Overview

The Trunk Impairment Scale (TIS) is a performance-based clinical measure developed to quantify motor impairment of the trunk in people recovering from stroke. It is administered in sitting and captures how well a person controls the trunk during quiet sitting, active weight shifts, and selective trunk movements. The original version published in 2004 organizes 17 items into three subscales, with a total score from 0 to 23. Higher scores indicate less impairment (better trunk motor control in the tested tasks).

Because trunk control is a gateway to transfers, reaching, and early mobility, the TIS is widely used in stroke rehabilitation for characterization at a single time point, tracking change with therapy, and communication among therapists, physicians, and teams planning discharge needs.

What the three subscales represent

Static sitting balance (maximum 7 points) probes the ability to maintain an upright, controlled trunk posture without back or arm support while minimal or no active displacement is required beyond holding midline alignment. Items in this block address whether the person can sustain sitting under defined conditions and how much external help or compensatory strategies are needed.

Dynamic sitting balance (maximum 10 points) examines controlled movement of the trunk in sitting: shifting weight, reaching, and responding to controlled challenges that require displacement of the center of mass while staying seated. This subscale often differentiates patients who “sit statically” from those who can use the trunk proactively for functional tasks.

Coordination of trunk movement (maximum 6 points) focuses on selective trunk motion—dissociating movement of the upper trunk, lower trunk, or pelvis as instructed—rather than only global flexion or extension. Poor coordination may appear as en bloc movement or excessive fixation of one region while another is supposed to move.

Together, the subscales reflect complementary aspects of trunk motor behavior: stability, dynamic control, and selective segmental control.

Standardized starting position and administration

Testing begins from a defined starting posture: the patient sits at the edge of a bed or plinth without back support and without arm rests, thighs supported, knees flexed to approximately 90 degrees, feet flat on the floor, and arms resting on the legs in a relaxed position. The head and trunk are aligned in midline as the baseline. If significant hypertonia makes the “arms on legs” position unrealistic, the published protocol allows the arms to be placed in a consistent alternative starting position so scoring remains fair across repeated assessments.

Items are explained verbally and may be demonstrated when helpful. Unless the scale’s rules specify otherwise for a given item, each item may be performed up to three times. The highest score achieved on that item is recorded. The patient may be corrected between attempts (for example, reminded of the task or repositioned to the start) so that the score reflects best effort under standard conditions rather than a single failed trial due to misunderstanding.

Administration time varies with patient tolerance and cognition but is often on the order of several minutes to roughly twenty minutes in clinical practice.

Scoring the original TIS (0–23)

Individual items use ordinal scoring (commonly 0, 1, and sometimes 2 or higher where defined in the manual) according to explicit criteria in the original publication’s appendix. Within each subscale, item scores are summed to yield:

• Static sitting balance: 0–7
• Dynamic sitting balance: 0–10
• Coordination: 0–6

The total TIS is the sum of the three subscale totals, ranging from 0 (maximum impairment on the scale) to 23 (no impairment relative to the scale’s ceiling).

Special rule: item 1 and discontinuation

A critical administrative rule in the original TIS is that if the first item of the static sitting balance subscale is scored 0, the total TIS is 0 and remaining items are not performed. That rule exists because subsequent tasks assume a minimal capacity to assume and briefly maintain the standardized sitting starting point. When this discontinuation applies, clinicians should document it explicitly rather than imputing subscale scores.

The CalcMD calculator mirrors this logic with an option to indicate item 1 scored 0, which forces the displayed total to 0 regardless of other numbers entered.

Interpreting scores in context

The TIS is an impairment-level measure in the ICF sense: it describes how trunk movements are performed under test conditions, not by itself whether the person is safe at home or independent in all activities of daily living. A single total score should be read alongside sitting balance for specific tasks, transfer quality, walking aids, cognition, vision, sensation, pain, and medical stability.

In stroke cohorts studied around the time of the scale’s development, lower totals were more common among people with limited ambulation or early subacute recovery, whereas higher totals approached values seen in healthy adults. Subscale profiles matter: some patients score relatively well on static sitting yet poorly on dynamic or coordination items, which can guide treatment emphasis (e.g., selective control drills versus dynamic weight-shift training).

When comparing patients or setting expectations, remember that age, sex, comorbidity, and pre-stroke activity level have been reported to associate with TIS performance in some analyses; longitudinal change within the same patient under consistent testing conditions is often more informative than a single comparison to a loose “normal” expectation.

Psychometric properties (original version)

In the stroke samples described in early TIS work, test–retest and inter-rater reliability for the total score and for the static and dynamic subscales were generally high, supporting use in clinical follow-up and research when raters are trained. The coordination subscale tended to show somewhat lower reliability coefficients than the other two, which is typical for shorter multi-item constructs that demand fine judgment of movement quality.

Construct validity was supported by strong relationships with other trunk and disability measures in those studies—for example, correlations in the expected direction with the Trunk Control Test and Barthel Index—indicating that better TIS performance co-occurred with better trunk control and greater independence in basic activities. Predictive validity work suggested trunk performance early after stroke could contribute information about later functional outcomes, particularly when combined with other clinical variables in multivariable models.

Floor and ceiling effects deserve attention: in some chronic or milder cohorts, the static subscale approached ceiling, motivating later measurement science work and revised versions of the instrument (see below).

TIS 2.0 and related versions

Subsequent Rasch-based work led to TIS 2.0, which retained dynamic and coordination dimensions but removed the static sitting balance subscale because of substantial ceiling effects in certain populations. TIS 2.0 is a different instrument with its own scoring and interpretation rules. The CalcMD tool described on this page implements arithmetic for the original three-subscale TIS total (0–23); if your documentation specifies TIS 2.0, use the appropriate form and scoring manual rather than this 0–23 sum.

Use in populations beyond stroke

Although developed and validated primarily in stroke rehabilitation, the TIS or adapted procedures have been explored in other neurological conditions (for example traumatic brain injury, Parkinson disease, multiple sclerosis, and cerebral palsy in pediatric adaptations). When the scale is applied outside its original population, teams should treat norms, responsiveness, and interpretive thresholds as provisional unless condition-specific evidence supports them.

Limitations and safety considerations

The TIS requires the patient to sit unsupported at the edge of a support surface and to follow instructions. It is inappropriate for individuals who cannot safely assume that position, who have unstable fractures or spine precautions that contradict the test position, or whose medical status (e.g., severe orthostatic intolerance, uncontrolled autonomic responses) makes repeated sitting trials unsafe. Cognitive impairment, language barriers, or neglect may invalidate scores unless accommodations are standardized and reported.

Scores can improve with learning effects if the exact same items are rehearsed frequently without blinded reassessment; serial testing should use consistent instructions and document therapy between assessments when interpreting change.

Using the CalcMD Trunk Impairment Scale calculator

After you administer and score the official items on a paper or electronic TIS form, enter the subscale sums into the calculator: static (0–7), dynamic (0–10), and coordination (0–6). The tool adds them to display the total out of 23. If item 1 of the static subscale was 0, select the discontinuation option so the total displays as 0 per protocol. The calculator does not observe the patient, substitute for training in item scoring, or replace clinical judgment about safety, goals, or disposition.