Tone management and other medical interventions Clients may have increased muscle tone due to cerebral palsy, traumatic brain injuries, or MS. Muscle tone is “a state of partial contraction that is characteristic of normal muscle, is maintained at least in part by a continuous bombardment of motor impulses originating reflexively, and serves to maintain body posture” (Tonus, n.d.). Managing tone within the seating system has always been challenging. Certain positions tend to “break up” muscle tone, particularly in clients with cerebral palsy. In general, increasing flexion and abduction of joints reduces extensor tone, for example. Some clients have mixed tone, such as increased extension of the extremities and low tone in the trunk and neck. Other clients have fluctuating muscle tone, often seen in conjunction with athetosis and dystonia. The goal in managing tone in seating is to find a functional balance between excessive tone and patterns of movement and low tone and postural collapse. Certain medical interventions can affect tone and, as a result, affect positioning. These interventions include orthoses, oral medications, injections, intrathecal medications, and Orthoses can sometimes affect tone. Orthoses provide external support to an area of the body to restrict movement in a given direction, provide stability, and minimize risk of orthopedic distortions. For example, ankle-foot orthoses maintain the ankle in a neutral position, which can reduce overall extension by limiting plantar flexion. Thoracic-lumbar-sacral orthoses (TLSOs) can support a low-tone trunk. Oral medications Oral medications have an overall effect on muscle tone. Common medications used to reduce muscle tone include baclofen, dantrolene, diazepam, and tizanidine (United Cerebral Palsy, 2015a). Depending on the dosing schedule, tone may change throughout the day. The client usually has to titrate up to a maintenance dose, and postural needs may change during this transition. Many of these oral medications can lead to drowsiness and can lower the seizure threshold. If a client is on too high a dose, trunk and head control may decrease, and secretions may increase. Injections and positioning Specific muscle groups can affect positioning in the seating system. For example, tight pectorals can pull a client into scapular protraction and trunk flexion. Injections in this area can promote a more upright trunk and head. Injections to the hamstrings may minimize a posterior pelvic tilt. The seating team must work closely with the medical team to achieve optimal results. The tone reduction achieved is short term, though therapy during this time can provide some long-term benefits by strengthening the opposing muscle group. Injections are also used to reduce muscle tone in specific areas of the body. The two most common injections are Botox (botulinum toxin type A) and phenol (Petropoulou, 2013). Botox surgeries. Orthoses A limited amount of Botox can be used each time, and so a limited number of injection sites may be selected. Botox destroys some of the muscle receptors temporarily, decreasing overall muscle activity. Effects last several months; however, during that time the antagonist muscle may strengthen, providing more sustained results (Petropoulou, 2013). Phenol Phenol destroys part of the motor nerve, also resulting in a temporary reduction of tone. Phenol tends to be used in larger muscles with no nearby sensory nerves, which could otherwise be damaged (Petropoulou, 2013).
Baclofen pump The baclofen pump is an intrathecal device that is placed in the abdomen and delivers baclofen through a catheter into the cerebral spinal fluid in the lower area of the spine (Figure 15). The client must usually stop all tone management medications before insertion of the pump. This can lead to difficulties with seating during this transitional time period. The baclofen dose is slowly raised, which may result in positional changes over a period of 3 to 18 months. The pump can achieve the same effects as oral baclofen but with much smaller doses and fewer side effects. The pump itself often can be seen through the skin of the abdomen, and care should be taken not to irritate this area with secondary seating components (e.g., constant rubbing of a pelvic positioning belt against the lower edge of the pump). Figure 15: Baclofen Pump
Note . From “Intrathecal Baclofen – Pictures,” Kids Health Info Factsheets, The Royal Children’s Hospital Melbourne, 2007, retrieved from http://www.rch.org.au/kidsinfo/fact_sheets/Intrathecal_ baclofen_pictures. Reprinted with permission. Dorsal rhizotomy Selective dorsal rhizotomy is still performed in some medical facilities. This surgical procedure cuts some of the motor nerve roots to the lower extremities. This procedure is often employed to improve gait in clients who are ambulatory. However, while reducing tone in the lower extremities, the procedure often partially reduces tone in the upper extremities as well (Petropoulou, 2013). Soft tissue surgical procedures Soft tissue surgical procedures that may affect muscle tone and positioning include tendon lengthening, releases, and transfers. Common muscles for which a tendon lengthening or release is performed include hamstrings and hip adductors. These procedures improve range of motion, which directly affects the client’s seated posture. Orthopedic surgeries Orthopedic surgeries are fairly common in clients with significant muscle tone, particularly in growing children. Bone growth is influenced by muscle imbalances, and this can result in orthopedic complications. Hip osteotomies are often required to realign the femur with the pelvis (United Cerebral Palsy, 2015b). Spinal fusions may be required if spinal asymmetries become significant. A client who requires these surgical interventions will demonstrate orthopedic limitations that must be addressed in a seating system. After surgery, the available range of motion and body shape may change dramatically, requiring seat modifications or new seating.
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Book Code: PTNC1023
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