This study reports our findings in assessing in vivo tumour growth with magnetic resonance imaging using a commercial magnet and antenna in F98 implanted Fischer rats. A comparison of T1 gadolinium-enhanced coronal MR scans and pathology specimens in corresponding animals was accomplished.

One rat was used in serial experiments to establish adequate imaging parameters. Afterward, 12 animals implanted with F98 cells underwent a MR study following intervals spanning five, ten, 15 and 20 days on a 1.5T human Siemens. Using a small loop antenna, a coronal T1 weighted MRI scan with Gadolinium was performed. Images were analyzed and volumes of enhancing tumour were calculated. The animals were sacrificed after the imaging procedure and brain were harvested and processed in pathology. Pathology specimens and MR images were analyzed using image processing software. One hematoxylin + eosin (H&E) slide per specimen was compared to the corresponding MR slice depicting the largest area of enhancement.

The MR enhancement areas obtained were 2.18mm2, 8.25mm2, 21.6mm2 and 23.17mm2 at five, ten, 15 and 20 days. Tumour margin measurements on pathologic samples produced areas of 0.29mm2, 4.43 mm2, 8.3mm2, and 12.9mm2 at five, ten, 15 and 20 days respectively.

The T1-enhancing images constantly overestimated the tumour bulk on H&E. This phenomenon is explained by enhancement of the brain around tumour, the extra-axial tumour growth, and a shrinking factor of 17% related to the fixation process. Nonetheless, the radiological tumour growth paralleled the histological samples. This technology is thus suitable to follow tumour growth in F98 implanted rats.

The timing of aneurysmal surgery for patients presenting within the period at risk for vasospasm (VS) is controversial. The goal of this study is to review our experience of surgically treated patients in the presence of angiographic VS.

From 1990-2004, 894 consecutive patients presented with an aneurysmal subarachnoid hemorrhage (SAH) and were treated with a policy of early surgery. We retrospectively analyzed the patients that had pre-operative angiographic VS. In this study, symptomatic VS was diagnosed when a decreased level of consciousness and/or focal deficit occurred after SAH in the presence of angiographic VS without confounding factors. Functional outcome was assessed three months after SAH using the Glasgow Outcome Scale.

Of the 40 patients studied, 62.5% were in good clinical grade Hunt & Hess (H&H 1-2) on admission; 25%, intermediate grade (H&H 3); 12.5%, poor grade (H&H 4-5). Surgery was performed 24 hours or less after initial angiography in 87.5% of patients and less than 48 hours in 97.5%. Pre-operative symptomatic VS was diagnosed in 25%. Postoperatively, angiographic VS was documented in 87.2%. Of the 30% of patients that presented post-operative symptomatic VS, 66.7% also demonstrated pre-operative symptomatic VS. The functional outcome was favorable in 92.5% of the studied patients. Two deaths occurred in patients presenting pre-operative early radiological and symptomatic VS.

Aneurysmal surgery, especially between 3-12 days following SAH, in the presence of asymptomatic pre-operative angiographic VS can be associated with a good outcome. Early surgery is not contra-indicated and might enable optimal treatment of VS.

To analyze our experience with a second radiosurgical treatment for brain arteriovenous malformations (BAVMs) after an unsuccessful first radiosurgical treatment.

Between 1993 and 2000, 242 patients were treated by the Toronto Sunnybrook Regional Cancer Center using a LINAC system. Fifteen of these patients required a second radiosurgical intervention due to the failure of the first procedure. Data was collected on baseline patient characteristics, BAVM features, radiosurgery treatment plan and outcomes. Brain arteriovenous malformation obliteration was determined by follow-up MRI and angiography and the obliteration prediction index (OPI) calculated according to a previously established formula.

The median interval between the first and second treatment was 46 months (range 39-109). The median follow-up after the second procedure was 39 months (range 26 to 72). The mean BAVM volume before the first treatment was 8.9cm3 (range 0.3-21) and before the second treatment was 3.6cm3 (range 0.2-11.6). The mean marginal dose during the first treatment was 18Gy (range 12-25) and during the second treatment was 16Gy (range 12-20). After the second treatment, nine patients had obliteration of their BAVM confirmed by angiography and one patient had obliteration confirmed by MRI, resulting in an obliteration rate of 66.6%, which is very comparable to that predicted by the OPI (65%). After the second treatment two patients had a radiation-induced complication (13.3%).

Retreatment of BAVM using a second radiosurgery procedure is a safe and effective option that offers the same rate of success as the initial radiosurgery and an acceptable risk of radiation-induced complication.

The histamine catabolite, Nα-methylhistamine, possesses a selective affinity for H3 receptors. For this reason, we considered evaluating the efficacy of this histaminergic H3 agonist in migraine prophylactic treatment.

To study the therapeutic potential of the subcutaneous administration of Nα-methylhistamine in migraine prophylaxis, in a Phase III clinical pharmacological study.

Using a controlled double-blind, placebo controlled clinical trial for 12 weeks, 60 patients with migraine, who fit the criteria established by the International Headache Society, were selected. The efficacy of subcutaneous administration of Nα-methylhistamine 1 to 3 ng twice a week against placebo was studied, evaluating the outcome of headache intensity, frequency, duration, and analgesic intake.

Comparison between the groups treated with placebo (n=30) and Nα-methylhistamine (n=30), on data collected for the 4th, 8th and 12th weeks of treatment, revealed that Nα-methylhistamine exerted a significant (p<0.0001) reduction (compared to placebo) in intensity, frequency, and duration of migraine attacks, as well as on the use of analgesic intake. No significant (p>0.05) adverse experiences or side effects developed in either group.

The present study provides evidence of the efficacy of Nα-methylhistamine, given subcutaneously at doses of 1 to 3 ng twice a week, offering a new therapeutic alternative and laying the clinical and pharmacological groundwork for the use of histaminergic H3-agonists in migraine prophylaxis, which may specifically inhibit the neurogenic edema response involved in migraine pathophysiology.

Medulloblastoma is the most common malignant central nervous system tumour in children but, in contrast, quite rare in adults. Hemispheric, rather than midline, cerebellar medulloblastomas are more common in older children and adults. We present the unusual case of a 71-year-old man who presented with a fourth ventricular mass that proved to be a medulloblastoma.

A 71-year-old man presented with progressive balance problems, slurred speech and double vision. A CT scan of the brain revealed a hyperattenuating, partially calcified, avidly enhancing mass within the fourth ventricle. Diffusion weighted MRI showed restricted diffusion within the mass. The patient underwent a midline suboccipital craniotomy and a subtotal resection was achieved.

Histological examination showed a densely cellular neoplasm composed of small cells with a tendency towards neuroblastic rosette formation. Most cells were strongly positive for neuron-specific enolase and synaptophysin. Ultrastructurally, tumour cells showed evidence of neuronal differentiation. These findings were consistent with a classical medulloblastoma.

Adult medulloblastoma should be considered in the differential diagnosis of a partially calcified hyperattenuating mass within the fourth ventricle.

To compare the inter-observer reliability of Alberta Stroke Programme Early CT Scoring (ASPECTS) with the ICE (Idealize-Close-Estimate) method of estimating > 1/3 middle cerebral artery territory (MCAT) infarction amongst stroke neurologists and to determine how well ASPECT Scoring predicts > 1/3 MCAT infarctions in acute ischemic stroke (AIS).

The European Cooperative Acute Stroke Study suggested that > 1/3 involvement of the MCAT on early CT scan was a risk factor for symptomatic intracerebral hemorrhage (SICH) following treatment with tissue plasminogen activator (tPA) for AIS but, in the absence of a systematic method of estimation had poor interobserver reliability (Kappa 0.49). The ICE method was developed to standardize the approach to estimating early MCAT infarct size and has very good interobserver reliability (Kappa 0.72). ASPECTS has comparable interobserver reliability and is reported to predict both neurological outcome and SICH.

Five stroke neurologists were tested with 40 AIS CT scans. Each performed blinded independent assessments of early ischemic changes with both ASPECTS and ICE. The reference standard was majority opinion of 1/3 MCAT determination of five neuroradiologists. A receiver operator curve (ROC) was constructed and likelihood ratios (LR) were calculated. Chance corrected agreement (kappa) and chance independent agreement (phi) were calculated for both methods, and analysis of variance was used to calculate reliability by intraclass correlation coefficient (ICC) for ASPECTS.

The LR for a positive test (> 1/3 MCAT) were extremely large and conclusive (approaching infinity) for ASPECTS of 0-3; were large and conclusive (30, 20, and 10) for ASPECTS of 4, 5, and 6 respectively; was an unhelpful 1 for ASPECTS of 7, and were again extremely large and conclusive (approaching zero) for ASPECTS of 8-10. A ROC plot supported an ASPECTS cutoff of < 7 as best for 1/3 MCAT estimation (94% sensitivity and 98% specificity). Kappa and Phi statistics were moderately good for both ASPECTS and ICE (0.7). ICC for ASPECTS was 0.8.

When experienced stroke neurologists utilize a formalized method of quantifying early ischemic changes on CT, either ASPECTS or ICE, the interobserver agreement and reliability are satisfactory. ASPECTS allows for a strong and conclusive estimation of the presence of 1/3 MCAT involvement and a cutoff point of < 7 results in best test performance.

Misdiagnosis of spontaneous intracranial hypotension remains a problem, despite increasing recognition.

Three patients with spontaneous intracranial hypotension presented with typical findings on lumbar puncture, magnetic resonance (MR) imaging, and radioisotope cisternography. All patients showed subdural effusions in the posterior fossa on axial T2-weighted MR imaging. Axial MR images of 112 patients with other conditions were also screened for this finding.

One of three patients had typical orthostatic headache, and the other two had continuous headache. The finding of subdural effusions in the posterior fossa on axial T2-weighted MR imaging disappeared after treatment. Similar findings were found in 14 of 112 patients with other conditions. Most of the patients were over 60 years old or had dementia or previous radiation therapy.

Subdural effusions in the posterior fossa can be identified by T2-weighted axial MR imaging, and are useful for the diagnosis of spontaneous intracranial hypotension and for verifying the effectiveness of treatment.

Non-invasive mechanical ventilation (BiPAP) has been introduced for use in neuromuscular respiratory disease such as amyotrophic lateral sclerosis and myasthenia gravis. There is no experience in Guillain-Barré syndrome.

We describe for the first time the use of BiPAP to assist in the work of breathing in two consecutive patients with progressing Guillain-Barré syndrome (GBS) and marginal pulmonary function.

Our initial attempts to use BiPAP in GBS and early neuromuscular respiratory failure were totally unsuccessful. There was marked initial improvement; however, emergency intubation was needed in both patients, one of which became acutely cyanotic.

Until more experience is available, we strongly warn against using BiPAP in deteriorating patients with GBS.

Rasmussen's encephalitis is a progressive disease characterized by severe progressive neurological and cognitive deficits. It is a difficult condition to treat with conventional medical treatment and requires, in most of the cases, surgical intervention.

We present the case of a patient with Rasmussen's encephalitis who presented with epilepsia partialis continua, who did not respond to antiepileptic treatment and was evaluated for possible surgical intervention.

The electroencephalographic studies revealed bihemispheric involvement during seizures, although magnetic resonance imaging (MRI) showed a marked right hemispheric atrophy. Hyperperfusion over the right hemisphere was seen with the performance of ictal single photon emission computed tomography (SPECT), which finally guided a right functional hemispherectomy and subsequent seizure control.

Ictal SPECT could be a useful tool in the armamentarium of tools used for the localization of the epileptogenic focus in patients with Rasmussen's encephalitis and other localization-related epilepsies.