Reducing radiation exposure and costs: CT body scout views with an enhanced protocol versus conventional radiography after shunt surgery

OBJECTIVE

Ventriculoperitoneal shunt implantation has become standard treatment for cerebrospinal fluid diversion, besides endoscopic third ventriculostomy for certain indications. Postoperative X-ray radiography series of skull, chest and abdomen combined with cranial CT are obtained routinely in many institutions to document the shunt position and valve settings in adult patients. Measures to reduce postoperative radiation exposure are needed, however, there is only limited experience with such efforts. Here, we aim to compare routine postoperative cranial CT plus conventional radiography series (retrospective arm) with cranial CT and body scout views only (prospective arm) concerning both diagnostic quality and radiation exposure.

PATIENTS AND METHODS

After introduction of an enhanced CT imaging protocol, routine skull and abdomen radiography was no longer obtained after VP shunt surgery. The image studies of 25 patients with routine postoperative cranial CT and conventional radiography (retrospective arm of study) were then compared to 25 patients with postoperative cranial CT and CT body scout views (prospective arm of study). Patient demographics such as age, sex and primary diagnosis were collected. The image quality of conventional radiographic images and computed tomography scout views images were independently analyzed by one neurosurgeon and one neuroradiologist.

RESULTS

There were no differences in quality assessments according to three different factors determined by two independent investigators for both groups. There was a statistically significant difference, however, between the conventional radiography series group and the CT body scout view imaging group with regard to radiation exposure. The effective dose estimation calculation yielded a difference of 0.05 mSv (two-tailed t-test, p = 0.044) in favor of CT body scout view imaging. Furthermore, the new enhanced protocol resulted in a reduction of cost and the use of human resources.

CONCLUSION

CT body scout view imaging provides sufficient imaging quality to determine shunt positioning and valve settings. With regard to radiation exposure and costs, we suggest that conventional postoperative shunt series may be abandoned.

Subthalamic Nucleus Deep Brain Stimulation Restores Motor and Sensorimotor Cortical Neuronal Oscillatory Activity in the Free-Moving 6-Hydroxydopamine Lesion Rat Parkinson Model

OBJECTIVES

Enhanced beta oscillations in cortical-basal ganglia (BG) thalamic circuitries have been linked to clinical symptoms of Parkinson's disease. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces beta band activity in BG regions, whereas little is known about activity in cortical regions. In this study, we investigated the effect of STN DBS on the spectral power of oscillatory activity in the motor cortex (MCtx) and sensorimotor cortex (SMCtx) by recording via an electrocorticogram (ECoG) array in free-moving 6-hydroxydopamine (6-OHDA) lesioned rats and sham-lesioned controls.

MATERIALS AND METHODS

Male Sprague-Dawley rats (250-350 g) were injected either with 6-OHDA or with saline in the right medial forebrain bundle, under general anesthesia. A stimulation electrode was then implanted in the ipsilateral STN, and an ECoG array was placed subdurally above the MCtx and SMCtx areas. Six days after the second surgery, the free-moving rats were individually recorded in three conditions: 1) basal activity, 2) during STN DBS, and 3) directly after STN DBS.

RESULTS

In 6-OHDA-lesioned rats (N = 8), the relative power of theta band activity was reduced, whereas activity of broad-range beta band (12-30 Hz) along with two different subbeta bands, that is, low (12-30 Hz) and high (20-30 Hz) beta band and gamma band, was higher in MCtx and SMCtx than in sham-lesioned controls (N = 7). This was, to some extent, reverted toward control level by STN DBS during and after stimulation. No major differences were found between contacts of the electrode grid or between MCtx and SMCtx.

CONCLUSION

Loss of nigrostriatal dopamine leads to abnormal oscillatory activity in both MCtx and SMCtx, which is compensated by STN stimulation, suggesting that parkinsonism-related oscillations in the cortex and BG are linked through their anatomic connections.

Primary and secondary gliosarcoma: differences in treatment and outcome

INTRODUCTION

There are only few studies comparing differences in the outcome of primary versus secondary gliosarcoma. This study aimed to review the outcome and survival of patients with primary or secondary gliosarcoma following surgical resection and adjuvant treatment. The data were also matched with data of patients with primary and secondary glioblastoma (GBM).

PATIENTS AND METHODS

Treatment histories of 10 patients with primary gliosarcoma and 10 patients with secondary gliosarcoma were analysed and compared. Additionally, data of 20 patients with primary and 20 patients with secondary GBM were analysed and compared. All patients underwent surgical resection of the tumour in our department. Follow-up data, progression-free survival (PFS), and median overall survival (mOS) were evaluated.

RESULTS

The median PFS in patients with primary gliosarcoma was significantly higher than in patients with secondary gliosarcoma (p = 0.037). The 6-month PFS rates were 80.0% in patients with primary and 30.0% in patients with secondary gliosarcoma. Upon recurrence, five patients with primary gliosarcoma and four patients with secondary gliosarcoma underwent repeat surgical resection. The mOS of patients with primary gliosarcoma was significantly higher than that of patients with secondary gliosarcoma (p = 0.031). The percentage of patients surviving at 1-year/2-year follow-up in primary gliosarcoma was 70%/20%, while it was only 10%/10% in secondary gliosarcoma. When PFS and mOS of primary gliosarcoma was compared to primary GBM, there were no statistically differences (p = 0.509; p = 0.435). The PFS and mOS of secondary gliosarcoma and secondary GBM were also comparable (p = 0.290 and p = 0.390).

CONCLUSION

Patients with primary gliosarcoma have a higher PFS and mOS compared to those with secondary gliosarcoma. In the case of tumour recurrence, patients with secondary gliosarcoma harbour an unfavourable prognosis with limited further options. The outcome of patients with primary or secondary gliosarcoma is comparable to that of patients with primary or secondary GBM.

Does Temporary Externalization of Electrodes After Deep Brain Stimulation Surgery Result in a Higher Risk of Infection?

OBJECTIVES

Deep brain stimulation (DBS) is a well-established surgical therapy for movement disorders that comprises implantation of stimulation electrodes and a pacemaker. These procedures can be performed separately, leaving the possibility of externalizing the electrodes for local field potential recording or testing multiple targets for therapeutic efficacy. It is still debated whether the temporary externalization of DBS electrodes leads to an increased risk of infection. We therefore aimed to assess the risk of infection during and after lead externalization in DBS surgery.

MATERIALS AND METHODS

In this retrospective study, we analyzed a consecutive series of 624 DBS surgeries, including 266 instances with temporary externalization of DBS electrodes for a mean of 6.1 days. Patients were available for follow-up of at least one year, except in 15 instances. In 14 patients with negative test stimulation, electrodes were removed. All kinds of infections related to implantation of the neurostimulation system were accounted for.

RESULTS

Overall, infections occurred in 22 of 624 surgeries (3.5%). Without externalization of electrodes, infections were noted after 7 of 358 surgeries (2.0%), whereas with externalization, 15 of 252 infections were found (6.0%). This difference was significant (p = 0.01), but it did not reach statistical significance when comparing groups within different diagnoses. The rate of infection with externalized electrodes was highest in psychiatric disorders (9.1%), followed by Parkinson's disease (7.3%), pain (5.7%), and dystonia (5.5%). The duration of the externalization of the DBS electrodes was comparable in patients who developed an infection (6.1 ± 3.1 days) with duration in those who did not (6.0 ± 3.5 days).

CONCLUSIONS

Although infection rates were relatively low in our study, there was a slightly higher infection rate when DBS electrodes were externalized. On the basis of our results, the indication for electrode externalization should be carefully considered, and patients should be informed about the possibility of a higher infection risk when externalization of DBS electrodes is planned.

Microsurgical posterior fossa re-exploration for recurrent trigeminal neuralgia after previous microvascular decompression: common grounds-scarring, deformation, and the "piston effect"

OBJECTIVE

Microvascular decompression (MVD) is a well-accepted treatment modality for trigeminal neuralgia (TN) with high initial success rates. The causes for recurrence of TN after previously successful MVD have not been fully clarified, and its treatment is still a matter of debate. Here, we present the surgical findings and the clinical outcome of patients with recurrent TN after MVD who underwent posterior fossa re-exploration.

METHODS

Microsurgical posterior fossa re-exploration was performed in 26 patients with recurrent TN (mean age 59.1 years) who underwent MVD over a period of 10 years. The trigeminal nerve was exposed, and possible factors for recurrent TN were identified. Arachnoid scars and Teflon granulomas were dissected meticulously without manipulating the trigeminal nerve. Outcome of posterior fossa re-exploration was graded according to the Barrow Neurological Institute (BNI) pain intensity score. Follow-up was analyzed postoperatively at 3, 12, and 24 months and at the latest available time point for long-term outcome.

RESULTS

The mean duration of recurrent TN after the first MVD was 20 months. Pain relief was achieved in all patients with recurrent TN on the first postoperative day. Intraoperative findings were as follows: arachnoid scar tissue in 22/26 (84.6%) patients, arterial compression in 1/26 (3.8%), venous contact in 8/26 (30.8%), Teflon granuloma in 14/26 (53.8%), compression by an electrode in Meckel's cave used for treatment of neuropathic pain in 1/26 (3.8%), evidence of pulsations transmitted to the trigeminal nerve through the Teflon inserted previously/scar tissue ("piston effect") in 15/26 (57.7%), and combination of findings in 18/26 (69.2%). At long-term follow-up (mean 79.5 months; range, 29-184 months), 21/26 (80.8%) patients had favorable outcome (BNI I-IIIa). New hypaesthesia secondary to microsurgical posterior fossa re-exploration occurred in 5/26 (19.2%) patients.

CONCLUSIONS

Posterior fossa re-exploration avoiding manipulation to the trigeminal nerve, such as pinching or combing, may be a useful treatment option for recurrent TN after previously successful MVD providing pain relief in the majority of patients with a low rate of new hypaesthesia.

Microelectrode recording and hemorrhage in functional neurosurgery: a comparative analysis in a consecutive series of 645 procedures

OBJECTIVE

Functional stereotactic neurosurgery including deep brain stimulation (DBS) and radiofrequency lesioning is well established and widely used for treatment of movement disorders and various other neurological and psychiatric diseases. Although functional stereotactic neurosurgery procedures are considered relatively safe, intracranial hemorrhage resulting in permanent neurological deficits may occur in 1%-3% of patients. Microelectrode recording (MER) has been recognized as a valuable tool for refining the final target in functional stereotactic neurosurgery. Moreover, MER provides insight into the underlying neurophysiological pathomechanisms of movement disorders and other diseases. Nevertheless, there is an ongoing controversy on whether MER increases the risk for hemorrhage. The authors aimed to compare the risk of hemorrhage in functional stereotactic neurosurgical procedures with regard to the use of MER.

METHODS

The authors performed a comparative analysis on a consecutive series of 645 functional neurosurgery procedures, including 624 DBS surgeries and 21 radiofrequency lesionings, to evaluate whether the use of MER would increase the risk for hemorrhage. MER was performed in 396 procedures, while no MER was used in 249 cases. The MER technique involved the use of a guiding cannula and a single trajectory when feasible. Postoperative CT scans were obtained within 24 hours after surgery in all patients and screened for the presence of hemorrhage.

RESULTS

Twenty-one intracranial hemorrhages were detected on the postoperative CT scans (3.2%). Of the 21 intracranial hemorrhages, 14 were asymptomatic and 7 were symptomatic. Symptoms were transient except in 1 case. There was no statistically significant correlation between hemorrhage and the use of MER at any site (subdural, ventricle, trajectory, target, whether asymptomatic or symptomatic). There were 4 cases of symptomatic hemorrhage in the MER group (1%) and 3 cases in those without MER (1.2%).

CONCLUSIONS

Intraoperative MER did not increase the overall risk of hemorrhage in the authors' experience using primarily a single MER trajectory and a guiding cannula.

Routine postoperative admission to the neurocritical intensive care unit after microvascular decompression: necessary or can it be abandoned?

Postoperative neurocritical intensive care unit (NICU) admission of patients who underwent craniotomy for close observation is common practice. In this study, we performed a comparative analysis to determine if there is a real need for NICU admission after microvascular decompression (MVD) for cranial nerve disorders or whether it may be abandoned. The present study evaluates a consecutive series of 236 MVD surgeries performed for treatment of trigeminal neuralgia (213), hemifacial spasm (17), vagoglossopharyngeal neuralgia (2), paroxysmal vertigo (2), and pulsatile tinnitus (2). All patients were operated by the senior surgeon according to a standard protocol over a period of 12 years. Patients were admitted routinely to NICU during the first phase of the study (phase I), while in the second phase (phase II), only patients with specific indications would go to NICU. While 105 patients (44%) were admitted to NICU postoperatively (phase I), 131 patients (56%) returned to the ward after a short stay in a postanaesthesia care unit (PACU) (phase II). Specific indications for NICU admission in phase I were pneumothorax secondary to central venous catheter insertion (4 patients), AV block during surgery, low blood oxygen levels after extubation, and postoperative dysphagia and dysphonia (1 patient, respectively). There were no significant differences in the distribution of ASA scores or the presence of cardiac and pulmonary comorbidities like congestive heart failure, arterial hypertension, or chronic obstructive pulmonary disease between groups. There were no secondary referrals from PACU to NICU. Our study shows that routine admission of patients after eventless MVD to NICU does not provide additional value. NICU admission can be restricted to patients with specific indications. When MVD surgery is performed in experienced hands according to a standard anaesthesia protocol, clinical observation on a neurosurgical ward is sufficient to monitor the postoperative course. Such a policy results in substantial savings of costs and human resources.

Mechanical Stability of Nano-Coatings on Clinically Applicable Electrodes, Generated by Electrophoretic Deposition

The mechanical stability of implant coatings is crucial for medical approval and transfer to clinical applications. Here, electrophoretic deposition (EPD) is a versatile coating technique, previously shown to cause significant post-surgery impedance reduction of brain stimulation platinum electrodes. However, the mechanical stability of the resulting coating has been rarely systematically investigated. In this work, pulsed-DC EPD of laser-generated platinum nanoparticles (PtNPs) on Pt-based, 3D neural electrodes is performed and the in vitro mechanical stability is examined using agarose gel, adhesive tape, and ultrasonication-based stress tests. EPD-generated coatings are highly stable inside simulated brain environments represented by agarose gel tests as well as after in vivo stimulation experiments. Electrochemical stability of the NP-modified surfaces is tested via cyclic voltammetry and that multiple scans may improve coating stability could be verified, indicated by higher signal stability following highly invasive adhesive tape stress tests. The brain sections post neural stimulation in rats are analyzed via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Measurements reveal higher levels of Pt near the region stimulated with coated electrodes, in comparison to uncoated controls. Even though local concentrations in the vicinity of the implanted electrode are elevated, the total Pt mass found is below systemic toxicologically relevant concentrations.

Analysis of risk factors for venous air embolism in the semisitting position and its impact on outcome in a consecutive series of 740 patients

OBJECTIVE

Routine use of the semisitting position, which offers several advantages, remains a matter of debate. Venous air embolism (VAE) is a potentially serious complication associated with the semisitting position. In this study, the authors aimed to investigate the safety of the semisitting position by analyzing data over a 20-year period.

METHODS

The incidence of VAE and its perioperative management were analyzed retrospectively in a consecutive series of 740 patients who underwent surgery between 1996 and 2016. The occurrence of VAE was defined by detection of bubbles on transthoracic Doppler echocardiography (TTDE) or transesophageal echocardiography (TEE) studies, a decrease of end-tidal CO2 (ETCO2) by 4 mm Hg or more, and/or an unexplained drop in systolic arterial blood pressure (≥ 10 mm Hg). From 1996 until 2013 TTDE was used, and from 2013 on TEE was used. The possible risk factors for VAE and its impact on surgical performance were analyzed.

RESULTS

There were 404 women and 336 men with a mean age at surgery of 49 years (range 1-87 years). Surgery was performed for infratentorial lesions in 709 patients (95.8%), supratentorial lesions in 17 (2.3%), and cervical lesions in 14 (1.9%). The most frequent pathology was vestibular schwannoma. TEE had a higher sensitivity than TTDE. While TEE detected VAE in 40.5% of patients, TTDE had a detection rate of 11.8%. Overall, VAE was detected in 119 patients (16.1%) intraoperatively. In all of these patients, VAE was apparent on TTDE or TEE. Of those, 23 patients also had a decrease of ETCO2, 18 had a drop in blood pressure, and 23 had combined decreases in ETCO2 and blood pressure. VAE was detected in 24% of patients during craniotomy before opening the dura mater, in 67% during tumor resection, and in 9% during wound closure. No risk factors were identified for the occurrence of VAE. Two patients had serious complications due to VAE. Surgical performance in vestibular schwannoma surgery was not affected by the presence of VAE.

CONCLUSIONS

This study shows that the semisitting position is overall safe and that VAE can be managed effectively. Persistent morbidity is very rare. The authors suggest that the semisitting position should continue to have a place in the standard armamentarium of neurological surgery.

Centromedian-Parafascicular and Somatosensory Thalamic Deep Brain Stimulation for Treatment of Chronic Neuropathic Pain: A Contemporary Series of 40 Patients

Introduction: The treatment of neuropathic and central pain still remains a major challenge. Thalamic deep brain stimulation (DBS) involving various target structures is a therapeutic option which has received increased re-interest. Beneficial results have been reported in several more recent smaller studies, however, there is a lack of prospective studies on larger series providing long term outcomes. Methods: Forty patients with refractory neuropathic and central pain syndromes underwent stereotactic bifocal implantation of DBS electrodes in the centromedian-parafascicular (CM-Pf) and the ventroposterolateral (VPL) or ventroposteromedial (VPM) nucleus contralateral to the side of pain. Electrodes were externalized for test stimulation for several days. Outcome was assessed with five specific VAS pain scores (maximum, minimum, average pain, pain at presentation, allodynia). Results: The mean age at surgery was 53.5 years, and the mean duration of pain was 8.2 years. During test stimulation significant reductions of all five pain scores was achieved with either CM-Pf or VPL/VPM stimulation. Pacemakers were implanted in 33/40 patients for chronic stimulation for whom a mean follow-up of 62.8 months (range 3-180 months) was available. Of these, 18 patients had a follow-up beyond four years. Hardware related complications requiring secondary surgeries occurred in 11/33 patients. The VAS maximum pain score was improved by ≥50% in 8/18, and by ≥30% in 11/18 on long term follow-up beyond four years, and the VAS average pain score by ≥50% in 10/18, and by ≥30% in 16/18. On a group level, changes in pain scores remained statistically significant over time, however, there was no difference when comparing the efficacy of CM-Pf versus VPL/VPM stimulation. The best results were achieved in patients with facial pain, poststroke/central pain (except thalamic pain), or brachial plexus injury, while patients with thalamic lesions had the least benefit. Conclusion: Thalamic DBS is a useful treatment option in selected patients with severe and medically refractory pain.

Pseudotumor cerebri syndrome in a child with Alagille syndrome: intracranial pressure dynamics and treatment outcome after ventriculoperitoneal shunting

Alagille syndrome (AS) is a rare multisystem disease of the liver, heart, eyes, face, skeleton, kidneys, and vascular system. The occurrence of pseudotumor cerebri syndrome (PTCS) in patients with AS has been reported only exceptionally. Owning to its rarity and a mostly atypical presentation, the diagnosis and natural history of affected patients remain uncertain. We report an atypical case of PTCS in a 4-year-old boy with a known history of AS who presented with bilateral papilledema (PE) on a routine ophthalmological examination. Visual findings deteriorated after treatment with acetazolamide. Continuous intracranial pressure (ICP) monitoring was then utilized to investigate ICP dynamics. Successful treatment with resolution of PE was achieved after ventriculoperitoneal shunting but relapsed due to growth-related dislocation of the ventricular catheter. This report brings new insights into the ICP dynamics and the resulting treatment in this possibly underdiagnosed subgroup of PTCS patients. It also demonstrates that ventriculoperitoneal shunting can provide long-term improvement of symptoms for more than 10 years.

Operative findings and outcome of microvascular decompression/adhesiolysis for trigeminal neuralgia in multiple sclerosis without demyelinating brain stem lesions

OBJECTIVE

Trigeminal neuralgia (TN) in multiple sclerosis (MS) poses several challenges for treatment. Although these patients often have typical attacks, they may not be considered as candidates for microvascular decompression (MVD). Here we report on surgical findings and long term follow-up of MVD/ adhesiolysis in a series of patients with multiple sclerosis but without demyelinating brain stem lesions.

METHODS

Fifteen patients with MS-related TN underwent MVD/ adhesiolysis. Demyelinating brain stem lesions were excluded radiologically. Outcome of the intervention was assessed according to the Barrow Neurological Institute (BNI) pain intensity score at 3, 12, 24 months follow-up and at the last available follow-up (mean 88.2 months, range 38-146).

RESULTS

All 15 patients benefited from MVD/adhesiolysis and were pain free on the first day of surgery. Intraoperative findings included arterial contact in 7/15 (47 %) patients, venous contact in 9/15 (60 %), and prominent arachnoid thickening in 12/15 (80 %). The distribution of the BNI pain intensity scores showed marked improvement at all follow-up evaluations. Five patients underwent repeat MVD/adhesiolysis for pain recurrence at a mean of 43 months after the first surgery. Long term evaluation at the last available follow-up demonstrated favorable outcome in 13/15 patients (BNI I-IIIa) (87 %), while 2/15 patients had limited benefit (BNI IV).

CONCLUSIONS

MS-related TN in patients without demyelinating brain stem lesions may be related either to vascular conflicts or to focal arachnoiditis at the trigeminal nerve entry zone. MVD/ adhesiolysis may be considered as a useful treatment option in this subgroup of patients with regard to long term outcome.

Long-Term Deep Brain Stimulation in Treatment-Resistant Obsessive-Compulsive Disorder: Outcome and Quality of Life at Four to Eight Years Follow-Up

BACKGROUND

Obsessive compulsive disorder (OCD) is a severe disabling disease, and around 10% of patients are considered to be treatment-resistant (tr) in spite of guideline-based therapy. Deep brain stimulation (DBS) has been proposed as a promising treatment for patients with trOCD. However, the optimal site for stimulation is still a matter of debate, and clinical long-term follow-up observations including data on quality of life are sparse. We here present six trOCD patients who underwent DBS with electrodes placed in the bed nucleus of the stria terminalis/anterior limb of the internal capsule (BNST/ALIC), followed for four to eight years after lead implantation.

MATERIALS AND METHODS

In this prospective observational study, six patients (four men, two women) aged 32-51 years and suffering from severe to extreme trOCD underwent DBS of the BNST/ALIC. Symptom severity was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), and quality of life using the World Health Organization Quality of Life assessment scale (WHO-QoL BREF). Follow-up was obtained at least for four years in all patients.

RESULTS

With chronic DBS for four to eight years, four of the six patients had sustained improvement. Two patients remitted and two patients responded (defined as >35% symptom reduction), while the other two patients were considered nonresponders on long-term. Quality of life markedly improved in remitters and responders. We did not observe peri-interventional side effects or adverse effects of chronic stimulation.

CONCLUSIONS

Chronic DBS of ALIC provides long-term benefit up to four to eight years in trOCD, although not all patients take profit. Targeting the BNST was not particularly relevant since no patient appeared to benefit from direct stimulation of the BNST. Quality of life improved in DBS responders, documented by improved QoL scores and, even more important, by regaining of autonomy and improving psychosocial functioning.

Microvascular decompression: is routine postoperative CT imaging necessary?

BACKGROUND

Postoperative head CT imaging is routinely performed for detection of postoperative complications following intracranial procedures. However, it remains unclear whether with regard to radiation exposure, costs, and possibly lack of consequences this practice is truly justified in various operative procedures. The objective of this study was to analyze whether routine postoperative CT imaging after microvascular decompression (MVD) is necessary or whether it may be abandoned.

METHODS

A series of 202 MVD surgeries for trigeminal neuralgia (179), hemifacial spasm (17), vagoglossopharyngeal neuralgia (2), paroxysmal vertigo (2), and pulsatile tinnitus (2) operated by the senior surgeon (JKK) and who had postoperative routine CT imaging was analyzed.

RESULTS

Routine postoperative CT imaging detected small circumscribed postoperative hemorrhage in 9/202 (4.4%) instances. Hemorrhage was localized at the site of the Teflon felt (1/9), the cerebellum (4/9), in the frontal subdural space (3/9), and in the frontal subarachnoid space (1/9). In two patients, asymptomatic hemorrhage was accompanied by mild cerebellar edema (1%), and another patient had mild transient hydrocephalus (0.5%). Furthermore, there were small accumulations of intracranial air in 86/202 instances. No other complications such as infarction or skull fracture secondary to fixation with the Mayfield clamp were detected. MVD had been performed for trigeminal neuralgia in 6/9 patients, for hemifacial spasm in 2/9, and in one patient with both. No patient underwent a second surgery. Hemorrhage was symptomatic at the time of imaging in only one instance who had mild postoperative gait ataxia. Two patients with hemorrhage developed delayed facial palsy most likely unrelated to hemorrhage which remitted with corticosteroid treatment. At 3-month follow-up and at long-term follow-up, they had no neurological deficits.

CONCLUSION

Routine postoperative CT imaging is not necessary after MVD in a standard setting in patients who do not have postoperative neurological deficits.

Neurobiological Mechanisms of Metacognitive Therapy - An Experimental Paradigm

INTRODUCTION

The neurobiological mechanisms underlying the clinical effects of psychotherapy are scarcely understood. In particular, the modifying effects of psychotherapy on neuronal activity are largely unknown. We here present data from an innovative experimental paradigm using the example of a patient with treatment resistant obsessive-compulsive disorder (trOCD) who underwent implantation of bilateral electrodes for deep brain stimulation (DBS). The aim of the paradigm was to examine the short term effect of metacognitive therapy (MCT) on neuronal local field potentials (LFP) before and after 5 MCT sessions.

METHODS

DBS electrodes were implanted bilaterally with stereotactic guidance in the bed nucleus of the stria terminalis/ internal capsule (BNST/IC). The period between implantation of the electrodes and the pacemaker was used for the experimental paradigm. DBS electrodes were externalized via extension cables, yielding the opportunity to record LFP directly from the BNST/IC. The experimental paradigm was designed as follows: (a) baseline recording of LFP from the BNST/IC, (b) application of 5 MCT sessions over 3 days, (c) post-MCT recording from the BNST/IC. The Obsessive-Compulsive Disorder- scale (OCD-S) was used to evaluate OCD symptoms.

RESULTS

OCD symptoms decreased after MCT. These reductions were accompanied by a decrease of the relative power of theta band activity, while alpha, beta, and gamma band activity was significantly increased after MCT. Further, analysis of BNST/IC LFP and frontal cortex EEG coherence showed that MCT decreased theta frequency band synchronization.

DISCUSSION

Implantation of DBS electrodes for treating psychiatric disorders offers the opportunity to gather data from neuronal circuits, and to compare effects of therapeutic interventions. Here, we demonstrate direct effects of MCT on neuronal oscillatory behavior, which may give possible cues for the neurobiological changes associated with psychotherapy.

Multisegmental Lumbar Corporectomy and Transcorporal Fixation for Correction of Extreme Thoracolumbar Kyphosis in Myelomeningocele with Chronic Decubitus

We introduce a novel technique for the treatment of severe kyphosis in myelomeningocele. A 5-year-old paraplegic boy with myelomeningocele presented with severe thoracolumbar kyphosis and a chronic ulcus at the site of the gibbus. The myelomeningocele had been treated during his first week of life, and an accompanying Chiari type II malformation had been treated by ventriculoperitoneal shunting. He subsequently developed a rapidly progressive thoracolumbar kyphosis with an angle of 180° between T10 and L5. He also suffered from a chronic superinfected skin ulcus at the site of the gibbus. Since the skin ulcus required plastic surgery reconstruction, we deemed classical posterior fixation after kyphectomy unfeasible. The subsequent operative steps of our novel surgical approach were performed in a single-stage surgery. First, a three-level lumbar corporectomy from L1 to L3 was performed. Subsequently, the body of the removed L2 vertebra was isolated and configured as an autologous graft to bridge the gap between the thoracic and the caudal lumbar spine. The graft was fixed via a transcorporal interbody fusion technique with titanium screws, and chopped autologous bone was added for fusion. The skin was closed using rotation flaps. At the 3-year follow-up, the patient and his family reported marked improvement of quality of life, imaging showed solid fusion and the wound was unremarkable. Our novel technique with transcorporal fixation provides new perspectives in the treatment of severe kyphosis and skin ulceration in myelomeningocele.

Experimental Rat Model for Brain Death Induction and Kidney Transplantation

Background: Experimental animal research has been pivotal in developing clinical kidney transplantation (KTx). One donor-associated risk factor with negative affect of transplantation outcome is brain death (BD). Many rat models for BD and KTx have been developed in the last decade, but no surgical guidelines have been developed for these models. Here, we describe a surgical technique for BD induction and the cuff technique for experimental KTx in rats.Methods: After intubation and mechanically ventilation of sixteen healthy adult male Sprague-Dawley rats were induction of BD performed. Animals were kept hemodynamically stable for eight hours. Then, the kidney was prepared and perfused with standard histidine-tryptophan-ketoglutarate solution. After explantation, grafts were immediately implanted in recipients using the cuff technique and reperfused. After 2 h of observation, animals were sacrificed by intravenous administration of potassium chloride.Results: In the early phase of BD, heart rate increased and mean arterial pressure decreased. Partial variations were observed in O₂ partial pressure, O₂ saturation, and HCO₃. During the 2-h observation phase, all transplanted kidneys were sufficiently perfused macroscopically. There was no hyperacute rejection.Conclusions: It is feasible to observe BD for 8 h with maintained circulation in small experimental settings. The cuff technique for KTx is simple, the complication rate is low, and the warm ischemia time is short, therefore, this could be a suitable technique for KTx in the rat model.

Challenges in cerebrospinal fluid shunting in patients with glioblastoma

Background

Cerebrospinal fluid (CSF) circulation disturbances may occur during the course of disease in patients with glioblastoma. Ventriculoperitoneal shunting has generally been recommended to improve symptoms in glioblastoma patients. Shunt implantation for patients with glioblastoma, however, presents as a complex situation and produces different problems to shunting in other contexts. Information on complications of shunting glioma patients has rarely been the subject of investigation. In this retrospective study, we analysed restropectively the course and outcome of glioblastoma-related CSF circulation disturbances after shunt management in a consecutive series of patients within a period of over a decade.

Methods

Thirty of 723 patients with histopathologically-confirmed glioblastoma diagnosed from 2002 to 2016 at the Department of Neurosurgery, Hannover Medical School, underwent shunting for CSF circulation disorders. Treatment history of glioblastoma and all procedures associated with shunt implementation were analyzed. Data on follow-up, time to progression and survival rates were obtained by review of hospital charts and supplemented by phone interviews with the patients, their relations or the primary physicians.

Results

Mean age at the time of diagnosis of glioblastoma was 43 years. Five types of CSF circulation disturbances were identified: obstructive hydrocephalus (n = 9), communicating hydrocephalus (n = 15), external hydrocephalus (n = 3), trapped lateral ventricle (n = 1), and expanding fluid collection in the resection cavity (n = 2). All patients showed clinical deterioration. Procedures for CSF diversion were ventriculoperitoneal shunt (n = 21), subduroperitoneal shunt (n = 3), and cystoperitoneal shunt (n = 2). In patients with lower Karnofsky Performance Score (KPS) (< 60), there was a significant improvement of median KPS after shunt implantation (p = 0.019). Shunt revision was necessary in 9 patients (single revision, n = 6; multiple revisions, n = 3) due to catheter obstruction, catheter dislocation, valve defect, and infection. Twenty-eight patients died due to disease progression during a median follow-up time of 88 months. The median overall survival time after diagnosis of glioblastoma was 10.18 months.

Conclusions

CSF shunting in glioblastoma patients encounters more challenge and is associated with increased risk of complications, but these can be usually managed by revision surgeries. CSF shunting improves neurological function temporarily, enhances quality of life in most patients although it is not known if survival rate is improved.

Development of Hyperkinesias after Long-term Pallidal Stimulation for Idiopathic Segmental Dystonia

Background

Chronic deep brain stimulation (DBS) of the globus pallidus internus (GPi) has become an established treatment for dystonia. While bradykinetic symptoms may occur on chronic stimulation, the appearance of hyperkinetic movements has not been well characterized.

Case Report

We report on the development of hyperkinesias after more than 10 years of GPi DBS.

Discussion

Hyperkinesias may evolve upon long-term GPi DBS in dystonia. This might be related to a combined effect consisting of a reduced threshold for effective GPi stimulation for dystonia and spread of current to the globus pallidus externus.

Telemetric Intracranial Pressure Recording via a Shunt System Integrated Sensor: A Safety and Feasibility Study

Background The dynamics of intracranial pressure (ICP) after shunt surgery in patients with normal pressure hydrocephalus (NPH) are poorly known. Temporarily implanted parenchymal pressure probes are reliable for accurate ICP monitoring; however, a disadvantage of this method is that the ICP probe has to be explanted after a period of time, requiring additional surgery. We present two patients with NPH with an integrated ICP measuring device in the shunt system that allows for long-term postoperative telemetric monitoring of ICP.

Methods Two patients (one man, 66 years old, and one woman, 78 years old) with normal pressure hydrocephalus underwent shunt surgery using the Aesculap-Miethke Sensor Reservoir (Potsdam) as an ICP measuring device integrated in the shunt system. On the first postoperative day and during follow-up examination 3 months later, several measurements of ICP were performed using a handheld device to read the Sensor Reservoir data. Postural changes such as lying down, sitting, and standing with different head postures were assessed according to an experimental protocol in a randomized order during which the ICP was measured.

Results There were clear ICP responses due to postural changes, in line with physiologically expected values. Because the highest sampling rate of the Aesculap-Miethke Sensor Reservoir is 1 Hz for continuous measurement of ICP, however, the collected data have to be considered an approximation for actual ICP dynamics.

Conclusion The Aesculap-Miethke Sensor Reservoir is an easy-to-use tool to measure ICP changes reliably in patients with a shunt system. The sampling rate and handling of data acquisition may eventually be developed further.

What Do Medical Students Know about Deep Brain Stimulation?

BACKGROUND

Deep brain stimulation (DBS) is an established therapy for movement disorders. It is currently under investigation in neuropsychiatric disorders. Neurophobia is a common phenomenon that might have a negative impact in medical education. Little is known about medical students' knowledge about DBS when they enter university and what they learn about it during their medical formation.

METHODS

A 10-item questionnaire was designed. Questions addressed indications for DBS, costs of DBS, complications, the percentage of Parkinson disease (PD) patients who might profit from DBS, etc. Students at Hannover Medical School were asked to complete the questionnaire in the preclinical study period and in the last year of the study.

RESULTS

Comparing the "early group" (204 students) and the "advanced group" (162 students), there was a significant gain of knowledge. More common disorders such as PD and tremor were known to be indications for DBS. Knowledge about the impact of DBS on specific symptoms in PD and about DBS targets was limited in both groups.

CONCLUSIONS

DBS is partly known among medical students in the preclinical phase with a gain of knowledge during further study. Future studies on this topic addressing general practitioners as neurologists are needed to better understand why knowledge on DBS is still limited.

Idiopathic Intracranial Hypertension in Monozygotic Female Twins: Intracranial Pressure Dynamics and Treatment Outcome

BACKGROUND

Familial cases of idiopathic intracranial hypertension (IIH) are exceedingly rare, and its occurrence in monozygotic twins has not been reported previously.

CASE DESCRIPTION

We report monozygotic female twins who developed IIH, one at age 25 years and the other at age 28 years. Continuous intracranial pressure (ICP) monitoring confirmed elevated ICP as measured initially by lumbar puncture. In both cases, successful treatment with resolution of papilledema and symptoms relief was achieved after ventriculoperitoneal shunting.

CONCLUSIONS

This report documents the first case of IIH in monozygotic twins and the associated changes in ICP dynamics. Interestingly, almost equivalent alterations in ICP dynamics were found in the 2 patients.

Optimizing in Vitro Impedance and Physico-Chemical Properties of Neural Electrodes by Electrophoretic Deposition of Pt Nanoparticles

Neural electrodes suffer from an undesired incline in impedance when in permanent contact with human tissue. Nanostructures, induced by electrophoretic deposition (EPD) of ligand-free laser-generated nanoparticles (NPs) on the electrodes are known to stabilize impedance in vivo. Hence, Pt surfaces were systematically EPD-coated with Pt NPs and evaluated for impedance as well as surface coverage, contact angle, electrochemically active surface area (ECSA) and surface oxidation. The aim was to establish a systematic correlation between EPD process parameters and physical surface properties. The findings clearly reveal a linear decrease in impedance with increasing surface coverage, which goes along with a proportional reduction of the contact angle and an increase in ECSA and surface oxidation. EPD process parameters, prone to yield surface coatings with low impedance, are long deposition times (40-60 min), while high colloid concentrations (>250 μg mL^-1 ) and electric field strengths (>25 V cm^-1 ) should be avoided due to detrimental NP assemblage effects.

Shunt Surgery in Idiopathic Intracranial Hypertension Aided by Electromagnetic Navigation

BACKGROUND

Idiopathic intracranial hypertension (IIH) is characterized by increased cerebrospinal fluid (CSF) pressure and normal or slit ventricles. Lumboperitoneal shunting had been favored by many investigators for CSF diversion in IIH for decades; however, it has been associated with various side effects. Because of the small ventricular size adequate positioning of a ventricular catheter is challenging.

OBJECTIVES

Here, we investigated the usefulness of electromagnetic (EM)-guided ventricular catheter placement for ventriculoperitoneal shunting in IIH.

METHODS

Eighteen patients with IIH were included in this study. The age of patients ranged from 5 to 58 years at the time of surgery (mean age: 31.8 years; median: 29 years). There were 2 children (5 and 11 years old) and 16 adults. Inclusion criteria for the study were an established clinical diagnosis of IIH, lack of improvement with medication, and the presence of small ventricles. In all patients EM-navigated placement of the ventricular catheter was performed using real-time tracking of the catheter tip for exact positioning close to the foramen of Monro. Postoperative CT scans were correlated with intraoperative screen shots to validate the position of the catheter.

RESULTS

In all patients EM-navigated ventricular catheter placement was achieved with a single pass. There were no intraoperative or postoperative complications. Postoperative imaging confirmed satisfactory positioning of the ventricular catheter. No proximal shunt failure was observed during the follow-up at a mean of 41.5 months (range: 7-90 months, median: 40.5 months).

CONCLUSIONS

EM-navigated ventricular catheter placement in shunting for IIH is a safe and straightforward technique. It obviates the need for sharp head fixation, the head of the patient can be moved during surgery, and it may reduce the revision rate during follow-up.

Electrophoretic deposition of ligand-free platinum nanoparticles on neural electrodes affects their impedance in vitro and in vivo with no negative effect on reactive gliosis

BACKGROUND

Electrodes for neural stimulation and recording are used for the treatment of neurological disorders. Their features critically depend on impedance and interaction with brain tissue. The effect of surface modification on electrode impedance was examined in vitro and in vivo after intracranial implantation in rats. Electrodes coated by electrophoretic deposition with platinum nanoparticles (NP; <10 and 50 nm) as well as uncoated references were implanted into the rat's subthalamic nucleus. After postoperative recovery, rats were electrostimulated for 3 weeks. Impedance was measured before implantation, after recovery and then weekly during stimulation. Finally, local field potential was recorded and tissue-to-implant reaction was immunohistochemically studied.

RESULTS

Coating with NP significantly increased electrode's impedance in vitro. Postoperatively, the impedance of all electrodes was temporarily further increased. This effect was lowest for the electrodes coated with particles <10 nm, which also showed the most stable impedance dynamics during stimulation for 3 weeks and the lowest total power of local field potential during neuronal activity recording. Histological analysis revealed that NP-coating did not affect glial reactions or neural cell-count.

CONCLUSIONS

Coating with NP <10 nm may improve electrode's impedance stability without affecting biocompatibility. Increased impedance after NP-coating may improve neural recording due to better signal-to-noise ratio.

Analysis of intracranial pressure time series using wavelets (Haar basis functions)

PURPOSE

Transforming intracranial pressure (ICP) into frequency domain commenced in the early 1980s, arriving at the conclusion that cerebrospinal dynamics were mapped by ICP spectral composition. Classical analysis tools were not suitable for handling intrinsic signal non-stationarity. To overcome inherent obstacles we introduce a novel approach based upon wavelets.

METHODS

During routine diagnostic volume pressure testing epidural ICP was acquired in 118 patients with suspected cerebrospinal fluid circulatory disorders. Pressure was digitised and conditioned to separate low frequent signal components (<heart rate). ICP fluctuations were computed by subtraction of original and low frequent ICP constituents. Subsequently, multiresolution analysis was performed on fluctuations by discrete Haar wavelet transform and coefficients displayed in dyadic fashion (scalogram).

RESULTS

Decomposition of ICP fluctuations led to typical patterns in the scalogram. Episodes of pathological wave activity and artificial ICP changes were topographically detectable in the time frequency plane.

CONCLUSIONS

The wavelet approach is a simple yet powerful signal processing method to estimate both static and dynamic properties of ICP in various clinical scenarios. It therefore outclasses classical spectral transforms that are limited to analysing real-world data. Haar wavelets are fast and robust. Their disadvantages seem not to counterbalance the advantages in this biomedical application.

Deep brain stimulation of the pedunculopontine tegmental nucleus modulates neuronal hyperactivity and enhanced beta oscillatory activity of the subthalamic nucleus in the rat 6-hydroxydopamine model

Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) area has been introduced as a novel surgical therapy for dopamine refractory gait problems, freezing and postural instability in the late stage of Parkinson's disease (PD). Lesions of the pedunculopontine tegmental (PPTg) nucleus, the equivalent of the PPN in rodents, were shown to reduce the elevated discharge rate of the subthalamic nucleus (STN) in the 6-hydroxydopamine (6-OHDA) rat model of PD. In order to further elucidate the modulatory effect of the PPTg on the STN we examined the effect of 25 Hz low frequency PPTg stimulation on neuronal single unit activity and oscillatory local field potentials (LFPs) of the STN, and on the electrocorticogram (ECoG) of the primary motor cortex region in rats with unilateral 6-OHDA induced nigrostriatal lesions. Stimulation of the PPTg reduced the enhanced firing rate in the STN, without affecting the firing pattern or approximate entropy (ApEn). It also reduced the activity in the beta band (15-30 Hz) of the STN, which is elevated in 6-OHDA lesioned rats, without affecting beta activity in the motor cortex. We showed a modulatory effect of PPTg stimulation on altered neuronal STN activity in the PD 6-OHDA rat model, indicating that PPTg DBS may alter activity of the basal ganglia circuitry at least partially. It remains unclear, however, how these changes are exactly mediated and whether they are relevant with regard to the descending PPTg projections in the lower brainstem.

Head trauma in children, part 3: clinical and psychosocial outcome after head trauma in children

With the aim of determining long-term outcome, the authors approached 38 families (average 2.1 years after trauma) with a questionnaire, following the acute-clinical treatment of head trauma of their children. Long-term damage was restricted almost exclusively to patients presenting with a Glasgow Coma Score < or =8. Paresis (16%), cranial nerve damage (13%), incontinence (5%), or coordinative disturbances (18%) continued. The older children stated that they influenced their life to a great extent (11%). Furthermore, many had mental and cognitive problems that occur quite frequently even in children with light head trauma and often only manifest after release from hospital. This causes problems and results in inferior performance (26%), especially at school, which is further complicated through lengthy periods of absence. The parents, especially, mentioned behavioral problems such as social withdrawal or aggressive demeanor, which led to tension also inside the family. A persistent vegetative state is rare after head trauma in children.

Respiratory function after lesions in medulla oblongata

OBJECTIVES

To evaluate the correlation of lesions of the brain as visualized in cranial magnetic resonance imaging (MRI) and the ability of spontaneous respiration.

METHODS

In a prospective concept, cranial MRI after traumatic brain injury or spontaneous intracerebral hemorrhage was performed in 250 subjects at an early stage. All MRI findings were correlated with respiratory conditions on the day of examination. Sedation was performed only to facilitate toleration of the artificial ventilation, as and when necessary. Spontaneous respiration could hence be registered clinically.

RESULTS

Thirteen subjects (5.2%) had no spontaneous respiration. In these cases, a bilateral lesion of the distal medulla oblongata could be displayed. In four of these cases, no additional injuries of the brainstem were detected. These subjects awoke 2 days after the impact with tetraparesis and apnea. Combined lesions of the medulla oblongata and other brainstem regions were found in nine subjects. All these patients died without awakening. In the absence of a bilateral lesion of the caudal medulla oblongata, spontaneous respiration was always possible. A unilateral lesion of the caudal medulla oblongata was visualized in one patient who had the ability of spontaneous respiration.

CONCLUSIONS

This work confirms the presence of autonomous respiratory centers within the caudal medulla oblongata that allows sufficient adequate respiration in coma. Respiration ceases in the presence of a bilateral lesion of this area.

Age-dependence of cerebrospinal parameters

OBJECTIVE

The records of 159 patients were reviewed who routinely underwent a classical volume-pressure testing procedure due to suspected cerebrospinal fluid circulatory disorders.

METHODS

Regression analyses were carried out to explain the cerebrospinal parameters' relationships to age. Least median squares (LMS) algorithms achieved robust estimation of simple linear model parameters. Also, method of weighted regression was used because of unequal variances in the observations.

RESULTS

Cerebrospinal elastance and resistance to outflow revealed significant LMS regressions: y = 0.171x + 7.460 (n = 159, p < 0.0001) and y = 0.096x + 1.871 (n = 97, p < 0.0001), respectively. Similarly, weighting data resulted in models such as y = 0.151x + 6.830 (p < 0.0001) for elastance and y = 0.087x + 1.730 (p < 0.0001) for resistance estimates. The intracranial pressure at rest showed no age-related dependency. Both clear clinical and morphological signs were found in 20% of patients.

CONCLUSION

Expecting no time-variant properties we surprisingly found a significant linear relationship in cerebrospinal parameters and age. Thus, parameter magnitudes are not likely dominated by a pathological process only but also determined by temporal system alterations.

Artificial elevation of brain tissue glycerol by administration of a glycerol-containing agent. Case report

In recent years the development of secondary brain damage and derangement of neurochemical parameters after severe head injury has been monitored using microdialysis. Provided the blood-brain barrier is intact, glycerol is regarded as a potential marker for membrane phospholipid degradation. The authors report a case in which marked elevation of interstitial glycerol was induced after exogenous administration of a glycerol-containing agent. A 25-year-old man was injured in a motorcycle accident and was admitted to the authors' institution with a unilateral dilated and fixed pupil and a Glasgow Coma Scale score of 3. Computerized tomography scans revealed a large subdural hematoma on the left side, subsequent midline shift, and generalized edema. Emergency craniotomy was performed for evacuation of the hematoma. The patient was prepared for multisensory monitoring and a microdialysis catheter was inserted into his left frontal lobe. After a routine enema containing 85% glycerol had been administered, the authors measured a marked increase in glycerol in the dialysate. This occurred while the patient was in as stable a condition as could be expected given the circumstances. The increase in interstitial glycerol in the injured tissue was most likely due to an impaired blood-brain barrier. Thus, the interstitial glycerol concentration had been corrupted by exogenous glycerol, and the marker properties of glycerol in this case became questionable. Consequently, administration of glycerol, which is frequently found in various infusions and emulsions, can promote secondary brain damage by adversely shifting osmotic gradients.

[Initiation of rehabilitation after surgery for herniated lumbar disk: pilot study of efficacy from the viewpoint of the surgical hospital]

The initiation of rehabilitation after lumbar disc surgery in Germany is up to the operating hospital. A decision between outpatient and inpatient rehabilitation is possible. Until now this decision is not based on scientific data but on the individual experience of the hospital. This prospective study compares the effect of outpatient and inpatient therapy: In 65 patients medical and psychosocial data were collected shortly before operation, 1 week and 6 months after surgery. Of these patients, 42 underwent inpatient, 21 outpatient rehabilitation, 2 patients renounced rehabilitation. The outpatient and inpatient rehabilitation groups showed no significant difference in testing before or shortly after the operation concerning subjective state of health and somatic findings. Some 6 months later, long term outcome was identical, i.e. the groups did not differ in psychosocial or medical respects. However, the inpatient rehabilitation group had taken significantly longer to return to work. This pilot study stresses the importance of further research on rehabilitation after lumbar disc surgery. It should be shared by surgeons and rehabilitation experts.

Treatment of elevated intracranial pressure by infusions of 10% saline in severely head injured patients

The management of intracranial pressure (ICP) is a factor in outcome of patients with head trauma. However, recent studies have revealed that the current strategies, which have been applied to control ICP for adequate cerebral perfusion, are unsatisfactory. Against this background, the efficacy of short-term infusions of hypertonic saline on ICP was investigated. In severely head injured (SHI) patients, hypertonic saline (100 ml 10% NaCl) was administered when standard agents (mannitol, sorbitol, THAM) failed in reducing ICP. To evaluate the pressure reduction after saline infusions the resulting ICP relaxations were analysed statistically in respect to the parameters amplitude, duration and dynamic behaviour of the ICP responses. In 42 randomized relaxations, the relative ICP decrease was 43% [28%-58%] (median [interquartile range]). The corresponding pressure drop was 18 mmHg [15-27 mm Hg]. Relaxations lasted for 93 min [64-126 min] and a relative ICP minimum was reached 26 min [12-33 min] after infusion. In the individual cases the temporal course of the parameters amplitude and decline interval depict a tendency toward lower and higher values, respectively, under conditions of a generally increasing ICP. As expected, the infusion of hypertonic saline reduces ICP in patients suffering from SHI. The pressure drop, duration and dynamic behaviour are suspected to depend both on the pressure level to reduce and concomitant medications.

Cerebral blood flow in chronic hydrocephalus--a parameter indicating shunt failure--new aspects

Prediction of outcome after shunt-therapy in chronic hydrocephalus syndrome is uncertain. Pathology reveals an impairment of cerebral blood flow (CBF). Based on this, we evaluated CBF and its significance for the assessment of prognosis. In 21 patients (mean age 69 years) selected for surgery, CBF was measured by PET (15O-H2O) before, about one week and 7 months (n = 14) after shunting. CBF was computed by a 1-compartmental model in the territories of the ACA, MCA and PCA. One PET slice in the height of the maximum projection of both cellae mediae was chosen. CBF data were standardized by cluster analysis. Three CBFClusters with significantly different CBF levels prior to shunting in the ACA, MCA and PCA territory, respectively, referred to the sample average (38.2 ml/100 ml/min) were found. These CBFClusters differed in clinical outcome: almost 50% and 90% of patients improved clinically in CBFCluster I, with a perfusion level lower than average, after one week and 7 months, respectively. In contrast, patients of CBFCluster II with an average perfusion did not improve. CBF changes 7 months after shunting related to global CBF before surgery showed a relationship with the clinical course. Clinical outcome corresponded with preoperative global CBF values. Cerebral blood flow lower than average forecasts clinical improvement. Our results suggest that measurement of CBF adds to the indication for surgery.

PET and CBF studies of chronic hydrocephalus: a contribution to surgical indication and prognosis

The authors investigate whether measurement of cerebral blood flow (CBF) in chronic hydrocephalus is a reliable indicator in selecting patients to undergo ventriculoperitoneal shunting. Global and regional CBF is quantified (Kety-Schmidt one-compartment model) by positron emission tomography in 21 patients. CBF is determined following injection of 15O-H2O at three time points: 1 week before, 7 days after, and 7 months after shunting. The neurological status of these patients is classified, and cerebrospinal fluid (CSF) dynamics continuous intracranial pressure [ICP] monitoring and CSF infusion tests) were assessed prior to surgery. Preoperative global CBF values correlate well with clinical outcome. Patients with a significantly lower global CBF value show clinical improvement after 7 months, whereas patients with higher CBF values do not (mean, 33 vs. 45 ml/100 ml per minute; p < 0.05). In contrast to conventional methods, including long-term ICP measurement and CSF infusion tests, preoperative global CBF values are discriminating in terms of clinical outcome. Thus, measurement of CBF may be helpful in evaluating the ultimate utility of shunt therapy in chronic hydrocephalus.

On the effect of calcium antagonists on cerebral blood flow in rats. A comparison of nimodipine and flunarizine

To assess the influence of nimodipine treatment in brain tissue at different levels of blood pressure, we estimated the cerebral blood flow using hydrogen clearance. Rats were treated with nimodipine (n = 8), its placebo (n = 10), flunarizine (n = 11) and its placebo (n = 10), and a group of controls (n = 10). Cerebral blood flow was estimated during arterial normo-, hyper- and hypotension. The lowest cerebral blood flow estimates calculated for nimodipine were 43.8 +/- 7.8, 90.9 +/- 13.3, and 33.6 +/- 6.1 ml/min/100 g for normo-, hyper- and hypotension, respectively. Cerebral blood flow in the nimodipine placebo group was 84.1 +/- 10.3, 139.9 +/- 19.9, and 55.2 +/- 10.5 ml/min/100 g. In the flunarizine group, the blood flow was 77.3 +/- 15.2, 144.7 +/- 15.0, and 43.8 +/- 5.9 ml/min/100 g. In the control group, cerebral blood flow was 90.0 +/- 29.1, 143.0 +/- 42.1, and 75.5 +/- 29.8 ml/min/100 g. The low blood flow in the nimodipine group might have been a consequence of brain edema caused by extravasates. Thus impaired blood flow reduces the usefulness of nimodipine in the prevention of vasospasm. Flunarizine is a potential alternative treatment of vasospasm treatment as well as for cerebral blood flow improvement, as shown in our experimental study.

Computed tomographic criteria and survival rate for patients with acute subdural hematoma

OBJECTIVE

Computed tomographic data from 174 patients with acute subdural hematoma were analyzed statistically to identify parameters that could be evaluated independently of clinical and neurological status to estimate outcome.

METHODS

This retrospective study was made necessary by the fact that the patients admitted usually had been treated with intubation, sedation, and artificial ventilation, which precludes neurological examination.

RESULTS

In surgically treated patients, the hematoma thickness ranged from 5 to 35 mm and the midline shift was 0 to 33 mm. In 81 patients (46.6%), the hematoma thickness was greater than the midline shift; in 24 patients (13.8%), the hematoma thickness equaled the midline shift; and in 69 patients (39.6%), the midline shift exceeded the hematoma thickness. Of the patients, 52% died after surgery, for 29% we obtained good or satisfying results, and 19% were in poor condition after therapy. The Kaplan-Meier survival analysis proved that the survival rate was only 50% for a hematoma thickness of approximately 18 mm and a midline shift of 20 mm. The survival function dropped markedly for midline shifts of more than 20 mm and converged to 0% for midline shifts of more than 25 mm. If the midline shift exceeded the hematoma thickness by 3 mm, the survival function was 50%; when the midline shift exceeded the hematoma thickness by 5 mm, the survival function was 25%. The Glasgow Outcome Scale scores were correlated significantly with these parameters. The parameters, which are the measured hematoma thickness, the midline shift, and the difference between the hematoma thickness and the midline shift, allow robust/adequate estimation of survival function and outcome for patients suffering from acute subdural hematoma.

CONCLUSION

Based on these data, indications for surgery could be assessed by means of video conferencing, i.e., without personal examination of the patients.

Testing the hydrocephalus shunt valve: long-term bench test results of various new and explanted valves. The need for model for testing valves under physiological conditions

13 new and 19 explanted hydrocephalus shunt valves were tested under perfusion for two weeks, using a modified ASTM test. Some manufacturers seem to have problems with quality control. Our results show large deviations in pressure-flow-characteristics in different valves, in some cases leading to an extremely high pre-shunt pressure. Test results almost corresponding to manufacturer's specifications were found in diaphragm valves and in some ball and spring valves. Results from slit valves usually varied widely, some being good, but others bad (much too high a pressure) or dangerous with even possibly fatal characteristics. Whilst laboratory performance may not correlate with clinical results, due to different impact of cerebrospinal fluid (CSF) pressure and flow on hydrocephalus shunting systems, manufacturers should provide devices that meet their supposed specifications. We developed an apparatus allowing simulation of different CSF production rates, CSF outflow resistances, CSF pressure waves caused by arterial and venous pulsation, breathing and coughing, and hydrostatic differential pressure caused by body position changes. This model enables testing of shunt valves under almost physiological conditions, thus closing the gap between conventional bench test results and clinical performance of hydrocephalus shunt valves.

Traumatic brain swelling and operative decompression: a prospective investigation

Since 1978, decompressive craniotomy was performed according to a standardized protocol. Exclusion criteria were age greater than or equal to 40 years, deleterious primary brain damage, operable space occupying lesions, larger infarctions in CT scan or irreversible brain stem incarceration/ischaemic damage as shown by bulbar syndrome, loss in BAEP or oscillating flow in TCD. Indication was given by progressive intracranial hypertension not controllable by conservative methods, if ICP decompensation was correlated with clinical (GCS, extension spasms, mydriasis) and electrophysiological (EEG, SEP, CCT) deteriorations. 18 patients were decompressed by unilateral. 19 by bilateral craniotomy with large fronto-parieto-temporal bone flap and a dura enlargement by use of temporal muscle/fascia. 37 patients at an age of 18 +/- 7 (4-34) years were operated 5 h-10 d after trauma. Recovery was surprisingly good: only 5 died, 2 due to an ARDS; 3 remained vegetative, all others achieved full social rehabilitation or remained moderately disabled. The best predictor of a favourable outcome was an initial posttraumatic GCS greater than or equal to 7. These in younger patients with delayed posttraumatic decompensation before irreversible ischaemic damage occurs.

[DNA profile, recurrence rate and progression of superficial G2 cancer of the urinary bladder]

In a retrospective study the prognostic value of flow cytometric DNA analysis was studied in 114 newly diagnosed cases with superficial bladder tumours. G1-tumours were generally diploid, G3-tumours almost exclusively aneuploid. G2-tumours exhibited a bimodal distribution with 50% diploid and 50% aneuploid cases respectively. Recurrence and progression correlated systematically with the ploidy level. Furthermore, the degree of aneuploidy is predictive for proneness to progression.