Patients with Parkinson's disease had similar improvement in motor function after either pallidal or subthalamic stimulation. Nonmotor factors may reasonably be included in the selection of surgical target for deep-brain stimulation. (ClinicalTrials.gov numbers, NCT00056563 and NCT01076452.)

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This study provides Class III evidence that improvement of motor symptoms of PD by DBS remains stable over 3 years and does not differ by surgical target. Neurology® 2012;79:55-65.

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The accuracy of the clinical diagnosis of corticobasal degeneration (CBD) is unknown. To determine its diagnostic accuracy, we presented 105 cases with known neuropathologic diagnoses, including CBD (n = 10), progressive supranuclear palsy (PSP, n = 24), Parkinson's disease (n = 15), diffuse Lewy body disease (n = 14), multiple system atrophy (n = 16), postencephalitic parkinsonism (n = 7), Pick's disease (n = 7), Creutzfeldt-Jakob disease (n = 4), Alzheimer's disease (n = 4), vascular parkinsonism (n = 3), and Whipple's disease (n = 1), as clinical vignettes to six neurologists unaware of the autopsy findings. Reliability was measured with the kappa statistics. The neurologists' clinical diagnoses were compared with clinicopathologic diagnoses for sensitivity, specificity, and positive predictive values at first and last clinic visits. The group reliability for the diagnosis of CBD significantly improved from moderate for the first visit (mean = 34 months after onset) to substantial for the last (68 months after onset). For the first visit, mean sensitivity for CBD was low (35%), but specificity was near-perfect (99.6%). For the last visit, mean sensitivity minimally increased (48.3%), and specificity remained stable. False-negative misdiagnoses mainly occurred with PSP. False-positive diagnoses were rare. The extremely low sensitivity of the clinical diagnosis of CBD suggests that this disorder is markedly underdiagnosed. Although the validity of the clinical diagnosis might have been improved if neurologists could have examined these patients, more important is that this disorder was misdiagnosed by the primary neurologists. In our data set, the best predictors for the diagnosis of CBD included limb dystonia, ideomotor apraxia, myoclonus, and asymmetric akinetic-rigid syndrome with late onset of gait or balance disturbances.

We assessed the validity and interrater reliability of neurologists who, using four different sets of previously published criteria for the clinical diagnosis of progressive supranuclear palsy (PSP), also called Steele-Richardson-Olszewski syndrome, rated 105 autopsy-proven cases of PSP (n = 24), Lewy body disease (n = 29), corticobasal ganglionic degeneration (n = 10), postencephalitic parkinsonism (n = 7), multiple system atrophy (n = 16), Pick's disease (n = 7), and other parkinsonian or dementia disorders (n = 12). Cases were presented in random order to six neurologists. Information from each patient's first and last visits to the medical center supplying the case was presented sequentially to the rater, and the rater's diagnosis was compared with the neuropathologic diagnosis of each case. Interrater agreement for the diagnosis of PSP varied from substantial to near perfect, but none of the criteria had both high sensitivity and high predictive value. Because of these limitations, we used a logistic regression analysis to identify the variables from the data set that would best predict the diagnosis. This analysis identified vertical supranuclear palsy with downward gaze abnormalities and postural instability with unexplained falls as the best features for predicting the diagnosis. From the results of the regression analysis and the addition of exclusionary features, we propose optimal criteria for the clinical diagnosis of PSP.

Introduction: Frequent falls and risk of injury are evident in individuals with Parkinson's disease (PD) as the disease progresses. There have been no reports of any interventions that reduce the incidence of falls in idiopathic PD. Purpose: Assess the benefit of gait and step perturbation training in individuals with PD. Design: Randomized, controlled trial. Setting: Outpatient research, education and clinical center in a tertiary care Veterans Affairs Medical Center. Outcome measures: Gait parameters, 5-step test, report of falls Subjects: Eighteen men with idiopathic PD in stage 2 or 3 of the Hoehn and Yahr staging Methods: Subjects were randomly assigned to a trained or control group. They were asked about any falls 2 weeks prior to and after an 8 week period. Gait speed, cadence, and step length were tested on an instrumented walkway. Subjects were timed while stepping onto and back down from an 8.8 cm step for 5 consecutive steps. Gait training consisted of walking on a treadmill at a speed greater than over ground walking speed while walking in 4 directions and while supported in a harness for safety. Step training consisted of suddenly turning the treadmill on and off while the subject stood in the safety harness facing either forwards, backwards, or sideways. Training occurred 1 hour per day, three times per week for 8 weeks. A two-factor (time and group) analysis of variance with repeated measures was used to compare the groups. Results: Substantial reduction occurred in falls in the trained group, but not in the control group. Gait speed increased in the trained group from 1.28 ± 0.33 meters/sec to 1.45 ± 0.37 meters/sec, but not in the control group (from 1.26 to 1.27 m/s). The cadence increased for both groups: from 112.8 to 120.3 steps/min for the trained group and 117.7 to 124.3 steps/min for the control group. Stride lengths increased for the trained group, but not the control group. The 5-step test speed increased in the trained group from 0.40 ± 0.08 steps/sec to 0.51 ± 0.12 steps/sec, and in the control group (0.36 ± 0.11 steps/sec to 0.42 ± 0.11 steps/sec). Conclusion: Gait and step perturbation training resulted in a reduction in falls and improvements in gait and dynamic balance. This is a promising approach to reduce falls for patients with PD.

The low PPV with relatively high sensitivity for the diagnosis of PD suggests overdiagnosis. Conversely, the extremely low sensitivity for the diagnosis of DLB suggests underdiagnosis. Although the case mix included in the study may not reflect the frequency of these disorders in practice, limiting the clinical applicability of the validity measures, the raters' results were similar to those of the primary neurologists who were not exposed to such limitations. Overall, our study confirms features suggested to predict these disorders, except for the early presence of postural imbalance, which is not indicative of either disorder.