A rare case of multicystic disseminated astrocytoma with pilomyxoid characteristics in a 4-year-old child.

Pilomyxoid astrocytomas are a more aggressive variant of pilocytic astrocytoma. Over the last 14 years, there has been increasing evidence to suggest that these tumours are distinct pathological entities to pilocytic astrocytomas. Radiological features of these tumours are slowly emerging in the neuroradiological literature. We report a unique radiological appearance of a multicystic, disseminated astrocytoma with pilomyxoid characteristics presenting in a 4-year-old boy and highlight the importance of considering this diagnosis with similar imaging.

Is the routine placement of a CSF reservoir following endoscopic third ventriculostomy justified?

Endoscopic third ventriculostomy (ETV) is a well established treatment for selected cases of obstructive hydrocephalus. However, it does carry a significant rate of failure, which can be abrupt and life threatening. The present study analyses the benefits versus the risks of routine CSF reservoir insertion during ETV. Clinical data obtained from the medical records of patients from a single neurosurgical centre who underwent ETV between August 2002 and February 2007 were analysed retrospectively. A total of 34 records were available with follow-up ranging from 3-56 months (Median 26 months) and with patient age range between 6 months - 75 yrs (median 19 years). During this period, one neurosurgeon routinely placed reservoirs in all patients undergoing ETV (n = 34). In all instances of reservoir insertion, Ommaya reservoirs were used. The number of patients in which the reservoir was tapped for diagnostic and/or therapeutic reasons was quantified, and all complications resulting from reservoir placement recorded. ETV success was defined by a lack of subsequent need for cerebrospinal fluid diversion. In total 13 of 34 (38%) reservoirs inserted were tapped at a later date and there were no complications associated with their insertion. Tapping of reservoirs helped determine which patients required subsequent ventriculoperitoneal (VP) shunting. In at least one case reservoir tapping was carried out as an emergency and was a crucial intermediate intervention prior to further surgery. The overall success rate of ETV was 65% (95% CI, 49-81%) with four complications associated with ETV: short-term memory loss, psychosis, and two cases of post-operative seizures. These complications were not attributed to CSF reservoir insertion but the ETV procedure itself. The routine placement of CSF reservoir following ETV thus seems justified with respect to the observed benefits and lack of complications associated with its placement.

A comparison of the early development of ischaemic damage following permanent middle cerebral artery occlusion in rats as assessed using magnetic resonance imaging and histology.

Recent developments in diffusion-weighted imaging (DWI) have enabled the pathological changes that occur during cerebral ischaemia to be studied. The present studies utilised DWI to investigate the development of early ischaemic changes following permanent middle cerebral artery (MCA) occlusion in the rat, which represents a model of stroke. An increased DWI signal was seen in the region of the occluded MCA and this was detectable as early as 1 h postocclusion. DWI images were obtained at nine stereotactic levels throughout the brain, providing a quantifiable measure of the volume of increased signal intensity in each animal. At 1 h post-MCA occlusion the hyperintense areas were seen in the frontoparietal cortex and lateral caudate nucleus; these areas represent the core of the infarct and no protection is seen with any compounds in these areas. There was a progressive increase in the area of hyperintensity up to 4 h post-MCA occlusion, and at this time point the hyper-intensity was seen in the dorsolateral cortex and caudate nucleus. At 4 h post-MCA occlusion there was a significant correlation between the volume of hemispheric and cortical ischaemic damage measured using DWI and histology. Thus, it appears that the increased DWI signal seen during the early time points after MCA occlusion was demarcating tissue that was destined for infarction. The area beyond the hyperintense region at 1 h represents the so-called "penumbral" region, because with increasing time (post-MCA occlusion) this area became incorporated into the infarct. There was also a slight increase in infarct size between 4 and 24 h, when assessed using DWI or histology, although two groups of animals were being compared, as opposed to the time-course study, in which just one group of animals was used. At 24 h post-MCA occlusion there was a good correlation between DWI, histology, and conventional T2 weighted imaging. There was no further increase in size of the infarct between 24 h and 7 days as assessed using histology and T2-weighted imaging. DWI could not be used to quantify infarct volume at 7 days because there was no uniform signal in the damaged area. At 7 days the area of infarction actually appeared to be darker in the diffusion-weighted images. The hyperintensity seen in diffusion-weighted images appears to decrease some time between 24 h and 7 days.(ABSTRACT TRUNCATED AT 400 WORDS)

CSF neuron-specific enolase as a quantitative marker of neuronal damage in a rat stroke model.

A technique for chronic cisternal cerebrospinal fluid (CSF) sampling in conscious rats was used to obtain multiple 50 microliters samples before and up to 7 days after middle cerebral artery occlusion. Neuron-specific enolase (NSE) concentrations were measured by radioimmunoassay using a readily available kit. The volume of infarction was measured by integrating the area of damage on 9 evenly spaced histological sections of the forebrain. This correlated well (r = 0.97, P less than 0.001) with the concentration of CSF neuron-specific enolase integrated over the first 5 days post occlusion, in animals with pure cortical and mixed cortical and striatal lesions. The correlation was maintained in animals given the NMDA antagonist MK-801. There was also a good correlation between the CSF NSE concentration 3 days post-MCAO and the volume of infarction (r = 0.92, P less than 0.01). It is therefore possible that CSF neuron-specific enolase may be useful as a quantitative marker of ischaemic damage in humans and provide a useful adjunct in the assessment of neuroprotective drugs in stroke.

The dose-response relationship and therapeutic window for dizocilpine (MK-801) in a rat focal ischaemia model.

The purpose of the present study was to examine the dose-response relationship and the maximum time for which effective therapy could be delayed for the N-methyl-D-aspartate antagonist dizocilpine (MK-801) as a neuroprotective agent in a permanent focal ischaemia model in the rat. The ED50 for dizocilpine in the amelioration of cortical damage in this model was found to be approximately 0.3 mg/kg (single i.p. dose, 30 min post onset of ischaemia) and significant protection was only obtained when therapy (3 mg/kg i.p.) was delayed for one hour or less after the onset of ischaemia. In a further experiment, dizocilpine 3 mg/kg i.p., produced a peak plasma level of 44 ng/ml and had a t1/2 elimination of 1.65 h.

Controversies in the prevention of neurosurgical infection.

Amongst post-operative infections, those associated with neurosurgery are of particular significance in view of their proximity to, or location within, the central nervous system. Superficial surgical site infections may be complicated by osteomyelitis of the calvarium and deeper extension to the meninges and cerebral parenchyma. The prevention, diagnosis and management of infections associated with implant devices provide similar challenges to those faced in orthopaedic and cardiac surgery. Whilst some consensus exists regarding the need for antimicrobial prophylaxis in the latter two disciplines, its place in neurosurgery remains controversial. When prophylaxis is considered, choice of antimicrobial agents should take account of up-to-date local information in relation to the relevant microbial ecology in hospitals and in the community setting. The potential for spread of blood-borne virus infections and transmissible spongiform encephalopathies in relation to neurosurgery must also be considered and it should be ensured that appropriate preventive strategies are in place.

Posterior fossa epithelial cyst: case report and review of the literature.

A 49-year old woman with progressive cranial nerve signs and hemiparesis was found at MR imaging and at surgery to have a cyst at the foramen magnum. Immunohistochemistry and electron microscopy showed an epithelial cyst of endodermal origin. MR findings were of an extraaxial mass, with short T1 and T2 times. Unless immunohistochemistry and electron microscopy are used in the final diagnosis of such cysts, all posterior fossa cysts lined by a single layer of epithelium should be described simply as epithelial cysts.

Recurrent self-inflicted craniocerebral injury: case report and review of the literature.

Self-inflicted craniocerebral injuries have been reported exclusively in mentally disturbed patients and criminals. We report a 28-year-old man with a severe mental disorder who initially hammered a nail into his brain and subsequently repeatedly inserted foreign objects into his brain. The literature is reviewed and the surgical and psychiatric management discussed.

Spinal epidural abscess: a diagnostic challenge.

The objective of the study was to highlight the diagnostic challenge of this elusive rare disease. A retrospective study of non-tuberculous spinal epidural abscesses (SEA) was carried out in Southern General Hospital, Glasgow, University Hospital of Wales, Cardiff, and Morriston Hospital, Swansea, from 1990 to 2000. Thirty-nine patients, consisting of 20 females and 19 males, with an age range from 20 to 85 years (mean: 61.1) were identified. Thirty-eight had localized back/neck pain. Eighteen were apyrexial. Twenty-nine demonstrated neurological deficit. All patients had raised inflammatory markers and gadolinium-enhanced magnetic resonance imaging (MRI) was diagnostic in 34. The most commonly identified organism was Staphylococcus aureus. All underwent surgical decompression, of which 13 required stabilization. Three died, seven lacked sphincter control and nine had motor deficit at the end of 1 year. It was concluded that fever is not mandatory for the diagnosis of SEA. Patients with localized back/neck pain and raised inflammatory markers need urgent MRI.

Triphenyltetrazolium chloride (TTC) as a marker for ischaemic changes in rat brain following permanent middle cerebral artery occlusion.

Triphenyltetrazolium chloride (TTC) was used to delineate ischaemic lesions in the rat brain at various times following middle cerebral artery occlusion. A comparison was made of TTC staining by immersion and perfusion techniques and conventional light microscopy. The lesions were quantified by measuring the ischaemic area at the sections corresponding to 7 mm in front of the AO line (atlas of Konig and Klippel). In animals examined 24 h after middle cerebral artery occlusion (MCAO), the area of infarction was 17.4 +/- 1.3 mm2 on the TTC perfused slices and 17.6 +/- 1.6 mm2 on the TTC immersed slices (mean +/- SEM). By contrast, there was a marked difference between the two TTC methods when tissues were examined at shorter intervals after artery occlusion. In the TTC-perfused animals, there was no significant difference between the mean areas of infarction measured at 5-20 min, 3-4 h, or 24 h post occlusion. Immersion in TTC, however, failed to reveal any consistent ischaemic damage when applied at the earlier post-occlusion times. Conventional histopathology demonstrated minimal lesions at 5-20 min but at 4 h or more the lesions were not significantly different from those demonstrated by TTC perfusion. TTC immersion staining can, thus, only be used as a reliable marker of cerebral ischaemia damage with post-occlusion survival periods of 24 h. TTC perfusion staining gives results not significantly different from histopathology at 4 h or more post-occlusion but at earlier intervals than 24 h it differs significantly from TTC immersion staining.(ABSTRACT TRUNCATED AT 250 WORDS)