Functional Gait Assessment – Parkinson’s Specific

Abstract

The Functional Gait Assessment (FGA), specifically adapted for use in patients with Parkinson’s disease, is a performance-based measure designed to evaluate mobility and predict fall risk. It is derived from the original Dynamic Gait Index (DGI), which comprises 8 items measuring gait function and stability. The FGA builds upon the DGI by incorporating 7 of the original items and adding 3 new items specifically relevant to assessing complex balance challenges in clinical populations.

Due to the significant overlap, the DGI and FGA are often addressed jointly within clinical protocols, such as the KNGF guideline for Parkinson’s disease. This joint inclusion ensures that standardized testing conditions, required materials, and scoring criteria are meticulously documented for clinicians utilizing these instruments in the rehabilitation of patients with Parkinson’s disease.

Keywords

Functional Gait Assessment, FGA, Parkinson’s disease, Dynamic Gait Index, DGI, Gait Assessment, Balance, Mobility, Fall Risk, Performance measure.

Authors

Wrisley DM (2003), KNGF-richtlijn Ziekte van Parkinson (Dutch Version, 2017).

Purpose

The primary purpose of the Functional Gait Assessment (FGA) is to evaluate and document a patient’s ability to execute various complex walking tasks that challenge dynamic balance. This assessment moves beyond simple straight-line walking to incorporate changes in speed, head movements, obstacles, and stair climbing, which are crucial indicators of real-world mobility and stability.

For the Parkinson-specific adaptation, the scale’s purpose is refined to accurately quantify mobility deficits and predict the likelihood of future falls in individuals diagnosed with Parkinson’s disease (PD). It serves as a vital tool for physical therapists to tailor rehabilitation strategies and monitor functional improvements over time, particularly focusing on tasks that elicit freezing of gait or postural instability.

Construct

The FGA measures the construct of Dynamic Balance and Gait Stability during complex ambulation. Dynamic balance refers to the ability to maintain equilibrium while moving, particularly when external or internal perturbations occur. Unlike static balance tests, the FGA requires the integration of sensory, motor, and cognitive systems to successfully navigate challenging environmental demands.

Specifically, the items added to the original DGI focus on tasks known to be particularly difficult for individuals with balance disorders, such as walking while performing cognitive tasks or ambulating in unpredictable environments. In the context of PD, the construct strongly relates to evaluating freezing of gait and postural instability, which are hallmark symptoms affecting mobility and increasing fall risk.

Validity

The validity of the FGA is generally considered strong, particularly its concurrent validity with the original Dynamic Gait Index (DGI), given the substantial overlap in items. For the general FGA, studies consistently demonstrate high predictive validity for identifying individuals at risk of falling across various neurological populations, including those with PD.

Content validity is enhanced in the Parkinson-specific version through its inclusion in the Dutch KNGF guideline, suggesting clinical relevance and appropriateness for assessing the specific mobility challenges encountered by this population. The modifications ensure that the assessment covers functional tasks critical for independent living and complex ambulation.

Reliability

The FGA is known to exhibit excellent psychometric properties, including high inter-rater and intra-rater reliability when administered by trained clinicians. This reliability stems from the clear operational definitions provided for each item and the standardized scoring criteria, which minimize subjectivity in performance rating.

For the specific version utilized within the KNGF framework for Parkinson’s disease, adherence to the documented test procedures ensures consistent measurement of gait performance. This consistency makes the scores highly dependable for tracking patient progress, comparing outcomes across different therapists, and making informed clinical decisions regarding treatment efficacy.

Factor Analysis

While the FGA is often treated as a unidimensional measure of dynamic balance, factor analyses of the original FGA have occasionally suggested a two-factor structure, separating steady-state walking from more complex, challenging tasks (e.g., pivot turns, walking with head movements). This structural consistency supports the scale’s ability to capture varied aspects of functional mobility essential for independent living.

For the Parkinson-specific application, the instrument’s structure aligns well with assessing domains known to be affected by the disease, such as postural control and motor planning. The careful selection and addition of items ensure that the assessment captures the necessary variance related to freezing and turning difficulties characteristic of advanced PD.

Instrument

Test Type: Performance

Format: Observational clinical assessment (10 items)

Language Available: Dutch (Nederlandse versie), Original English

Population Group: Adults, Elderly

Age Group: Typically 18+

Population Details: Individuals with balance disorders, specifically targeted for patients with Parkinson’s disease.

Test Methodology: The patient performs a series of 10 walking and balance tasks, scored on a 4-point ordinal scale (0 to 3), yielding a maximum score of 30. The methodology requires standardized equipment (e.g., measuring tape, stopwatch, obstacles) and careful observation of gait parameters and stability during locomotion.

The original PDF forms related to the Parkinson-specific adaptation (ZvP) are available:

• The original PDF Toelichtingsformulier (Explanation Form) can be downloaded here: FGA-form-ZvP.pdf
• The original PDF Meetinstrument (Measurement Instrument) can be downloaded here: FGA-meetinstr-ZvP.pdf

Keywords

Gait function, Dynamic Balance, Mobility assessment, Postural stability, KNGF, Performance-based, Ziekte van Parkinson, Physical Therapy, Rehabilitation.

Authors

Author ORCID Identifier: N/A

Affiliation Email addresses: N/A

Correspondence Address: Wrisley DM (2003); KNGF (2017) regarding the specific adaptation implemented in the Netherlands.

Permissions & Fee and Test Year

The original FGA was developed by Wrisley DM in 2003. The specific Dutch adaptation for Parkinson’s disease was formalized and published within the KNGF-richtlijn Ziekte van Parkinson in 2017.

The FGA is generally considered a non-proprietary clinical tool, meaning it is typically free for use in clinical and research settings. Users should, however, adhere to the guidelines set forth by the specific national clinical bodies, such as the KNGF, when utilizing the Parkinson-specific version to ensure standardized administration and appropriate interpretation of results.

Reference’s

• Wrisley DM, Walker ML, Echternach JL, Strasnick B. (2003). Reliability and validity of the Dynamic Gait Index in people with vestibular disorders. Archives of Physical Medicine and Rehabilitation, 84(10), 1548-1553.
• Wrisley DM, Musolino MC. (2009). The Functional Gait Assessment: conditions for test administration and psychometric properties. Archives of Physical Medicine and Rehabilitation, 90(2), 346-350.
• Koninklijk Nederlands Genootschap voor Fysiotherapie (KNGF). (2017). KNGF-richtlijn Ziekte van Parkinson. [Reference for the Dutch guideline incorporating the FGA adaptation].

Items of the Functional Gait Assessment – Parkinson-specifiek

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The source content did not provide the explicit list of 10 scale items for the Functional Gait Assessment – Parkinson-specifiek. The instrument consists of 7 items retained from the Dynamic Gait Index (DGI) and 3 additional items relevant to balance problems. These items typically include assessments of:

• Gait on a level surface (normal speed).
• Change in gait speed (slow and fast).
• Gait with horizontal head turns.
• Gait with vertical head turns.
• Gait pivot turn.
• Stepping over obstacles.
• Gait with narrow base of support.
• Gait backward.
• Stairs (Ascending/Descending).
• Gait with eyes closed (or another complex task added for balance assessment).