-facet junction as confirmed by fluoroscopy. Drilling of the keyhole. The axilla of the root is exposed while preserving most of the facet complex. Epidural exploration until an extruded or subligamentous disc fragment(s) is removed. If needed, removal of the dorsal bone overlying the root exiting in the foramen. The adequacy of decompression is assessed by palpating the root along its course with a small nerve hook. Closure by layers. No drain. POSTOPERATIVE MANAGEMENT: Same day mobilization. No external brace. RESULTS: Minimally invasive posterior cervical foraminotomy (MI-PCF) was used to treat 103 patients for unilateral cervical radiculopathy. Mean follow-up was 32 months. Despite 1 cerebrospinal fluid leak, 1 wound hematoma, and 1 radiculitis during the early postoperative period, no patients required revision surgery. Visual analog scale (VAS) scores for neck/shoulder and arm improved significantly in the early postoperative period (3 months) and were maintained with time (p < 0.001). Neck Disability Index (NDI) improved significantly postoperatively but worsened slightly during follow-up (p < 0.001). Anterior decompression and fusion (ACDF) was required at the index level by 3 patients (mean: 55 months later) and at the adjacent level by 4 patients (mean: 27 months later).

Correction to: Minimally invasive posterior cervical foraminotomy for treatment of radiculopathy : An effective, time-tested, and cost-efficient motion-preservation technique.

Correction to: Oper Orthop Traumatol 2017 https://doi.org/10.1007/s00064-017-0516-6 In this article the following acknowledgement was missing:Acknowledgement: With the kind assistance of Deutsche Arthrose-Hilfe e. ….

[Low back pain in rheumatoid arthritis]. / Rückenschmerz bei rheumatoider Arthritis.

Low back pain (LBP) in patients with rheumatoid arthritis (RA) has so far been of little concern in clinical investigations. The main focus of scientific publications on spinal problems in RA was the cervical spine. In a recent study, we could demonstrate that LBP in RA patients leads to a significantly higher degree of disability and depression as well as to a reduction in quality of life compared to RA patients without LBP. If there is a specific reason for the additional symptom of LBP, such as spinal stenosis or segmental instability, surgical treatment may be indicated to improve disability and quality of life. For a successful outcome of spinal surgery it is important to address the specific aspects of RA patients, such as poor bone quality and the immunosuppressive effect of antirheumatic drug treatment. Whenever possible, minimally invasive surgical techniques should be used and the immunosuppressive medication should be stopped before surgery.

New Measurements of the Beam Normal Spin Asymmetries at Large Backward Angles with Hydrogen and Deuterium Targets.

New measurements of the beam normal single spin asymmetry in the electron elastic and quasielastic scattering on the proton and deuteron, respectively, at large backward angles and at ⟨Q^{2}⟩=0.22 (GeV/c)^{2} and ⟨Q^{2}⟩=0.35 ( GeV/c)^{2} are reported. The experimentally observed asymmetries are compared with the theoretical calculation of Pasquini and Vanderhaeghen [Phys. Rev. C 70, 045206 (2004).PRVCAN0556-281310.1103/PhysRevC.70.045206]. The agreement of the measurements with the theoretical calculations shows a dominance of the inelastic intermediate excited states of the nucleon, πN and the Δ resonance. The measurements explore a new, important parameter region of the exchanged virtual photon virtualities.

Unilateral laminoplasty with lateral mass screw fixation for less invasive decompression of the cervical spine: a biomechanical investigation.

PURPOSE: To compare the stabilization behavior of additional unilateral mass screw fixation with current standard procedures in patients with cervical spondylotic myelopathy (CSM) in a biomechanical study. METHODS: Ten human C2-C7 cervical specimens were tested under various segment conditions: native (NAT), laminoplasty (LP), laminoplasty with unilateral (LPU) or bilateral (LPB) stabilization, laminectomy with bilateral stabilization (LCB), and laminectomy. The instrumented level was from C3 to C6. For each segment condition, in vitro flexibility tests were performed using a spinal simulator and an applied load of ±2.5 Nm. The three-dimensional kinematics of the entire cervical segment in three main loading directions [flexion-extension (FE), lateral bending (LB), and axial rotation (AR)] was measured with an ultrasonic motion analysis system. Analysis of variance followed by a post hoc test was used to determine differences under the specific segment conditions to assess the parameters range of motion (ROM) and neutral zone (NZ). RESULTS: For FE, the total ROM of laminoplasty (-6.3% difference to NAT) and laminectomy (+6.4%) remained at the level of native (p > 0.56), whereas the instrumentations LPU (-37.1%), LPB (-44%), and LCB (-43.2%) lead to significant reductions (p < 0.01) without significant differences in LPU to LPB and LCB (p > 0.38). The same results were found with LB. For AR, the stabilization of all instrumentations was less pronounced, but had the same tendency seen for FE and AR. The results for the NZ showed equivalent values as that for ROM. CONCLUSION: The degree of stabilization was as expected for LC and LCB; namely, no stabilization for LC and maximal stabilization for LCB. LPU exhibited almost the same degree of stabilization as LCB. LPU could be a new treatment option for less invasive decompression for multilevel CSM.

The translaminar approach for cranially extruded lumbar disc herniations.

OBJECTIVE: To remove extruded disc fragments impinging the exiting root. To spare the interlaminar space and the facet joint. INDICATION: Cranially migrated disc herniation. CONTRAINDICATION: Severe spinal canal stenosis. SURGICAL TECHNIQUE: Microscope from skin to skin, 25 mm skin incision about 5 mm off the midline, conventional subperiosteal route or transmuscular access by blunt splitting the multifidus muscle. A translaminar hole (diameter 10 mm) is drilled off. The epidural exploration starts along the thecal sac until the axilla of the exiting root is reached. An extruded or subligamentous disc fragment(s) is removed. If an extensive annular perforation is detected, the disc space should be cleared (20% of the cases). POSTOPERATIVE MANAGEMENT: Same day mobilization. RESULTS: A total of 84 patients (46 men) underwent the translaminar approach. The mean age was 57 years (range 27-80 years). Follow-up examinations by an independent observer at 1 and 6 weeks; 3, 6 and 12 months and once yearly thereafter (mean follow-up 27 months). Extruded (61%) and subligamentous (39%) disc fragments were found. In 4 cases the translaminar hole was enlarged to a laminotomy. In 12 patients the disc space was cleared. The outcome (MacNab criteria) was excellent (67%), good (27%), fair (5%), and poor (1%). The incidence of recurrent disc herniations was 7%.

Microsurgical extraforaminal decompression of lumbar root canal stenosis.

OBJECTIVE: To decompress the lumbar spinal nerve impinged peripherally to the lateral recess. To avoid in selected cases the pedicle screw fixation and fusion of the segment. INDICATION: Single level radiculopathy in degenerative scoliosis or in degenerative disc disease without segmental instability. CONTRAINDICATIONS: Scoliosis > 30° at the index level, lateral listhesis > 6 mm, mobile vertebral slip. SURGICAL TECHNIQUE: Microscope from skin to skin. A 35-mm skin incision about 40 mm off the midline. Transmuscular access by blunt splitting of the paravertebral muscles pointing about 40° towards the midline. Insertion of an expandable tubular retractor or of a speculum counter retractor system. Dissection of the target lumbar nerve in the midst of the extraforaminal fat tissue. Enlargment of the root canal mostly by drilling and using thin foot plate punches. The nerve is decompressed from peripherally to the lateral rim of the yellow ligament. Closure by layers. Drainage is usually not required. POSTOPERATIVE MANAGEMENT: Same day mobilization. RESULTS: The clinical results in 22 cases (15 men) of extraforaminal nerve root involvement were studied. Because of the very selective indication the patients were recruited over a 3-year time-span. The mean age was 64 years (range 50-82 years). An independent follow-up examination was performed 3 months and 1 year following surgery. The mean FU was 27 months (range 41-22 months). According to the modified MacNab criteria, the results were excellent (45%), good (23%), fair (14%), and poor (18%). Four patients underwent second surgery for pedicle screw fixation and fusion. Persistent low back pain was the most common cause of an unsatisfactory postoperative course.

Measurement of strange quark contributions to the vector form factors of the proton at Q2 = 0.22 (GeV / c)2.

A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q;{2} = 0.22 (Ge V / c);{2} is reported here. The measured asymmetry is A_{LR} = (-17.23 +/- 0.82_{stat} +/- 0.89_{syst}) x 10;{-6}. The standard model prediction assuming no strangeness is A_{0} = (-15.87 +/- 1.22) x 10;{-6}. In combination with previous results from measurements at forward angles, it is possible to disentangle for the first time the strange form factors at this momentum transfer, G_{E};{s} = 0.050 +/- 0.038 +/- 0.019 and G_{M};{s} = -0.14 +/- 0.11 +/- 0.11.

[Complications of surgical interventions on the spinal column]. / Komplikationen bei operativen Eingriffen an der Wirbelsäule.

The number of surgical interventions for spinal diseases has greatly increased due to rapid improvements in surgical techniques. The close anatomical relationship between neural and bony structures and the various anatomical approaches to the spinal column lead to a large variety of possible surgical complications. Therefore, it seems helpful to differentiate the complications with respect to their origin. An incorrect positioning of the patient can result in palsy or even blindness. Surgical access to the spine depends on the pathology and the surgical target. Typical complications can be explained by the anatomical situation, such as the vicinity of the esophagus in the anterior approach to the cervical spine or the great vessels in anterior procedures to the lumbar spine. Complication during the surgical manipulation of the spine can be related to either decompression procedures of neural structures or spinal implants. The correction of spinal deformities can result in very specific complications.

[An undiagnosed plasma cell myeloma. Complication after performing spinal anesthesia]. / Ein nichtdiagnostiziertes Plasmozytom. Spinalanästhesie mit Folgen.

A male patient developed neurological deficits after an uneventful spinal anesthesia. After 2 months without any improvement an epidural hematoma was presumed. Magnet resonance imaging detected inflammatory tissue and destruction at lumbar levels L2/3. The inflammatory tissue had to be removed via laminectomy. Histology of the excised tissue revealed a plasma cell myeloma that was not diagnosed prior to spinal anesthesia 2 months previously.

Impact of low back pain on functional limitations, depressed mood and quality of life in patients with rheumatoid arthritis.

Low back pain (LBP) and rheumatoid arthritis (RA) are common orthopedic problems, but there is little information on the importance of LBP in RA patients. The aim of this study was to investigate how LBP affects functional limitations, depressed mood, and quality of life in patients with RA. A complex questionnaire was answered by 281 RA patients, including questions about their RA and their experience of LBP. Functional limitations were assessed using the Hannover Activities of Daily Living questionnaire (ADL), depressed mood using the Center for Epidemiological Studies Depression Scale (CES-D) and health-related quality of life using the Short Form 12 health questionnaire (SF-12). The prevalence of LBP in RA patients was 53.4%. RA patients with LBP displayed a significantly higher degree of disability and depression than RA patients without LBP. There were no differences between the two groups with regard to the duration of RA, the number of operations or medication. LBP is an important factor for the physical and psychological behavior of RA patients. Therefore, the onset of LBP should not be overlooked or underestimated.

[Imaging in rheumatology. Degenerative diseases of the spine]. / Bildgebende Verfahren in der Rheumatologie. Bildgebung bei degenerativen Erkrankungen der Wirbelsäule.

Degeneration of the spine is a common reason for pain in the musculoskeletal system. Radiography is an important tool for diagnosis and differential diagnosis. Cost efficacy and economy of time are advantages in using conventional x-rays. Although narrowing of intervertebral disc spaces, irregular ossification of the vertebral end-plate as well as osteophytes, facet joint osteoarthritis and spondylolisthesis can be observed, early changes in the discs or the subdiscal bone can not be detected by x-rays. Moreover, 3-dimensional imaging is not possible. Computer tomography (CT) and magnetic resonance imaging (MRI) are reliable for identifying disorders of the spine and soft-tissue. Differentiation between inflammation, trauma and tumor is possible. There is still a problem with the relationship between the information obtained by x-rays or MRI and clinical symptoms. Therefore, interpretation of radiological examinations assumes a knowledge of clinical symptoms and the different kinds of diseases which are possible.

[The new curriculum for surgery in Hamburg, Germany]. / Integrierte operative Medizin: Die studentische Ausbildung in der Chirurgie in Hamburg.

In October 2004, the medical faculty of Hamburg University started a program to restructure completely clinical teaching according to new state regulations of June 2002. In this new curriculum design, the surgical disciplines were horizontally and vertically interconnected and integrated, with a focus on practical training and problem-based teaching. This study describes the concept of clinical teaching and presents the student evaluation results of the first four blocks with a focus on performance in surgical disciplines. There was high student satisfaction with the new program, compared with results before October 2004 and also with respect to other disciplines within the new curriculum. This was especially true for the practical courses in the newly established skills lab. Future developments in e-learning and practical teaching in the skills lab are necessary to overcome restrictions on medical education due to changes in the German health care system.

Evidence for strange-quark contributions to the nucleon's form factors at Q2=0.108 (GeV/c)2.

We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q(2)=0.108 (GeV/c)(2) and at a forward electron scattering angle of 30 degrees p)=[-1.36+/-0.29(stat)+/-0.13(syst)]x10(-6). The expectation from the standard model assuming no strangeness contribution to the vector current is A(0)=(-2.06+/-0.14)x10(-6). We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be G(s)(E)+0.106G(s)(M)=0.071+/-0.036 at Q(2)=0.108 (GeV/c)(2). We again find the value for G(s)(E)+0.106G(s)(M) to be positive, this time at an improved significance level of two sigma.