Evaluating the Adult with Cerebral Palsy for ... - Physical Therapy

Evaluating the Adult with Cerebral Palsy for 

Specialized Adaptive Seating 

Lynda Hollett Hundertmark 

PHYS THER. 1985; 65:209-212. 

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LYNDA HOLLETT HUNDERTMARK 

Physical therapists may not expect to have a pronounced effect on the neurodevelopmental 

function of the cerebral palsied adult because the neuroplasticity 

of the child is no longer present in the adult. Adapting the environment to such 

an adult, therefore, becomes of utmost importance. The wheelchair may be the 

most important structure of the environment for cerebral palsied adults. I present 

methods for assessing the severely involved adult client and evaluating adaptations 

of the wheelchair for therapeutic seating. The anterior and posterior tilt of 

the pelvis and the vertical angle of the backrest are emphasized in achieving 

therapeutic seating for the severely multiply handicapped adult. 

Key Words: Adult, Cerebral palsy, Wheelchair. 

Adaptive seating for severely disabled cerebral palsied children 

has been a subject of increasing concern in recent years. 

The literature, however, has rarely addressed the needs of 

adults with cerebral palsy. As physical therapists, we have 

often focused our attention on mobile and changing children 

with cerebral palsy. Many severely multiply handicapped 

adults, however, also require the knowledge and skills of 

physical therapists to adapt the environment to individual 

needs. Adaptive seating may be the most important device 

available for any client who cannot be comfortably, safely, 

and functionally seated in a commercially available wheelchair. 

The adaptive wheelchair should be "therapeutically" designed 

to improve the overall function of the client. Goals 

may include providing increased mobility for the client or 

improving the client's posture, muscle tone, or ability to eat, 

digest, and breathe properly. Interaction with the environment 

from the upright position may also enhance psychosocial 

and cognitive development of the client. 

In my experience, most adult clients requiring highly specialized 

seating have severe extensor spasticity. Nearly all these 

clients have severe scoliosis with vertebral rotation, and many 

retain early developmental reflexes (tonic labyrinthine reflex 

and tonic neck reflexes) that impair or prevent normal functioning. 

With rare exceptions, adult clients have moderate or 

severe contractures that are often permanently fixed. These 

problems often preclude seating in commercial wheelchairs 

without extensive adaptations. 

The therapeutic success of the adapted seat depends on the 

accuracy and comprehensiveness of the initial seating assessment. 

Sitting posture, tone, reflex patterns, and musculoskeletal 

limitations must be accurately assessed in the upright 

position. The appearance of symmetrical posture is often 

deceptive when the trunk, pelvis, hip, and knees are not 

carefully observed with clothing removed. The purpose of this 

Ms. Hundertmark was Program Coordinator for Physical Therapy, Wassaic 

Developmental Center, Wassaic, NY, at the time this article was written. She 

is now a consultant and educator in the field of adaptive equipment and 

developmental disabilities in private practice, R.D. 2, Clove Valley Rd, La- 

Grangeville, NY 12540 (USA). 

This article was submitted March 16, 1984; was with the author for revision 

14 weeks; and was accepted August 16, 1984. 

article is to suggest a method for assessing severely multiply 

handicapped adults for adaptive seating. I discuss observations 

of changes of tone, reflexes, and normal reactions as seating 

positions are altered. I explain the "fitting chair" and assessment 

of the orientation of the client in relation to gravity in 

the chair. Finally, I present problems inherent in wedging the 

wheelchair seat and reclining the seat insert to overcome 

extensor spasticity. 

ASSESSMENT 

The therapist working with children may assess changes of 

postural tone and reflexes as they are carried, moved in the 

lap of the therapist, and placed in different positions. Children 

may often be hypotonic rather than spastic, are also more 

mobile, and will almost certainly change during the growing 

process. 1 Adults, on the other hand, are frequently more fixed 

in their movement patterns. They may have learned to use 

abnormal reflexes functionally or to "fix" with spasticity 

against a backrest or calf panel for stability. Only a careful 

and precise assessment of the client can determine how the 

client may gain or lose function with various adaptations. 

The client should be evaluated in the sitting position over 

the side of a mat table. Beginning at the pelvis, 24 particular 

attention must be paid to anterior and posterior tilt and to 

lateral symmetry because restriction in any direction will 

cause changes throughout the body. For the very involved 

client, the therapist may assume a position behind the client, 

knees astride the client, and hands on the pelvic crests. An 

assistant may stabilize the client's feet and knees at or as near 

90 degrees as possible with the thighs evenly supported on the 

mat. With this high degree of support and control at the 

pelvis, the therapist slowly shifts the client's weight laterally, 

forward, and backward. The therapist may need to use her 

own body to shift the client's entire trunk forward from the 

pelvis, sometimes rotating the client's trunk to encourage 

relaxation. The therapist must accurately assess the position 

of the superior iliac spines as the trunk is moved to assure 

that apparent movement of the pelvis is not in fact occurring 

in the back. The therapist should note if reflexes or abnormal 

Volume 65 / Number 2, February 1985 209 

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movement patterns increase or decrease as the pelvis and 

trunk are moved in all planes. 

Lateral mobility of the pelvis must be assessed with attention 

to uneven distribution of the weight-bearing surface. 

Lateral movement may be severely restricted in the scoliotic 

client, and frequently one pelvic crest and the lowest rib are 

very near each other. Because the goal is to distribute the 

client's weight as evenly as possible, changes in posture must 

be observed as the weight is shifted more evenly over both 

ischia. 

The therapist should observe the impact of rightingreactions 

on sitting posture. As the pelvis is tilted anteriorly, 

righting and equilibrium reactions may result in head and 

trunk extension and hip and knee flexion.If the pelvis is tilted 

posteriorly in the presence of rightingreactions, the client will 

often bear weight on the sacrum and flex forward. With the 

neck in flexion, the head may right into extension or may 

remain in flexion, leaving the client looking down. Equally 

important, a posterior tilt in sitting may permit, and even 

encourage, extension of the hips, which widens the 90-degree 

hip angle and may then trigger the full extensor pattern. 5 

Although clinicians widely recognize that the hips must maintain 

an angle of 90 degrees or less to prevent extensor spasticity, 

2, 3,6 the posterior pelvic tilt is often overlooked as a starting 

point of hip extension in the sitting position. 

Righting reactions will also influence posture if the client's 

back is reclined, regardless of the angle of the hips. 7 At only 

5 degrees of a reclined position, the client may tend to flex 

the head slightly forward as we do in the seat of a car. If 

reclined more than 15 degrees, a client with rightingresponses 

may begin to curl the trunk into flexion. 

Changes in the lower extremities must be observed as the 

pelvis is moved. Because the hamstrings are two-joint muscles, 

stabilizing below the knee with a heel or leg support of any 

sort in the presence of hamstring spasticity may result in 

undesirable hip extension and posterior pelvic tilt. The client 

then may "sit on the sacrum, always slipping forward out of 

thewheelchair." 5(p280) 

Positions of the pelvis and trunk also significantly affect 

head position and control. As noted above, flexion of the 

head sometimes occurs when a seat is reclined. More often, 

however, contact of the back of the head with an extended 

backrest in a reclined or tilted position may trigger extensor 

spasticity. A therapist may, therefore, find it beneficial to 

avoid use of an extended backrest or head support and bring 

the client fully upright. The head may then extend freely 

without contributing to the full extensor pattern. 

Finally, the therapist must observe the position and function 

of the upper extremities as the head, trunk, and pelvis 

are changed. As extensor tone of the trunk is reduced through 

positional changes, the arms may be needed to maintain 

stability. A tray may provide some support, but the client 

who must lean on the elbows to keep from slumping forward 

may be free to do little else with the upper extremities. The 

arms may also demonstrate increase or decrease of the symmetric 

or asymmetric tonic neck reflexes with postural 

changes. The overall effect of the tonic reflexes on function 

should determine whether posture responses should be stimulated 

or inhibited by the adaptive unit. 

The position of the body in relation to gravity must also be 

assessed. Nwaobi et al, in a recent EMG study of low back 

extensor activity of spastic cerebral palsied children, suggested 

that "orientation of the body with respect to gravitational 

force" may be as important a factor in hyperactivity of 

extensors as the angle of the hip. 7(p180) Because we cannot 

readily assess the effect of body orientation with the hips at 

predetermined angles (usually 90°) while the client sits over 

the side of a mat, a "fitting chair" must be used for this 

assessment. 

THE FITTING CHAIR 

Only during a trial phase in a wheelchair can we see the in 

situ effects of each adjustment. Then, the goals resulting from 

the previous seating assessment can be applied in a "fitting 

chair." Whether a specially made fitting chair, or simply an 

available wheelchair is used, adjustability is the key. We must 

adjust width; depth; height of the footboard, armrests, and 

backrest; and the angle of the seat to the client's measurements 

and medical and therapeutic needs. If the client is using a 

wheelchair, a simple seat insert of tri-wall* (triple-density 

cardboard) may be angled by placing "spacers" of wood, triwall, 

or other material along the front edge of the seat. The 

angle of the backrest may be altered in the same manner. 

Pieces of foam or blocks may provide all the adjustability 

needed in width and depth of the seat. 

The optimal position for seating a client is 90 degrees 

horizontal for the seat and 90 degrees vertical for the backrest. 2 

The client should be placed in the fittingchair as close to this 

ideal position as possible. Accommodations for a scoliosis, 

such as a back contour of foam or other material, should be 

included. The pelvis should be positioned in neutral in the 

following three planes: with slight anterior tilt, equal weight 

bearing on the ischia, and iliac crests equally against the 

backrest to straighten pelvis and trunk rotation if "windblown" 

posture is present. The therapist may findit necessary 

to place the client to one side of the seat and allow the knees 

to drift to the opposite side to assure that the pelvis and trunk 

are not rotated. The corrected position may then be maintained 

by the use of a wedge-shaped cushion along the abducted 

femur. Any other contractures and deformities must 

also be accommodated in the fittingchair. 

As the angles of the seat and backrest are altered, the 

therapist can observe changes in the client. The seat angle 

may be altered by use of spacers, and a block moved behind 

the backrest from bottom to top will vary the trunk angles. 

The tilt of the entire unit may be changed by placing a wedge 

beneath the front casters and moving it slowly until the best 

angle is noted by the client's posture (Fig. 1). 

Remember, it is the tilt of the pelvis that influences posture 

and tone throughout the body. The optimal position of the 

pelvis in sitting is slight anterior tilt. Various methods may 

be used during the assessment to achieve this position. Bergen 

and Colangelo suggested cutting out the area of the backrest 

that the buttocks contact so that the lower part of the pelvis 

extends further back in the chair than the trunk. 2 Wedging 

the top of a back insert forward may also tilt the pelvis and 

trunk anteriorly and in my clinical experience, excellent results 

have been attained using this method with some very 

spastic clients. A soft ethafoam lumbar roll, usually 2 in† 

thick, may work well to prevent a persistent posterior tilt in a 

* Tri-wall Containers, Inc, Wassaic, NY 12592. 

† 1 in = 2.54 cm. 

210 PHYSICAL THERAPY 


PRACTICE 

limited number of clients, who often have low muscle tone 

rather than high muscle tone. 

Therapists should assess the foot-support system in the 

fitting chair. Because many clients for adaptive seating have 

hamstring spasticity or knee flexion contractures beyond 75 

degrees, footrests extended in front of the casters in the usual 

position are not appropriate. To prevent the hamstrings from 

functioning as hip extensors, a foot box or lengthened foot 

support may be used to allow 90 degrees or more of flexion 

at the knees (Fig. 2). The foot box should extend forward 

beyond the reach of the heels and back under the seat as 

needed. Calf panels or pads should not be used with this type 

of foot box to avoid hamstring facilitation. 

When the client is seated fully upright, a tray may be 

suitable for support much the way we use a table or desk top. 

Plans for the tray should usually be determined during the 

assessment process. The fit, height, and tilt of the tray are 

important in achieving the best posture and muscle tone. A 

tilted tray may help to maintain hands in midline and in 

contact with each other. A tray may also be essential for 

clients whose muscle tone decreases excessively when the hips 

and trunk are at a 90-degree angle. The tray may be provided 

with a high inner rim for trunk support, or it may provide 

support only through the arms as the elbows rest on the tray. 

Fig. 1. Optimal angle of the seating unit can be determined by 

placing a wedge beneath front casters to observe varying angles of 

tilt. 

DISCUSSION 

Bergen and Colangelo noted that "a majority of clients with 

disorders of tone show a posterior pelvic tilt when sitting" 

because of "overactivity of hip extensors. " 2(p5) They also noted 

that the posterior tilt leads to the full extension pattern. The 

pelvis must, therefore, approximate as nearly as possible the 

normal anterior tilt position in sitting. Wedging the seat 

invariably increases the posterior tilt in clients who lack full 

hip mobility. This loss of the anterior tilt is the reason that 

wedging of the seat has often been unsuccessful in correcting 

the problem of extensor spasticity in sitting. 

Underlying the practice of wedging is the firm belief that 

reducing the angle of the hips to 90 degrees or less inhibits 

extensor spasticity. That premise is not in question here. If 

the pelvis is tilted posteriorly, however, the hip angle may 

only appear to be 90 degrees. The true angle of the hip will 

often be significantly greater than 90 degrees. The true angle 

determines whether spasticity will be inhibited. 

The reclining position, often used with a wedged seat for 

severely spastic clients, is successful only in a passive sense. 

As spasticity subsides and the client relaxes, he may sink back 

into the seat rather than extending out of the wheelchair. 

Moreover, extensor activity is not reduced by reclining and 

may actually increase. In the aforementioned EMG study by 

Nwaobi et al, reclining the back as little as 15 degrees with 

the hips maintained at 90 degrees flexion produced more low 

back extensor myoelectric activity than when the back was 

straight upright. 7 At 30 degrees of a reclined position, with 

the hips maintained at 90 degrees, extensor tone was still 

higher. The results of this study suggest that reclining a client 

either elicits the supine tonic labyrinthine reflex, or contact 

of the back or the head with a headrest initiates the extensor 

response. Nwaobi et al do not speculate on either of these 

reactions as possible contributing factors. 7 In either event, we 

must be aware of the results of this study and carefully assess 

Fig. 2. A foot box extended back behind the uprights and under 

the seat prevents the hamstrings from extending the hips. 

the effects of reclining the backrest or tilting the insert when 

positioning our severely involved cerebral palsied clients. 

CONCLUSION 

Not all clients can be positioned or assessed as I have 

described, and so these procedures have exceptions. Some 

clients may require surgical correction before they can be 

brought to an upright position. Those with severe hydrocephalus 

or very low tone may be unable to bear the full weight 

of the head and trunk vertically. The fitting chair will reveal 

instances where clients have used postural reflexes or hypertonicity 

for function. Unfortunately, it may not be possible 

to provide a substitute that will allow the client as much 

Volume 65 / Number 2, February 1985 211 


function or independence as the abnormal movements may 

provide. The therapist has little alternative, in such cases, but 

to provide adaptations that enable the client to use these 

movements as optimally as possible. 

Acknowledgments. I extend my appreciation to Mary Ann 

Delaney, whose neurodevelopmental training and discussions 

greatly broadened my knowledge and awareness of handling 

and evaluating cerebral palsied clients; and to Ed Mohler, 

MD, whose questions and willingness to listen led to learning 

and discovery. I give special thanks to Gil Recchia, Adaptive 

Equipment Specialist, who accepts the impossible as a challenge 

to his own creativity. 

REFERENCES 

1. Bobath KA: A Neurophysical Basis for the Treatment of Cerebral Palsy. 

Philadelphia, PA, JB Lippincott Co, 1980 

2. Bergen AF, Colangelo C: Positioning the Client with Central Nervous 

System Deficits: The Wheelchair and Other Adapted Equipment. Valhalla, 

NY, Valhalla Rehabilitation Publications, 1982 

3. Trefler E, Hanks S, Huggins P, et al: A modular seating system for cerebral 

palsied children. Dev Med Child Neurol 20:199-204,1978 

4. Finnie NR: Handling the Young Cerebral Palsied Child at Home, rev ed. 

New York, NY, EP Dutton Inc. 1970 

5. Rang M, Douglas G, Bennet G, et al: Seating for children with cerebral 

palsy. J Pediatr Orthop 1:279-287,1981 

6. Carrington E: A seating position for a cerebral palsied child. Journal of 

Occupational Therapy 32:179-181,1978 

7. Nwaobi O, Brubaker C, Cusick B, et al: Electromyographic investigation 

of extensor activity in cerebral palsied children in different seating positions. 

Dev Med Child Neurol 25:175-183, 1983 

212 PHYSICAL THERAPY 




Lynda Hollett Hundertmark 

PHYS THER. 1985; 65:209-212. 

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