Axonal branching in the projections from the paramedian reticular nucleus to the cerebellar cortex

Injections of fluorescent tracers into cat cerebellar cortex gave evidence of collateral axonal branching of neurons situated in the paramedian reticular nucleus. These branched reticulocerebellar projections were distributed to opposing sides of the cerebellum, in particular the anterior lobe and the ansiform lobule. No topographical organization was observed in the PRN. Less than 30% of ipsilaterally projecting reticulocerebellar fibers had contralaterally directed collateral branches. These results are in keeping with a bilateral fastigial projection to the PRN forming a feedback loop circuit through which orthostatic reflexes may be mediated.     

Morbidity and infection in combined subdural grid and strip electrode investigation for intractable epilepsy.

The coverage of large surface areas of the brain for electrographic monitoring purposes necessitates a craniotomy to achieve comprehensive sampling. We undertook a review and prospective analysis over 3 years of 38 patients undergoing craniotomy for electrode implantation. The indication for invasive monitoring was to determine candidacy for resective surgery in patients whose seizure focus was not well localized by scalp electroencephalography and other noninvasive testing. Prophylactic cultures from the epidural space were obtained at electrode removal. There were five positive epidural cultures. All five patients went on to seizure-free status. Two positive cultures occurred in patients without obvious infection and who were not treated with antibiotics. Other complications included individual cases of atrial fibrillation, pulmonary edema, postoperative fever, and epidural hematoma. There was no mortality or permanent neurologic morbidity related to craniotomy for electrode placement. There was a 7.9% rate of clinical infection per patient and a 5.7% rate per craniotomy side. This study has identified several factors that significantly correlate with positive epidural culture results: > 100 electrodes, more than ten cables, more than 14 days of implantation, and more than one cable exit site.     

Leukoaraiosis Predicts Short-term Cognitive But not Motor Recovery in Ischemic Stroke Patients During Rehabilitation

Background: Leukoaraiosis has been shown to impact functional outcomes after acute ischemic stroke. However, its association with domain specific recovery after ischemic stroke is uncertain. We sought to determine whether pre-existing leukoaraiosis is associated with short-term motor and cognitive recovery after stroke. Methods: We retrospectively studied ischemic stroke patients admitted to acute inpatient rehabilitation (AIR) between January 2013 and September 2015. Patient baseline characteristics, infarct volume, prestroke modified Rankin Scale, stroke cause, rehabilitation length of stay, and Functional Independence Measure (FIM) scores were recorded. Leukoaraiosis severity was graded on brain magnetic resonance imaging using the Fazekas scale. Multiple linear regression was used to determine factors independently associated with the total, cognitive, and motor FIM scores at AIR discharge, respectively. Results: Of 1600 ischemic stroke patients screened, 109 patients were included in the final analysis. After adjustment, the initial National Institute of Health Stroke Scale (β ?0.541, confidence interval [CI] ?0.993 to ?0.888; P = 0.020) and pre-existing leukoaraiosis severity (β ?1.448, CI ?2.861 to ?0.034; P = 0.045) independently predicted the total FIM score. Domain specific analysis showed that infarct volume (β ?0.012, CI ?0.019 to ?0.005; P = 0.002) and leukoaraiosis severity (β ?0.822, CI ?1.223 to ?0.410; P = 0.0001) independently predicted FIM cognitive scores at discharge from AIR. Leukoaraiosis did not predict FIM motor score (P = 0.17). Conclusions: Leukoaraiosis severity is an independent predictor of total and cognitive, but not motor FIM scores after AIR for acute ischemic stroke. This highlights that leukoaraiosis affects poststroke recovery in a domain specific fashion, information that may aid counseling of patients and families as well as tailor rehabilitative efforts.     

Quantitative multi-compartmental SPECT image analysis for lateralization of temporal lobe epilepsy

This study assesses the utility of compartmental analysis of SPECT data in lateralizing ictal onset in cases of a putative mesial temporal lobe epilepsy (mTLE). An institutional archival review provided 46 patients (18M, 28F) operated for a putative mTLE who achieved an Engel class Ia postoperative outcome. This established the standard to assure a true ictal origin. Ictal and interictal SPECT images were separately coregistered to T1-weighted (T1W) magnetic resonance (MR) image using a rigid transformation and the intensities matched with an l(1) norm minimization technique. The T1W MR image was segmented into separate structures using an atlas-based automatic segmentation technique with the hippocampi manually segmented to improve accuracy. Mean ictal-interictal intensity difference values were calculated for select subcortical structures and the accuracy of lateralization evaluated using a linear classifier. Hippocampal SPECT analysis yielded the highest lateralization accuracy (91%) followed by the amygdala (87%), putamen (67%) and thalamus (61%). Comparative FLAIR and volumetric analyses yielded 89% and 78% accuracies, respectively. A multi-modality analysis did not generate a higher accuracy (89%). A quantitative anatomically compartmented approach to SPECT analysis yields a particularly high lateralization accuracy in the case of mTLE comparable to that of quantitative FLAIR MR imaging. Hippocampal segmentation in this regard correlates well with ictal origin and shows good reliability in the preoperative analysis.     

Paraffin-embedded tissue as a source of RNA for gene expression analysis in oral malignancy

OBJECTIVE: To assess the feasibility of using archival oral mucosal tissue to examine gene expression at the ribonucleic acid (RNA) level.
MATERIALS AND METHODS: We describe the isolation of RNA from 8 nm sections of formalin-fixed paraffin-embedded oral mucosal tissue. RNA was reverse transcribed and three candidate genes amplified by polymerase chain reaction (PCR). The ribosomal protein S14 gene is a housekeeping gene which has been used as an internal standard in several quantitative PCR protocols. The thymidine kinase (TK) gene is expressed at low levels in most tissues and, with a well-documented genomic organisation, is a useful tool for discrimination between genomic DNA and cDNA. The RIa gene is reported to be overexpressed in many cancer cell lines, in malignant tissue and in vitro transformed cellS. RESULTS: The S14 gene, the TK gene and the RIα gene of the cAMP-dependent protein kinase (PKA) were amplified successfully from formalin-fixed paraffin-embedded tissue sections. The TK primer pair is a useful additional tool in the unambiguous identification of RNA-derived species.
CONCLUSION: RNA suitable for reverse transcribed (RT)-PCR was extracted from archival oral mucosal tissue. This should permit rapid sequence analysis of transcribed tumor suppressor genes and oncogenes in this material. Furthermore, the RT-PCR approach described may allow quantification of gene expression in oral mucosal archival material processed in a standard fashion.     

Effects of injection mechanics, pH of infusate and 6-hydroxydopamine on cerebromicrovascular permeability in rats

The effects of altering the rate, manner and vehicle used for intracerebral injection upon microvascular permeability were studied in Sprague-Dawley rats employing horseradish peroxidase histochemistry. The volume of vehicle delivered and the site of intracerebral injection were kept constant. In comparison to continuous infusion, vascular permeability was significantly greater following manual (intermittent) injections; however, no differences were found when the infusion rate was decreased 10-fold. Use of a buffered vehicle (Hanks' balanced salt solution) with pH adjusted to 7.4, in contrast to the more commonly used non-buffered vehicle (saline-ascorbate), resulted in significant reductions in permeability. The apparent influence of the agent 6-hydroxydopamine (6-OHDA) on changes in vascular permeability was found to vary depending on the type and pH of the vehicle used for injection. Significantly greater permeability resulted with saline-ascorbate (pH 3.1) as the vehicle when compared to Hanks' balanced salt solution (pH 7.4). Changes in vascular permeability can therefore be produced by varying mechanical and vehicular factors which, in the case of 6-OHDA, far outweigh previously reported permeability changes specifically attributed to this neurotoxin.     

Size estimation and magnification error in radiographic imaging: implications for classification of arteriovenous malformations.

PURPOSETo assess magnification error in digital subtraction angiography as it pertains to arteriovenous malformation (AVM) size.METHODSA rectangular grid phantom with equally spaced markers mounted in a stereotactic frame was imaged with digital angiographic equipment. The location and orientation of the grid was altered relative to the central plane of the phantom. Both linear and area measurements were made according to the perceived location of phantom markers using a standard catheter calibration technique and compared with stereotactically derived estimates. Finally, a single case example of an angiographically imaged rolandic AVM was used to compare linear dimensions obtained with both described techniques.RESULTSThe determination of location and size with standard angiographic imaging is subject to error because of the divergent geometry of the incident x-ray beam. The resulting nonconstant geometric magnification causes errors in linear measurements of 10% to 13% at depths of 7 cm from the calibration plane. Errors in area measurements at the same position increase by 20% to 25%. Measurements of maximum diameter or cross-sectional area may have an additional error when nonspherical objects are inclined to the viewing direction (40% at 45 degrees inclination). These errors are reduced to less than 1 mm using the stereotactic technique. Some commercial angiographic systems have internal software to enable a spatial calibration based on known distances in the image or on the diameter of a catheter. The catheter technique was accurate in the calibration direction (perpendicular to the catheter axis) but had a 12% error in the direction parallel to the catheter because of a nonunity aspect ratio in the video system. Measurement of the dimensions of a rolandic AVM using the catheter calibration technique had an error that ranged from -3% to +26% (standard error, 20%) with respect to the stereotactic technique.CONCLUSIONSNumerous nonstereotactic referential systems for determining linear distances are inherently erroneous by varying degrees compared with the stereotactic technique. Area and volume determinations naturally increase this error further. To the extent that no standardized method for determining linear distances exists, significant variations in estimation of AVM size result. Classification schemes for AVMs have been hampered by this technical error.