Prevalence of cerebral microhemorrhages in amateur boxers as detected by 3T MR imaging

BACKGROUND AND PURPOSE

The evidence for traumatic brain injury in amateur boxers is controversial. Hypothetically, sudden acceleration of the head due to the impact of the blow during the boxing fight might result in diffuse axonal injury or contusion. We wanted to determine whether cerebral microhemorrhages occur more often in amateur boxers than in nonboxers.

MATERIALS AND METHODS

In 42 male, classical amateur boxers and in 37 healthy, nonboxing male volunteers we performed cranial MR imaging at 3T. The study protocol included a transverse dual spin-echo MR imaging sequence, a 3D sagittal magnetization-prepared rapid acquisition of gradient echo sequence, a coronal T2*-weighted sequence, and an axial time-of-flight MR angiography sequence. MR imaging data were made anonymous before 2 neuroradiologists independently evaluated the images. In addition, the following risk factors were assessed: total numbers of fights and knockouts, weight division, and duration of boxing. We compared the group proportions of microhemorrhages with Fisher test of exact probability.

RESULTS

There was a statistically higher prevalence of cerebral microhemorrhages in the group of boxers (3 of 42; 7.1%) than in nonboxing persons (0 of 37; 0%). This difference was not statistically significant, however (P = .2479; Fisher exact test).

CONCLUSION

Although we detected more microhemorrhages in amateur boxers than in nonboxing persons, this difference did not prove to be significant.

Herpes simplex virus colitis complicating ulcerative colitis: A case report and brief review on superinfections

In patients with inflammatory bowel disease herpes simplex virus infection has been described as a major cause of morbidity and mortality, especially in immunocompromised individuals. Here we present the case of a 35-year old woman with an exacerbation of ulcerative colitis caused by herlpes simplex virus infection (HSV-2). The diagnosis was confirmed histologically following subtotal colectomy. After intravenous treatment with aciclovir for 2 weeks postoperative hematochezia stopped. Herpes simplex virus colitis is a rare but potentially fatal complication of immunosuppressive treatment in patients with inflammatory bowel disease. Prompt diagnosis and efficient antiviral therapy are mandatory to improve prognosis.

A new system for continuous recurrent laryngeal nerve monitoring

Existing nerve monitoring devices in thyroid surgery are - except for one - mainly intermittently working nerve identification tools. We present a new vagal electrode which allows true continuous monitoring of the recurrent laryngeal nerve (RLN). The electrode was designed as a tripolar hybrid cuff electrode consisting of polyimide, gold and platinum layers embedded in a flexible silicon cuff which can be opened at the long side for introducing the nerve. It is fully implantable and atraumatic. The evoked potentials are sensed by standard thyroid electrodes. Real-time signal analysis and audio feedback are achieved by specially designed software. Homogeneous and stable signals were recorded throughout the operations. Thus real-time computer-based signal analysis was possible. Evoked potentials reached 300-900 mV. Mean time to place the cuff electrode was 5.5 min. The nerve was stimulated a mean of 63 min (range 55-99 min). No RLN lesions were detected postoperatively. The new vagal electrode was easy to handle and led to stable and reproducible signals. The stimulation current could be kept extremely low due to the special geometry of the electrode. It offers the possibility for uninterrupted, continuous laryngeal nerve monitoring in thyroid surgery. In an ongoing clinical trial its compatibility as an add-on for existing nerve monitoring devices is being tested.

Aquaporin 4 regulation during acute and long-term experimental Herpes simplex virus encephalitis

Structural damage of the central nervous system (CNS) often leads to severely disabling residual symptoms despite effective antiviral therapy during Herpes simplex virus encephalitis (HSVE). Edematous space-occupying lesions are pathological and neuroradiological well-known phenomena for this disease. The molecular mechanisms of brain edema development in HSVE are poorly understood, the regulation of water brain-blood barrier (BBB) permeability might be disturbed. Aquaporin 4 (AQP4) is the predominant aquaporin expressed in the brain. Aquaporin 1 (AQP1) plays a role in cerebrospinal fluid modulation. Previous studies suggest that alterations of AQP expression play an important role in the development of brain edema. The mRNA expression of AQP4, AQP1, of their physiologically associated proteins Alpha-syntrophin and KIR 4.1 and of the structural glial protein glial fibrillary acid protein (GFAP) was analyzed in a well-established mice model simulating the human disease. Our data demonstrate a significant down-regulation of AQP4 in the acute phase of disease and an up-regulation of AQP4 and AQP1 in the long term. These results reveal the complex transcription pattern of AQP4, AQP1, KIR 4.1, alpha-syntrophin, and GFAP during HSVE and suggest a role for AQP4 regulation in the pathophysiology of acute and long-term HSVE. AQP4 modulation could be a potential target for brain edema treatment during HSVE.

MMP-2 and MMP-9 levels in peripheral blood after subarachnoid hemorrhage

MMPs play an important role in ischemic and hemorrhagic stroke. We analyzed replicate serum samples from 20 normal healthy individuals to assess reproducibility of MMP determinations, and found that MMP-2 and MMP-9 determinations were quite consistent. We then studied the serum levels of MMP-2 and MMP-9 in patients suffering from subarachnoid hemorrhage (SAH), another stroke subtype. Serum MMP-2 and MMP-9 levels from SAH patients were measured sequentially using gelatine zymography in 11 patients after acute SAH. The occurrence of intracerebral aneurysms and vasospasms and the initial Hunt and Hess score were analysed in relation to MMP-levels. MMP-2 levels are significantly decreased while MMP-9 levels are increased in SAH patients relative to controls. MMP-2 levels remain depressed out to day 12 post SAH, but MMP-9 levels may recover by day 12.

Contrast-enhanced Ultrasound in Dermatomyositis- and Polymyositis

OBJECTIVE

To evaluate prospectively contrast-enhanced ultrasound (CEUS) in patients suspected of having dermatomyositis or polymyositis.

METHODS

In 35 patients (23 women, 12 men; mean age, 51 years+/-16 years) who were suspected of having dermatomyositis or polymyositis, perfusion in clinically affected skeletal muscles was quantified with contrast-enhanced intermittent power Doppler ultrasound. By applying a modified model that analyzed the replenishment kinetics of microbubbles, the perfusion-related parameters blood flow, local blood volume and blood flow velocity were measured. Findings were compared with muscle biopsy appearances and with the results of MRI that was performed with a 1.5-Tesla unit. Receiver operating characteristic analysis was performed and optimum thresholds for diagnosis of myositis were determined.

RESULTS

Eleven patients had histologically confirmed dermatomyositis or polymyositis and showed significantly higher blood flow velocity (P=.01 for dermato- and P<.001 for polymyositis), blood flow (P<.001 for dermato- and polymyositis), and blood volume (P=.007 for dermato- and P<.001 for polymyositis) on contrast-enhanced ultrasound than those who did not have myositis. An increase in signal intensity on T2-weighted MR images was found in all patients with myositis. MRI had a sensitivity, specificity, positive (PPV), and negative predicting values (NPV) of 100%, 88%, 77%, and 100% for diagnosis of myositis, respectively. CEUS blood flow was the best ultrasound measure for diagnosis of dermato- or polymyositis with sensitivity, specificity, PPV, and NPV of 73%, 91%, 80%, and 88%, respectively.

CONCLUSIONS

Increased skeletal muscle perfusion measured by CEUS could serve as an additional measurer for the diagnosis of an inflammatory myopathy.

Pathologic Skeletal Muscle Perfusion in Patients with Myositis: Detection with Quantitative Contrast-enhanced US—Initial Results

PURPOSE

To prospectively determine whether contrast material-enhanced ultrasonography (US) can depict inflammation-induced changes in muscle perfusion for patients suspected of having dermatomyositis or polymyositis and to compare these findings with those of magnetic resonance (MR) imaging and muscle biopsy.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Perfusion in skeletal muscles was quantified with contrast-enhanced intermittent power Doppler US by applying a modified model that analyzed the replenishment kinetics of microbubbles. In 22 patients (16 women, six men; mean age, 52 years +/- 17) who were suspected of having myositis and in 10 healthy volunteers (two women, eight men; mean age, 28 years +/- 4), contrast-enhanced US of the clinically affected right biceps muscle was performed to measure blood flow, blood volume, and blood flow velocity. Additionally, the right upper arm was examined with a 1.5-T unit by using three different MR imaging techniques. Findings were compared with the results of clinical examinations and muscle biopsy. Data for perfusion-related parameters obtained at contrast-enhanced US were analyzed by using a nonparametric Mann-Whitney U test.

RESULTS

Eight patients had histologically confirmed myositis and showed significantly higher blood flow velocity (P = .01), blood flow (P = .001), and blood volume (P = .002) at contrast-enhanced US than did patients who did not have myositis. Blood flow velocity (P = .001) and blood flow (P = .002) were significantly higher in patients with myositis than in volunteers. An increase in signal intensity on T2-weighted MR images was found in all patients with myositis, while contrast material enhancement on fat-suppressed T1-weighted MR images was found in only four of seven patients with myositis.

CONCLUSION

Initial results show that contrast-enhanced US is a feasible method for noninvasively demonstrating increased perfusion in the involved muscle groups in patients with myositis.

Differential mRNA expression of neurotrophic factors GDNF, BDNF, and NT-3 in experimental herpes simplex virus encephalitis

Glial cell line-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) mRNA levels were studied in the course of murine herpes simplex virus encephalitis. Induction of GNDF and NT-3 (both P < 0.05) was found during acute encephalitis. Despite absence of clinical impairment, both neurotrophic factors were overexpressed 2 months (NT-3) and 6 months (GDNF) following infection (both P < 0.05). Neurotrophic factors play an important role in neuronal survival and recovery after acute injury to the central nervous system (CNS) and may represent an additional therapeutic target for treatment of viral encephalitis.

Increased presence of matrix metalloproteinases 2 and 9 in short- and long-term experimental herpes simplex virus encephalitis

Herpes simplex virus encephalitis (HSVE) causes elevated morbidity and mortality despite antiviral treatment. Virus-independent mechanisms may perpetuate brain damage. Matrix metalloproteinases (MMPs) target extracellular matrix components. This study describes the protein and mRNA expression of MMP2 and MMP9 in experimental HSVE in the short and long term. Ten SJL-NBOM mice were infected with neurovirulent HSV-1 and compared with nine controls. The presence of MMP2 and MMP9 in brain tissue was analyzed with sodium-dodecyl-sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gelatin zymography and mRNA expression of MMP2 and MMP9 with quantitative real-time PCR at days 7, 21 and 180 post-inoculation. Infected animals had a significantly elevated gelatinolytic activity of MMP2 at all time points, and of MMP9 at days 21 and 180. Increased presence of MMP2 and MMP9 in chronic HSVE may contribute to ongoing damage. Inhibition of MMP2 and MMP9 might be a suitable target for therapeutic intervention.

In vivomonitoring of acute flavivirus (Modoc) encephalitis with regional and whole-brain quantitative diffusion magnetic resonance imaging

In vivo imaging of structural changes in the brain of patients with encephalitis has become an important aid in diagnostic and therapeutic procedures. Diffusion-weighted magnetic resonance imaging (DWI) was employed to quantitate regional and whole-brain diffusion-weighted MRI changes in a hamster model for acute flavivirus encephalitis. The regional apparent diffusion coefficient (ADC) was determined in hyperintense regions seen on T2-weighted images (i.e., the thalamic area and the temporal lobe), but anatomical variation and structural heterogeneity of encephalitic lesions severely impeded the placement of regions of interest (ROI). Therefore, quantitative whole-brain diffusion-weighted imaging was carried out and revealed a significantly reduced ADC (P = .02) in the brain of hamsters with acute encephalitis (n = 7) as compared to that of healthy, uninfected controls (n = 3). Furthermore, the ADC histogram demonstrated a reduced peak height and center of gravity during the acute encephalitis. Our findings could further support the use of diffusion-weighted imaging for in vivo monitoring of acute flavivirus encephalitis and for the study of therapeutic approaches.

Differential regulation of Toll-like receptor mRNAs in experimental murine central nervous system infections

Toll-like receptors (TLR) play a key role in the recognition of microbial components. We investigated the differential regulation of TLR mRNA expression in bacterial and viral mouse models of central nervous system infection. Streptococcus pneumoniae meningitis led to an enhanced expression of TLR2, TLR4 and TLR9 mRNA. In Escherichia coli meningitis, TLR2, TLR4 and TLR7 mRNA expression was increased and Herpes simplex encephalitis caused a rise of TLR4 mRNA. In organotypic hippocampal cultures treatment with S. pneumoniae R6 led to increased expression of TLR2 and TLR3 mRNA. Our data provide evidence that regulation of TLR mRNA is not fully specific for the molecular patterns of the infectious pathogen. The TLR mRNA regulation observed probably represents a combination of specific response to the causative pathogen and non-specific activation of the innate immune system.

[Multiple sclerosis: imaging, diagnostic criteria and differential diagnosis]

Multiple sclerosis (MS) is the most common demyelinating inflammatory disease of the central nervous system (CNS), presenting with multifocal, disseminated inflammatory lesions referred to as plaques. Magnetic resonance imaging (MRI) typically depicts multiple, round to oval, circumscript lesions predominantly involving periventricular and subcortical white matter, brainstem and cerebellum. More recent investigations have demonstrated that the macroscopically visible plaques only present the tip of the iceberg: Already early in its course, MS causes neuroaxonal damage and diffusely involves the entire brain parenchyma including normal appearing white matter. These changes are reflected by strongly T1w hypointense lesions and atrophy of early onset, by reduction of the neuronal Marker N-acetylaspartate (NAA) on spectroscopy, by a decrease of the magnetization transfer ratio (MTR), by an increased in diffusibility and decreased anisotropy on diffusion-weighted imaging (DWI). MRI imaging is an important tool in the diagnosis of MS by revealing the characteristic spatial and temporal dissemination of the cerebral and spinal manifestations of this disease. Diagnostic criteria increase the diagnostic specificity and allow better differentiation from other diseases with multifocal white matter abnormalities.

[Brain abscesses after extracranial infections of the head and neck area]

The authors report on 20 immunocompetent patients with brain abscess after 12 cases of middle ear, seven tooth and a single frontal sinus infection. The clinical aspects, hematochemical and microbiological data, the role of imaging diagnostics (CT, MR) and the type of treatment are analysed. Neurosurgery was performed on 17 patients (85%), eight of whom subsequently underwent evacuation of the primary source of infection (four mastoidectomies, two timpanoplasties, two tooth extractions). Mastoidectomy was eventually carried out on one of the three patients who did not undergo neurosurgery. Microbiological diagnosis was possible in nine patients through culture examination: Proteus mirabilis in three cases, Peptostreptococcus sp. in two, Micrococcus varians, Proteus vulgaris, Streptococcus sanguis and Streptococcus viridans not typed in single cases. The pus was sterile in eight patients (47.1% of those operated). An association of two antimicrobial agents was used in 18 patients, while in two cases monotherapy was preferred, based on the isolated bacteria. Treatment lasted on average 38 days. The most frequently used therapy regimen (75%) was the association of a beta-lactam drug with chloramphenicol or metronidazole. Therapy was successful in 19/20 patients; one patient died. There was no significant difference in prognostic terms with regard to sex, age, duration of symptoms prior to diagnosis, clinical picture at onset, number and size of abscesses or type of treatment. Recognising the first clinical signs and symptoms (headache, fever, alterations in consciousness, focal neurological deficit, epileptic seizures) is extremely important for prompt diagnosis of brain abscess.

Experimental herpes simplex virus encephalitis: inhibition of the expression of inducible nitric oxide synthase in mouse brain tissue

In the brain tissue of 36 mice infected with herpes simplex virus type 1, strain F, we determined the expression of inducible nitric oxide synthase (iNOS) with semiquantitative reverse transcription polymerase chain reaction. The viral burden was quantitated by polymerase chain reaction. Nitric oxide, induced by iNOS, may contribute to neuronal cell damage following virus infection. As the experimental therapeutic strategy in herpes simplex virus encephalitis (HSVE), we used: N-nitro-L-arginin (L-NA), a selective inhibitor of iNOS; and combination therapies of either methylprednisolone/acyclovir or L-NA/acyclovir. The viral burden peaked in acute disease, and then returned to a low baseline value, except in untreated controls. The expression of iNOS mRNA was suppressed by L-NA and by acyclovir/corticosteroids. INOS inhibition may provide an additional therapeutic strategy targeted specifically to suppress iNOS expression as a potential secondary mechanism of tissue damage in acute and chronic HSVE.

[First continuous nerve monitoring in thyroid gland surgery]

A new "all in one" sensing device was developed for continuous transtracheal intraoperative monitoring and in situ detection of the recurrent laryngeal nerve (RLN) during thyroid surgery.

PATIENTS AND METHODS

The new system is based on a double-balloon endotracheal tube with integrated atraumatic stimulating and tracing electrodes. The recurrent laryngeal nerve is stimulated transtracheally and compound action potentials are recorded from the laryngeal muscles. Fifty-five patients were introduced into a phase-one clinical trial. Thirty-five patients with primary thyroid operations, 20 patients with reoperations, 10 of whom had neck dissections. All patients were evaluated laryngoscopically and phoniatrically by an ENT specialist before and after surgery.

RESULTS

Compound muscle action potentials were recorded continuously during the whole operation and responded sensitively to tension and pressure to the nerve. There were no accidental permanent RLN palsies.

CONCLUSION

The new system offers five advantages: (1) it is atraumatic; (2) it is easy to use; (3) it can monitor continuously with an audio feedback to the surgeon; (4) it works outside the operation field; and (5) it is highly sensitive, even indicating reversible irritation to the nerve.

Herpes simplex virus encephalitis: chronic progressive cerebral MRI changes despite good clinical recovery and low viral load - an experimental mouse study

Cranial magnetic resonance imaging (MRI) is a sensitive diagnostic tool for the in vivo detection of morphological abnormalities in herpes simplex virus encephalitis (HSVE). We performed a long-term MRI study in a mouse model of HSVE. Cranial MRI findings were compared with the viral load within brain tissue, the presence of HSV DNA in the cerebrospinal fluid (CSF), a daily clinical assessment and post-mortem neurohistopathological studies. A 1.5 T cranial MRI scanner with standard spin-echo sequences was used. Viral load within the brain and the presence of HSV DNA in cerebrospinal fluid were determined by a polymerase chain reaction assay. Clinically, animals were severely affected within the first 2 weeks and recovered thereafter. Focal histopathological and MRI abnormalities involved predominantly limbic structures, a pattern that mimics human disease. Severity and extent of abnormalities had increased at 6 months despite clinical improvement. HSV DNA was present in CSF during the acute disease only. Brain viral load peaked at day 10 and declined thereafter. MRI as an in vivo monitoring approach may reveal chronic progressive changes in HSVE, despite clinical recovery and low viral load in the brain. Secondary, not directly virus-mediated, mechanisms of tissue damage may contribute to tissue damage of HSVE.

Acyclovir treatment of experimentally induced herpes simplex virus encephalitis: monitoring the changes in immunologic NO synthase expression and viral load within brain tissue of SJL mice

The effect of acyclovir treatment on viral burden and the expression of immunologic nitric oxide synthase (iNOS) within brains of 42 HSV-1 F infected mice was studied by using a titration PCR assay for HSV-1 DNA and a semiquantitative RT-PCR for iNOS mRNA. iNOS mediated NO-production may possibly be involved in secondary mechanisms of brain injury following virus infection, which may account for treatment failures in human herpes simplex virus encephalitis (HSVE). Following infection, a parallel increase of iNOS mRNA and HSV-1F-DNA occurred with peaks after 7 days that were both significantly lower under acyclovir treatment. Six months post infection viral load had declined, but iNOS mRNA expression in both treated and untreated mice was still enhanced as compared with mock infected controls. This suggests that acyclovir decreases iNOS expression via inhibition of viral replication shortly after infection but fails to influence elevated iNOS within the brain late in the course of experimental HSVE.

Herpes simplex virus encephalitis: cranial magnetic resonance imaging and neuropathology in a mouse model

We performed a long-term magnetic resonance imaging (MRI) study in a mouse model of herpes simplex virus encephalitis. Mice were infected with herpes simplex virus type 1 (HSV-1) strain F. A 1.5-T cranial MRI scanner with standard spin-echo sequences was used. Neuropathological studies included immunohistochemistry. The presence of HSV DNA in brain tissue was determined with a polymerase chain reaction assay. Clinical assessment was performed daily: within the first 2 weeks the animals were severely affected and recovered thereafter. MRI and histopathological abnormalities corresponded well. HSV DNA was detectable initially and at 6 months. Extent and severity of structural abnormalities increased at 6 months. MRI offers a new in vivo approach for the detection of structural changes in the disease course of experimental herpes simplex virus encephalitis.

Herpes simplex virus encephalitis: long-term comparative study of viral load and the expression of immunologic nitric oxide synthase in mouse brain tissue

In the brain tissue of 21 mice infected with herpes simplex virus type 1 (HSV-1) strain F we determined the expression of immunologic nitric oxide synthase (iNOS) as a potential mediator of neuronal injury with a semiquantitative reverse transcription polymerase chain reaction. Viral burden in brain tissue was quantitated with a dilutional polymerase chain reaction assay. Viral burden and iNOS-expression peaked at day 7 following infection. Thereafter viral burden declined to a low baseline value at 6 months following infection, whereas iNOS-expression was still 4-fold increased compared to baseline levels. In experimental herpes simplex virus encephalitis iNOS, as one potent mediator of neuronal injury, is upregulated in the acute and chronic disease. In future, in addition to antiviral treatment, inhibitors of iNOS might offer new therapeutic strategies in herpes simplex virus encephalitis.

Quantitation of herpes simplex virus type 1 DNA in cells of cerebrospinal fluid of patients with herpes simplex virus encephalitis

We used a nested polymerase chain reaction assay to quantitate the number of viral copies in cells of CSF of eight patients with herpes simplex virus encephalitis (HSVE). The viral load was monitored in serial CSF samples during the course of disease and correlated to clinical symptoms, radiologic manifestations, efficacy of acyclovir treatment, and overall clinical outcome. Before treatment, HSV type 1 (HSV-1) copies were detected at a mean value of 1,786/10(5) (range, 5 to 8,333/10(5) cells; median, 81/10(5) cells). During therapy, HSV-1 DNA decreased gradually to a mean value of 6 copies/10(5) cells (range, 0 to 33 copies/10(5) cells; median, 0 copies/10(5) cells) within 6 to 21 days and disappeared or was barely detectable before treatment completion in most cases. The HSV-1 burden in the CSF did not clearly correlate with the severity of clinical signs or the degree of cranial imaging findings and overall outcome. Quantitation of HSV-1 copies allows rapid and reliable monitoring of antiviral therapy. The absence of a clear correlation between viral load in the CSF and morbidity may suggest a role for indirect mechanisms of brain injury in HSVE.

[Transtracheal monitoring of the recurrent laryngeal nerve. Prototype of a new tube]

A new sensing device for the continuous intraoperative monitoring of the recurrent laryngeal nerve is presented. It is based on a double ballooned endotracheal tube including stimulating and tracing electrodes. The system is characterised by three advantages: 1) it is atraumatic, 2) it is operating completely outside the operating field (extraterritorially), 3) nerve function is being monitored continuously from the time of intubation to the time of extubation. The presented system has been evaluated in piglets. First results in humans will be available shortly.

HSV and the CNS

Herpes simplex virus encephalitis (HSVE) is an encephalitis with a predelection for the temporal lobes and related structures that is caused by HSV-1 or HSV-2. Because HSV has many properties that would be ideal for a gene transfer vector targeting the nervous system, an understanding of HSVE is of experimental, as well as clinical, importance to neuroscientists. Herpesviruses have a characteristic architecture of the virion. The molecular aspects of HSVE include the consequences of latency and neurovirulence. Studies on neurovirulence have focused on peripheral multiplication of HSV, the invasion of the CNS, and growth in the CNS. The virus appears to gain access to the CNS via the olfactory and trigeminal nerves and, transneuronally, the limbic system. The definition of latency has still to be clarified; in general, latency includes three separable phases: establishment, maintenance, and reactivation. In humans, there exists a large overlap of clinical presentations of patients with HSVE and those of patients with encephalitis of other origin. However, the presence of memory loss, personality changes, and olfactory hallucinations correlate with the limbic and temporal lobe pathology in HSVE and are characteristic. Several factors correlate with poor outcome in patients: age, time of establishment of therapy, and level of consciousness on admission of patients.

A new technique: serial puncture of the cisterna magna for obtaining cerebrospinal fluid in the mouse--application in a model of herpes simplex virus encephalitis

This report describes a new technique for obtaining cerebrospinal fluid from the living mouse (SJL/NBom) in a model of herpes simplex virus encephalitis which is also applicable to other mouse models. The puncture technique was performed in living animals which had been infected with Herpes Simplex Virus Type I strain F in the living animal. The cisterna magna was micro-surgically prepared: The neck muscles were dissected microscopically down to the dura which subsequently was punctured by a glass micropipette. This newly developed minimally invasive technique was performed in a group of living animals (n = 20) and results compared with those of a second group of perfusion fixed animals (n = 20). For the first time, repeated cerebrospinal fluid punctures of individual, living animals are possible. This is of great value for the assessment of new therapeutic and diagnostic strategies in experimental research using mouse models. In addition, this refined methodology significantly reduces the number of experimental animals.

Rare diseases mimicking acute vertebrobasilar artery thrombosis

Acute ischaemia of the vertebrobasilar circulation leads to a variety of clinical manifestation and is mostly due to cardiogenic or artery-to-artery embolism. We describe four neurological emergency situations involving vertebrobasilar artery aclusion of other origins; basilar migraine, extrinsic compression by rheumatoid inflammatory tissue, generalized vasculitis in subacute rheumatic fever and basilar artery dissection. The differential diagnosis of acute vertebrobasilar artery occlusion may have an important impact on patient management.

MRI monitoring of experimental cerebral ischaemia: comparison of two models

In experimental stroke research one of the key questions is whether animals models truly reflect human disease. One important reason for modelling stroke is to produce tissue changes that can be used to validate the correlation between the results of advanced radiological imaging and pathology. The aim of this study was to compare two minimally invasive rat models of focal ischaemic stroke as to their ability to simulate clinical stroke reproducibly. In one model a focal infarct was induced using the photochemical Rose Bengal technique. The second model was based on transvascular occlusion of the middle cerebral artery using a cervical approach. In all animals we performed MRI at different times with two different paramagnetic contrast agents. The time course of blood-brain-barrier disruption in the Rose Bengal model differed entirely from that in human brain ischaemia. The experimental stroke showed marked contrast enhancement in the first hour after the onset of ischaemia. On the other hand, the MRI changes in the suture occlusion model were very similar to the changes observed in human brain ischaemia: no early disruption of the blood-brain-barrier and increased T2-signal 4-6 h after the onset of stroke. We hope that the suture occlusion model will be used for research not only by basic and clinical scientists but also by radiologists, who, using modern imaging methods, may greatly influence the diagnosis as well as the management of this devastating disease.

Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk

PURPOSE

To investigate the incidence and prognostic value of local brain swelling, the extent of parenchymal hypodensity, and the hyperdense middle cerebral artery sign as shown by CT within the first 5 hours after the onset of symptoms in patients with angiographically proved middle cerebral artery trunk occlusions.

METHODS

Fifty-three patients were studied prospectively with CT 46 to 292 minutes (median, 120; mean, 134 +/- 59) after symptom onset and scored clinically at admission and 4 weeks later. All patients were treated with recombinant tissue plasminogen activator (30 to 100 mg).

RESULTS

Early CT showed parenchymal hypodensity in 43 patients (81%), local brain swelling in 20 patients (38%), and hyperdensity of the middle cerebral artery trunk in 25 patients (47%). Hypodensity covering more than 50% of the middle cerebral artery territory had an 85%, local brain swelling a 70%, and the hyperdense middle cerebral artery sign a 32% positive predictive value for fatal clinical outcome. Specificity of these findings for fatal outcome was 94%, 83%, and 51%, respectively, and sensitivity was 61%, 78% and 44%, respectively.

CONCLUSIONS

Early CT in acute middle cerebral artery trunk occlusion is highly predictive for fatal clinical outcome if there is extended hypodensity or local brain swelling despite aggressive therapeutic attempts such as thrombolysis or decompressive surgery.

Accelerated methaemoglobin formation: potential pitfall in early postoperative MRI

Postoperative magnetic resonance imaging (MRI) of glioblastomas to assess residual tumour should be performed within the first 4 days following surgery. Early methaemoglobin formation near the resection site may mimic residual tumour if only gadolinium-DTPA-enhanced images are obtained. In a prospective study 24 of 54 patients (44%) showed well-defined areas of increased signal intensity on unenhanced T1-weighted images performed soon after surgery. By in vitro experiments we showed that hydrogen peroxide used in neurosurgery as a styptic agent accelerates formation of methaemoglobin when added to whole blood samples.