A Brief Clinical Tool to Easily Identify The Subtypes of Parkinson’s Disease

We recently finished another round of the increasingly popular Physiopedia Volunteer Orientation Course. As part of the final assignment members were tasked to write an original piece of work to share with the profession, the contributions were of the highest quality. Below is the great piece of work written by Arnold Fredrick D’Souza.

Parkinson’s disease (PD) is classified into two subtypes based on the dominance of either of its primary motor symptoms: tremor-dominant (TD) or postural instability and gait difficulty (PIGD). The knowledge of these subtypes will allow the clinician to formulate an ideal exercise program for the client and predict the progression of the disease. It is fairly difficult for a novice clinician to reliably detect these subtypes.

A cross-sectional study investigated the utility of various clinical outcome measures for the purpose of effectively identifying them. The authors used the Unified Parkinson’s Disease Rating Scale (UPDRS) or Movement Disorders Society revision (MDS-UPDRS) for the purpose of classifying the subjects as TD or PIGD. They compared the results of these exhaustive tests with brief balance tests such as 360° turn test, one-leg stance, a reactive postural control test, and tandem walk test. These tests were derived from four items of the Fullerton Advanced Balance (FAB) Scale.

Out of all the four brief tests, the 360° turn test was able to more effectively differentiate between TD and PIGD, with high sensitivity. A higher step count (greater than 7) and longer duration to complete the turn indicate PIGD. Therefore, the 360° turn test can quickly screen for PIGD, albeit with low specificity, if the clinician is unable to perform the MDS-UPDRS due
to lack of experience or shortage of time. The results are noteworthy in case the client will not be able to visit his physician for a brief period, allowing the therapist to rapidly ascertain the prognosis of the disease. To overcome the shortcomings of exclusively using the 360° turn test, the tandem walk test can be used in addition to it. The combined administration of the 360° turn test and tandem walk test results in a very high specificity in identifying individuals with PIGD.

It is worth noting that the authors performed these investigations during the “off” period, in contrast to the real-world scenario where the majority of individuals with PD revisit the physiotherapy clinic during the “on” period after the initial diagnosis of the disease. Nevertheless, the study offers clinicians a quick and easy clinical tool to reliably classify the subtypes of PD, when elaborate testing is not feasible.