Aqueductal CSF Stroke Volume Is Increased in Patients with Idiopathic Normal Pressure Hydrocephalus and Decreases after Shunt Surgery.

BACKGROUND AND PURPOSE: Increased CSF stroke volume through the cerebral aqueduct has been proposed as a possible indicator of positive surgical outcome in patients with idiopathic normal pressure hydrocephalus; however, consensus is lacking. In this prospective study, we aimed to compare CSF flow parameters in patients with idiopathic normal pressure hydrocephalus with those in healthy controls and change after shunt surgery and to investigate whether any parameter could predict surgical outcome. MATERIALS AND METHODS: Twenty-one patients with idiopathic normal pressure hydrocephalus and 21 age- and sex-matched healthy controls were prospectively included and examined clinically and with MR imaging of the brain. Eighteen patients were treated with shunt implantation and were re-examined clinically and with MR imaging the day before the operation and 3 months postoperatively. All MR imaging scans included a phase-contrast sequence. RESULTS: The median aqueductal CSF stroke volume was significantly larger in patients compared with healthy controls (103.5 µL; interquartile range, 69.8-142.8 µL) compared with 62.5 µL (interquartile range, 58.3-73.8 µL; P < .01) and was significantly reduced 3 months after shunt surgery from 94.8 µL (interquartile range, 81-241 µL) to 88 µL (interquartile range, 51.8-173.3 µL; P < .05). Net flow in the caudocranial direction (retrograde) was present in 11/21 patients and in 10/21 controls. Peak flow and net flow did not differ between patients and controls. There were no correlations between any CSF flow parameters and surgical outcomes. CONCLUSIONS: Aqueductal CSF stroke volume was increased in patients with idiopathic normal pressure hydrocephalus and decreased after shunt surgery, whereas retrograde aqueductal net flow did not seem to be specific for patients with idiopathic normal pressure hydrocephalus. On the basis of the results, the usefulness of CSF flow parameters to predict outcome after shunt surgery seem to be limited.

The idiopathic normal-pressure hydrocephalus Radscale: a radiological scale for structured evaluation.

BACKGROUND AND PURPOSE: Despite the important role of imaging in diagnosing idiopathic normal-pressure hydrocephalus (iNPH), a structured overall assessment of radiological signs is still lacking. The purpose of this study was to construct a radiological scale, composed of morphological signs of iNPH, and compare it with clinical symptoms. METHODS: In this prospective, population-based study of iNPH, 168 individuals (93 females) [mean age 75 (range 66-92) years] underwent computed tomography of the brain and a neurological examination with assessment of clinical symptoms according to Hellström's iNPH scale. Two radiologists, blinded to clinical data, independently evaluated and measured eight radiological parameters, i.e. Evans' index, callosal angle, size of temporal horns, narrow high-convexity sulci, dilated Sylvian fissures, focally dilated sulci, peri-ventricular hypodensities and bulging of the lateral ventricular roof. RESULTS: In a linear regression model, all parameters except ventricular roof bulging were significantly associated with clinical iNPH symptoms. The seven remaining parameters were summarized into a total iNPH Radscale score ranging from 0 to 12. There was a significant correlation (r = 0.55, P < 0.001) between the total iNPH Radscale score and clinical symptoms. The inter-rater agreement for the included radiological parameters was high (intraclass correlation, 0.74-0.97). CONCLUSION: The iNPH Radscale may become a valuable diagnostic screening tool, allowing a structured radiological assessment. A high iNPH Radscale score together with clinical symptoms should raise suspicion of iNPH, motivating further evaluation for shunt surgery.

Arterial Spin-Labeling Perfusion MR Imaging Demonstrates Regional CBF Decrease in Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND AND PURPOSE: Regional cerebral blood flow has previously been studied in patients with idiopathic normal pressure hydrocephalus with imaging methods that require an intravenous contrast agent or expose the patient to ionizing radiation. The purpose of this study was to assess regional CBF in patients with idiopathic normal pressure hydrocephalus compared with healthy controls using the noninvasive quantitative arterial spin-labeling MR imaging technique. A secondary aim was to compare the correlation between symptom severity and CBF. MATERIALS AND METHODS: Differences in regional cerebral perfusion between patients with idiopathic normal pressure hydrocephalus and healthy controls were investigated with pseudocontinuous arterial spin-labeling perfusion MR imaging. Twenty-one consecutive patients with idiopathic normal pressure hydrocephalus and 21 age- and sex-matched randomly selected healthy controls from the population registry were prospectively included. The controls did not differ from patients with respect to selected vascular risk factors. Twelve different anatomic ROIs were manually drawn on coregistered FLAIR images. The Holm-Bonferroni correction was applied to statistical analyses. RESULTS: In patients with idiopathic normal pressure hydrocephalus, perfusion was reduced in the periventricular white matter (P < .001), lentiform nucleus (P < .001), and thalamus (P < .001) compared with controls. Cognitive function in patients correlated with CBF in the periventricular white matter (r = 0.60, P < .01), cerebellum (r = 0.63, P < .01), and pons (r = 0.71, P < .001). CONCLUSIONS: Using pseudocontinuous arterial spin-labeling, we could confirm findings of a reduced perfusion in the periventricular white matter, basal ganglia, and thalamus in patients with idiopathic normal pressure hydrocephalus previously observed with other imaging techniques.

Discrepancy in prevalence of Huntington's disease in two Swedish regions.

BACKGROUND: Huntington's disease (HD) is a neurodegenerative disease with an autosomal dominant pattern of inheritance. The prevalence varies between different geographical regions with an estimated average in Europe of about 6/100 000. Parts of northern Sweden are known to have an accumulation of HD, but no prevalence studies have been undertaken for 50 years. OBJECT: The aim of this study was to estimate the prevalence of HD in the two different Swedish counties of Jämtland and Uppsala and compare them with the reported prevalence in Europe. METHOD: Patients registered with the diagnosis of HD were identified through medical records in each county. Presymptomatic patients were excluded. We also compared the annual number of individuals with HD registered in the database of the National Board of Health and Welfare in these regions, with all of Sweden. RESULTS: The prevalence of HD was found to be 22.1/100 000 in Jämtland and 4.9/100 000 in Uppsala county. The mean age was 62.2 years and 61.8 years, respectively. The annual average of patients with HD registered at inpatient care was 1.5/100 000 in Jämtland, 0.44/100 000 in Uppsala county, and 0.56/100 000 in all of Sweden. CONCLUSION: The prevalence of patients with the diagnosis of HD is four times higher in the county of Jämtland than in the county of Uppsala, where the prevalence is more similar to the average in Europe. Our results support earlier findings of regional variations of HD prevalence with an accumulation in certain parts of northern Sweden.

Challenges in diagnosing normal pressure hydrocephalus: Evaluation of the diagnostic guidelines.

PURPOSE: To evaluate the present diagnostic guidelines of idiopathic normal pressure hydrocephalus (iNPH) in a sample from the general population. METHODS: A total of 168 individuals (93 females, 75 males), mean age 75 years (range 66-92) with and without symptoms of iNPH underwent a CT-scan of the brain, a neurological examination with assessment of the triad symptoms, i.e. gait disturbances, memory impairment and urgency incontinence. The participants were then diagnosed as "unlikely", "possible" and "probable" iNPH according to the American-European and the Japanese guidelines, respectively. Separately, a senior consultant in neurology diagnosed each patient based on the overall clinical picture. RESULTS: Obtaining a diagnosis of "probable iNPH" was three times more likely according to the American-European guidelines (n = 35) compared to the Japanese guidelines (n = 11) or the neurologist (n = 11). The concordance was highest (Kappa = 0.69) between the Japanese guidelines and the neurologist. CONCLUSIONS: Considerable discrepancies were found when diagnosing iNPH according to two international guidelines and a neurologist, respectively. The Japanese guidelines, which include a minimum of two triad symptoms, were most concordant with the neurologist. As a step towards widely accepted, standardized diagnostic criteria, we suggest a revision of the current guidelines, preferably into one common diagnostic system.

Quantitative MRI for Rapid and User-Independent Monitoring of Intracranial CSF Volume in Hydrocephalus.

BACKGROUND AND PURPOSE: Quantitative MR imaging allows segmentation of different tissue types and automatic calculation of intracranial volume, CSF volume, and brain parenchymal fraction. Brain parenchymal fraction is calculated as (intracranial volume - CSF volume) / intracranial volume. The purpose of this study was to evaluate whether the automatic calculation of intracranial CSF volume or brain parenchymal fraction could be used as an objective method to monitor volume changes in the ventricles. MATERIALS AND METHODS: A lumbar puncture with drainage of 40 mL of CSF was performed in 23 patients under evaluation for idiopathic normal pressure hydrocephalus. Quantitative MR imaging was performed twice within 1 hour before the lumbar puncture and was repeated 30 minutes, 4 hours, and 24 hours afterward. For each time point, the volume of the lateral ventricles was manually segmented and total intracranial CSF volume and brain parenchymal fraction were automatically calculated by using Synthetic MR postprocessing. RESULTS: At 30 minutes after the lumbar puncture, the volume of the lateral ventricles decreased by 5.6 ± 1.9 mL (P < .0001) and the total intracranial CSF volume decreased by 11.3 ± 5.6 mL (P < .001), while brain parenchymal fraction increased by 0.78% ± 0.41% (P < .001). Differences were significant for manual segmentation and brain parenchymal fraction even at 4 hours and 24 hours after the lumbar tap. There was a significant association using a linear mixed model between change in manually segmented ventricular volume and change in brain parenchymal fraction and total CSF volume, (P < .0001). CONCLUSIONS: Brain parenchymal fraction is provided rapidly and fully automatically with Synthetic MRI and can be used to monitor ventricular volume changes. The method may be useful for objective clinical monitoring of hydrocephalus.

Preoperative prognostic value of MRI findings in 108 patients with idiopathic normal pressure hydrocephalus.

BACKGROUND AND PURPOSE: MR imaging is used in the diagnostic evaluation of patients with idiopathic normal pressure hydrocephalus. The aim of this study was to describe the prevalence of several imaging features and their prognostic use in the selection of shunt candidates with idiopathic normal pressure hydrocephalus. MATERIALS AND METHODS: Preoperative MR imaging scans of the brain were retrospectively evaluated in 108 patients with idiopathic normal pressure hydrocephalus who had undergone a standardized, clinical evaluation before and 12 months after shunt surgery. The MR imaging features investigated were the Evans index, callosal angle, narrow sulci at the high convexity, dilation of the Sylvian fissure, diameters of the third ventricle and temporal horns, disproportionately enlarged subarachnoid space hydrocephalus, flow void through the aqueduct, focal bulging of the roof of the lateral ventricles, deep white matter hyperintensities, periventricular hyperintensities, and focal widening of sulci and aqueductal stenosis. RESULTS: In logistic regression models, with shunt outcome as a dependent variable, the ORs for the independent variables, callosal angle, disproportionately enlarged subarachnoid space hydrocephalus, and temporal horns, were significant (P < .05), both in univariate analyses and when adjusted for age, sex, and previous stroke. CONCLUSIONS: A small callosal angle, wide temporal horns, and occurrence of disproportionately enlarged subarachnoid space hydrocephalus are common in patients with idiopathic normal pressure hydrocephalus and were significant predictors of a positive shunt outcome. These noninvasive and easily assessed radiologic markers could aid in the selection of candidates for shunt surgery.

Measurement of CSF dynamics with oscillating pressure infusion.

INTRODUCTION: Infusion tests are used to diagnose and select patients with idiopathic normal pressure hydrocephalus (INPH) for shunt surgery. The test characterizes cerebrospinal fluid dynamics and estimates parameters of the cerebrospinal fluid system, the pressure-volume index (PVI) and the outflow conductance (Cout). The Oscillating Pressure Infusion (OPI) method was developed to improve the test and reduce the investigation time. The aim of this study was to evaluate the new OPI method by comparing it with an established reference method. METHODS: Forty-seven patients (age 71.2 ± 8.9 years) with communicating hydrocephalus underwent a preoperative lumbar infusion investigation with two consecutive infusion protocols, reference (42 min) and new (20 min), that is, 94 infusion tests in total. The OPI method estimated Cout and PVI simultaneously. A real-time analysis of reliability was applied to investigate the possibility of infusion time reduction. RESULTS: The difference in Cout between the methods was 1.2 ± 1.8 µl/s/kPa (ΔRout = -0.8 ± 3.5 mmHg/ml/min), P < 0.05, n = 47. With the reliability analysis, the preset 20 min of active infusion could have been even further reduced for 19 patients to between 10 and 19 min. PVI was estimated to 16.1 ± 6.9 ml, n = 47. CONCLUSIONS: The novel Oscillating Pressure Infusion method produced real-time estimates of Cout including estimates of reliability that was in good agreement with the reference method and allows for a reduced and individualized investigation time.

The CSF tap test in normal pressure hydrocephalus: evaluation time, reliability and the influence of pain.

BACKGROUND: The cerebrospinal fluid tap test (TT) is a diagnostic tool used to select patients with idiopathic normal pressure hydrocephalus (iNPH) for shunt surgery. The procedure and the evaluation of the TT vary between centres. We aimed to describe the evaluation time after the TT, to assess the variability between repeated measurements, the interrater agreement of the gait tests chosen and finally to investigate whether pain affects the gait performance post-TT. METHODS: Forty patients (21 men and 19 women) under evaluation for iNPH underwent a TT. Standardized gait analyses were performed before and 2, 4, 6, 8 and 24 h after the TT and repeated twice on every occasion. Independent of each other, two investigators evaluated the quality of gait. At each assessment time, the patients graded headache and back pain on a visual analogue scale. RESULTS: Twenty-seven patients (15 men and 12 women) responded to TT. Improvements in gait speed and number of steps were significant at every assessment time post-TT. The variability between two measurements was low (Intra class correlation coefficient=0.97), and the inter-rater agreement was good with a κ=0.74. Pain correlated negatively with improvement in gait speed (r=-0.40, P<0.05). CONCLUSIONS: We suggest that the TT can be evaluated at any time within the first 24 h and should be repeated if the patient does not initially improve. Gait analysis appears reliable between two evaluators. Further, it is indicated that post-lumbar puncture pain negatively affects the gait and should be minimized.

Migrainous infarction: a Nordic multicenter study.

BACKGROUND AND PURPOSE: Migrainous infarction (MI), i.e., an ischemic stroke developing during an attack of migraine with aura is rare and the knowledge of its clinical characteristics is limited. Previous case series using the International Classification of Headache Disorders (ICHD) included <10 cases which make conclusions less valid. This study aimed to describe characteristics and outcome of MI in a larger sample. METHODS: We analyzed demographic data, risk factors, migraine medication, stroke localization, symptoms, and outcome in a sample of 33 patients with MI according to second edition of the ICHD criteria collected from seven Nordic headache clinics. RESULTS: Amongst 33 patients with MI, there were 20 (61%) women and 13 (39%) men with the median age for stroke of 39 (range 19-76) years. Traditional risk factors for stroke were rare compared with Scandinavian young ischemic stroke populations. During the acute phase, 12 (36%) patients used ergotamines or triptans. Stroke was located in the posterior circulation in 27 (82%) patients and cerebellum was involved in 7 (21%). Except in two patients with brainstem infarctions, the outcome was favorable with total recovery or limited residual symptoms. CONCLUSIONS: The prevalence of traditional risk factors was low and the infarctions were predominantly located in posterior circulation territory, supporting theories of migraine specific mechanisms. The outcome was in general favorable.

A 3-year follow-up of headache diagnoses and symptoms in Swedish schoolchildren.

Information is sparse concerning the incidence and prognosis of headache in children from the general population, especially of tension-type headache. In this study, headache diagnoses and symptoms were reassessed in 122 out of 130 schoolchildren after 3 years. Nearly 80% of those with headache at first evaluation still reported headache at follow-up. Although the likelihood of experiencing the same headache diagnosis and symptoms was high, about one-fifth of children with tension-type headache developed migraine and vice versa. Female gender predicted migraine and frequent headache episodes predicted overall headache at follow-up. The estimated average annual incidence was 81 and 65 per 1000 children, for tension-type headache and migraine, respectively. We conclude that there is a considerable risk of developing and maintaining headache during childhood. Headache diagnoses should be reassessed regularly and treatment adjusted. Girls and children with frequent headache have a poorer prognosis and therefore intervention is particularly important in these groups.

Prevalence of headache in Swedish schoolchildren, with a focus on tension-type headache.

To estimate the prevalence of tension-type headache, migraine and other headaches, 1850 schoolchildren, age 7-15 years, from the city of Uppsala, were invited to complete a questionnaire. The response rate was 74.1%. To validate the information from the questionnaires, 131 children and their parents were interviewed. Using the criteria of the International Headache Society, the 1-year prevalence of tension-type headache and migraine was 9.8 and 11.0%, respectively. However, these prevalence rates increased considerably, to 23.0 and 17.0%, respectively, when excluding the criteria defining the number of earlier episodes and duration of headache. The prevalence of headache increased with age, similarly in girls and boys up to 11 years, and thereafter only in girls. The preponderance in teenage girls was even more pronounced for tension-type headache than for migraine. Our results indicate an increase over time in headache prevalence when compared with findings in a study conducted in the same city in 1955.

Headache in schoolchildren: agreement between different sources of information.

The level of agreement between different sources of information, i.e. questionnaires, interviews and diaries, was evaluated in a sample of 129 schoolchildren, 69 girls and 60 boys, ranging in age from 7 to 17 years. Headache diagnoses and headache features showed high agreement between questionnaires and subsequent interviews. The concordance between questionnaires and interviews for headache diagnoses increased, and the number of unclassified headaches decreased, when the International Headache Society (IHS) duration criterion was excluded. When comparing headache frequency reported in questionnaires and interviews with diary recordings, the agreement was low and the frequency higher in the diaries. Overall, the agreement between questionnaires, interviews and diaries was not related to age or gender. The questionnaire may serve as a valid source of information in studies of headache in schoolchildren. Prospective recordings in diaries provide additional information, in particular of low-intensity headache. In children, the IHS duration criterion should be modified or excluded.

Shear rebond strength of Rexillium III to enamel using resin composite cements.

This investigation evaluated the shear rebond strength of Rexillium III to enamel using various resin composite luting systems (Panavia, Imperva Dual, ABC Enhanced, C&B Metabond, Optibond, and Comspan). Cast Rexillium III cylinders (3.9 x 6.0 mm) were bonded to human molar buccal enamel surfaces (n = 8) with each cement type after etching with 37% phosphoric acid for 30 seconds. Bonded specimens were stored in distilled water for 7 days at 37 degrees C +/- 2 degrees C and thermocycled (1,500 cycles) in 5 degrees C and 55 degrees C water baths (1 minute dwell time). Specimens were randomly tested in shear mode on an Instron Testing Machine at a crosshead speed of 0.5 mm per minute. Debonded specimens were then rebonded after appropriate metal conditioning and re-etching the enamel surface for 30 seconds. Analysis of variance (P < 0.001) and the Ryan-Einot-Gabriel-Welsh multiple range test showed significant differences between several of the resin cements (P < 0.05). Panavia exhibited significantly higher shear rebond strength than any of the other cements tested. Only Imperva Dual exhibited a significantly lower shear rebond strength compared to its initial shear bond strength.

Shear bond strength of Rexillium III to enamel using resin composite cements.

This study evaluated the shear bond strength of Rexillium III (Jeneric Pentron, Wallingford, CT) to enamel using various resin composite luting systems. Cast alloy cylinders (3.9 mm X 6.0 mm) were bonded with each cement to human molar buccal enamel surfaces (n = 8). The enamel was etched using a 35% phosphoric acid solution for 30 seconds. Bonded specimens were stored in distilled water for 7 days at 37 degrees C and thermocycled (1,500 cycles) in 5 degrees C and 55 degrees C water baths (1-minute dwell time). Specimens were randomly tested in shear using a crosshead speed of 0.5 mm per minute. Use of a one-way analysis of variance (P < .001) and Ryan-Einot-Gabriel-Welsh multiple range test showed significant differences between several of the resin cements. Panavia exhibited a significantly higher shear bond strength than any of the other cements tested.

Compressive characteristics of an internally threaded post system.

PURPOSE: The effects of oblique compressive forces were evaluated for extracted teeth restored with posts of solid and internally threaded designs. MATERIALS AND METHODS: A group of 25 roots was restored with crowns supported by Para-post dowels and pin-retained composite resin cores, and a second group was restored with gold copings cast to internally threaded stainless steel-post prototypes. Samples were then embedded in epoxy resin and loaded at 45 degrees until failure. Failure force and type were statistically analyzed to determine statistical difference (P < .05) between groups. RESULTS: No statistical difference was shown between groups for either fracture force or type. CONCLUSIONS: The internally threaded post system resisted oblique loading forces similarly to a solid post system.

Histopathologic effects of kinetic cavity preparation for the removal of enamel and dentin. An in vivo animal study.

Recent developments in technology, direct placement restorative materials, and cavity preparation design have renewed interest in kinetic cavity preparation, a term to describe the use of air-abrasion for removal of tooth structure. This study compared the pulpal response of 120 teeth in mixed-breed dogs treated with four kinetic cavity preparation combinations of pressure (80 psi and 160 psi) and aluminum oxide particle sizes (27 microns and 50 microns) to those treated with high-speed rotary burs. Class V buccal preparations were made and restored with an interim material. Teeth were collected 72 hours after surgery, decalcified, sectioned, stained with hematoxylin and eosin, and blindly evaluated by two examiners at the minimal dentin thickness. Samples were graded for extent of displacement, disruption, inflammation, and necrosis of pulpal structures. Differences between groups were analyzed with the use of Bonferroni-adjusted multiple Mann-Whitney-Wilcoxon tests with p < 0.05 being significant. Higher pressures and smaller particles yielded significantly fewer pulpal effects than the high-speed treated teeth whereas lower pressures and larger particles were not significantly different for most effects evaluated. No adverse soft tissue effects were noted when kinetic cavity preparation was directed at attached gingiva.

Scanning electron micrographic effects of air-abrasion cavity preparation on human enamel and dentin.

Recent developments in technology and restorative materials have renewed interest in air abrasion as a means of tooth preparation. The technique, also called kinetic cavity preparation, uses kinetic energy to remove tooth structure. The purpose of this investigation was to use scanning electron microscopy to compare the effects of this technique to those of high-speed burs on extracted human teeth. Class V buccal preparations were made on five teeth with a No. 34 carbide bur used at 400,000 rpm and on 23 teeth with kinetic cavity preparation using differing combinations of aluminum oxide particle sizes and delivery pressures. Features of the specimens prepared at high speed included sharp line angles, chipping of the cavo-surface margin, and striated internal surfaces. Kinetic cavity preparations had rounded cavo-surface margins and internal line angles. The surfaces were microscopically rough and the dentinal tubules were occluded. There was little difference in appearance between specimens treated with various combinations of particle sizes and delivery pressures.

Retentive characteristics of an internally threaded post system.

Internally threaded, stainless steel posts 10 mm in length and 1.82 mm in diameter or stainless-steel Para-Post dowels 1.7 mm in diameter were cemented in extracted human teeth with zinc phosphate cement. Titanium alloy screws 1.5 mm in diameter were placed in the internally threaded posts and tensile force was applied to the screws or Para-Post dowels until dislodgment of the post or fracture. The retention of the Para-Post system was significantly greater than the experimental posts. Although all screws exhibited deformation, there was no breakage or distortion of the internally threaded posts or Para-Post dowels. Retention for both systems exceeded reported forces generated in humans.

A potential MRI hazard: forces on dental magnet keepers.

The objective of this study was to determine the forces on dental prosthetic magnet keepers, with a view to assessing the potential for patient injury during magnetic resonance imaging (MRI). Four pre-formed keepers and one castable keeper alloy were tested. Magnetizations and high field susceptibilities were determined for each of the five specimens using data from a vibrating sample magnetometer. The magnetic field intensity with respect to distance from the main magnet coil was obtained from the manufacturer (1-5 tesla General Electric Signa Imaging System). A plot of force versus distance from the main coil and the maximum force at the magnet portal was determined for each specimen. The maximum forces ranged from 0.12-0.24 N for the pre-formed keepers and 3.67 MNm-3 for the castable alloy. It was concluded that the risk of patient injury by displacement is minimal, if the keepers are properly attached to supporting structures.