***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: We have review ed the clinical and pathological diagnoses of 143 cases of parkinsonism seen by neurologists associated with the movement disorders service at The National Hospital for Neurology and Neurosurgery in London who came to neuropathological examination at the United Kingdom Parkinson 's Disease Society Brain Research Centre , over a 10-year period between 1990 and the end of 1999 . Seventy-three ( 47 male , 26 female ) cases were diagnosed as having idiopathic Parkinson 's disease ( IPD ) and 70 ( 42 male , 28 female ) as having another parkinsonian syndrome . The positive predictive value of the clinical diagnosis for the whole group was 85.3 % , with 122 cases correctly clinical ly diagnosed . The positive predictive value of the clinical diagnosis of IPD was extremely high , at 98.6 % ( 72 out of 73 ) , while for the other parkinsonian syndromes it was 71.4 % ( 50 out of 70 ) . The positive predictive values of a clinical diagnosis of multiple system atrophy ( MSA ) and progressive supranuclear palsy ( PSP ) were 85.7 ( 30 out of 35 ) and 80 % ( 16 out of 20 ) , respectively . The sensitivity for IPD was 91.1 % , due to seven false-negative cases , with 72 of the 79 pathologically established cases being diagnosed in life . For MSA , the sensitivity was 88.2 % ( 30 out of 34 ) , and for PSP it was 84.2 % ( 16 out of 19 ) . The diagnostic accuracy for IPD , MSA and PSP was higher than most previous prospect i ve clinicopathological series and studies using the retrospective application of clinical diagnostic criteria . The seven false-negative cases of IPD suggest a broader clinical picture of disease than previously thought acceptable . This study implies that neurologists with particular expertise in the field of movement disorders may be using a method of pattern recognition for diagnosis which goes beyond that inherent in any formal set of diagnostic criteria Few detailed clinico-pathological correlations of Parkinson 's disease have been published . The pathological findings in 100 patients diagnosed prospect ively by a group of consultant neurologists as having idiopathic Parkinson 's disease are reported . Seventy six had nigral Lewy bodies , and in all of these Lewy bodies were also found in the cerebral cortex . In 24 cases without Lewy bodies , diagnoses included progressive supranuclear palsy , multiple system atrophy , Alzheimer 's disease , Alzheimer-type pathology , and basal ganglia vascular disease . The retrospective application of recommended diagnostic criteria improved the diagnostic accuracy to 82 % . These observations call into question current concepts of Parkinson 's disease as a single distinct morbid entity Overdiagnosis of Parkinson 's disease ( PD ) is suggested by specialist review of community diagnosis , and in postmortem studies . In specialist centers 4 to 15 % of patients entered into clinical trials as early PD do not have functional imaging support for a PD diagnosis . In a European multicenter , prospect i ve , longitudinal study , we compared clinical diagnosis with functional SPECT imaging using [123I]FP-CIT ( DaTSCAN , GE Healthcare ) . Repeat observations were performed over 3 years in patients with tremor and /or parkinsonism in whom there was initial diagnostic uncertainty between degenerative parkinsonism and nondegenerative tremor disorders .  Video-recording of clinical features was scored independently of functional imaging results by two blinded clinicians at 36 months (= gold st and ard clinical diagnosis ) . Three readers , unaware of the clinical diagnosis , classified the images as normal or abnormal by visual inspection . The main endpoint was the sensitivity and specificity of SPECT imaging at baseline compared with the gold st and ard . In 99 patients completing the three serial assessment s , on-site clinical diagnosis overdiagnosed degenerative parkinsonism at baseline in diagnostically uncertain cases compared with the gold st and ard clinical diagnosis ( at 36 months ) , the latter giving a sensitivity of 93 % and specificity of 46 % . The corresponding baseline [123I]FP-CIT SPECT results showed a mean sensitivity of 78 % and a specificity of 97 % . Inter-reader agreement for rating scans as normal or abnormal was high ( Cohen 's kappa = 0.94 - 0.97 ) Background This study examines the clinical accuracy of movement disorder specialists in distinguishing tremor dominant Parkinson 's disease ( TDPD ) from other tremulous movement disorders by the use of st and ardised patient videos . Patients and methods Two movement disorder specialists were asked to distinguish TDPD from patients with atypical tremor and dystonic tremor , who had no evidence of presynaptic dopaminergic deficit ( subjects without evidence of dopaminergic deficit ( SWEDDs ) ) according to 123I-N-ω-fluoro-propyl- 2β-carbomethoxy-3β-(4-iodophenyl ) nortropane ( [ 123I ] FP-CIT ) single photon emission computed tomography ( SPECT ) , by ‘ blinded ’ video analysis in 38 patients . A diagnosis of parkinsonism was made if the step 1 criteria of the Queen Square Brain Bank criteria for Parkinson 's disease were fulfilled . The review er diagnosis was compared with the working clinical diagnosis drawn from the medical history , SPECT scan result , long term follow-up and in some cases the known response to dopaminergic medications . This comparison allowed a calculation for false positive and false negative rate of diagnosis of PD . Results High false positive ( 17.4 - 26.1 % ) and negative ( 6.7 - 20 % ) rates were found for the diagnosis of PD . The diagnostic distinction of TDPD from dystonic tremor was reduced by the presence of dystonic features in treated and untreated PD patients . Conclusion Clinical distinction of TDPD from atypical tremor , monosymptomatic rest tremor and dystonic tremor can be difficult due to the presence of parkinsonian features in tremulous SWEDD patients . The diagnosis of bradykinesia was particularly challenging . This study highlights the difficulty of differentiation of some cases of SWEDD from PD CONTEXT Pramipexole and levodopa are effective medications to treat motor symptoms of early Parkinson disease ( PD ) . In vitro and animal studies suggest that pramipexole may protect and that levodopa may either protect or damage dopamine neurons . Neuroimaging offers the potential of an objective biomarker of dopamine neuron degeneration in PD patients . OBJECTIVE To compare rates of dopamine neuron degeneration after initial treatment with pramipexole or levodopa in early PD by means of dopamine transporter imaging using single-photon emission computed tomography ( SPECT ) with 2beta-carboxymethoxy-3beta(4-iodophenyl)tropane ( beta-CIT ) labeled with iodine 123 . DESIGN Sub study of a parallel-group , double-blind r and omized clinical trial . SETTING AND PATIENTS Eighty-two patients with early PD who were recruited at 17 clinical sites in the United States and Canada and required dopaminergic therapy to treat emerging disability , enrolled between November 1996 and August 1997 . INTERVENTIONS Patients were r and omly assigned to receive pramipexole , 0.5 mg 3 times per day with levodopa placebo ( n = 42 ) , or carbidopa/levodopa , 25/100 mg 3 times per day with pramipexole placebo ( n = 40 ) . For patients with residual disability , the dosage was escalated during the first 10 weeks , and subsequently , open-label levodopa could be added . After 24 months of follow-up , the dosage of study drug could be further modified . MAIN OUTCOME MEASURES The primary outcome variable was the percentage change from baseline in striatal [(123)I]beta-CIT uptake after 46 months . The percentage changes and absolute changes in striatal , putamen , and cau date [(123)I]beta-CIT uptake after 22 and 34 months were also assessed . Clinical severity of PD was assessed using the Unified Parkinson Disease Rating Scale ( UPDRS ) 12 hours off anti-PD medications . RESULTS Sequential SPECT imaging showed a decline in mean ( SD ) [(123)I]beta-CIT striatal uptake from baseline of 10.3 % ( 9.8 % ) at 22 months , 15.3 % ( 12.8 % ) at 34 months , and 20.7 % ( 14.4 % ) at 46 months-approximately 5.2 % per year . The mean ( SD ) percentage loss in striatal [(123)I]beta-CIT uptake from baseline was significantly reduced in the pramipexole group compared with the levodopa group : 7.1 % ( 9.0 % ) vs 13.5 % ( 9.6 % ) at 22 months ( P = .004 ) ; 10.9 % ( 11.8 % ) vs 19.6 % ( 12.4 % ) at 34 months ( P = .009 ) ; and 16.0 % ( 13.3 % ) vs 25.5 % ( 14.1 % ) at 46 months ( P = .01 ) . The percentage loss from baseline in striatal [(123)I]beta-CIT uptake was correlated with the change from baseline in UPDRS at the 46-month evaluation ( r = - 0.40 ; P = .001 ) . CONCLUSIONS Patients initially treated with pramipexole demonstrated a reduction in loss of striatal [(123)I]beta-CIT uptake , a marker of dopamine neuron degeneration , compared with those initially treated with levodopa , during a 46-month period . These imaging data highlight the need to further compare imaging and clinical end points of PD progression in long-term studies CONTEXT Since there is no diagnostic biological marker for Parkinson disease ( PD ) , the diagnosis is based on the results of clinical assessment . The accuracy of diagnosis improves with time and repeated assessment s. Studies that require only inclusion of early cases of PD present a diagnostic challenge . Previous studies concluded that initial diagnoses of PD made by general neurologists were incorrect in 24 % to 35 % of the cases when patients were examined at autopsy . Experts in movement disorders are expected to have greater accuracy of initial diagnosis of PD . OBJECTIVE To determine the evolution of clinical diagnosis in patients with early PD made initially by experts in PD . DESIGN Eight hundred patients with mild parkinsonian symptoms ( Hoehn and Yahr stage 1 or 2 ) who received a diagnosis of PD less than 5 years before the beginning of the study were included in the original Deprenyl and Tocopherol Antioxidative Therapy for Parkinson 's Disease study . These patients were followed up prospect ively with repeated clinical assessment s. The following clinical criteria were used to reassess the initial diagnosis : investigator 's confidence in the diagnosis of PD , presence of atypical clinical features , findings of imaging studies , response to levodopa , and results of  autopsy examinations . RESULTS The mean + /- SD duration of illness in the 800 cases at enrollment was 2.2+/-1.3 years , and the mean + /- SD Hoehn and Yahr stage was 1.6+/-0.5 . The mean + /- SD follow-up was 6.0+/-1.4 years ( range , 0.2 - 7.6 years ) . In 5 cases , PD was not confirmed at autopsy , and in 15 patients , the results of imaging studies indicated the presence of other pathological conditions . Of the 550 cases treated with levodopa , 49 ( 8.9 % ) had little or no improvement ; 6 of these cases overlap with either autopsy or imaging study exclusion criteria . Two other cases had at least 4 of the 6 atypical clinical features arguing against the diagnosis of PD . Thus , of the 800 patients , 65 ( 8.1 % ) did not have PD according to the study criteria . Compared with those patients with the final diagnosis of PD , in the diagnoses of 60 patients without autopsy , the duration of symptoms ( mean + /- SD , 7.2+/-2.0 years vs. 8.3+/-1.9 years ; P<.001 ) and the duration of follow-up ( 5.3+/-1.6 years vs. 6.1+/-1.3 years ; P<.001 ) were shorter . CONCLUSIONS We found that 65 ( 8.1 % ) of patients initially diagnosed as having PD were later found to have an alternate diagnosis based on multifactorial clinical diagnostic criteria . This alternate diagnosis indicated that experts in PD changed their diagnoses infrequently during the 7.6-year follow-up BACKGROUND Despite the known benefit of levodopa in reducing the symptoms of Parkinson 's disease , concern has been expressed that its use might hasten neurodegeneration . This study assessed the effect of levodopa on the rate of progression of Parkinson 's disease . METHODS In this r and omized , double-blind , placebo-controlled trial , we evaluated 361 patients with early Parkinson 's disease who were assigned to receive carbidopa-levodopa at a daily dose of 37.5 and 150 mg , 75 and 300 mg , or 1 
    Output:
    
Our systematic review indicates that  DAT SPECT imaging  seems to be accurate to detect nigrostriatal cell loss in patients with parkinsonism