Acute Levodopa Challenge Test Research Articles

Subjective Perceived Motor Improvement after Acute Levodopa Challenge in Parkinson’s Disease

Previous studies found a poor association between parkinsonian patient's reported subjective improvement after commencing dopaminergic treatment and improvements in objective measures of motor impairment by clinician. To compare PD patient's subjective perceived motor improvement after acute levodopa challenge test with objective motor improvement assessed by the clinician using the UPDRS part III. To analyze clinical characteristics, i.e. age, disease duration, cognitive performance or severity of axial features, that may have influenced patient's perception. Fifty-seven consecutive PD patients (23 women, 34 men; mean age, 63.4±7.7 years) (Hoehn and Yahr off score, 2.5±0.7; mean disease duration, 11.4±4.1 years) completed the acute levodopa challenge. The percentage of improvement in motor disability, i.e. objective motor improvement, was determined with respect to the off-drug condition. Bland & Altman visual analysis reveals a high degree of correlation between objective and subjective perceived motor improvement. Both the axial sub-scores in the off- and on-state (respectively, P = 0.006 and P = 0.024) and the presence of peak-dose dyskinesia (P = 0.043) significantly influence the difference between objective and subjective perceived motor improvement. This is the first study reporting on how PD patients assessed their motor improvement after acute levodopa challenge. These findings suggest a strong correlation between objective motor improvement assessed by the clinician using the UPDRS part III and subjective perceived motor improvement reported by the patient.

Do patients with late-stage Parkinson's disease still respond to levodopa?

BackgroundLate-stage Parkinson’ disease (PD) is dominated by loss of autonomy due to motor and non-motor symptoms which can be marginally corrected by medications adjustments. However, controversy exists on the mechanisms underlying the apparent decrease of benefit from levodopa. ObjectiveTo study the response to levodopa in late-stage PD (LSPD). Methods20 LSPD patients (Schwab and England ADL Scale <50 or Hoehn Yahr Stage >3 in MED ON) and 22 PD patients treated with subthalamic deep brain stimulation (DBS) underwent an acute levodopa challenge test. MDS-UPDRS-III and the modified Abnormal Involuntary Movement Scale were evaluated in off and after administration of a supra-maximal levodopa dose. ResultsLSPD patients had a median age of 78.8 (IQR: 73.5–82) and median disease duration of 14 years (IQR: 10-19.75). DBS patients had a median age of 66 (IQR: 61-72) and median disease duration of 18 years (IQR: 15-22). LSPD and DBS patients' MDS-UPDRS-III score improved 11.3% and 37% after levodopa, respectively. Rest tremor showed the largest improvement, while axial signs did not improve in LSPD. However, the magnitude of levodopa response significantly correlated with dyskinesias severity in LSPD patients. One third of LSPD and 9% of DBS patients reported moderate drowsiness. ConclusionsLSPD patients show a slight response to a supra-maximal levodopa dose, which is greater if dyskinesia are present, but it is frequently associated with adverse effects. A decrease in levodopa response is a potential marker of disease progression in LSPD.

Ultrasound Strain Elastography in Assessment of Muscle Stiffness in Acute Levodopa Challenge Test: A Feasibility Study

To evaluate the feasibility of ultrasound strain elastography in assessing the response of muscle stiffness to the acute levodopa test, we prospectively performed strain elastography on the biceps brachii muscle (BBM) of 18 patients to diagnose Parkinson's disease. BBM and subcutaneous tissue strains (deformations) were produced by external compression with an ultrasound transducer and estimated using 2-D speckle tracking. We used the strain ratio (SR = BBM strain/reference strain) to assess BBM stiffness. The rate of increase in SR [rate = (SR after levodopa−SR before levodopa)/SR before levodopa] was used to assess the muscle stiffness response to levodopa. SR significantly increased after levodopa administration in 11 patients with Parkinson's disease (p = 0.02), whereas it did not in 7 patients with parkinsonian syndrome (from non-Parkinson's causes) (p = 0.14). The area under the receiver operating characteristic curve for the rate of increase in SR in determining Parkinson's disease was 0.96. The rate of increase in SR seems to be feasible in evaluating the effect of levodopa on muscle stiffness in the diagnosis of Parkinson's disease.

Levodopa challenge test and123I-metaiodobenzylguanidine scintigraphy for diagnosing Parkinson's disease

To explore the possibility of a generally applicable tool for the immediate diagnosis of Parkinson's disease (PD) in its early stage, we compared the sensitivity and specificity of an acute levodopa challenge test with that of (123) I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. A consecutive series of 45 patients with extrapyramidal symptoms were recruited to the acute levodopa challenge and evaluated for improvement by use of the Unified Parkinson's Disease Rating Scale motor scores. Of these patients, 32 of them were also examined by MIBG scintigraphy. The patients were followed up for at least 24 months, and 22 patients were diagnosed as having clinically definite PD. The sensitivity and specificity of the acute levodopa challenge test to predict clinical diagnosis of PD were 81.8% and 81.8%, respectively, which were better than those obtained by MIBG scintigraphy (62.5% and 62.5%). In both early- and middle-stages of PD, the test gave better sensitivity than MIBG scintigraphy. Considering that the well-established and frequently referred clinical diagnostic criteria require longitudinal observation for at least 24 months, the acute levodopa challenge test can be used as an immediate diagnostic tool for PD with sensitivity and specificity comparable to those of MIBG.

Levodopa response in dementia with lewy bodies: A 1-year follow-up study

Purpose To evaluate levodopa responsiveness in patients with probable dementia with Lewy bodies (DLB) compared to early Parkinson’s disease (PD) patients. Methods Twenty four cases with DLB and 21 with PD underwent a baseline assessment with UPDRS (sub-item II and III) and an acute levodopa challenge test. Positive response to acute levodopa test was defined as an improvement of at least 15% in the tapping test, and at least 25% in the walking test and rigidity or tremor score. Subsequently, all patients were treated continuously with levodopa and evaluated after 6 and 12 months by means of UPDRS II/III. Results Positive response to the acute levodopa test was observed in 55% of DLB patients (acute DLB responders), and in 90% of PD patients (acute PD responders). Acute DLB responders showed increased latency, and reduction of both duration and amplitude of response to acute levodopa in comparison with acute PD responders. At the 6-month follow-up visit, acute DLB responders showed a greater motor benefit compared with acute DLB non-responders. This improvement was similar to that observed in PD patients. However, at 1-year follow-up acute DLB responders showed a faster worsening of UPDRS III scores compared with acute PD responders, implying a reduction of levodopa efficacy. Conclusions Positive response to acute levodopa test can occur in DLB patients and may be predictive of long-term benefit of chronic levodopa therapy, although the motor improvement is less impressive than in PD patients.