Objective assessment of spasticity by pendulum test: a systematic review on methods of implementation and outcome measures

Abstract

Background Instrumented pendulum test is an objective and repeatable biomechanical method of assessment for spasticity. However, multitude of sensor technologies and plenty of suggested outcome measures, confuse those interested in implementing this method in practice. Lack of a standard agreement on the definition of experimental setup and outcome measures adds to this ambiguity and causes the results of one study not to be directly attainable by a group that uses a different setup. In this systematic review of studies, we aim to reduce the confusion by providing pros and cons of the available choices, and also by standardizing the definitions. Methods A literature search was conducted for the period of 1950 to the end of 2019 on PubMed, Science Direct, Google Scholar and IEEE explore; with keywords of “pendulum test” and “Spasticity”. Results Twenty-eight studies with instrumented pendulum test for assessment of spasticity met the inclusion criteria. All the suggested methods of implementation were compared and advantages and disadvantages were provided for each sensor technology. An exhaustive list categorized outcome measures in three groups of angle-based, angular velocity-based, and angular acceleration-based measures with all different names and definitions. Conclusions With the aim of providing standardized methodology with replicable and comparable results, sources of dissimilarity and ambiguity among research strategies were found and explained with the help of graphical representation of pendulum movement stages and corresponding parameters on the angular waveforms. We hope using the provided tables simplify the choices when implementing pendulum test for spasticity evaluation, improve the consistency when reporting the results, and disambiguate inconsistency in the literature.

Pendulum test parameters are useful for detecting knee muscle hypertonia and quantifying response to an intrathecal baclofen bolus injection

“…To complement clinical assessment, neurophysiological and biomechanical protocols of different complexities have been developed to add objectivity [7][8][9][10]. Due to its low cost, easy setup, and simple administration, the Wartenberg pendulum test [11] has been used to assess knee muscle hypertonia in various neurologic populations (see Rahimi et al [12] for a recent review); however, the value of the pendulum test for quantifying more severe spasticity has been questioned [13][14][15].…”

A portable system to measure knee extensor spasticity after spinal cord injury

“…The pendulum test is a biomechanical evaluation that is easy and quick to implement and requires minimal training for the operators. The ease of implementation of the test and the possibility to instrument it with a variety of commercially available sensors [ 51 ] contributed to its popularity for measuring knee extensor spasticity alongside clinical scales. To facilitate adoption in the clinics, portable sensors like IMUs, electrogoniometers, accelerometers or gyroscopes are preferred over optical tracking systems or systems based on video recordings.…”

Assessment of Passive Upper Limb Stiffness and Its Function in Post-Stroke Individuals Wearing an Inertial Sensor during the Pendulum Test

“…This approach was motivated by the fact that the inertial sensor is a small, light, and practical device, which does not cause discomfort to the subjects. The sensor provides qualitative and quantitative information related to muscle tone [ 28 , 29 , 30 , 31 ], such as the regularity of movement balance, observation of the sinusoidal curve with irregularities, and more frequent alterations in individuals with spasticity.…”