[Imaging for disorders in neurology and neurosurgery]

Imaging has become increasingly important for diagnosis and treatment of disorders in neurology and neurosurgery. Often, however, physicians are uncertain which imaging modality to chose for diagnosis and which techniques can be used to help for treatment. To answer a specific question clinicians have to rely on history and clinical findings. According to a cardinal clinical symptom or sign the imaging technique with the highest sensitivity and specificity for the given problem is chosen. In this review imaging techniques for the most common cardinal symptoms and signs in neurology and neurosurgery which need imaging for management are discussed.

Patent foramen ovale and neurosurgery in sitting position: a systematic review

We have conducted a systematic review of air embolism complications of neurosurgery in the sitting position and patent foramen ovale (PFO) closure. It assesses the risk and benefit of PFO closure before neurosurgery in the sitting position. The databases Medline, Embase, and Cochrane Controlled Trial Register were systematically searched from inception to November 2007 for keywords in both topics separately. In total, 4806 patients were considered for neurosurgery in sitting position and 5416 patients underwent percutaneous PFO closure. The overall rate of venous air embolism during neurosurgery in sitting position was 39% for posterior fossa surgery and 12% for cervical surgery. The rate of clinical and transoesophageal echocardiography detected paradoxical air embolism was reported between 0% and 14%. The overall success rate for PFO closure using new and the most common closure devices was reported 99%, whereas the average risk of major complications is <1%. On the basis of our systematic review, we recommend screening for PFO and considering closure in cases in which the sitting position is the preferred neurosurgical approach. Our proposed management including the time of PFO closure according to available data is presented. However, the conclusions from our systematic review may be limited due to the lack of level A evidence and from using data from observational cohort studies. Thus, definite evidence-based recommendations require prospective evaluation of the issue in well-designed studies.

The silent loss of neuronavigation accuracy: a systematic retrospective analysis of factors influencing the mismatch of frameless stereotactic systems in cranial neurosurgery

BACKGROUND Neuronavigation has become an intrinsic part of preoperative surgical planning and surgical procedures. However, many surgeons have the impression that accuracy decreases during surgery. OBJECTIVE To quantify the decrease of neuronavigation accuracy and identify possible origins, we performed a retrospective quality-control study. METHODS Between April and July 2011, a neuronavigation system was used in conjunction with a specially prepared head holder in 55 consecutive patients. Two different neuronavigation systems were investigated separately. Coregistration was performed with laser-surface matching, paired-point matching using skin fiducials, anatomic landmarks, or bone screws. The initial target registration error (TRE1) was measured using the nasion as the anatomic landmark. Then, after draping and during surgery, the accuracy was checked at predefined procedural landmark steps (Mayfield measurement point and bone measurement point), and deviations were recorded. RESULTS After initial coregistration, the mean (SD) TRE1 was 2.9 (3.3) mm. The TRE1 was significantly dependent on patient positioning, lesion localization, type of neuroimaging, and coregistration method. The following procedures decreased neuronavigation accuracy: attachment of surgical drapes (DTRE2 = 2.7 [1.7] mm), skin retractor attachment (DTRE3 = 1.2 [1.0] mm), craniotomy (DTRE3 = 1.0 [1.4] mm), and Halo ring installation (DTRE3 = 0.5 [0.5] mm). Surgery duration was a significant factor also; the overall DTRE was 1.3 [1.5] mm after 30 minutes and increased to 4.4 [1.8] mm after 5.5 hours of surgery. CONCLUSION After registration, there is an ongoing loss of neuronavigation accuracy. The major factors were draping, attachment of skin retractors, and duration of surgery. Surgeons should be aware of this silent loss of accuracy when using neuronavigation.

Integrated Segmentation of Brain Tumor Images for Radiotherapy and Neurosurgery

Image-based modeling of tumor growth combines methods from cancer simulation and medical imaging. In this context, we present a novel approach to adapt a healthy brain atlas to MR images of tumor patients. In order to establish correspondence between a healthy atlas and a pathologic patient image, tumor growth modeling in combination with registration algorithms is employed. In a first step, the tumor is grown in the atlas based on a new multi-scale, multi-physics model including growth simulation from the cellular level up to the biomechanical level, accounting for cell proliferation and tissue deformations. Large-scale deformations are handled with an Eulerian approach for finite element computations, which can operate directly on the image voxel mesh. Subsequently, dense correspondence between the modified atlas and patient image is established using nonrigid registration. The method offers opportunities in atlasbased segmentation of tumor-bearing brain images as well as for improved patient-specific simulation and prognosis of tumor progression.

What is New and Innovative in Emergency Neurosurgery? Emerging Diagnostic Technologies Provide Better Care and Influence Outcome: A Specialist Review

The development of emergency medical services and especially neurosurgical emergencies during recent decades has necessitated the development of novel tools. Although the gadgets that the neurosurgeon uses today in emergencies give him important help in diagnosis and treatment, we still need new technology, which has rapidly developed. This review presents the latest diagnostic tools, which offer precious help in everyday emergency neurosurgery practice. New ultrasound devices make the diagnosis of haematomas easier. In stroke, the introduction of noninvasive new gadgets aims to provide better treatment to the patient. Finally, the entire development of computed tomography and progress in radiology have resulted in innovative CT scans and angiographic devices that advance the diagnosis, treatment, and outcome of the patent. The pressure on physicians to be quick and effective and to avoid any misjudgement of the patient has been transferred to the technology, with the emphasis on developing new systems that will provide our patients with a better outcome and quality of life.

Predictive value of cerebrospinal fluid (CSF) lactate level versus CSF/blood glucose ratio for the diagnosis of bacterial meningitis following neurosurgery.

The value of cerebrospinal fluid (CSF) lactate level and CSF/blood glucose ratio for the identification of bacterial meningitis following neurosurgery was assessed in a retrospective study. During a 3-year period, 73 patients fulfilled the inclusion criteria and could be grouped by preset criteria in one of three categories: proven bacterial meningitis (n = 12), presumed bacterial meningitis (n = 14), and nonbacterial meningeal syndrome (n = 47). Of 73 patients analyzed, 45% were treated with antibiotics and 33% with steroids at the time of first lumbar puncture. CSF lactate values (cutoff, 4 mmol/L), in comparison with CSF/blood glucose ratios (cutoff, 0.4), were associated with higher sensitivity (0.88 vs. 0.77), specificity (0.98 vs. 0.87), and positive (0.96 vs. 0.77) and negative (0.94 vs. 0.87) predictive values. In conclusion, determination of the CSF lactate value is a quick, sensitive, and specific test to identify patients with bacterial meningitis after neurosurgery.

Ventricular enlargement due to acute hypernatremia in a patient with a ventriculoperitoneal shunt

Patients requiring CSF shunts frequently have comorbidities that can influence water and electrolyte balances. The authors report on a case involving a ventriculoperitoneal shunt in a patient who underwent intravenous hyperhydration and withdrawal of vasopressin substitution prior to scheduled high-dose chemotherapy regimen for a metastatic suprasellar germinoma. After acute neurological deterioration, the patient underwent CT scanning that demonstrated ventriculomegaly. A shunt tap revealed no flow and negative opening pressure. Due to suspicion of proximal shunt malfunction, the comatose patient underwent immediate surgical exploration of the ventricle catheter, which was found to be patent. However, acute severe hypernatremia was diagnosed during the procedure. After correction of the electrolyte disturbances, the patient regained consciousness and made a good recovery. Although rare, the effects of acute severe hypernatremia on brain volume and ventricular size should be considered in the differential diagnosis of ventriculoperitoneal shunt failure.

Kinematic improvement following Botulinum Toxin-A injection in upper-limb spasticity due to stroke

Background Focal spasticity is a significant motor disorder following stroke, and Botulinum Toxin Type-A (BoNT-A) is a useful treatment for this. The authors evaluated kinematic modifications induced by spasticity, and whether or not there is any improvement following injection of BoNT-A. Methods Eight patients with stroke with upper-limb spasticity, showing a flexor pattern, were evaluated using kinematics before and after focal treatment with BoNT-A. A group of sex- and age-matched normal volunteers acted as a control group. Results Repeated-measures ANOVA showed that patients with stroke performed more slowly than the control group. Following treatment with BoNT-A, there was a significant improvement in kinematics in patients with stroke, while in the control group, performance remained unchanged. Conclusions Focal treatment of spasticity with BoNT-A leads to an adaptive change in the upper limb of patients with spastic stroke.

Long-term outcome analysis of the supraclavicular surgical release for the treatment of thoracic outlet syndrome

This is a long-term outcome analysis of patients who underwent surgical treatment with a supraclavicular release for thoracic outlet syndrome (TOS).

Decompressive craniectomy after intra-arterial thrombolysis: safety and outcome

Data on decompressive craniectomy (DC) after intra-arterial thrombolysis (IAT) for treatment of malignant middle cerebral artery (MCA) stroke are lacking.

Posterior versus anterior circulation strokes: comparison of clinical, radiological and outcome characteristics

Physicians treating patients with posterior circulation strokes (PCS) tended to debate more on whether or not to introduce anticoagulation rather than performing investigations to identify stroke aetiology, as in patients with anterior circulation strokes (ACS). Recent findings suggest that stroke aetiologies of PCS and ACS are more alike than dissimilar, suggesting that PCS deserve the same investigations as ACS. The characteristics and current diagnostic evaluation between patients with PCS and ACS were compared.

Pituitary surgery for small prolactinomas as an alternative to treatment with dopamine agonists

Despite the fact that consensus guidelines recommend long-term dopamine agonist (DA) therapy as a first-line approach to the treatment of small prolactinoma, some patients continue to prefer a primary surgical approach. Concerns over potential adverse effects of long-term medical therapy and/or the desire to become pregnant and avoid long-term medication are often mentioned as reasons to pursue surgical removal. In this retrospective study, 34 consecutive patients (30 female, 4 male) preferably underwent primary pituitary surgery without prior DA treatment for small prolactinomas (microprolactinoma 1-10 mm, macroprolactinoma 11-20 mm) at the Department of Neurosurgery, University of Bern, Switzerland. At the time of diagnosis, 31 of 34 patients (91%) presented with symptoms. Patients with microprolactinomas had significantly lower preoperative prolactin (PRL) levels compared to patients with macroprolactinomas (median 143 μg/l vs. 340 μg/l). Ninety percent of symptomatic patients experienced significant improvement of their signs and symptoms upon surgery. The postoperative PRL levels (median 3.45 μg/l) returned to normal in 94% of patients with small prolactinomas. There was no mortality and no major morbidities. One patient suffered from hypogonadotropic hypogonadism after surgery despite postoperative normal PRL levels. Long-term remission was achieved in 22 of 24 patients (91%) with microprolactinomas, and in 8 of 10 patients (80%) with macroprolactinomas after a median follow-up period of 33.5 months. Patients with small prolactinomas can safely consider pituitary surgery in a specialized centre with good chance of long-term remission as an alternative to long-term DA therapy.

IVIG blocks complement deposition mediated by anti-GM1 antibodies in multifocal motor neuropathy

The pathogenesis of multifocal motor neuropathy (MMN) has yet to be established. MMN patients often carry anti-GM1 IgM antibodies, suggesting an autoimmune process involving complement. Intravenous immunoglobulin (IVIG) is the first line treatment, but its action mechanism is unknown.