Design, Fabrication, and Administration of the Hand Active Sensation Test (HASTe)

Summary

The Hand Active Sensation Test (HASTe) is a valid and reliable measure of haptic performance, which has been used successfully to identify impaired haptic touch in individuals with stroke. The purpose of this paper is to describe the design, fabrication and administration of the HASTe.

Abstract

The concept of personalizing neurologic rehabilitation, based on individual impairments, has experienced a recent surge. In parallel, the number of outcome measures of upper extremity motor performance has grown. However, clinicians and researchers lack practical, quantitative measures of the hand’s natural role as a receptor of the environment. The Hand Active Sensation Test (HASTe), developed by Williams and colleagues in 2006, is a valid and reliable measure of haptic performance. Though not available commercially, the HASTe can be fabricated from inexpensive materials, and it has been used successfully to identify impairments in haptic touch in individuals with stroke. (Williams, 2006). This paper presents the methods of design and fabrication of the HASTe testing kit, as well as a visual screen to be used during administration, and instructions for the tests administration and scoring.

Introduction

Imagine the feel of a loved one’s hand. It is calloused or smooth? Strong or delicate? Warm or cool? Do you hold it in a handshake or with fingers intertwined? If you have evoked a memory, it is likely grounded in your ability to use movement of your hands to solicit somatosensory information, which is called haptic touch, or active sensation. Characteristics that can be determined with haptic touch include size, shape, weight, texture, surface compliance, and temperature.  Haptic receptors include proprioceptors, which are found in the skin, muscles, tendons, and joints, as well as cutaneous receptors, both of which are activated during manual exploration of objects. Different hand actions aid in the determination of object characteristics. For example, repeatedly performing a lateral rubbing motion across an object may expose texture properties, or lifting the object in the hand may reveal object weight. Therefore, both manual dexterity and somatosensation are vital to haptic performance and the human experience.

Following stroke, both somatosensory and motor impairments contribute to diminished haptic performance. ¹ Poststroke motor impairments are common and well defined, with approximately 70% of stroke survivors experiencing some level of paresis. ¹ Somatosensory impairments after stroke are also common, occurring in 47-89% ^2-4 of individuals. Researchers agree that both cutaneous and proprioceptive impairments are common after stroke. For a thorough characterization of the consequences of stroke on somatosensory domains the reader is referred to the works by of Carey et al., ² Connell et al., ⁵ and Sullivan. ⁴

Somatosensory impairments contribute to diminished rehabilitation outcomes, ⁶ upper limb coordination, ⁷ function and quality of life.⁸ However, quantification of somatosensory impairments, especially active sensation, is lacking in clinical practice in part due to the fact that somatosensory loss is less apparent and more difficult to quantify than motor impairments.⁹ Measures which have been developed to quantify active sensation include the Byl-Chyney-Boczai Sensory Discriminator (BCB), ¹⁰ the stereognosis component of the Revised Nottingham Sensory Assessment, ¹¹ the Functional Tactile Object Recognition Tests (fTORT), ¹²  the Manual Form Perception Test (a subset of the Sensory Information and Praxis Test), ¹³ and the Haptic Object Recognition Test (HORT). ¹⁴ Although these measures are available, a recent systematic review, which sought to describe how somatosensory impairments in the arm and hand relate to upper limb problems following stroke, concluded that clinicians and researchers currently lack valid and reliable tests of somatosensation. ¹⁵ Therefore, addressing the availability of clinically useful and parametrically sound measures of haptic performance is essential.

The Hand Active Sensation Test (HASTe) is an 18-item match-to-sample test of weight and texture discrimination, originally published by Williams and colleagues in 2006. ¹⁶ The HASTe is a measure of haptic touch and is sensitive to haptic impairments in individuals with stroke (indicated by fewer than 13 correct matches). As the HASTe seeks to measure haptic perception, as minimum criteria, individuals need the abilities to grasp and lift with the hand and arm and follow the test instructions. In the International Classification of Functioning, Disability and Health (ICF) model, ¹⁷ the HASTe is considered an activity level measurement. The HASTe takes between 15-30 min to administer per hand tested. Advantages of the HASTe include that it is inexpensive, total of material prices for 2015 estimated at $100, and easy to construct and that it’s 18-point scale provides greater resolution regarding performance than more common dichotomous characterization of “intact” or “impaired”.

The purpose of this paper is to describe the design, fabrication and administration of the HASTe. While it is possible to infer the test set-up from the original HASTe publication, this paper provides detailed methods for fabricating a visual screen and a HASTe test kit, both to be used during testing. The equipment required for assembly, as well as a detailed list of all required materials is listed in the Table of Materials. A single sheet with instructions for administering and scoring the HASTe is also provided as the following:

APPENDIX 1: HASTe  Administration Instructions and Score Sheet         Participant ID#_______  Date_______

Set Up:  Seat the test participant at a table (table ~29 inches high and chair seat ~18 inches high) with, initially, the dominant or less impaired upper extremity resting on the table and placed under the assembled visual screen. During the test, keep all objects in numerical order to maintain organization.

Demonstration Trials:  Administer two demonstration trials prior to scoring. Provide the participant with objects A and B, and instruct him/her to compare the objects’ weights. Then, provide the participant with objects A and C, and instruct him/her to compare the objects’ textures. Offer feedback only for the demonstration trials.

Scored Trials:  There will be 18 trials scored per extremity, with a maximum of 5 min allowed for each. Instruct the participant to manually explore the specified test object (identified “test” in the tables below) with the dominant or less impaired hand, then explore each of the three possible object matches (numbered otherwise within each trial box below) with this same hand. The possible matches will vary by either weight or texture, but never by both within one trial.  Instruct the participant to find the match of the original object and tell him/her they can touch each object as many times as needed to determine an answer.  Do not inform the participant as to which object property (texture or weight) he or she is matching within a trial, and do not assist the participant with manual exploration of the objects. Indicate the participant’s final answer for each trial in the tables below by circling the number of that object. Test the more impaired upper extremity after the participant completes the test with the less impaired upper extremity. Using the tables below, score the test by determining the number of correct matches from a total of 18 trials per hand (one box per trial below).

Verbal Instructions to Participant: “Use one hand to manually explore the test object first. Then, explore each of the three possible matches, which vary by either weight or texture but never by both within one trial.  Find the match. You can touch each object as many times as you need to determine your answer. There will be 18 trials. You have a maximum of 5 min for each trial.”

Protocol

1. Design and Fabrication of Visual Screen and HASTe (See "Table of Materials" for All Required Equipment and Materials):

1. Assemble Visual Screen (Figure 1):
   1. Cut four pieces of 0.5-inch PVC pipe (material a) to 10 inches (these form the base of the screen). Cut three pieces of 0.5-inch PVC pipe to 20 inches (these form the upright portion of the screen).
   2. Insert two pieces of 10-inch pipe into both PVC Tee’s (parallel openings) (material b). Insert two pieces of 20-inch pipe into each of the remaining holes of the PVC Tee’s (perpendicular to the 10-inch pieces). Insert PVC elbows (material c) on each of the open ends of the 20-inch pipes.
   3. Insert each end of the third 20-inch PVC pipe into each of the open PVC elbows. Do not glue PVC joints if easier folding/storage of visual screen is desired. Glue PVC joints for a permanent visual screen, if desired. Drape pillow case (material d) over top pipe. Secure with binder clips (material e) or safety pins.

Figure 1: Set-up of the HASTe. Participants should be seated at a table. The visual screen between the participant and the test objects. The objects for one trial are removed from the test kit and offered to the participant in the following order: test object first, then each of the three possible matches, in the order indicated in Appendix 1: Administration Instructions and Score Sheet. Please click here to view a larger version of this figure.

2. Assemble HASTe Testing Kit (includes 9 test objects, a duplicate set of 9 sample objects, and 3 example objects) (Figure 2)
   1. Cut 21 pieces of 1.5-inch diameter PVC pipe (material f) into 4-inch lengths. Cut cork (material g) into 21 strips, each 4 x 7 inches. Overlay each cork over PVC to ensure no overlap at seam or ends of pipe.
   2. Trim excess cork flush to edge. Coat each of the 21 pieces of pipe (one-by-one) with all purpose cement (material h) and wrap with cork.
   3. Measure and cut six 4 x 7-inch pieces of self-adhesive laminate (material i) and six 4 x 7-inch pieces of brown paper (material j). Trim excess. Wrap six pieces with self-adhesive laminate.
   4. Coat six pieces with all purpose cement and wrap with brown paper wrapping. Coat one piece with all purpose cement and wrap with sandpaper (material k). Coat two pieces with all purpose cement and wrap with glossy cardstock (material l).
   5. Measure and lay out eight pieces of clay (material m), each weighing 2.2 ounces. Measure and lay out six pieces of clay, each weighing 3.2 ounces. Measure and lay out seven pieces of clay, each weighing 4.2 ounces.
   6. Mold two 2.2-ounce, 3.2-ounce, and 4.2-ounce pieces of clay into a solid block to fill the diameter of the pipe. Insert each into the center of a pipe covered in brown paper wrapping. Repeat step with pipes covered with cork and self-adhesive laminate.
   7. Mold two 2.2-ounce pieces of clay into a solid block to fill the diameter of the pipe. Insert one into the center of a pipe covered in glossy cardstock and one into the pipe covered in sand paper.
   8. Mold one 4.2-ounce piece of clay into a solid block to fill the diameter of the pipe. Insert into the center of a pipe covered in glossy cardstock .
   9. Fill each pipe to capacity with closed-cell packing foam (material n). Weigh components to ensure accuracy of weight to 0.1 ounce.
   10. Coat each end cap (material o) with all purpose cement and firmly insert into both ends of each pipe.
   11. Label each object with weight (on the bottom) and number (on the top) as to be visible to the examiner.
   12. Cover test objects 1T, 2T and 3T with cork, then brown paper, and weigh to 6, 7, and 8 ounces, respectively. Cover test objects 4T, 5T, and 6T only and weigh to 6, 7, and 8 ounces, respectively. Cover test objects 7T, 8T, and 9T with cork, then self-adhesive laminate, and weigh to 6, 7, and 8 ounces, respectively.
   13. Label sample objects 1-9 (exact duplicates of the test objects).
   14. Label the three example objects A, B, and C. Cover example objects A and B with glossy card stock (weighing 6 and 8 ounces, respectively). Cover example object C in sand paper (weighing 6 ounces). (Example objects are not shown in Figure 2.)
   15. Sore and transport all test items in a plastic storage box (material p).

Figure 2: Organization of the HASTe Test Objects. The test objects are ordered 1-9 and marked with a ‘T’. The nine sample objects, which participants match to the test objects by weight or texture, are also numbered 1-9 and ordered, as shown.

2. Administration of HASTe:

1. Seat participants at a standard height table (~29 inch) and chair (~18 inch). Adjust the heights such that the participant can rest and move the test arm comfortably on the table. Place the test arm under a visual screen, as shown in Figure 3, to prevent participant from seeing the test arm, the objects, or the examiner.
   Note: Test the less impaired upper extremity first, if the participant being tested has a more impaired upper extremity.
2. Instruct participant to grasp and lift the example objects to freely determine differences between weight and texture. Provide feedback for the two demonstration trials only.
3. Administer two demonstration trials prior to scoring. Have participant compare objects A and B to illustrate differences in weight. Have participant compare objects A and C to illustrate differences in texture.
4. Do not offer feedback on the patient’s performance during trials of the scored test. Do not assist the patient with manual exploration of the objects. Organize test materials for all 18 trials by keeping objects in numerical order. (Figure 2)
5. Provide verbal instructions to the participant: “Use one hand to manually explore the test object first. Then, explore each of the three possible matches, which vary by either weight or texture but never both within one trial.  Find the match. Touch each object as many times as needed to determine the answer. There will be 18 trials. With a maximum of 5 min for each trial.”
6. Repeat test instructions during test administration at the discretion of the examiner or upon request of the participant. Do not inform participant as to which object property (weight or texture) they are matching within a trial.
7. Slide objects to and away from the participant’s hand, per the participant’s request, if his or her elbow or shoulder movement prevents them from moving between objects (Figure 3).
8. Have the participant indicate their choice verbally or by pointing to their choice upon finding the match. Administer the next trial. Do not have participant describe, in any manner, the object properties or explain why they chose the match that they did.
9. Score the test by determining the number of correct matches from a total of 18 trials per hand. Use Appendix 1: Administration Instructions and Score Sheet and the overall organization shown in Figure 2 in order to reduce examiner error.
10. Analyze and interpret HASTe scores as a measure of haptic performance with the following considerations.  
    Note: The intervals between ranks on the HASTe, an ordinal scale, may not be consistent and may not be known. However, like many clinical measures, it may be meaningful and appropriate to apply statistical inference as though the data were interval, as shown in Figure 4.

Figure 3: Offering the HASTe Objects to the Participant. The objects can be placed in the participant’s hand, but the examiner should avoid assisting the participant with object manipulation.

Results

Williams and colleagues published the original study, which established the reliability and validity of the HASTe, in 2006. Based on that study, individuals scoring fewer than 13 correct matches on the HASTe are considered to have impaired haptic performance, while those scoring between 13 and 18 are considered to have unimpaired haptic performance. ¹⁶ When an individual scores 6 or fewer correct matches, it is considered a chance score, based on the odds in an 18 trial/3 item match to sample design.

Discussion

Evidence suggests that similar to motor recovery following stroke, somatosensory recovery requires task specific training. ^18,19,20 Therefore, if we aim to improve the hands performance as a haptic receptor, haptic impairments must be identified. ¹⁵ The opportunity to quantify haptic ability in the clinic and laboratory has been limited, to some extent, based on the availability of valid and reliable outcome measures.  The large number of stroke survivors with somatosensory impairmen...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Equipment Needed for Assembly
Tape measure			To measure lengths of materials
PVC saw			To cut PVC pieces to appropriate lengths given below
Scissors			To cut paper, cork and laminating material
Scale accurate to 0.1 ounce			To determine exact weight of test objects
Sharpie Permanent Marker			To label test item number and weight
Visual Screen Materials	Company	Catalog Number
0.5-inch PVC Pipe (Sch. 40 Plain-End Pipe)	Home Depot	530048	104 inches total, will be cut into four 10-inch and three 20-inch pieces
0.5-inch PVC Tee (Sch. 40 SxSxS Tee)	Home Depot	406005RMC	Two pieces
PVC Elbow (Lasco 0.5-inch Dia 90 degree PVC Sch 40 Side Outlet Elbow)	Home Depot	413005RMC	Two pieces
Pillowcase			One to be hung from the PVC frame as a visual shield
ACCO Binder Clips, Medium	amazon.com	72050	Two to hold the pillowcase to the PVC frame
Testing Kit Materials
1.5-inch PVC Sch. 40 DWV Plain End Pipe	Home Depot	531111	85 inches total, will be cut into 21 4-inch pieces
Quartet Cork Roll, 1/16-inch thick	amazon.com	NA	1 roll, 24x48 inches, will be cut into 42 4x7-inch pieces to cover all test and example items
Oatey all purpose cement for CPVC and PVC	Home Depot	308213	8 ounce can, to use to adhere cork, paper and end caps to PVC test items
Avery Self-Adhesive Laminating Roll	amazon.com	73610	One 24x600-inch roll, will be cut into six 4x7-inches pieces to cover cork on six test objects
Brown Builder's Paper	Home Depot	35140	One roll, will be cut into six 4x7-inch pieces to cover cork on six test objects
3M Pro Grade 9 Sandpaper	Home Depot	25060P-G	One piece 4x7 inches, to use to cover one example item
Ranger Glossy Cardstock	amazon.com	NA	One 8.5x11-inch, 10-Pack, white, will be cut into two 4x7-inch pieces to cover example items
Marblex-durable self modeling clay in moist form	amaco.com/shop/	X-242	One 5-pound package, used to achieve correct weights of test objects
Medium density polyethylene packing foam	amazon.com	NA	One foam sheet, 220 poly, charcoal, 2x24x18 inches, to fill the remaining space in test objects after clay has been inserted
Knock Out Plug for 1.5-inch PVC	Home Depot	85000	42 caps to seal the ends of the 21 test items
Sterilite 6-quart plastic storage box	Home Depot	16428960	One to store/transport test objects