Risk factors for progression of visual field abnormalities in normal-tension glaucoma

PURPOSE

To uncover risk factors for the highly variable individual rates of progression in cases of untreated normal-tension glaucoma.

METHODS

Visual field data were assembled from 160 subjects (160 eyes) enrolled in the collaborative normal-tension glaucoma study during intervals in which the eye under study was not receiving intraocular pressure-lowering treatment during prerandomization and postrandomization intervals. Analyses included multivariate analysis of time-dependent Cox proportional hazard, Kaplan-Meier analysis of "survival" without an increment of visual field worsening, and comparison of slopes of change in mean deviation global index over time.

RESULTS

Most migraine occurred in women, but analysis demonstrated that gender and presence of migraine contribute separately to the overall risk. The risk ratio for migraine, adjusted for the other variables was 2.58 (P =.0058), for disk hemorrhage was 2.72 (P =.0036), and for female gender 1.85 (P =.0622). The average fall in the mean deviation index was faster in nonmigrainous women than in nonmigrainous men (P =.05). Suggesting genetic influence, Asians had a slower rate of progression (P =.005), and the few black patients enrolled had a tendency for faster progression. However, self-declared history of family with glaucoma or treated for glaucoma did not affect the rate of progression. Neither age nor the untreated level of intraocular pressure affected the rate of untreated disease progression, despite their known influence on prevalence.

CONCLUSIONS

Whereas risk factors for prevalence help select populations within which to screen for glaucoma, the factors that affect the rate of progression help decide the expected prognosis of the individual's untreated disease and thereby the frequency of follow-up and aggressiveness of the therapy to be undertaken.

Biochemical variations in the synaptic level of dopamine precede motor fluctuations in Parkinson's disease: PET evidence of increased dopamine turnover

Motor fluctuations are a major disabling complication in the treatment of Parkinson's disease. To investigate whether such oscillations in mobility can be attributed to changes in the synaptic levels of dopamine, we studied prospectively patients in the early stages of Parkinson's disease with a follow-up after at least 3 years of levodopa treatment. At baseline, 3 positron emission tomography (PET) scans using [11C]raclopride before and after (1 hour and 4 hours) orally administered levodopa were performed on the same day for each patient. Patients who developed "wearing-off" fluctuations during the follow-up period had a different pattern of levodopa-induced changes in [11C]raclopride binding potential (BP) from that observed in patients who were still stable by the end of the follow-up. Thus, 1 hour post-levodopa the estimated increase in the synaptic level of dopamine was 3 times higher in fluctuators than in stable responders. By contrast, only stable responders maintained increased levels of synaptic dopamine in the PET scan performed after 4 hours. These results indicate that fluctuations in the synaptic concentration of dopamine precede clinically apparent "wearing-off" phenomena. The rapid increase in synaptic levels of dopamine observed in fluctuators suggests that increased dopamine turnover might play a relevant role in levodopa-related motor complications.

Biochemical variations in the synaptic level of dopamine precede motor fluctuations in Parkinson's disease: PET evidence of increased dopamine turnover

Motor fluctuations are a major disabling complication in the treatment of Parkinson's disease. To investigate whether such oscillations in mobility can be attributed to changes in the synaptic levels of dopamine, we studied prospectively patients in the early stages of Parkinson's disease with a follow-up after at least 3 years of levodopa treatment. At baseline, 3 positron emission tomography (PET) scans using [11C]raclopride before and after (1 hour and 4 hours) orally administered levodopa were performed on the same day for each patient. Patients who developed "wearing-off" fluctuations during the follow-up period had a different pattern of levodopa-induced changes in [11C]raclopride binding potential (BP) from that observed in patients who were still stable by the end of the follow-up. Thus, 1 hour post-levodopa the estimated increase in the synaptic level of dopamine was 3 times higher in fluctuators than in stable responders. By contrast, only stable responders maintained increased levels of synaptic dopamine in the PET scan performed after 4 hours. These results indicate that fluctuations in the synaptic concentration of dopamine precede clinically apparent "wearing-off" phenomena. The rapid increase in synaptic levels of dopamine observed in fluctuators suggests that increased dopamine turnover might play a relevant role in levodopa-related motor complications.

Natural history of normal-tension glaucoma

OBJECTIVE

A recently reported randomized study described the role of intraocular pressure (IOP) in normal-tension glaucoma (NTG) pathogenesis and the effect of therapeutic lowering of IOP. This is a report of an analysis of the natural course of NTG during the time eyes were not receiving therapy, either in the time interval awaiting randomization or after being randomly assigned not to receive treatment to lower the IOP.

DESIGN

Analysis of prospectively collected data on the long-term course of a cohort of untreated subjects with normal-tension glaucoma, a subset of subjects enrolled in a randomized controlled clinical trial. RANDOMIZATION AND SUBJECT SELECTION: If the field defect in the study eye threatened the point of fixation, the subject was randomly assigned to start on treatment immediately or to be observed without treatment until progression was documented. Otherwise, an eye was randomly assigned only when and if, subsequent to enrollment, it showed visual field progression, progression of optic disc cupping, or a new disc hemorrhage.

PARTICIPANTS

Data were collected for this report on 160 subjects observed without treatment among a total enrollment of 260. They consist of 49 subjects who were randomly assigned on enrollment not to receive therapy, 24 followed without treatment for a time until later being randomly assigned to treatment, 31 similarly followed without treatment and who were later randomly assigned to be followed for an additional time without treatment, and 56 who enrolled but were never randomly assigned.

MAIN OUTCOME MEASURES

Visual field data were used in this report only from the interval during which the eye had not been assigned to receive therapy and were analyzed by two measures of progression: the "survival" time to meeting a criterion of confirmed localized progression and the rate of change in the mean deviation (MD) index over time.

RESULTS

The four subgroups just described were similar at baseline, except that the average MD index was slightly better for the 56 eyes that never progressed during the period of follow-up. By Kaplan-Meier analysis of all untreated subjects combined, approximately one third showed localized progression within 3 years and about half within 5 to 7 years. Of subjects followed for 3 years or more, 62 of 109 did not show a statistically significant negative slope of MD regressed over time, whereas the others showed a statistically significant MD decline, mainly between -0.2 and -2 db per year.

CONCLUSIONS

Some cases of NTG progress more rapidly than others. Although approximately half of cases showed a confirmed localized visual field deterioration by 7 years, the change is typically small and slow, often insufficient to measurably affect the MD index.

Intravenous tissue plasminogen activator for acute ischemic stroke: A Canadian hospital's experience

BACKGROUND AND PURPOSE

In the United States, tissue plasminogen activator (tPA) was approved for treatment of acute ischemic stroke in 1996. Its use has only recently been approved in Canada. We sought to evaluate the safety, feasibility, and efficacy of treatment in a Canadian hospital setting.

METHODS

A combined retrospective and prospective review is presented of 46 consecutive patients treated with intravenous tPA at our hospital with a treatment protocol similar to that of the National Institute of Neurological Disorders and Stroke (NINDS) trial.

RESULTS

Symptomatic intracranial hemorrhage at 36 hours occurred in 1 patient (2.2%). The median time to treat was 165 minutes, with a median "door-to-needle" time of 84 minutes. Compared with patients presenting initially at our hospital, patients transferred from another institution for tPA therapy were treated closer to the 3-hour time window (mean 173 versus 148 minutes, P:<0.001) but had a shorter door-to-needle time (43 versus 102 minutes, P:<0.001). For every 10 minutes closer to the 3-hour time window that any patient arrived at the hospital, 7 minutes was saved in the door-to-needle time (correlation coefficient 0.9, P:<0.001). Patient outcome did not differ from that in the NINDS trial (P:>0.75).

CONCLUSIONS

Our safety and patient outcome data compare favorably with NINDS and Phase IV data. Although a 3-hour treatment window was feasible, the median door-to-needle time lengthened as more treatment time was available and the door-to-needle time was beyond recommended standards. This review has prompted changes in our community to improve treatment efficiency.

Long term outcome of unilateral pallidotomy: follow up of 15 patients for 3 years

OBJECTIVES

With the advent of new antiparkinsonian drug therapy and promising results from subthalamic and pallidal stimulation, this study evaluated the long term efficacy of unilateral pallidotomy, a technique which has gained popularity over the past decade for the management of advanced Parkinson's disease.

METHODS

The 15 patients reported here are part of the original cohort of 24 patients who underwent posteroventral pallidotomy for motor fluctuations and disabling dyskinesias 3 years ago as part of a prospective study. Evaluation scales included the unified Parkinson's disease rating scale, the Goetz dyskinesia scale, and the Purdue pegboard test.

RESULTS

When compared with the prepallidotomy scores, the reduction in the limb dyskinesias and off state tremor scores persisted on the side contralateral to pallidotomy at the end of 3 years (dyskinesias were reduced by 64% (p<0.01) and tremor by 63% (p<0.05). Other measures tended to deteriorate. The dosage of antiparkinsonian medications did not change significantly from 3 months prepallidotomy to 3 years postpallidotomy.

CONCLUSIONS

Although unilateral pallidotomy is useful in controlling the contralateral dyskinesias and tremor 3 years after surgery, all other early benefits disappear and activities of daily living continue to worsen.

Evidence for impaired presynaptic dopamine function in parkinsonian patients with motor fluctuations

We used [18F]6-fluorodopa (FD) positron emission tomography (PET) to examine the severity of nigrostriatal dopaminergic dysfunction in 67 patients with Idiopathic Parkinsonism (IP), 52 with fluctuations and 15 with a stable response to levodopa. FD uptake (Ki) was reduced by 12% in the caudate (p = 0.08) and by 28% in the putamen (p = 0.0004) of patients with fluctuations compared to those with a stable response. However, there was considerable overlap of FD Ki values between the two groups. The fluctuators had a longer symptom duration (11.6 +/- 5.7 years) than the patients with a stable response to levodopa (4.3 +/- 2.4 years; p < 0.0001) and the age of onset of symptoms was earlier in the fluctuators (43.9 +/- 8.9 versus 54.1 +/- 10.4; p = 0.0004). Similar reductions in FD Ki in the fluctuators persisted following adjustment for these variables (7.5% in the caudate and 26% in the putamen; p = n.s. and 0.007, respectively). When smaller groups (n = 15 each) were matched for duration of symptoms, the reduction in caudate Ki in the fluctuators was only 1.9% (p = n.s.), but there was still a 24% reduction in putamen Ki (p = 0.05). These findings suggest that fluctuators and non-fluctuators may differ in the severity of their nigrostriatal damage and provide modest support for the hypothesis that fluctuations may in part reflect altered "buffering" capacity of dopaminergic nerve terminals. However, the considerable overlap between groups suggests that other factors such as altered postsynaptic mechanisms and/or increased turnover of dopamine may make a substantial contribution to the development of motor fluctuations.

Metatarsalgia and rheumatoid arthritis--a randomized, single blind, sequential trial comparing 2 types of foot orthoses and supportive shoes

OBJECTIVE

To compare the effects of semi-rigid and soft orthoses worn in supportive shoes, and supportive shoes worn alone, on metatarsal phalangeal (MTP) joint pain. MTP joint synovitis, and lower extremity function in patients with rheumatoid arthritis.

METHODS

Twenty-eight subjects referred to occupational therapy received in random order 3 interventions for 12 week trials, separated by 2 week washouts. A crossover design compared effectiveness of interventions.

RESULTS

Twenty-four subjects completed the study. A reduction in mean pain scores from baseline to final visits showed that semi-rigid orthoses had a highly significant effect on pain. Soft orthoses did not show a significant effect on pain from baseline to final visit, nor did shoes worn alone. None of the interventions had a significant effect on synovitis or function.

CONCLUSION

Semi-rigid orthoses worn in supportive shoes were an effective treatment for metatarsalgia. Supportive shoes worn alone or worn with soft orthoses did not provide pain relief for metatarsalgia.

Embryonic ventral mesencephalic grafts improve levodopa-induced dyskinesia in a rat model of Parkinson's disease

We investigated the role of dopamine neurons in the manifestation of levodopa-induced dyskinesia in a rat model of Parkinson's disease. Daily treatment with a subthreshold dose of levodopa gradually induced abnormal involuntary movements (AIM) in 6-hydroxydopamine-lesioned rats, which included stereotypy and contraversive rotation. After 4 weeks of levodopa treatment, rats with mild and severe AIM were assigned to two treatment subgroups. The graft subgroup received embryonic ventral mesencephalic tissue into the striatum, whilst the sham-graft subgroup received vehicle only. Rats continued to receive levodopa treatment for 3 months post-graft. Brain sections at the level of the basal ganglia were processed for autoradiography using a ligand for dopamine transporter, and in situ hybridization histochemistry for mRNAs encoding postsynaptic markers. Levodopa-induced AIM significantly improved in grafted rats. The severity of AIM correlated inversely with the density of dopamine nerve terminals in the striatum (P < 0. 001), with almost no AIM when the density of dopamine nerve terminals was >10-20% of normal. Embryonic dopamine neuronal grafts normalized not only mRNA expression for preproenkephalin (PPE) in the indirect pathway, but also mRNA expression for prodynorphin (PDyn) in the direct pathway, which was upregulated by levodopa treatment. AIM scores correlated linearly with expression of PPE mRNA in the indirect pathway (P < 0.001) and also with PDyn mRNA in the direct pathway (P < 0.001). We conclude that embryonic dopamine neuronal grafts may improve levodopa-induced dyskinesia by restoring altered activities of postsynaptic neurons, resulting not only from dopamine denervation, but also from levodopa therapy, provided that the density of striatal dopaminergic nerve terminals is restored above a 'threshold' level.

Head tremor in cervical dystonia

OBJECTIVE

To compare the clinical characteristics, natural history, and therapeutic outcome of patients with cervical dystonia (CD) with head tremor (HT+) and without head tremor (HT-).

METHODS

We prospectively evaluated 114 consecutive patients of CD over a 9-month period with a detailed questionnaire. Chi-square and t-tests were employed for statistical analysis.

RESULTS

Seventy-eight (68.4%) patients had head tremor and 27 of them (34.6%) had tremor as one of the first symptoms. Age at onset of symptoms were similar in HT+ and HT- groups; however there was a higher prevalence in women in the former group (66.7% vs. 41.7%; p=0.01). HT+ patients had more frequent positive family history of essential-like hand/head tremor (21.8% vs. 5.5%; p<0.05), associated neck pain (92.3% vs. 77.8%: p<0.05), and essential-like hand tremor (40% vs. 8.3%; p<0.001). They also appeared to have more frequent history of preceding head/neck trauma (14.1% vs. 8.3%), frequent head rotation (88.5% vs. 69.4%) and antecollis (12.8% vs. 5.5%) but less often head tilt (37.2% vs. 47.2%) and gestes antagonistes (60.2% vs. 75%) than the HT- patients; however these differences were not statistically significant. The frequency of prior psychiatric illnesses, the incidence of dystonias in other parts of the body, frequency of retrocollis and shoulder elevation, and spontaneous remission were similar in the two groups.

CONCLUSION

Head tremor is common in CD and is more commonly associated with hand tremor and family history of tremor or other movement disorders. This supports a possible genetic association between CD and essential tremor (ET). Linkage studies are required to evaluate the genetic association between CD and ET.

In vivo positron emission tomographic evidence for compensatory changes in presynaptic dopaminergic nerve terminals in Parkinson's disease

Clinical symptoms of Parkinson's disease (PD) do not manifest until dopamine (DA) neuronal loss reaches a symptomatic threshold. To explore the mechanisms of functional compensation that occur in presynaptic DA nerve terminals in PD, we compared striatal positron emission tomographic (PET) measurements by using [11C]dihydrotetrabenazine ([11C]DTBZ; labeling the vesicular monoamine transporter type 2), [11C]methylphenidate (labeling the plasma membrane DA transporter), and [18F]dopa (reflecting synthesis and storage of DA). Three consecutive PET scans were performed in three-dimensional mode by using each tracer on 35 patients and 16 age-matched, normal controls. PET measurements by the three tracers were compared between subgroups of earlier and later stages of PD, between drug-naive and drug-treated subgroups of PD, and between subregions of the parkinsonian striatum. The quantitative relationships of [18F]dopa and [11]DTBZ, and of [11C]methylphenidate and [11C]DTBZ, were compared between the PD and the normal control subjects. We found that [18F]dopa Ki was reduced less than the binding potential (Bmax/Kd) for [11C]DTBZ in the parkinsonian striatum, whereas the [11C]methylphenidate binding potential was reduced more than [11C]DTBZ binding potential. These observations suggest that the activity of aromatic L-amino acid decarboxylase is up-regulated, whereas the plasma membrane DA transporter is down-regulated in the striatum of patients with PD.

Prognostic implications of differences in telomere length between normal and malignant cells from patients with chronic myeloid leukemia measured by flow cytometry

Chronic myeloid leukemia (CML) is a clonal, multilineage myeloproliferative disorder characterized by the Philadelphia chromosome (Ph) and a marked expansion of myeloid cells. Previous studies have indicated that the telomere length in blood cells may indicate their replicative history. However, the large variation in telomere length between individuals complicates the use of this parameter in CML and other hematologic disorders. To circumvent this problem, we compared the telomere length in peripheral blood or bone marrow cells with purified normal (Ph(-)) T lymphocytes from the same CML patient using fluorescence in situ hybridization and flow cytometry. Overall telomere fluorescence was significantly reduced in Ph(+) cells from patients with CML compared to blood leukocytes from normal individuals (P < 0.001) or normal (Ph(-)) T lymphocytes from the same individuals (n = 51, P < 0.001). Cells from patients in accelerated phase or blast phase (AP/BP) showed significantly shorter average telomere length than cells from patients in chronic phase (CP, P = 0.02) or cytogenetic remission (CR, P = 0.03). Patients in CP who subsequently developed BP within 2 years had significantly shorter telomeres than those who did not develop BP for at least 2 years (P < 0.05). Accelerated replication-dependent telomere shortening in Ph(+ )versus Ph(-) leukocytes supports previous evidence that Ph(+) stem cells cycle more actively than their counterparts in normal individuals. Our data further suggest that telomere shortening may serve as a surrogate marker of disease progression in patients with CP CML, supporting a mechanistic link between CML stem cell turnover, genetic instability, and malignant evolution in this disease. (Blood. 2000;95:1883-1890) (Blood. 2000;95:1883-1890)

At issue: schizophrenia and rheumatoid arthritis: the negative association revisited

A strong negative association between schizophrenia and rheumatoid arthritis (RA), implying low comorbidity, has been found in 12 of 14 previous studies, which we review. To this literature we add two recently acquired data sets encompassing 28,953 schizophrenia patients, only 31 of whom had comorbid RA. Integrating our new data into those of the previous nine studies, which stratified their populations according to psychiatric diagnosis, we obtain a median frequency of RA in schizophrenia populations of 0.09 percent and a mean frequency of 0.66 percent, well below the expected range of 1 percent. These data robustly support prior studies. We also present a meta-analysis evaluating the association between the two diseases by integrating information derived from nine data sets, each furnishing an estimate of the relative risk of RA in schizophrenia patients versus that in other psychiatric patients. We find that the estimated rate of RA among schizophrenia patients is only 29 percent of the corresponding rate in other psychiatric patients. Further, the relative risk of RA in schizophrenia patients versus that in the general population is even less than 29 percent and could be as low as one-third of this value. We present a new hypothesis involving the platelet activating factor system in an effort to account for this negative association and review the suggestions of other investigators toward this end. Finally, we consider the glutamatergic system dysfunction hypothesis of schizophrenia and suggest a possible common pharmacological approach that may ameliorate some of the symptomatology of both schizophrenia and RA.

Post-traumatic cervical dystonia: a distinct entity?

BACKGROUND/OBJECTIVE

The incidence of head/neck trauma preceding cervical dystonia (CD) has been reported to be 5-21%. There are few reports comparing the clinical characteristics of patients with and without a history of injury. Our aim was to compare the clinical characteristics of idiopathic CD (CD-I) to those with onset precipitated by trauma (CD-T).

METHODS

We evaluated 114 consecutive patients with CD over a 9-month period. All patients were interviewed using a detailed questionnaire and had a neurological examination. Their clinical charts were also reviewed.

RESULTS

Fourteen patients (12%) had mild head/neck injury within a year preceding the onset of CD. Between the two groups (CD-I and CD-T), the gender distribution (F:M of 3:2), family history of movement disorders (32% vs. 29%), the prevalence of gestes antagonistes (65% vs. 64%), and response to botulinum toxin were similar. There were non-specific trends, including an earlier age of onset (mean ages 43.3 vs. 37.6), higher prevalence of neck pain (86% vs. 100%), head tremor (67% vs. 79%), and dystonia in other body parts (23% vs. 36%) in CD-T.

CONCLUSIONS

CD-I and CD-T are clinically similar. Trauma may be a triggering factor in CD but this was only supported by non-significant trends in its earlier age of onset.

Occupational risk factors in Parkinson's disease

BACKGROUND

An apparent excess of teachers and healthcare workers among the Parkinson's disease patients of a large tertiary care movement disorders clinic suggested the hypothesis that high exposure to viral (or other) respiratory infections in these occupations might be a risk factor for Parkinson's disease.

METHODS

A case-control study of the association between occupation and Parkinson's disease was conducted. Cases (414) were all Parkinson's disease patients seen at the University of British Columbia Hospital Movement Disorders Clinic between 1986 and 1993, residing in Greater Vancouver, and under 65 in 1991. Controls (6,659) were randomly selected from the 1991 Canadian Census.

FINDINGS

Parkinson's disease was associated with teaching (OR 2.50, 95% CI 1.67-3.74) and occupation in healthcare services (OR 2.07, 95% CI 1.34-3.20), but there were several other substantial associations, both positive and negative.

INTERPRETATION

While referral bias cannot be ruled out, the authors find the consistency of the overall pattern of associations with the respiratory infection hypothesis striking.

Unilateral pallidotomy for reduction of parkinsonian pain

OBJECT

The goal of this study was to determine whether unilateral pallidotomy reduces parkinsonian pain.

METHODS

Twenty-one patients suffering from Parkinson's disease (PD) were followed prospectively for 1 year after they had undergone a unilateral pallidotomy to assess the procedure's effect on pain related to PD. Pain unrelated to PD was not studied. Patients scored the level of their PD pain on an ordinal scale (0-10 points) preoperatively and 6 weeks and 1 year postoperatively. The results were analyzed using Wilcoxon's paired-ranks test (with Bonferroni correction) and showed a significant reduction in overall pain scores at 6 weeks (p < 0.001) and 1 year (p = 0.001) following pallidotomy. Various types of PD pain are described and their possible pathophysiological mechanisms are presented.

CONCLUSIONS

Unilateral pallidotomy significantly reduces pain attributable to Parkinson's disease.

Reassessment of unilateral pallidotomy in Parkinson's disease. A 2-year follow-up study

Unilateral pallidotomy has gained popularity in treating the motor symptoms of Parkinson's disease. We present the results of a 2-year post-pallidotomy follow-up study. Using the Unified Parkinson's Disease Rating Scale (UPDRS), the Goetz dyskinesia scale and the Purdue Pegboard Test (PPBT), we evaluated 20 patients at regular intervals both off and on medications for 2 years post-pallidotomy. There were no significant changes in the dosages of antiparkinsonian medications from 3 months pre-pallidotomy to 2 years post-pallidotomy. On the side contralateral to the operation, the improvements were preserved in 'on'-state dyskinesia (83% reduction from pre-pallidotomy to 2 years post-pallidotomy, P < 0.001) and 'off'-state tremor (90% reduction from pre-pallidotomy to 2 years post-pallidotomy, P = 0.005). There were no statistically significant differences between pre-pallidotomy scores and those at 2 years post-pallidotomy in ipsilateral dyskinesia, axial dyskinesia, 'off'- or 'on'-state PPBT, 'off'-state Activities of Daily Living (ADL) and 'off'-state gait and postural stability. After 2 years, the 'on'-state ADL scores worsened by 75%, compared with pre-pallidotomy (P = 0.005). We conclude that 2 years after pallidotomy, the improvements in dyskinesia and tremor on the side contralateral to pallidotomy are preserved, while the initial improvements in most other deficits disappear, either because of progression of pathology or loss of the early efficacy achieved by surgery.

Reproducibility studies with 11C-DTBZ, a monoamine vesicular transporter inhibitor in healthy human subjects

The reproducibility of (+/-)-alpha-[11C] dihydrotetrabenazine (DTBZ) measures in PET was studied in 10 healthy human subjects, aged 22-76 y.

METHODS

The scan-to-scan variation of several measures used in PET data analysis was determined, including the radioactivity ratio (target-to-reference), plasma-input Logan total distribution volume (DV), plasma-input Logan Bmax/Kd and tissue-input Logan Bmax/Kd values.

RESULTS

The radioactivity ratios, plasma-input Bmax/Kd and tissue-input Bmax/Kd all have higher reliability than plasma-input total DV values. In addition, measures using the occipital cortex as the reference region have higher reliability than the same measures using the cerebellum as the reference region.

CONCLUSION

Our results show that DTBZ is a reliable PET tracer that provides reproducible in vivo measurement of striatal vesicular monoamine transporter density. In the selection of reference regions for DTBZ PET data analysis, caution must be exercised in circumstances when DTBZ binding in the occipital cortex or the cerebellum may be altered.

Reporting risks and benefits of therapy by use of the concepts of unqualified success and unmitigated failure: applications to highly cited trials in cardiovascular medicine

BACKGROUND

The NNT (number needed to treat) and NNH (number needed to harm) are useful in conveying the results of clinical trials because they emphasize the effort that must be expended to accomplish a single, tangible outcome. But NNT conveys the effort required to achieve a positive outcome without distinguishing between the presence or absence of treatment-related adverse events. Similarly, NNH conveys harm without accounting for the achievement or lack of achievement of the benefit of therapy. Consequently, a mathematical model was developed to extend the NNT and NNH to represent the effort required to achieve "unqualified success" (NNTUS, treatment success without treatment-induced side effects) and "unmitigated failure" (NNHUF, lack of treatment success with treatment-induced side effects).

METHODS AND RESULTS

NNTUS was calculated by adjusting the absolute risk reduction to allow for the probability of not incurring a treatment-related adverse event. NNHUF was similarly calculated by adjusting the absolute risk of incurring a treatment-related adverse event by the probability of not incurring any treatment-related benefit. The impact of conveying clinical trial data by the use of NNT, NNTUS, NNH, and NNHUF is illustrated by means of 11 highly cited trials identified systematically from the cardiovascular literature. The treatment effort measured by the NNTUS and the NNHUF was consistently higher than that given by the traditional NNT and NNH. These increments ranged from 1% to several hundred percent.

CONCLUSIONS

The NNTUS and the NNHUF represent the treatment effort required on average to achieve 1 unqualified success and 1 unmitigated failure. NNTUS and NNHUF balance benefit and harm in an objective way and are relevant for making service delivery decisions.

On the survival time of a tangled neuron in the hippocampal CA4 region in parkinsonism dementia complex of Guam

In diseases such as the Parkinson dementia complex of Guam (PDC) or Alzheimer's disease, susceptible neurons develop intracellular tangles (iNFTs) and then die, leaving behind extracellular tangles (eNFTs). We performed counts of healthy neurons, iNFTs, and eNFTs in the hippocampus of Guamanian Chamorros who were neurologically normal or who suffered from PDC. The total of surviving and dead neurons in the CA4 region was remarkably constant from case to case, indicating that eNFTs are not phagocytosed. Since cases of recent PDC showed only marginal tangle formation in CA4, we concluded that tangle development in CA4 commenced close to the onset of the disease. Based on this assumption, as well as the further assumption that the average rate of tangle development and the average lifetime of a tangled neuron do not alter as the disease progresses, we derived equations to determine the average lifetime of tangled neurons. The results varied from 0.13 years for the most rapidly progressing case to 7.98 years for the most slowly developing case. The average for 8 cases was 2.51 years.

Ultrasound fetal biometry charts for a North American Caucasian population

PURPOSE

This study was done to produce enhanced fetal biometry charts and graphs presenting percentile values as a function of fetal age.

METHODS

The relationships between the ultrasound measurements of 10 fetal parameters and menstrual age were determined by a cross-sectional study. Data were obtained from 508 to 790 fetuses. Anatomic structures were scanned and measured 3 times during 1 routine sonographic examination. The study group consisted of 1,396 Caucasian women who had normal singleton fetuses with confirmation of menstrual dates by sonography before 14 weeks and for whom complete pregnancy outcome information was available. For each of the 10 parameters, percentile curves were derived for the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles.

RESULTS

Ready-to-use fetal measurement charts and graphs are presented in a format giving the percentile values as a function of fetal age. There were no significant differences between male and female fetuses.

CONCLUSIONS

These fetal biometry charts and graphs, obtained from a North American Caucasian population, enhance previously published data.

Age-dependent decline of dopamine D1 receptors in human brain: a PET study

Radioligand binding studies in animals have demonstrated age-related loss of dopamine receptors in the caudate and putamen. In humans, while age-related declines in dopamine D2 receptors have been consistently reported, the effects of ageing on D1 receptors have been controversial. We used positron emission tomography (PET) with [11C]SCH 23390 to investigate dopamine D1 receptor binding in 21 normal volunteers aged 22-74 years. We also assessed their motor function with a Modified Columbia Score (MCS) and the Purdue Pegboard Test (PPBT). D1 binding potentials were derived using a graphical analysis with a cerebellar tissue input function. Standard linear regression techniques were used to determine the age-related rate of decline of D1 binding. We found an age-dependent decrease of D1 receptor binding in the caudate (6.9% per decade) and putamen (7.4% per decade). There was also a significant inverse correlation between [11C]SCH 23390 binding in the occipital cortex and age (8.6% decline per decade). PPBT score also decreased with age (P = 0.007). There was a direct correlation between PPBT score and D1 binding potential. We conclude that dopamine D1 receptor density declines with age and that the effects of physiological ageing may play a role in the expression of extrapyramidal disorders in the elderly.

Quantitative comparison of three- and two-dimensional PET with human brain studies

The aim of this study was to test the quantitation accuracy of three-dimensional PET in brain scanning.

METHODS

Three-dimensional data from 11 human subjects were tested using 11C-dihydrotetrabenazine, 11C-Schering 23390 and 18F-FDG as tracers. Two-dimensional scans were performed on the same subjects and the distribution volume, distribution volume ratio and local metabolic rate of glucose (LMRGlu) values obtained from these were used as reference. Three-dimensional data were processed as follows: iterative convolution subtraction scatter correction, detector normalization including radial and axial geometric factors, attenuation correction extracted from a two-dimensional transmission scan, Kinahan-Rogers reconstruction and region-of-interest-based sensitivity calibration.

RESULTS

No major systematic differences between the two methods were found. The agreement between the two-dimensional and three-dimensional data was within 5%. Although statistical analysis generally did not show this difference to be significant, reliability analysis indicated that comparing two-dimensional and three-dimensional data might introduce some inaccuracies.

CONCLUSION

Three-dimensional PET yields quantitatively valid results for brain scanning.