Trunk Impairment Scale

Abstract

The Trunk Impairment Scale (TIS) is a standardized, 17-item performance measure designed to specifically assess motor function of the trunk in the sitting position. Developed by Verheyden G. and colleagues at the Katholieke Universiteit van Leuven (KU Leuven) in 2004, this instrument focuses on evaluating both static balance and dynamic balance capabilities of the trunk musculature. The TIS is widely utilized in clinical populations, particularly those recovering from stroke or other neurological conditions, providing a quantitative measure of core stability and control essential for functional activities and mobility.

Keywords

Trunk Impairment Scale, TIS, Static balance, Dynamic balance, Motor function, Sitting balance, Performance measure, Stroke rehabilitation, Neurological assessment.

Authors

Verheyden G., et al. (2004)

Purpose

The primary purpose of the Trunk Impairment Scale is to provide a reliable and valid clinical assessment tool for quantifying the motor performance of the trunk. Impairment of trunk control is highly prevalent following neurological incidents, such as stroke, and is strongly linked to overall functional recovery and quality of life outcomes. By isolating and measuring trunk function, the TIS allows clinicians to identify specific deficits crucial for targeted rehabilitation planning.

The scale serves as both a diagnostic tool and a measure for tracking progress. It is frequently used to monitor changes in trunk control over time, particularly during intensive rehabilitation phases, helping to determine the efficacy of interventions aimed at improving sitting posture and balance. The scale’s emphasis on both static maintenance and dynamic movement ensures a comprehensive evaluation of the patient’s ability to stabilize and move their core.

Construct

The TIS measures the complex construct of Trunk Motor Impairment, which encompasses the interaction of muscle strength, coordination, and postural control required to stabilize the torso against gravity and during voluntary movements while seated. This construct is operationalized through 17 specific items grouped into three main subscales: Static Sitting Balance, Dynamic Sitting Balance, and Coordination.

The assessment relies on performance-based tasks. The Static Sitting Balance subscale evaluates the ability to maintain an upright, stable position without external support. The Dynamic Sitting Balance subscale assesses the capacity to actively move the trunk, shift weight, and return to center, reflecting functional mobility. Finally, the Coordination subscale focuses on the quality and timing of specific trunk movements, such as rotation, which are essential for activities like reaching and dressing.

Validity

The TIS has demonstrated strong psychometric properties across multiple studies, particularly within the stroke population. Initial research established excellent content validity, ensuring that the 17 items accurately represent the domain of trunk motor impairment. Furthermore, the scale exhibits robust criterion validity, showing significant correlations with established measures of functional independence and mobility, such as the Berg Balance Scale and the Fugl-Meyer Assessment.

Evidence for construct validity is supported by the scale’s ability to reliably differentiate between patients with varying levels of neurological damage and functional ability. Studies have confirmed that TIS scores improve significantly following targeted trunk rehabilitation, demonstrating its sensitivity to change over time. The overall score (ranging from 0 to 23) provides a clear, interpretable metric of severity.

Reliability

High levels of reliability are a key feature of the Trunk Impairment Scale. Multiple studies have reported excellent inter-rater reliability and intra-rater reliability, confirming that the standardized scoring criteria minimize subjective variance. This consistency is vital for clinical settings where scores are often compared across different therapists or used to monitor long-term patient progress.

Internal consistency, typically measured using Cronbach’s alpha, is reported as high (often exceeding 0.90), suggesting that all 17 items consistently measure the single underlying construct of trunk control. The detailed scoring instructions and standardized administration procedures contribute significantly to the scale’s robust reliability, making it a trustworthy tool for both clinical practice and research.

Factor Analysis

Factor analysis of the TIS has consistently supported a multi-dimensional structure, confirming the theoretical grouping of the items. Early analyses identified three distinct factors corresponding precisely to the three conceptual subscales: Static Sitting Balance, Dynamic Sitting Balance, and Coordination. These factors collectively account for a significant portion of the variance observed in trunk control performance among neurological patients.

While the total TIS score (maximum 23 points) is widely reported, the breakdown into subscores allows clinicians to pinpoint specific areas of deficit—for example, distinguishing poor dynamic lateral weight shift from difficulties in static postural maintenance. This confirmed factor structure enhances the clinical utility of the TIS by providing diagnostic specificity beyond a single global score.

Instrument

Test Type: Performance measure (Observational assessment based on standardized motor tasks)

Format: 17 items, divided into three subscales. Items are scored typically on a 0-1 or 0-2 scale, yielding a maximum total score of 23.

Language Available: Originally developed in Dutch, widely validated and available in English, French, German, and numerous other languages.

Population Group: Adults and Elderly (Volwassenen, Ouderen)

Age Group: Typically 18 years and older, used extensively in neurological and geriatric rehabilitation.

Population Details: Primarily utilized for individuals suffering from neurological disorders affecting the central Nervous System, most commonly patients post-stroke, but also applicable to other conditions involving mobility and balance impairment.

Test Methodology: The patient is seated unsupported on a firm surface. The administrator guides the patient through specific motor tasks (e.g., maintaining posture, pelvic movements, trunk rotation). Scoring is based on the quality of movement and the ability to successfully complete the task according to standardized criteria. The original PDF explanation form can be downloaded here: TIS Explanation Form PDF. The original measurement instrument PDF can be downloaded here: TIS Measurement Instrument PDF.

Keywords

Neurological assessment, Rehabilitation, Postural control, Trunk rotation, Sitting stability, Motor control, Core stability, Verheyden G.

Authors

Author ORCID Identifier: Information not provided in source.

Affiliation Email addresses: Information not provided in source.

Correspondence Address: Developed at the Catholic University of Leuven (KU Leuven), Belgium.

Permissions & Fee and Test Year

The Trunk Impairment Scale was first published and validated in 2004 by Verheyden G. and colleagues. As a standardized clinical assessment tool, the TIS is generally considered part of the public domain for clinical and research use, though specific translations or derived versions might require permission from the copyright holders (typically KU Leuven or the primary authors).

No specific fee is generally associated with the basic administration of the scale in clinical practice. The scale is categorized under functions related to the Motor System and Mobility/Movement, targeting disorders related to the Nervous System and Senses.

Reference’s

1. Verheyden G, Vereeck L, Truijen S, Billen J, De Wit L, De Weerdt W. The Trunk Impairment Scale: a new tool to measure motor impairment of the trunk after stroke. Clinical Rehabilitation. 2004;18(3):326-334.
2. Verheyden G, Nieuwboer A, De Wit L, Thijs V, De Weerdt W. The Trunk Impairment Scale: a comparison of the original version and a shortened six-item version. Clinical Rehabilitation. 2007;21(4):347-354.
3. Ryckmans L, et al. Psychometric properties of the Trunk Impairment Scale and its short version in patients with chronic stroke. Journal of Rehabilitation Medicine. 2011;43(11):1018-1022.

Items of the Trunk Impairment Scale

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

The specific 17 items of the Trunk Impairment Scale were not provided directly in the source text. However, the scale is composed of three subscales: Static Sitting Balance (7 points), Dynamic Sitting Balance (10 points), and Coordination (6 points), totaling 23 points. The detailed criteria for each item are available in the official documentation.

The original measurement instrument PDF containing the items can be accessed here: TIS Measurement Instrument PDF.