Rare variants analysis of cutaneous malignant melanoma genes in Parkinson's disease

A shared genetic susceptibility between cutaneous malignant melanoma (CMM) and Parkinson's disease (PD) has been suggested. We investigated this by assessing the contribution of rare variants in genes involved in CMM to PD risk. We studied rare variation across 29 CMM risk genes using high-quality genotype data in 6875 PD cases and 6065 controls and sought to replicate findings using whole-exome sequencing data from a second independent cohort totaling 1255 PD cases and 473 controls. No statistically significant enrichment of rare variants across all genes, per gene, or for any individual variant was detected in either cohort. There were nonsignificant trends toward different carrier frequencies between PD cases and controls, under different inheritance models, in the following CMM risk genes: BAP1, DCC, ERBB4, KIT, MAPK2, MITF, PTEN, and TP53. The very rare TYR p.V275F variant, which is a pathogenic allele for recessive albinism, was more common in PD cases than controls in 3 independent cohorts. Tyrosinase, encoded by TYR, is the rate-limiting enzyme for the production of neuromelanin, and has a role in the production of dopamine. These results suggest a possible role for another gene in the dopamine-biosynthetic pathway in susceptibility to neurodegenerative Parkinsonism, but further studies in larger PD cohorts are needed to accurately determine the role of these genes/variants in disease pathogenesis.

Olfaction in Parkin single and compound heterozygotes in a cohort of young onset Parkinson's disease patients

BACKGROUND

Parkin related Parkinson's disease (PD) is differentiated from idiopathic PD by absent or sparse Lewy bodies, and preserved olfaction. The significance of single Parkin mutations in the pathogenesis of PD is debated.

OBJECTIVES

To assess olfaction results according to Parkin mutation status. To compare the prevalence of Parkin single heterozygous mutations in patients diagnosed with PD to the rate in healthy controls in order to establish whether these single mutations could be a risk factor for developing PD.

METHODS

Parkin gene mutation testing was performed in young onset PD (diagnosed <50 years old) to identify three groups: Parkin homozygous or compound heterozygote mutation carriers, Parkin single heterozygote mutation carriers, and non-carriers of Parkin mutations. Olfaction was tested using the 40-item British version of the University of Pennsylvania smell identification test (UPSIT).

RESULTS

Of 344 young onset PD cases tested, 8 (2.3%) were Parkin compound heterozygotes and 13 (3.8%) were Parkin single heterozygotes. Olfaction results were available in 282 cases (eight compound heterozygotes, nine single heterozygotes, and 265 non-carriers). In Parkin compound heterozygotes, the median UPSIT score was 33, interquartile range (IQR) 28.5-36.5, which was significantly better than in single Parkin heterozygotes (median 19, IQR 18-28) and non-carriers (median score 22, IQR 16-28) (ANOVA P < 0.001). These differences persisted after adjusting for age, disease duration, gender, and smoking (P < 0.001). There was no significant difference in UPSIT scores between single heterozygotes and non-carriers (P = 0.90).

CONCLUSIONS

Patients with Parkin compound heterozygous mutations have relatively preserved olfaction compared to Parkin single heterozygotes and non-carriers. The prevalence of Parkin single heterozygosity is similar to the 3.7% rate reported in healthy controls.

Alpha-synuclein in peripheral tissues and body fluids as a biomarker for Parkinson's disease - a systematic review

Parkinson's disease (PD) is neuropathologically characterized as an alpha-synucleinopathy. Alpha-synuclein-containing inclusions are stained as Lewy bodies and Lewy neurites in the brain, which are the pathological hallmark of PD. However, alpha-synuclein-containing inclusions in PD are not restricted to the central nervous system, but are also found in peripheral tissues. Alpha-synuclein levels can also be measured in body fluids. The aim of this study was to conduct a systematic review of available evidence to determine the utility of alpha-synuclein as a peripheral biomarker of PD. We searched PubMed (1948 to 26 May 2013), Embase (1974 to 26 May 2013), the Cochrane Library (up to 26 May 2013), LILACS (up to 26 May 2013) and CINAHL (up to 26 May 2013) for the studies of alpha-synuclein in peripheral tissues or body fluids in PD. A total of 49 studies fulfilled the search criteria. Peripheral tissues such as colonic mucosa showed a sensitivity of 42-90% and a specificity of 100%; submandibular salivary glands showed sensitivity and specificity of 100%; skin biopsy showed 19% sensitivity and 80% specificity in detecting alpha-synuclein pathology. CSF alpha-synuclein had 71-94% sensitivity and 25-53% specificity for distinguishing PD from controls. Plasma alpha-synuclein had 48-53% sensitivity and 69-85% specificity. Neither plasma nor CSF alpha-synuclein is presently a reliable marker of PD. This differs from alpha-synuclein in solid tissue samples of the enteric and autonomic nervous system, which offer some potential as a surrogate marker of brain synucleinopathy.

Baseline [(123) I]FP-CIT SPECT (DaTSCAN) severity correlates with medication use at 3 years in Parkinson's disease

BACKGROUND

Presynaptic dopaminergic deficiency on dopamine transporter imaging supports a clinical diagnosis of Parkinson's disease and correlates with the severity of rigidity and bradykinesia. Baseline dopaminergic deficiency predicts clinical severity, but the relationship with subsequent medication use has not been reported.

METHODS

A randomly selected cross section of 83 Parkinson's disease (PD) patients who had [(123) I] FP-CIT SPECT at the time of clinical diagnosis was identified. Dopaminergic deficiency was graded 1, 2 or 3 with increasing severity using visual assessment and by semiquantitative analysis of putamen and caudate uptake. Antiparkinson medication usage and clinical severity by Hoehn and Yahr were noted annually to 3 years.

RESULTS

In 83 patients (66% male, median age 65.0 years, IQ 55.4-71.8), [(123) I]FP-CIT SPECT was grade 1 in 20 (24%), grade 2 in 53 (64%) and grade 3 in 10 patients (12%). Dopamine transporter uptake ratios were inversely associated with antiparkinson medication usage (r = -0.26, P = 0.0201) and Hoehn Yahr stage (r = -0.32, P = 0.0029) at 3 years from baseline, but there was considerable variation in drug usage in individual patients. At 3 years, patients with grade 1 scans at baseline received a median dose of 325 levodopa equivalent units (LEU) (interquartile range 175-433); grade 2 scan patients 400 LEU (interquartile range 300-635); and grade 3 scan patients 460 LEU (interquartile range 252-658).

CONCLUSION

The degree of reduction in presynaptic dopaminergic uptake at baseline is associated with higher antiparkinson drug dosage at follow-up, but the wide variation means that the baseline FP-CIT SPECT does not reliably predict drug use in individual cases.

Inhaled dry powder apomorphine (VR040) for 'off ' periods in Parkinson's disease: an in-clinic double-blind dose ranging study

BACKGROUND

'Off' periods increase as Parkinson's disease (PD) progresses and the benefits of standard therapy wane. Subcutaneous apomorphine rescues 'off' periods, but patient self-injection and adverse cutaneous effects are sometimes problematic.

METHODS

We assessed safety, tolerability and efficacy of inhaled dry powder apomorphine (VR040) in a double-blind clinic-based Phase II study. Of 48 patients recruited at nine sites, 47 were randomized 2:1 inhaled apomorphine/placebo. Respirable doses (drug predicted to reach the lung), ascending through 1.5, 2.3, 3.0 and 4.0 mg until efficacy was achieved, were administered to patients in a practically defined 'off' state. The primary endpoint was the response in unified PD rating scale Part 3 (UPDRS 3), at the highest dose received by the patient. Secondary endpoints included time to 'on', the proportion of patients converting from 'off' to 'on', and duration of 'on'.

RESULTS

In the 47 intent-to-treat patients with PD, mean age 60.6 years, the mean UPDRS 3 improvement was significantly greater for VR040 at 26.8 points (standard deviation 12.0), vs 14.9 (16.3) for placebo (treatment difference 11.6, 95% confidence interval 2.3-20.9, P = 0.016). Rapid apomorphine absorption (2-7 min) translated to rapid (mean 10 min) reversal from the 'off' state. Adverse effects did not differ between VR040 and placebo; no patient discontinued due to an adverse event; one serious adverse event (constipation) in the VR040 group was considered unrelated to trial medication.

CONCLUSIONS

Inhaled apomorphine shows significant promise as a replacement for intermittent subcutaneous injections; further studies are appropriate to optimize efficacy and tolerability.

Phase IIa randomized double-blind, placebo-controlled study of inhaled apomorphine as acute challenge for rescuing 'off' periods in patients with established Parkinson's disease

BACKGROUND AND PURPOSE

In this first study of inhaled apomorphine (VR040) in patients with Parkinson's disease, the primary objective was to find the minimum efficacious dose of apomorphine that was useful in rescuing patients during 'off' periods. Safety, tolerability and pharmacokinetics of inhaled apomorphine were assessed during the study.

METHODS

A double-blind, placebo-controlled, randomized trial of three escalating single doses of inhaled apomorphine (0.2, 0.5 and 0.8 mg fine particle dose) versus placebo (3 : 1 active:placebo) was performed. Parkinson's motor severity assessments by a clinician, and disease state assessment by the patient, were performed at baseline during an 'off' state, and at specified times after test drug administration. Safety assessments (including vital signs, electrocardiogram and forced expiratory volume) were performed, and plasma apomorphine levels measured.

RESULTS

All 24 patients completed the study, and considering the three dose levels together, inhaled apomorphine did not significantly increase the proportion of patients switching from 'off' to 'on' (0/6 at 0.2 mg, 3/6 at 0.5 mg and 2/6 at 0.8 mg vs. 1/6 for placebo), or decrease the time from 'off' to 'on' post-treatment (10 min for 0.5 mg, 40 min for 0.8 mg, vs. 20 min for placebo). However, there was a suggestion of benefit at the higher doses (5/12 switched 'on' at the 0.5 or 0.8 mg doses, vs. 1/6 for placebo). There were no serious adverse events and treatment was well tolerated. Peak plasma concentration was 1-3 min post-dose, and plasma level dose proportionality was observed.

CONCLUSIONS

Inhaled apomorphine was safe and well tolerated at the doses tested for an acute challenge to rescue 'off' periods, but efficacy at these doses was limited. A follow-up study at higher doses is appropriate given these initial findings.

Duration of L-dopa and dopamine agonist monotherapy in Parkinson's disease

The expected duration of initial antiparkinson monotherapy before the need for supplementation is not clearly defined for routine practice. The aim of this study was to define the length of L-dopa (L-3, 4-dihydrophenylalanine) and dopamine agonist monotherapy. The duration of monotherapy and discontinuation rates were investigated in a natural observational setting by plotting Kaplan-Meier survival curves. Out of 345 patients, 180 (52.2%) received L-dopa and 165 (47.8%) received a dopamine agonist as initial monotherapy. Half of the patients starting L-dopa received supplementary therapy with- in 3.6 years (95% confidence interval, 3.2-4.6), significantly longer than for dopamine agonist monotherapy (half required a second agent at 2.3 years [2.0-2.9]; P = 0.00017). Discontinuation of L-dopa therapy was 1%. Dopamine agonists were stopped (due to side-effects like impulse control disorders [6%], somnolence [4%] and light-headedness [3%]) in 20% over four years. The duration and tolerability of L-dopa and dopamine agonists as initial Parkinson's disease monotherapy are defined in this study; this may form part of the information exchange with patients.

Accuracy of subjective and objective handwriting assessment for differentiating Parkinson's disease from tremulous subjects without evidence of dopaminergic deficits (SWEDDs): an FP-CIT-validated study

Handwriting examinations are commonly performed in the analysis of tremor and Parkinson's disease (PD). We analyzed the accuracy of subjective and objective assessment of handwriting samples for distinguishing 27 PD cases, 22 with tremulous PD, and five with akinetic-rigid PD, from 39 movement-disorder patients with normal presynaptic dopamine imaging (subjects without evidence of dopamine deficiency or SWEDDs; 31 with dystonic tremor (DT), six indeterminate tremor syndrome, one essential tremor, one vascular parkinsonism). All handwriting analysis was performed blind to clinical details. Subjective classification was made as: (1) micrographia, (2) normal, or (3) macrographia. In addition, a range of objective metrices were measured on standardized handwriting specimens. Subjective assessments found micrographia more frequently in PD than SWEDDs (p = 0.0352) and in akinetic-rigid than tremulous PD (p = 0.0259). Macrographia was predominantly seen in patients with dystonic tremor and not other diagnoses (p = 0.007). Micrographia had a mean sensitivity of 55 % and specificity of 84 % for distinguishing PD from SWEDDs and mean sensitivity of 90 % and specificity of 55 % for distinguishing akinetic-rigid PD from tremulous PD. Macrographia had a sensitivity of 26 % and specificity of 96 % for distinguishing DT from all other diagnoses. The best of the objective metrices increased sensitivity for the distinction of SWEDDs from PD with a reduction in specificity. We conclude that micrographia is more indicative of PD than SWEDDs and more characteristic of akinetic-rigid than tremulous PD. In addition, macrographia strongly suggests a diagnosis of dystonic tremor.

Olfaction in patients with suspected parkinsonism and scans without evidence of dopaminergic deficit (SWEDDs)

BACKGROUND

Positron emission tomography and single photon emission computed tomography scanning have 87-94% sensitivity and 80-100% specificity to differentiate patients with Parkinson's disease (PD) from control subjects and patients with essential (ET) or atypical tremor. More than 10% of patients diagnosed as early PD can have scans without evidence of dopaminergic deficiency (SWEDDs). This study investigated whether smell tests can help identify possible cases with SWEDDs.

METHODS

The 40 item University of Pennsylvania Smell Test (UPSIT) was used to evaluate the sense of smell in 21 SWEDDs patients. Twenty-six ET patients, 16 patients with a diagnosis of idiopathic adult onset dystonia (D), 191 non-demented PD patients and 136 control subjects were also tested. Multiple regression analyses were used to compare the mean UPSIT score in the SWEDDs group with the other four groups (ET, D, PD and controls) after adjusting for the effects of relevant covariates.

RESULTS

The mean UPSIT score for the SWEDDs group was greater than in the PD group (p<0.001) and not different from the mean UPSIT in the control (p = 0.7), ET (p = 0.4) or D (p = 0.9) groups. Smell tests indicated a high probability of PD in only 23.8% of SWEDDs as opposed to 85.3% of PD patients.

CONCLUSIONS

In a patient with suspected PD, a high PD probability on smell testing favours the diagnosis of PD, and a low PD probability strengthens the indication for dopamine transporter imaging.

Problematic gambling on dopamine agonists: Not such a rarity

Excessive gambling is recognized with dopamine agonist therapy, but the prevalence is unknown. We assessed the prevalence of excess gambling by specific prospective enquiry in Parkinson's disease patients attending six West Scotland movement disorder clinics. Of 388 patients taking anti-Parkinson medication, 17 (4.4%) developed pathological gambling, all of whom were prescribed dopamine agonists. Thus, 8% of patients taking dopamine agonists had pathological gambling. Pathological gambling is not uncommon, and patients should be made aware of this potential adverse effect.

Updated guidelines for the management of Parkinson's disease

New data on diagnosis, drug therapy, surgery and psychosocial concerns have emerged since the publication of the 1998 Guidelines for the Management of Parkinson's Disease. This article reviews new data and addresses issues left unanswered in the previous guidelines.

Characterization of ultrasound-detected cerebral microemboli in patients undergoing cardiac catheterization using an in vitro middle cerebral artery model

Cerebral embolization has been documented as one of the complications of diagnostic heart catheterization by transcranial Doppler (TCD). This study aimed to evaluate our hypothesis that the nature of embolic signals involved in different stages of catheter manipulation may be distinct. TCD-detected cerebral emboli occurring at different phases of cardiac catheterization were registered and differentiated by comparing their acoustic signatures with the Doppler signals generated from clinically frequently encountered embolic materials in an in vitro middle cerebral artery model. We found that there was a significant difference in embolic signal intensity and duration between different phases of cardiac catheterization. Our data suggest that different types of emboli may be involved in different phases of the catheterization. Cathet Cardiovasc Intervent 2001;53:323-330.

Tolerability of the low-affinity, use-dependent NMDA antagonist AR-R15896AR in stroke patients: a dose-ranging study

BACKGROUND AND PURPOSE

AR-R15896AR is a use-dependent, low-affinity blocker of the NMDA ion channel with neuroprotective effects in animal models of focal cerebral ischemia. This study aimed to establish the highest safe and tolerated loading and maintenance dosing regimen of AR-R15896AR in acute ischemic stroke patients and to determine the associated plasma concentrations of AR-R15896AR.

METHODS

This was a 4-part, multicenter, randomized, double-blind, placebo-controlled study in 175 patients (mean age, 69 years) within 24 hours of acute stroke symptom recognition. Ascending 60-minute intravenous infusion loading doses of AR-R15896AR were initially examined (100, 150, 200, 250, or 300 mg or placebo in 3:1 randomization, n=36 treated); in part 2, 250, 275, or 300 mg was compared with placebo (n=33). In part 3, a 250-mg loading dose was followed by 9 maintenance doses of 60, 75, 90, 105, or 120 mg every 8 hours versus placebo in 3:1 randomization (n=59); subsequently, in part 4, maintenance doses of 90, 105, and 120 mg after the 250-mg loading dose were directly randomized against placebo (n=42). Safety, tolerability, and pharmacokinetics were the primary end points; NIHSS at 1 week and Barthel and modified Rankin scores at 1 month were also recorded, but the study was neither designed nor powered to assess efficacy.

RESULTS

Rates for mortality and serious adverse events (SAE) were similar in active and placebo groups (9% mortality and 23% SAE for all active combined versus 11% mortality and 33% SAE for placebo). Adverse events associated with AR-R15896AR were dizziness, vomiting, nausea, stupor, and some agitation/hallucination. Withdrawal from treatment occurred only in response to loading doses with AR-R15896AR: placebo, 3 of 46 (7%); 250 mg, 11 of 89 (12%); 275 mg, 1 of 8 (12.5%); and 300 mg, 3 of 15 (20%). No significant difference in outcome was observed between groups. Plasma concentrations of AR-R15896AR were 1524+/-536 ng/mL at the end of the 250-mg loading infusion and were 1847+/-478 ng/mL at steady state after the 9 maintenance doses of 120 mg.

CONCLUSIONS

The maximum tolerated loading infusion of AR-R15896AR in this study was 250 mg over a period of 1 hour. Subsequent maintenance infusions of 120 mg every 8 hours were well tolerated. With these doses, putative neuroprotective concentrations of 1240 ng/mL are attained by the loading dose and are satisfactorily maintained thereafter. The loading dose may be improved further by adjustment on an individual patient basis, but tolerability issues remain.

Correlation of Parkinson's disease severity and duration with 123I-FP-CIT SPECT striatal uptake

The variability in clinical features and the masking effects of drug therapy in Parkinson's disease (PD) can affect clinical assessment of disease severity. The aim of this study was to assess the imaging of dopamine transporters using 123I-FP-CIT SPECT and its correlation with disease staging, severity, and duration. Differences between the clinical severity of the onset and non-onset side and the corresponding striatal uptake ratios were also examined. Forty-one patients with PD (nine unilateral, 32 bilateral clinical features) were studied. Clinical severity was determined by using the Unified Parkinson's Disease Rating Score (UPDRS). Unilateral UPDRS was calculated from unilateral arm and leg resting and action tremor, rigidity, finger taps, hand movements, alternating movements, and leg agility. 123I-FP-CIT striatal uptake was expressed as the ratio of specific:nonspecific (SP:NS) uptake for defined brain areas. Patients with PD who had unilateral symptoms showed a significant difference between the ipsilateral and contralateral SP:NS ratios in both the caudate and putamen, but there was a considerable overlap between between the two sides. This result was repeated in patients with bilateral symptoms and there was overlap of SP:NS ratios between the two groups. For the whole group of patients with PD, striatum, caudate, and putamen SP:NS ratios correlated with disease severity assessed by UPDRS and duration of disease. The SP:NS ratios correlated with the bradykinesia subscore but not with rigidity or tremor subscore. In conclusion, this study provides further evidence that the SP:NS ratio is a robust measure of disease severity correlating with duration of PD. However, variability in uptake values suggest that factors other than nigrostriatal degeneration may contribute to disease severity. Correlation with bradykinesia but not with tremor may indicate an origin for tremor outwith the dopamine transporter system. 123I-FP-CIT SPECT offers significant potential in defining the nigrostriatal changes in PD.

Randomized trial of graded compression stockings for prevention of deep-vein thrombosis after acute stroke

Graded compression stockings are commonly used to prevent deep-vein thrombosis (DVT) after stroke, but their efficacy in this setting has not been evaluated. Extrapolation of effectiveness from trials in patients undergoing elective surgery may be inappropriate. We undertook a randomized, controlled trial, with blinded data review, in a University hospital Acute Stroke Unit. Patients were allocated to graded compression stockings or to standard care alone. DVT incidence was determined at baseline and at day 7+/-2 by colour-flow Doppler ultrasound. Ninety-eight patients with acute, immobilizing stroke were randomized; 97 had full outcome data. One patient had clinically manifest DVT, and no patient had pulmonary thromboembolism. DVT was detected in 7/65 patients allocated stockings, and 7/32 controls (odds ratio 0.43, 95% CI 0.14-1.36); DVT involving femoral veins was detected in 3/65 and 2/32. In the first week after stroke, radiologically-detected DVT remains common, but is usually clinically silent. Proximal DVT is less common. Graded compression stockings produced a reduction in DVT incidence comparable to that in other patient groups, but the reduction was not statistically significant, and the magnitude of effect size requires confirmation. There is greater doubt over efficacy in early prevention of proximal DVT.

Accurate differentiation of parkinsonism and essential tremor using visual assessment of [123I]-FP-CIT SPECT imaging: the [123I]-FP-CIT study group

OBJECTIVE

To evaluate whether visual assessment of [123I]-FP-CIT (DaTSCAN, Nycomed Amersham, plc) single photon emission computerized tomography (SPECT) images can differentiate between parkinsonism and essential tremor (ET).

METHODS

[123I]-FP-CIT SPECT imaging was conducted in a six-center study of 158 patients with a clinical diagnosis of parkinsonism compared with 27 ET cases and 35 healthy volunteers. Striatal uptake of the radioligand was graded normal or abnormal, and abnormal images were further graded to three levels of severity. An institutional read whereby each center visually assessed the images blinded to the clinical data and a consensus blinded read by a panel of five was undertaken.

RESULTS

The institutional reading scored 154 of 158 cases of parkinsonism abnormal, all 27 cases of ET as normal, and 34 of 35 healthy volunteers as normal compared with the consensus blinded read scoring 150 cases of parkinsonism as abnormal, 25 ET cases as normal, and 33 healthy volunteers as normal. Sensitivity for the clinical diagnosis of parkinsonism was 97% and specificity for ET was 100% for the institutional read, whereas sensitivity was 95% and specificity 93% for the consensus blinded read. Semiquantitative analysis of specific: nonspecific caudate and putamen uptake were consistent with the results of visual inspection.

CONCLUSION

Visual assessment of [123I]-FP-CIT SPECT images is an easily applied diagnostic test which is helpful in the differential diagnosis of tremor disorders and in confirming a clinical diagnosis of a hypokinetic-rigid syndrome.

Identification of echocardiographic "smoke" in a bench model with transcranial Doppler ultrasound

BACKGROUND AND PURPOSE

Spontaneous echo contrast in cardiac chamber has been indicated as a source of cerebral embolism. The nature of the echocardiographic smokelike signal is still not fully understood. This study was designed to regenerate spontaneous echo contrast and verify its thromboembolic characters in an in vitro model.

METHODS

Spontaneous echo contrast was reproduced in an expansion chamber under low flow conditions in a close circulation system. The spontaneous echo contrast was monitored and recorded with a 2-dimensional cardiosonography system and a transcranial Doppler device. Meanwhile, clinically commonly encountered embolic materials such as whole-blood clots, platelet aggregate-rich plasma, air bubbles, and 100-mL normal saline were injected into this monitored circuit. The differentiation of spontaneous echo contrast from emboli was performed by both visual observations of the echo images and offline Doppler signal intensity analysis. Average signal intensities produced by spontaneous contrast and injection of embolic materials and saline were compared. Furthermore, the effect of Doppler-detected flow velocity on generation of spontaneous contrast was also evaluated.

RESULTS

Spontaneous echo contrast was reproduced at low flow settings (90 to 120 mL/min) in this model. There was no significant difference in average signal intensity between the flow with spontaneous echo contrast and that without the echo (P=0.71). However, injection of embolic materials or normal saline did not generate smokelike image but caused much higher average signal intensity than the flow with spontaneous contrast (P<0.001). Injection of normal saline also increased average signal intensity.

CONCLUSIONS

Our results suggest that smokelike echo is a special echo phenomenon occurring at low flow situations and does not itself produce material capable of embolizing into the systemic circulation.

Neuroprotection for acute stroke: making clinical trials work

BACKGROUND

With the exception of the National Institutes of Neurological Disorders and Stroke trial of recombinant tissue plasminogen activator, clinical trials in stroke have failed to show improved outcome. If further negative results such as those of recent large neuroprotective trials are to be avoided, trial methodology must be reevaluated.

SUMMARY

Because there is little evidence from animal focal ischemia models for protection of white matter, glia, or subcortical neurons, the logical target population for initial clinical trials is patients with middle cerebral artery stroke involving cerebral cortex. Clinical differentiation of moderate to large middle cerebral stroke from lacunar stroke is possible with the Oxfordshire Community Stroke Project classification but less readily achieved by numerical stroke scales. Several imaging techniques can further distinguish middle cerebral stroke patients with a "penumbra" potentially amenable to intervention from those without a penumbra, in whom outcome appears already determined. The window for intervention may be better defined by imaging than by time alone. Shortened follow-up periods may reduce variation in outcome attributable to differences in provision of rehabilitation or secondary preventative treatments among centers, and imaging may provide useful surrogate end points.

CONCLUSIONS

Clinical trials restricted to patients with large middle cerebral stroke accompanied by radiological evidence of a penumbra should be an essential component of drug development. Slower recruitment may be offset by extended time windows and requirements for fewer patients. Imaging may define surrogate evidence of biological effect prior to embarking on a phase 3 program.

Consensus on microembolus detection by TCD. International Consensus Group on Microembolus Detection

Transcranial Doppler ultrasound is capable of detecting microembolic material, both gaseous and solid, within the intracranial cerebral arteries. To avoid discrediting this promising and exciting new technique, experts in this field met in January 1997 in Frankfurt, Germany, to discuss the limitations and problems of embolus detection and to determine guidelines for its proper use in clinical practice, as well as in scientific investigations. In particular, the authors suggest that studies report the following parameters: (1) ultrasound device, (2) transducer type and size, (3) insonated artery, (4) insonation depth, (5) algorithms for signal intensity measurement, (6) scale settings, (7) detection threshold, (8) axial extension of sample volume, (9) fast Fourier transform (FFT) size (number of points used), (10) FFT length (time), (11) FFT overlap, (12) transmitted ultrasound frequency, (13) high-pass filter settings, and (14) recording time. There was agreement that no current system of automatic embolus detection has the required sensitivity and specificity for clinical use.

Effects of prolonged infusions of the NMDA antagonist aptiganel hydrochloride (CNS 1102) in normal volunteers

Blockade of the N-methyl D-aspartate (NMDA) receptor by the ion-channel-blocking drug aptiganel hydrochloride (CNS 1102, Cerestat) is neuroprotective in focal cerebral ischemia. Short intravenous infusions of up to 30 microg/kg have been well tolerated by healthy male volunteers. We undertook a randomized, double-blind, placebo-controlled study in 20 male volunteers to examine the safety, tolerability, and cardiovascular and psychomotor effects of a dosing paradigm similar to that envisaged for therapeutic use. Aptiganel HCl was infused over 4 h in total doses of 15, 32, 50, or 73 microg kg. Mean arterial pressure increased significantly with dose group (p < 0.01, analysis of covariance). Motor reaction time was related to maximal plasma concentration (r2 = 0.21, p < 0.001). Transient symptoms and signs of peripheral paresthesiae, light-headedness, and euphoria were seen at total doses of 32 microg/ kg. Higher doses were associated with motor retardation, perceptual disturbances, and hallucinations (one case). Clearance was 125 +/- 55 L/h, and volume of distribution was 537 +/- 1,261. Total doses of up to 32 microg/kg of aptiganel HCl infused over 4 h are well tolerated by healthy males. Aptiganel HCl causes elevation of blood pressure and is associated with central nervous system symptoms and signs similar to other noncompetitive NMDA antagonists.

Perindopril reduces blood pressure but not cerebral blood flow in patients with recent cerebral ischemic stroke

BACKGROUND AND PURPOSE

The relationship between high blood pressure and the incidence of stroke is well established. Currently the effects of lowering blood pressure in patients with established cerebrovascular disease is undetermined, and there is continuing concern regarding the treatment of patients soon after a stroke event. Angiotensin-converting enzyme inhibitors maintain cerebral blood flow despite lowering blood pressure in patients with heart failure and otherwise uncomplicated hypertension. We tested the hypothesis that perindopril, an angiotensin-converting enzyme inhibitor with a gradual onset of action and a minimal first-dose hypotensive effect, lowers blood pressure without adversely affecting cerebral blood flow in patients 2 to 7 days after symptoms of cerebral infarction.

METHODS

Patients were randomized to receive 15 days of oral perindopril (4 mg) or placebo in a double-blind study. Blood pressure was monitored semiautomatically. Cerebral blood flow was calculated from internal carotid artery and vertebral Doppler ultrasound, supplemented by middle cerebral artery blood velocities.

RESULTS

Twenty-four patients completed the protocol; four additional patients were withdrawn for reasons unrelated to treatment. Patients on perindopril had a placebo-corrected reduction in blood pressure of 19/11 mm Hg. Blood pressure remained reduced after 2 weeks of treatment. In contrast, total cerebral blood flow was unaffected by perindopril. Neurological symptoms improved similarly in both groups.

CONCLUSIONS

Perindopril was well tolerated and effectively reduced blood pressure without reducing carotid territory blood flow in patients with symptoms of recent cerebral ischemia.

Detection of microemboli by transcranial Doppler ultrasound

Doppler ultrasound detection of abnormally high-pitched signals within the arterial waveform offers a new method for diagnosis, and potentially for prediction, of embolic complications in at-risk patients. The nature of Doppler "microembolic" signals is of particular interest in patients with prosthetic heart valves, where a high prevalence of these signals is observed. Monitoring the middle cerebral artery with 2-MHz transcranial Doppler ultrasound (TC-2000, Nicolet Biomedical; Warwick, UK), we looked for microemboli signals in 150 patients (95 women and 55 men), and found 1 or more signals during a 30-min recording in 89% of 70 patients with Bjork-Shiley valves (principally monostrut), 54% of 50 patients with Medtronic-Hall valves, and 50% of 30 patients with Carpentier-Edwards valves (p < 0.001, chi 2). In the patients with Bjork-Shiley valves, the mean number of signals per hour was 59 (range, 42-86; 95% confidence interval), which was significantly higher than the mean in patients with Medtronic-Hall and Carpentier-Edwards valves (1.5[range, 0.5-2.5] and 1 [range, 0-5.3], respectively; both p < 0.04, multiple comparisons. Bonferroni correction). In the patients undergoing serial pre- and postoperative studies, the causative role of the valve implant was emphasized. There was no correlation between the number of emboli signals and a prior history of neurologic deficit, cardiac rhythm, previous cardiac surgery, or the intensity of oral anticoagulation, in patients with prosthetic heart valves. In Bjork-Shiley patients, dual (mitral and aortic) valves were associated with more signals than were single valves. In Medtronic-Hall patients, the signal count was greater for valves in the aortic position than it was for valves in the mitral position. Comparative studies of Doppler emboli signals in other clinical settings suggest a difference in composition or size of the underlying maternal between prosthetic valve patients and patients with carotid stenosis. These studies also suggest that the signals are of gaseous origin in valve patients. The clinical significance of continuing microembolism remains to be determined.

A pilot study of streptokinase for acute cerebral infarction

We evaluated intravenous streptokinase in the treatment of cerebral infarction. Following neurological assessment and cerebral computed tomography (CT), patients aged 40-80 years with symptoms of anterior circulation acute ischaemic stroke were given 1.5 M units streptokinase or saline placebo in a double-blind randomized study. Twenty patients (10 streptokinase, 10 placebo), 11 males, 9 females, aged 57-79 years, were treated out of 512 consecutive admissions to the acute stroke unit over a 2-year period. Initial CT was normal in 11 (6 placebo, 5 streptokinase) and showed early signs of cerebral infarction in nine (4 placebo, 5 streptokinase). Median times from symptom onset to treatment were 5.2 h (placebo) and 5.8 h (streptokinase). Streptokinase treatment was associated with symptomatic hypotension in one patient. Repeat CT at 72 h demonstrated intracerebral haematoma in two patients and haemorrhagic infarction in one patient in the streptokinase group; the two cases of haematoma formation were associated with neurological deterioration and death. One patient in the placebo group had evidence of haemorrhagic infarction at 72 h. There were three deaths in each treatment group, all within the first 14 days. Patients with acute stroke can be evaluated with CT and treated with streptokinase within 6 h, but the opportunity for treatment is currently limited to few patients. Streptokinase treatment is not without risk, but potential clinical benefit justifies ongoing multicentre randomized trials.

On the origin of cerebrovascular microemboli associated with prosthetic heart valves

Application of transcranial Doppler ultrasonography to asymptomatic prosthetic heart valve patients can result in the detection of transient high intensity signals, similar to those induced by the passage of emboli. However, the origin of these signals is unknown. An in vitro study has been undertaken to investigate the capacity of prosthetic heart valves to generate high intensity Doppler signals in the absence of blood. A pulse duplicator, filled with a seeded saline solution, was used to function prosthetic heart valves under mock-physiological conditions. A Björk-Shiley Monostrut valve was mounted in the aortic port while a tri-leaflet control valve was fixed in the mitral port. At stations upstream and downstream from the Björk-Shiley valve, flow was monitored using pulsed wave Doppler ultrasound (Nicolet TC-2000, 2 MHz probe). The effect of damping the harsh closure of the mechanical valve was investigated by applying a thin layer of soft adhesive tape between the valve occluder and outer ring. For all valve configurations, transient high intensity Doppler signals, characteristic of microemboli and similar to those observed in clinical studies of prosthetic heart valve patients, were detected downstream from the aortic port. The number of microemboli signals did not change significantly between sites at 20 cm and 40 cm downstream from the aortic valve. Damping the Björk-Shiley valve closure greatly reduced (by 80%) the number of microemboli signals detected. It is concluded that Doppler microemboli signals can be generated by prosthetic heart valves while functioning in the absence of the formed elements of blood, and that the number of microemboli signals produced depends upon the rate of energy dissipation at valve closure.

Clinical pharmacology of CNS 1102 in volunteers

The high affinity noncompetitive N-methyl-D-aspartate receptor antagonist CNS 1102 (aptiganel hydrochloride, Cambridge NeuroScience, Cambridge, MA.) is neuroprotective in preclinical models of stroke when administered as pretreatment or up to 60 minutes postischemia, and has potential for treatment of acute stroke or traumatic brain injury in man. A total of 55 healthy male subjects have participated in three separate studies to determine the clinical pharmacology of CNS 1102, 43 of whom have received CNS 1102 in doses of up to 100 micrograms/kg. Administration of CNS 1102 has been studied as a 15-minute intravenous infusion, as a 15-minute loading intravenous infusion followed by a 4-hour maintenance infusion, or as a fixed-dose intravenous bolus over 90 seconds. CNS 1102 in normal volunteers is well tolerated in total doses up to 32 micrograms/kg whether as a bolus injection, 15-minute infusion or 4-hour infusion. Central nervous system affects are evident within minutes of administration, implying rapid drug penetration. CNS 1102 has a large and variable volume of distribution (mean +/- standard deviation, 6.2 +/- 1.9 l/kg), variable clearance (115 +/- 77 l/h), and plasma half-life of approximately 4.5 hours. Adjustment of doses by subject weight does not improve variability of these parameters, and fixed doses may thus be administered. CNS 1102 causes dose-dependent elevation of blood pressure, accompanied by clinical evidence of vasoconstriction. Global cerebral blood flow is maintained, whilst middle cerebral artery flow velocity increases. Symptoms of light-headedness, disorientation and paresthesia progress through euphoria, disinhibition, and hallucinations to psychomotor retardation, paranoia and catatonia as total administered dose increases.

Transcranial Doppler ultrasound signals associated with prosthetic heart valves: an in vitro study

The application of transcranial Doppler (TCD) ultrasonography to asymptomatic prosthetic heart valve patients can result in detection of localized bursts of high intensity signals, similar to those caused by the passage of emboli. The origin of these signals is not known. In order to investigate this phenomenon in a simplified, more controllable environment, a TCD machine was used to record flow downstream from mechanical prosthetic heart valves in a mock circulatory loop. The model, which uses a saline solution seeded with silk particles (< 15 micrometers) as the circulatory fluid, recreates the principal hydrodynamic characteristics of the left heart and systemic circulation. Reproducibility of the system was established through repeated testing of a Monostrut valve. Three different mechanical valve types, (Monostrut, Medtronic Hall, St. Jude Medical) were tested over a range of simulated cardiac outputs, and the effect of valve size was investigated with four Omniscience tilting disc valves (21, 23, 25 and 29 mm). Average energy of the reflected Doppler signal was used to quantify the amount of high intensity Doppler signal, QTCD. TCD signals recorded in vitro were visually and aurally similar to those found in prosthetic heart valve patients. All valve types generated exponentially more QTCD with increasing simulated cardiac output. Differences amongst valve types were only significant at higher flow outputs, with the Monostrut valve producing the greatest QTCD. Larger valves consistently generated greater QTCD than smaller valves. In conclusion, TCD signals found in prosthetic heart valve patients can be reproduced, at least qualitatively, using a mock circulatory loop which does not incorporate the formed elements of blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasonic evaluation of movement of the diaphragm after acute cerebral infarction

Respiratory dysfunction is an important complication of acute stroke but its mechanisms are poorly understood. Previous indirect assessments suggest that paralysis of the diaphragm occurs contralateral to the cerebral lesion. Diaphragmatic excursion was studied with real time ultrasound during quiet and deep breathing in 50 patients within 72 hours of acute stroke and 40 controls. During quiet breathing, hemidiaphragmatic movements were not significantly different between right hemispheric stroke, left hemispheric stroke, and controls. During deep inspiration, there was a significant bilateral reduction in hemi-diaphragmatic excursion in patients with stroke, for both right hemispheric stroke and left hemispheric stroke when compared with controls (both P < 0.001). Thus isolated hemidiaphragmatic paresis does not occur but maximal excursion of the diaphragm is reduced bilaterally in patients with acute stroke. This is a likely contributor to the respiratory dysfunction after acute stroke.

Transcranial Doppler ultrasound in commercial air divers: a field study including cases with right-to-left shunting

Many cases of decompression illness occur in divers using recommended decompression tables. Doppler ultrasound has been used for over 20 yr and has shown the presence of venous bubbles in asymptomatic divers working well within decompression limits. Previous studies have demonstrated an increased prevalence of patent foramen ovale in divers who have suffered neurologic decompression illness. It has been postulated that right-to-left shunting through a patent foramen ovale could allow arterialization of these bubbles, causing symptoms and signs of acute decompression illness and possibly chronic subclinical neurologic impairment. We set out to determine the incidence of bubbles in the cerebral circulation of commercial divers decompressing from air dives. Using transcranial Doppler ultrasound (TCD), the middle cerebral arteries of 17 divers were monitored after surfacing from depths ranging between 3 and 50 m. Peripheral contrast injection with simultaneous transthoracic echocardiography and TCD was used to screen for right-to-left shunting. Right-to-left shunting was detected in four divers by TCD (one at rest, two after a Valsalva maneuver, and one only after coughing); however, echocardiography was positive in only one of these subjects after a Valsalva maneuver (TCD was positive at rest in this subject). Seventy-three TCD recordings were performed in four settings: 41 after underwater decompression, 18 after surface decompression, 10 in the interval between surfacing and entering the decompression chamber, and 4 after a chamber dive. Twenty-three of these recordings were in four subjects with right-to-left shunting; no bubbles were detected in any of these recordings.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and cerebral hemodynamic responses to the noncompetitive N-methyl-D-aspartate (NMDA) antagonist CNS 1102

The excitatory amino acid antagonists are being developed as neuroprotective drugs aimed at limiting ischemic neuronal damage. Their hemodynamic and neurologic side effects are important in assessing safety and tolerability. We studied CNS 1102, a high-affinity noncompetitive N-methyl-D-aspartate (NMDA) receptor-channel antagonist, in normal volunteers. The effects of 2 mg CNS 1102 were assessed in a single-blind, placebo-controlled, fixed-dose, cross-over trial comparing administration by intravenous infusion for 15 min or bolus for 2 min in 8 healthy male subjects. Cerebral hemodynamics were studied with carotid and vertebral duplex ultrasound imaging, common carotid artery walltracking, and middle cerebral artery velocity readings. CNS 1102 administration was associated with light-headedness, mild disorientation, perioral and peripheral paresthesias, and flushing. Mean arterial blood pressure (MAP) increased significantly from baseline 1 h after CNS 1102 administration, with a maximal increase of 17 mm Hg over placebo. Pulse rate was unchanged. Common carotid artery pulsatility decreased by 38.4% [8.3-64.5, 95% confidence interval (CI)] and vertebral pulsatility by 43.8% [11.5-74.1], both p < 0.02. No significant differences were detected for other velocity and flow parameters. Middle cerebral artery mean velocity increased by 4.6 cm/s (1.6-7.8 cm/s) and diastolic velocity by 4.6 cm/s (2.4-7.3 cm/s) (both p < 0.01), but systolic velocity was unchanged. The middle cerebral pulsatility index decreased by 11% (3.8-16.1), p < 0.001. CNS 1102 is well tolerated at a fixed dose of 2 mg in normal volunteers. Cerebral arteriolar constriction is inferred from the ultrasound results.(ABSTRACT TRUNCATED AT 250 WORDS)

Poor accuracy of stroke scoring systems for differential clinical diagnosis of intracranial haemorrhage and infarction

The differentiation of cerebral infarction and cerebral haemorrhage is the most important first step in the management of acute stroke, because clinical management of the two disorders differs substantially. The Guy's Hospital and Siriraj stroke diagnostic scores were developed to aid clinicians in this decision. We have tested the performance of the two scores on a group of 1059 patients admitted to the acute stroke unit (ASU) at the Western Infirmary, Glasgow, with suspected stroke between May, 1990, and December, 1993. The diagnosis was confirmed as stroke by computed tomography (CT) scanning or necropsy (n = 10) in 991 patients. For each clinical score we subjectively identified the cut-off point that maximised sensitivity to cerebral haemorrhage with the smallest loss of specificity. At its optimum cut-off point the Guy's Hospital score had a sensitivity for the diagnosis of haemorrhage of 70% and specificity of 64%. The corresponding figures for the Siriraj score at its optimum cut-off point were 68% sensitivity and 64% specificity. The overall predictive accuracy of both scores was 64%. The greater complexity of the Guy's Hospital score (thirteen variables included) did not result in substantially superior performance to the Siriraj score (five variables). This validation study suggests that neither score is useful for exclusion of haemorrhage before anticoagulant treatment is initiated or as a diagnostic screening procedure for trials of low-risk treatments such as aspirin. Our findings emphasise the need for routine CT scanning in this setting, since this method remains the most accurate for differentiating between haemorrhage and infarction.

Differentiation between gaseous and formed embolic materials in vivo. Application in prosthetic heart valve patients

BACKGROUND AND PURPOSE

Doppler emboli detection is an established technique, but the nature of the underlying embolic material remains unclear. The intensity and spectral distribution of emboli signals could help to distinguish between signals arising from formed and gaseous emboli. We undertook this study to develop and evaluate a differentiation algorithm based on the spectral characteristics of emboli signals. Subsequently the algorithm was applied to patients with mechanical prosthetic cardiac valves.

METHODS

Emboli signals detected in patients with carotid disease, acute stroke, and atrial fibrillation were used as formed emboli data, and signals detected in patients undergoing cardiac catheterization studies were used as gaseous emboli data. For each embolus signal, the maximal amplitude, the sum of amplitudes, and the spectral intensity distribution were calculated. Two hundred emboli signals from each category were used to develop a differentiation algorithm, which was subsequently evaluated on 501 additional solid and 995 gaseous emboli signals. The same algorithm was used to analyze 5958 emboli signals detected in 60 patients with mechanical prosthetic valves.

RESULTS

The best results were obtained with an algorithm based on both the maximal amplitude and the sum of amplitudes (sensitivity, 99%; specificity, 96.5%). On subsequent evaluation, the sensitivity and specificity of the algorithm were 99.6% and 89.8%, respectively. Of the 5958 emboli signals detected in prosthetic valve patients, 92.4% were classified as gaseous.

CONCLUSIONS

Differentiation between gaseous and formed emboli signals, as detected by transcranial Doppler in vivo, is feasible by means of spectral analysis. Application of the differentiation algorithm in prosthetic valve patients suggests that the embolic material in these patients is gaseous. The possibility of distinguishing between different formed embolic materials with this technique remains to be evaluated.