One of the most debilitating aspects of Parkinson’s Disease (PD) is Freezing of Gait (FOG), the sensation of the feet sticking to the ground when movement is initiated or during active movement. Levodopa, commonly prescribed for PD patients, is not always successful in treating FOG; for some patients, when Levodopa levels are increased, FOG not only persists but increases. As FOG progresses, the likelihood of falling increases, leading to a greater incidence of injury and reduced quality of life.


It is a challenge to treat Levodopa unresponsiveness in FOG. Patient diaries and questionnaires are commonly used to record its symptoms, frequency, and severity. But self-reporting is inherently subjective, and as cognitive impairments increase with the progression of PD, self-reporting becomes less reliable. Patients are frequently unable to provide accurate reports on whether changes in Levodopa titrations cause improvements or worsen their gait and balance at home. Additionally, in a controlled setting, clinicians may assess patients between dose adjustments without knowing their home environment. This makes clinical dose adjustment of Levodopa difficult.


Can data-driven gait analysis improve Levodopa titration and Freezing Of Gait?


Researchers at the Movement Disorders Clinic at the University of Arkansas for Medical Sciences set out to determine if Levodopa dosing can be optimized via gait kinematics to improve FOG symptoms and benefit gait stride length and stride velocity. Their goal was to utilize certain spatiotemporal gait parameters to determine their utility in gait optimization in PD patients. Protokinetics’ PKMAS software and ZENO Walkway were used to measure and assess these parameters.


The study, Utility of objective gait measures in levodopa-unresponsive freezing in Parkinson’s, included six PD patients between the ages of 70-77 with a history of falls from gait freezing. Each patient used a walker to help prevent falls and had FOG symptoms that were unresponsive to Levodopa.


Each patient underwent gait evaluation in both the OFF and ON state for three different doses of Levodopa, starting with their home dose. They walked eight lengths at a comfortable pace on a pressure-sensitive 20′ x 4′ Zeno Walkway mat and the data from the pressure sensors was collected and analyzed using Protokinetics PKMAS software.


In each patient, four spatiotemporal gait parameters were measured:


  1. Stride Length (SL) 

In previous studies, Stride Length decreased in those with FOG compared to those who did not show symptoms. It was also suggested in earlier studies that the sequence effect of successive reduction in stride length when the patient already displays reduced stride length may provoke FOG.


  1. Stride Velocity (SV)

A slowing Stride Velocity is a core feature of PD.


  1. Swing Phase Percent (SW%)

Decreased time spent in Swing Phase Percent of the gait cycle suggests a greater shuffling of gait.


  1. Foot Strike Length (FL)

The same researchers previously concluded that foot-strike length occurs with increased variability in those with FOG vs. those who display no symptoms.


With the data insights gained through the Protokinetics PKMAS and ZENO Walkway, the researchers optimized Levodopa dosing in all 6 of the patients with moderate to severe ON-state Freezing Of Gait. In 5 patients, Levodopa dosages were reduced; in 3 patients, FOG improved; in 4 patients, self-reported fall frequency improved.


Additionally, PKMAS and ZENO Walkway revealed a variety in gait dynamics in patients with FOG. Three different patterns emerged:


  1. Improved gait at one Levodopa dose and then an improvement and plateau with an increased dose.
  2. At higher doses, initial gate improvement was followed by a decline.
  3. At higher doses, a minimal improvement followed by a decline.


In their conclusion, the authors stated: “Integrating objective assessments into clinical care can help individualize therapy. It can also help decrease medication burden as 5 of our patients ended up on lower doses of Levodopa. In cases of difficult to control, Levodopa-unresponsive (or ON-state) freezing of gait, Levodopa titration using objectively measured spatiotemporal gait parameters can provide clinical utility. Therefore, we suggest that the introduction of objective gait assessments into our clinical care algorithms should become standard of care in the future.”


Read More: Utility of objective gait measures in levodopa-unresponsive freezing in Parkinson’s.