Does clinical intolerance to a diagnostic acute levodopa challenge differentiate multiple system atrophy from PD?

Predicting Long-Term Outcome of Patients of Early Parkinsonism with Acute Levodopa Challenge Test

Objectives

The aim of this study was to evaluate the sensitivity and specificity of various outcomes of acute levodopa challenge test (ALCT) namely improvement of motor function, development of dyskinesia and intolerance; to predict the diagnosis of idiopathic Parkinson's disease (IPD) or Parkinson-plus syndrome; to predict levodopa responsiveness and levodopa-induced dyskinesia (LID) during long-term therapy.

Methods

ALCT was performed on 89 patients with parkinsonism of <2 years and were followed up for 18 months. Improvement of UPDRSm by ≥30% was considered positive.

Results

The test was positive in 37 (43.5%) and negative in 48 (56.5%) of 85 patients completing it. Of the 75 patients completing 18 months' follow-up 34 (45.3%) were diagnosed as IPD. A positive ALCT predicted a clinical diagnosis of IPD with sensitivity and specificity of 97.4% and 70.7% respectively. The predictive value of ALCT for long-term levodopa responsiveness was less than predicting a diagnosis of IPD. While appearance of dyskinesia during ALCT had a low predictive value for future LID (sensitivity 14.3%), it had high predictive value for a diagnosis of multisystem atrophy (MSA) (91% specificity and 37.5% sensitivity). The appearance of symptoms of levodopa intolerance (SLI) during ALCT could predict a clinical diagnosis of MSA with high specificity (95.5%) and moderate sensitivity (50%).

Conclusion

Levodopa responsiveness during ALCT was useful in predicting a diagnosis of IPD but not long-term response to levodopa. The development of dyskinesia during ALCT could not correctly predict LID, but could predict a diagnosis of MSA. The appearance of SLI during ALCT could also predict MSA correctly.

Levodopa challenge test: indications, protocol, and guide

A drug challenge test in Parkinson's disease, such as the levodopa challenge test (LCT), is an easy and generally safe procedure, which has been used by clinicians for various indications. The results of the test have significant implications in the management of patients, from preoperative evaluation for deep brain stimulation to providing the basis for medication adjustments to address motor or non-motor fluctuations and dyskinesias. This paper reviews the different indications and protocols commonly used in an acute LCT. Potential complications of the procedure and an overview of levodopa responsiveness and unresponsiveness are also discussed.

Prediction of the Levodopa Challenge Test in Parkinson's Disease Using Data from a Wrist-Worn Sensor

The response to levodopa (LR) is important for managing Parkinson’s Disease and is measured with clinical scales prior to (OFF) and after (ON) levodopa. The aim of this study was to ascertain whether an ambulatory wearable device could predict the LR from the response to the first morning dose. The ON and OFF scores were sorted into six categories of severity so that separating Parkinson’s Kinetigraph (PKG) features corresponding to the ON and OFF scores became a multi-class classification problem according to whether they fell below or above the threshold for each class. Candidate features were extracted from the PKG data and matched to the class labels. Several linear and non-linear candidate statistical models were examined and compared to classify the six categories of severity. The resulting model predicted a clinically significant LR with an area under the receiver operator curve of 0.92. This study shows that ambulatory data could be used to identify a clinically significant response to levodopa. This study has also identified practical steps that would enhance the reliability of this test in future studies.

Side effects induced by the acute levodopa challenge in Parkinson's Disease and atypical parkinsonisms

Introduction

Acute levodopa challenge may be performed to predict levodopa chronic responsiveness. The aim of the study was to investigate frequency of side effects during the acute levodopa challenge in PD and atypical parkinsonisms.

Methods

We enrolled 34 de novo PD patients and 29 patients affected by atypical parkinsonisms (Multiple System Atrophy, MSA, n = 10; Progressive Supranuclear Palsy, PSP, n = 12 and Corticobasal Degeneration, CBD, n = 7) who underwent an acute levodopa challenge. Side effects occurring during test were recorded.

Results

Side effects were more frequent among atypical parkinsonisms as unique group when compared to PD patients (64.3% versus 23.5%; p-value 0.002) with an adjusted OR of 4.36 (95%CI 1.40–13.5). Each atypical parkinsonisms showed almost double occurrence of side effects (MSA 90%, PSP 41.7% and CBD 57%).

Conclusions

Side effects during acute levodopa challenge may be frequent in atypical parkinsonisms. This information could be useful in order to better prepare the patient for the test. Furthermore, it could represent a useful cue in differential diagnosis with PD.