PKG Device Shown to Detect Abnormal Movements in Parkinson’s, Bradykinesia

The Parkinson’s Personal KinetiGraph (PKG), a small motion sensor device that can be worn on the wrist like a watch in patients with Parkinson’s disease, can be used to detect abnormal movements, especially those associated with bradykinesia at the earlier stages of the disorder, an observational study has found.

The study, “More Sensitive Identification for Bradykinesia Compared to Tremors in Parkinson’s Disease Based on Parkinson’s KinetiGraph (PKG),” was published in the journal Frontiers in Aging Neuroscience.

Slowness or difficulty performing certain movements, also known as bradykinesia, is one of the earlier motor symptoms of Parkinson’s.

The PKG is a motion sensor device developed by Global Kinetics that has been approved by the FDA to measure and monitor several motor symptoms of Parkinson’s, including tremors, bradykinesia, and involuntary movements known as dyskinesia. It is worn on the wrist of the individual’s most affected side.

Once placed on the wrist, the device not only continuously measures these motor parameters — it also can be used to set reminders on when patients should take their medications, particularly levodopa.

The PKG watch also can indicate the relationship between medication and symptoms, “which is conducive to adjusting drugs, monitoring disease development, optimizing levodopa medication, and controlling the daily dose of levodopa, which may prevent sports complications,” the researchers wrote.

The team noted that “prevention of sports complications is important,” and that the factors for such difficulties due to Parkinson’s include age of disease onset, its severity, and the dose of medication given.

Now, the researchers reported the findings of an observational study that aimed to determine how well the data picked up by the PKG motion sensor device matched other clinical score measures of Parkinson’s motor symptoms.

Additionally, the team also sought to determine if the PKG motion sensor device would be suitable to detect early motor symptoms associated with the disease.

The observational study involved a total of 100 patients — 60 men and 40 women, with an average age of 66 — and was carried out in Fuzhou, China. Among the participants, 35 were at the early stages of the disease (Hoehn and Yahr stage 1–2), and 65 at an intermediate-to-advanced stage of Parkinson’s (Hoehn and Yahr stage 2.5–5).

During the study, participants were instructed to wear the PKG device continuously for at least six days. The researchers then analyzed data extracted from the device, including the bradykinesia score (BKS), the dyskinesia score (DKS), the percent time tremor (PTT), and the fluctuation and dyskinesia score (FDS).

The BKS and DKS scores are calculated by two algorithms incorporated in the PKG device and indicate the likelihood scores for the two complications. The PTT indicates the percentage of device-reading time in which patients experienced tremors, while the FDS is a summary score of motor fluctuations and dyskinesias.

In addition to PKG data, patient scores were analyzed on several validated measures of Parkinson’s motor symptoms, including the total scores of the Unified Parkinson’s disease rating scale part III (UPDRS III, motor examination), the UPDRS III-bradykinesia scores, the UPDRS III-rigidity scores, and the Wearing-off Questionnaire-9 (WOQ-9) scores. The WOQ-9 screens for the wearing off of medications, particularly levodopa.

Statistical analyses showed that BKS scores for bradykinesia obtained from the PKG device were highly correlated with all three UPDRS III scores, especially in the subset of patients who were still at the earlier stages of Parkinson’s.

A correlation also was found between percent time tremor scores, or the time patients experienced tremors, on the data obtained from the PKG device and the UPDRS III tremor scale.

Additionally, the data showed that BKS scores tended to be more serious in patients whose symptoms started, and were more severe, on the left side of their body, than in those whose symptoms started, and were more noticeable, on the right side of their body.

“Our findings support the feasibility of using the PKG to detect abnormal movements, especially bradykinesia in PD [Parkinson’s disease]. It is suitable for the early detection, remote monitoring, and timely treatment of PD symptoms,” the researchers concluded.