Anterior Uncoforaminotomy in the Treatment of Recurrent Radiculopathy after Anterior Cervical Discectomy with Fusion

BACKGROUND

In patients after anterior cervical discectomy (ACD) with fusion newly developed retrospondylophytes or incomplete decompression of the nerve root can cause recurrent radicular pain. Anterior cervical uncoforaminotomy (uncoforaminotomy) is an operative method which removes the causative degenerative pathology at the level of the neural foramen leaving untouched the inserted graft at this level.

METHOD

Between February 2004 and April 2005, 7 patients underwent uncoforaminotomy after ACD with fusion for the treatment of recurrent cervical radiculopathy in our neurosurgical department. Prior to treatment patients received a computed tomography (CT) and a neurological examination. Anterior uncoforaminotomy was performed thereafter (for technical details see publication by Jho, 1996). A postoperative CT scan was done before discharge. Follow-up examination was performed eight weeks after surgery.

FINDINGS

Five patients underwent the operation at C5/6, one patient was operated at C6/7 and one patient had the operation at two levels (C5/6 and C6/7). At discharge six patients had excellent or good results.

CONCLUSION

Uncoforaminotomy is a good method for the treatment of newly acquired spondylotic spurs in the foramen or incomplete osseous decompression after ACD with fusion and recurrent radicular pain.

Oral bisphosphonates fail to prevent bone loss from androgen deprivation therapy in men with prostate cancer

14643

Background: Androgen deprivation therapy (ADT) is a widely administered treatment for prostate cancer. However, ADT is associated with accelerated bone loss, osteoporosis, and fractures (Shahinian, NEJM 2005; 352:154). According to Smith et al, annual bone loss on ADT approaches 9% (Smith, NEJM 2001;345:948), using QCT densitometry, a highly sensitive test for the detection of osteoporosis in men. Intravenous bisphosphonates (pamidronate, zolendronate) have been shown to prevent ADT-related bone loss in randomized phase III trials. We performed a retrospective analysis to determine if oral bisphosphonates effectively prevent bone loss in men receiving ADT. Methods: Twenty two men, ages 60–80, were placed on alendronate or risendronate at the initiation of ADT. Baseline and follow-up bone mineral densitometry (BMD) studies were performed with QCT densitometry. Repeat BMD was performed 12- 27 months (mean = 17mo) after the baseline BMD. Percentage change in bone density was annualized. Within each treatment group, the hypothesis of no mean change from baseline was analyzed using a paired t test. Results: Mean baseline bone density was 122.6mg/cc. Mean follow-up bone density was 112.7mg/cc. For the whole group, the annualized mean change in BMD was negative 7.77%/yr (p = 0.0003). Of note, 9/22 men maintained or gained bone density (-1.26% to +5.95%). 13/22 men lost at least 6.03% (-6.03% to -23.2%). There was no unexpected toxicity or fractures. Conclusions: In this retrospective study, prophylactic oral bisphosphonates do not protect against accelerated ADT-induced bone loss in men with prostate cancer.

No significant financial relationships to disclose.

Strahlenexposition bei der digitalen Vollfeldmammographie mit einem Selen-Flachdetektor

PURPOSE

Calculation of the average glandular dose for mammography on a full-field digital mammography system using a selenium flat-panel detector.

MATERIALS AND METHODS

Mammographic examinations were carried out using the Selenia digital mammographic system from Lorad/Hologic. 1992 mammographies of 500 patients in cranio-caudal and medio-lateral projections were evaluated. Based on the recorded exposure conditions (tube voltage, tube loading, filtration, compressed breast thickness), the entrance surface air kerma was calculated by multiplying the tube loading by the measured tube output and was corrected according to the inverse square law. The average glandular dose was determined for each exposure by multiplying the entrance surface air kerma value by the relevant conversion factor for a breast composition of 50 % adipose tissue and 50 % glandular tissue by weight.

RESULTS

The mean values for patient age and compressed breast thickness were 61 years and 58 mm, respectively. The average glandular dose was 1.57 mGy for a single view (1.46 mGy for cranio-caudal view images and 1.68 mGy for medio-lateral view images).

CONCLUSION

Full-field digital mammography with a selenium flat-panel detector requires a dose similar to that of units with a flat-panel detector based on amorphous silicon and a dose approximately 20 % lower than that of conventional screen/film mammography.

Deutsch-jozsa algorithm using triggered single photons from a single quantum dot

We demonstrate a two-qubit Deutsch-Jozsa algorithm with single photons from a single InP quantum dot. The qubits are implemented via the spatial mode and the polarization of a single photon. Our photon source is operated both under continuous and pulsed excitation, the latter allowing deterministic quantum logic by generating photons on demand with a strong suppression of two-photon events. The computation reached a success probability of up to 79%. We also exploit the concept of decoherence-free subspaces that helps to make our experimental setup robust against sources of phase noise.

Dynamic Cerebral Autoregulation in Patients with Ruptured and Unruptured Aneurysms after Induction of General Anesthesia

INTRODUCTION

Blood pressure management in patients undergoing surgery for clipping of aneurysms is demanding. More information about the ability of cerebral vessels to normally regulate cerebral blood flow may have a direct influence on the intraoperative management. In patients with subarachnoid hemorrhage (SAH) a disturbance of cerebral autoregulation has been reported and it correlated with the severity of the bleeding in these studies. The impairment of autoregulation was demonstrated using static measurements of cerebral pressure autoregulation. However, the dynamic component of the autoregulatory capacity seems to be of importance in the acute setting after SAH. The aim of this study was to evaluate dynamic pressure autoregulation in patients undergoing surgery for intracranial aneurysms.

PATIENTS/MATERIAL AND METHODS

36 patients with a mean age of 45 years were evaluated, 26 patients with acute SAH, 10 patients with unruptured aneurysms. Cerebral autoregulation in normocapnia was tested using thigh cuffs to alter arterial blood pressure and continuous registration of the blood flow velocities with transcranial Doppler sonography. After the induction of general anesthesia under normocapnia the autoregulatory index (ARI) was calculated (values between 0-9). Patient groups were compared using Wilcoxon- and Spearman's rank test.

RESULTS

The two patient groups were comparable with regard to gender, age, PaCO(2), blood flow velocities and blood pressure. In patients with SAH mean ARI was 3.1/3.3 (right/left side) compared to 4.7/4.6 (right/left side) in patients without SAH. The difference was statistically significant (Wilcoxon p = 0.0399). The degree of impairment of the autoregulatory capacity increased significantly (p = 0.006) with the severity of the SAH (Hunt&Hess and Fisher scale).

CONCLUSION

Dynamic pressure autoregulation is impaired in patients after SAH compared to patients without SAH and correlates with the severity of the SAH. We propose that autoregulation should be measured in all patients with SAH or that an impaired autoregulation should be taken into account in patients with SAH undergoing surgery in the acute phase.

Neurosurgical operations with the patient in sitting position: analysis of risk factors using transcranial Doppler sonography

BACKGROUND

One major risk factor of the sitting position for neurosurgery is air embolism, especially in patients with persistent foramen ovale (PFO). The first aim of this prospective study was to evaluate a bedside method for detecting PFO using transcranial Doppler sonography (TCD) with contrast medium. A second aim was to address intraoperative monitoring, patient positioning and the occurrence and clinical relevance of air embolism.

METHODS

Ninety patients with a mean age of 56.5 yr (range 14-81 yr) undergoing surgery in sitting position were investigated by TCD with contrast agent to detect functional PFO, that is PFO that can be provoked with a Valsalva manoeuvre. In patients in whom TCD was not possible, transcranial duplex sonography, duplex sonography of the carotid artery at the neck or transoesophageal ECG was performed.

RESULTS

In 26 patients PFO was detected. Thirteen of them presented a persistent PFO with high-intensity transient signal in both middle cerebral arteries without Valsalva manoeuvre. The intraoperative positioning in these patients was adapted to the risk for a paradoxical air embolism, although, after surgical recommendations, three patients with a persistent PFO underwent surgery in sitting position. Intraoperative air embolisms were seen in 8 of 80 patients in sitting or semi-sitting position with air aspirable through the central venous catheter.

CONCLUSION

To address the risk of a paradoxical air embolism, especially in patients undergoing surgery in sitting position, preoperative detection of PFO is advisable. If surgery is performed in seated PFO patients, additional monitoring and special care are warranted.

Analysis of Surgical Management of Calvarial Tumours and First Results of a Newly Designed Robotic Trepanation System

This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87 %) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66 % of the patients and dural involvement in 46 %. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome.

Rapid calculation of biological effects in ion radiotherapy

We describe a method for fast calculation of biological effects after ion irradiation. It is an alternative derivative of the established local effect model (LEM) and has been integrated into GSI's TRiP98 treatment planning system. We show that deviations from our classic approach for treatment planning are less than 5% for therapeutical doses, but calculational speed can be improved by one to two orders of magnitude. This will allow sophisticated methods of treatment planning for ion irradiation, taking biological effects fully into account.

[Vertebroplasty and kyphoplasty in osteoporotic fractures of vertebral bodies -- a prospective 1-year follow-up analysis]

PURPOSE

Kyphoplasty and vertebroplasty offer two minimally invasive operative stabilization procedures for vertebral compression fractures. The purpose of this prospective study was to investigate whether both procedures are able to reduce pain and to preserve postoperative vertebral height during a 1-year follow up.

MATERIALS AND METHODS

Osteoporotic vertebral fractures were treated in 42 cases, 20 patients (15 female, 5 male) underwent vertebroplasty, 22 patients (14 female, 8 male) underwent kyphoplasty. 32 vertebral fractures were treated with vertebroplasty and 35 vertebral fractures were treated with kyphoplasty. Symptomatic levels were identified by correlating the clinical presentation with conventional radiographs, CT or/and MRI. During the follow up reduction of pain was determined. Radiographic scans were performed pre- and postoperatively and after 3, 6 and 12 months. The vertebral height and endplate angles were measured to assess the restoration of the sagittal alignment. The effects on pain symptoms were measured on a self-reported Visual Analog Scale (VAS) and the Oswestry score was documented.

RESULTS

The median pain scores (VAS) decreased significantly for kyphoplasty and vertebroplasty from pre- to post-treatment, as did the Oswestry score (p < 0.05). No significant differences could be found between both groups for the median pain score (VAS) and the Oswestry score. Kyphoplsty led to a significant restoration of the vertebral height and reduction of kyphosis (p < 0.05). During the 1-year follow up both operation techniques were able to stabilize the height of the vertebral body.

CONCLUSION

Kyphoplasty and vertebroplasty are effective minimally invasive procedures for the stabilization of osteoporotic vertebral fractures leading to a statistically significant reduction in pain. Kyphoplasty restores significantly vertebral body height in fresh fractures. The restoration of vertebral height and reduction of kyphosis may have an influence on the long term clinical outcome. This has to be evaluated in a long term prospective study.

Intra- and extravascular volume status in patients undergoing mitral valve replacement

BACKGROUND AND OBJECTIVE

Cardiopulmonary bypass is associated with changes of intra- and extravascular volume status often resulting in cardiopulmonary dysfunction. The purpose of this prospective double-blind study was to evaluate the influence of different priming solutions of the extracorporeal circuit on intra- and extravascular volume status and haemodynamics in patients undergoing elective mitral valve replacement.

METHODS

Twenty-two patients with mitral valve insufficiency were randomly allocated into two equal groups. In Group 1 cardiopulmonary bypass was primed with a nearly isooncotic solution consisting of 4% albumin. The second group received a pure crystalloid priming solution. The thermo-dye indicator dilution technique was used for the assessment of cardiac output, central and pulmonary blood volume, right ventricular end-diastolic volume and total blood volume.

RESULTS

Patients in the crystalloid group showed increased intraoperative fluid requirements. Significantly more fluid was accumulated in the extravascular space whereas total blood volume was decreased after surgery. Stroke volume index (SVI) was significantly decreased in the immediate postoperative period when compared to baseline. As indicated by the increase in extravascular fluid content after surgery, both colloid and crystalloid priming volumes were transferred to the extravascular space.

CONCLUSION

The use of colloid priming solutions in patients with mitral valve insufficiency leads to less fluid requirements and significantly reduced fluid shift in the interstitium. However, these changes are not associated with changes in haemodynamic parameters or short term outcome.

Improvement of the local effect model (LEM)--implications of clustered DNA damage

An improvement of the Local Effect Model (LEM) is presented which takes clustered DNA damage into account. Single strand breaks (SSBs) and double strand breaks (DSBs) are distributed stochastically onto the DNA molecule and additional DSBs are recorded. Consideration of this additional damage leads to a modification of the underlying photon survival curve at high doses. As a consequence of the new approach, the ratio of maximum relative biological effectiveness (RBE) values to minimum RBEs is increased. This can be understood in terms of a higher radiation effect resulting from the cluster damage at high local doses. We find that the extended LEM including cluster effects reproduces experimental data for V79 cells significantly better than the original LEM.