Martin Weinzierl

The use of dynamic O-(2-18F-fluoroethyl)-l-tyrosine PET in the diagnosis of patients with progressive and recurrent glioma

BACKGROUND We evaluated the diagnostic value of static and dynamic O-(2-[(18)F]fluoroethyl)-L-tyrosine ((18)F-FET) PET parameters in patients with progressive or recurrent glioma. METHODS We retrospectively analyzed 132 dynamic (18)F-FET PET and conventional MRI scans of 124 glioma patients (primary World Health Organization grade II, n = 55; grade III, n = 19; grade IV, n = 50; mean age, 52 ± 14 y). Patients had been referred for PET assessment with clinical signs and/or MRI findings suggestive of tumor progression or recurrence based on Response Assessment in Neuro-Oncology criteria. Maximum and mean tumor/brain ratios of (18)F-FET uptake were determined (20-40 min post-injection) as well as tracer uptake kinetics (ie, time to peak and patterns of the time-activity curves). Diagnoses were confirmed histologically (95%) or by clinical follow-up (5%). Diagnostic accuracies of PET and MR parameters for the detection of tumor progression or recurrence were evaluated by receiver operating characteristic analyses/chi-square test. RESULTS Tumor progression or recurrence could be diagnosed in 121 of 132 cases (92%). MRI and (18)F-FET PET findings were concordant in 84% and discordant in 16%. Compared with the diagnostic accuracy of conventional MRI to diagnose tumor progression or recurrence (85%), a higher accuracy (93%) was achieved by (18)F-FET PET when a mean tumor/brain ratio ≥2.0 or time to peak <45 min was present (sensitivity, 93%; specificity, 100%; accuracy, 93%; positive predictive value, 100%; P < .001). CONCLUSION Static and dynamic (18)F-FET PET parameters differentiate progressive or recurrent glioma from treatment-related nonneoplastic changes with higher accuracy than conventional MRI.

Combined motor and somatosensory evoked potentials for intraoperative monitoring: intra- and postoperative data in a series of 69 operations

The primary objective of neurophysiologic monitoring during surgery is to avoid permanent neurological injury resulting from surgical manipulation. To prevent motor deficits, either somatosensory (SSEP) or transcranial motor evoked potentials (MEP) are applied. This prospective study was conducted to evaluate if the combined use of SSEP and MEP might be beneficial. Combined SSEP/MEP monitoring was attempted in 100 consecutive procedures, including intracranial and spinal operations. Repetitive transcranial electric motor cortex stimulation was used to elicit MEP from muscles of the upper and lower limb. Stimulation of the tibial and median nerves was performed to record SSEP. Critical SSEP/MEP changes were defined as decreases in amplitude of more than 50% or increases in latency of more than 10% of baseline values. The operation was paused or the surgical strategy was modified in every case of SSEP/MEP changes. Combined SSEP/MEP monitoring was possible in 69 out of 100 operations. In 49 of the 69 operations (71%), SSEP/ MEP were stable, and the patients remained neurologically intact. Critical SSEP/ MEP changes were seen in six operations. Critical MEP changes with stable SSEP occurred in 12 operations. Overall, critical MEP changes were recorded in 18 operations (26%). In 12 of the 18 operations, MEP recovered to some extent after modification of the surgical strategy, and the patients either showed no (n = 10) or only a transient motor deficit (n = 2). In the remaining six operations, MEP did not recover and the patients either had a transient (n = 3) or a permanent (n = 3) motor deficit. Critical SSEP changes with stable MEP were observed in two operations; both patients did not show a new motor deficit. Our data again confirm that MEP monitoring is superior to SSEP monitoring in detecting impending impairment of the functional integrity of cerebral and spinal cord motor pathways during surgery. Detection of MEP changes and adjustment of the surgical strategy might allow to prevent irreversible pyramidal tract damage. Stable SSEP/MEP recordings reassure the surgeon that motor function is still intact and surgery can be continued safely. The combined SSEP/ MEP monitoring becomes advantageous, if one modality is not recordable.

Endoscopic transtentorial ventriculocystostomy and cystoventriculoperitoneal shunt in a neonate with Dandy-Walker malformation and associated aqueductal obstruction.

Objective: Shunting of the lateral ventricle and the posterior fossa cyst is the advocated surgical therapy for children with Dandy-Walker malformation (DWM) and associated aqueductal obstruction. The high rate of complications of combined shunting stimulated the authors to search for an alternative surgical solution. Clinical Presentation/Intervention: After transtentorial endoscopic ventriculocystostomy, a cystoventricular catheter, connected to a peritoneal shunt, was placed in a neonate with DWM and associated aqueductal obstruction. Immediately prior to ventriculocystostomy, the presence of a blocked third ventricular outflow was reconfirmed by contrast medium injection. Neuronavigation was required to define the surgical path from the lateral ventricle through the tentorium and the overlying small rim of brain parenchyma into the posterior fossa cyst. The postoperative clinical course was uneventful with radiologically proven reduction of the size of the ventricular system and the cyst. Conclusion: Cystoventriculoperitoneal shunt placement after transtentorial endoscopic ventriculostomy is a surgical alternative in very young children with DWM and associated aqueductal obstruction.

Management of hydrocephalus in infants by using shunts with adjustable valves.

OBJECT Previous reports suggest that the use of adjustable differential-pressure valves may improve shunt performance. The absence of a flow- or siphon-controlled mechanism, however, is a concern. The goal of this prospective study was to assess the efficacy of valve adjustments in preventing slitlike ventricles in children < 6 months old after the first shunt insertion. METHODS A total of 15 infants < 6 months of age who were undergoing initial shunt placement were included. Imaging was performed preoperatively, at 14 days postoperatively, and every 4 weeks thereafter. Ventricle size was assessed using ultrasonography and MR imaging or cerebral CT scanning at 1 and 2 years postoperatively. Clinical follow-up duration was 24 months for all patients. Valve settings were changed by 50 mm H(2)O if ventricle size decreased by 30% compared to preoperative size. RESULTS The valve pressure setting was increased to 200 mm H(2)O in 11 children within the follow-up time, whereas ventricle size decreased from 0.6 +/- 0.08 to 0.39 +/- 0.09 (frontal/occipital horn ratio, mean +/- standard deviation). There was neither clinical nor radiological evidence of underdrainage. CONCLUSIONS The adjustable differential-pressure valve used in this study was not effective in preventing slitlike ventricles in the majority of patients. Despite the small number of patients, this study provides a rationale for examining whether new shunt designs (gravitational shunt valves) are superior to conventional shunt systems in managing challenging hydrocephalus problems.

Jefferson fracture in a child--illustrative case report.

In adults, atlas burst fractures (Jefferson fractures) are not uncommon. In the pediatric population, they are extremely rare, and only few cases have been reported so far. They all showed a highly consistent clinical presentation with rare neurological deficits as well as recovery with full function without any surgical intervention. We describe a case of a Jefferson fracture in a 7.5-year-old-boy after falling onto the top of his head, presenting solely with slight neck pain. The initial radiological characteristics are presented on magnetic resonance imaging (MRI) and computer tomography (CT); the bony bridging and fusion of the fracture sites are demonstrated on CT during the course of the healing. The patient was placed in a rigid cervical collar, and his physical examination results remained normal according to age. Complete fusion of both fracture sites was seen on the third follow-up 6.5 months after presentation. In this rare case of a Jefferson fracture in a child monitored by radiological imaging techniques, important aspects of conservatively treated atlas burst fractures are illustrated. It underlines their benign character and favorable outcome with full functional recovery without any surgical intervention.

Experience with a gravitational valve in the management of symptomatic overdrainage in children with shunts

OBJECT Symptomatic overdrainage in children with shunt-treated hydrocephalus represents one of the more difficult shunt-related diseases and may require repeated surgery. Gravity-assisted valve design has become a standard device to avoid overdrainage in many European pediatric hydrocephalus centers. However, the use of a gravitational valve for relieving symptoms associated with overdrainage has not yet been addressed. The goal of this study was to evaluate the effectiveness of a gravitational valve in the treatment of symptomatic overdrainage in children with shunts. METHODS Seventeen children with an adjustable shunt system and symptomatic overdrainage were treated by insertion of a gravitational valve. Clinical and radiological outcome were monitored for a minimum of 12 months after surgery. RESULTS Implantation of a gravitational valve resulted in either resolution (n = 12) or improvement (n = 5) of the symptoms. In 1 patient, symptoms remained almost unchanged and the gravitational valve had to be upgraded, resulting in resolution of the symptoms. During follow-up, the pressure setting of the adjustable differential pressure valve had to be changed in 7 patients. CONCLUSIONS The gravitational valve was effective in improving symptomatic overdrainage in the majority of patients in the present study. Because the ideal pressure setting for a given patient is hard to determine a priori, adjustable valve systems appear to be beneficial.

Endothelin-mediated induction of heme oxygenase-1 in the spinal cord is attenuated in transgenic mice overexpressing superoxide dismutase

Spinal cord blood flow and the induction of heme oxygenase-1 (HO-1), an indicator of oxidative stress, were studied in the spinal cords of adult wild-type and transgenic mice overexpressing the antioxidant copper, zinc superoxide dismutase (CuZn SOD) after intrathecal administration of the potent vasoactive peptide endothelin-1 (ET-1). Gelfoam, saturated with ET-1 (40, 80, or 400 micromol/L), was positioned in the intrathecal space at the midthoracic level in anesthetized animals. Blood flow was continuously monitored by laser Doppler for 10 min after the intrathecal application of ET-1. There was a significant reduction in spinal cord blood flow to approximately 40% of control values by 10 min after the intrathecal application of the peptide in both wild-type and transgenic mice. Moreover, SB209670, a nonselective endothelin receptor antagonist, blocked this reduction in flow. Each animal was euthanized 24 h after the intrathecal administration of ET-1, and the spinal cord was prepared for quantitative immunocytochemistry. HO-1 was primarily induced in astrocytes near the dorsal surface of the spinal cord in wild-type mice. This induction was attenuated in both wild-type, treated with SB209670, and untreated transgenic mice. Together, these findings suggest that ET-1 mediates oxidative stress in the spinal cord through the modulation of spinal cord blood flow.

Extended pterional orbital decompression in severe orbital cellulitis.

Summary. Background: Bacterial orbital cellulitis is a relatively uncommon infective process, which can threaten the function of orbital structures. Apart from antibiotic therapy, sinus surgery with or without abscess drainage via an orbito-otorhinolaryngological approach might be necessary. Case description: We present three cases of severe orbital cellulitis, leading to increasing loss of vision, proptosis, afferent pupillary disturbances and restriction of extra-ocular movements, despite antibiotic therapy. After extended pterional orbital decompression and reducing the orbital pressure by removal of the lateral and superolateral orbital walls, all patients showed distinct improvement of initial symptoms, without any complications related to the operation. Interpretation: Extended pterional orbital decompression represents an effective treatment alternative and supplement in cases of a severe, threat to ocular function due to orbital cellulitis, where acute reduction of pressure on orbital, neural and vascular structures is intended.

A Multisensor Implant for Continuous Monitoring of Intracranial Pressure Dynamics

In humans, intracranial pressure (ICP) is not only influenced by pathology, but also by orientation in space and body movements. Therefore, it is proposed to measure ICP dynamics and body acceleration simultaneously. An algorithm for acceleration analysis was developed to monitor orientation in space and allow more accurate examination of ICP dynamics during quiet periods.

Attenuated induction of heme oxygenase after intrathecal exposure to lysed blood in mice overexpressing superoxide dismutase

Induction of heme oxygenase-1 (HO-1) in the spinal cord was studied in adult wildtype and transgenic mice overexpressing the antioxidant copper, zinc superoxide dismutase (CuZn SOD) 24 h after intrathecal infusion of heterologous lysed blood. Double immunolabeling techniques were used to determine the extent to which HO-1 was induced in astrocytes and microglia/macrophages. HO-1 was induced in both astrocytes and microglia/macrophages in the dorsal horns near the site of infusion of lysed blood in all mice. However, the number of HO-1 labeled cells was significantly less in the transgenic as compared to the wildtype animals. Together, these findings suggest that lysed blood preferentially induces HO-1 in glia and macrophages through the generation of oxidative stress.