Spinal Muscular Atrophy is an autosomal recessive disease caused by a defect in the SMN1 gene.  This gene codes the SMN protein which is essential for motor neuron survival.  The lack of the SMN protein results in functional loss of motor neurons in the anterior horn of the spinal cord.  Located on human chromosome 5 at location 5q13 are two quite similar genes, SMN1 and SMN2.  SMN2 can only code approximately 10-20% of functional SMN protein (SMN-fl).  All SMA patients retain at least one to four copies of the SMN2 gene which allows some level of normal SMN protein production and some survival of motor neurons.  The severity of SMA is related to the number of copies of SMN2 and their ability to produce SMN-fl. This post addresses clinical application of the Convaid Trekker.

The clinical manifestations include progressive muscle wasting/weakness as a result of the lack of motor neuron function, poor muscle tone, delays in motor development, respiratory compromise with ventilator dependency a possibility, areflexia in extremities, fisted hands, fasciculations of the tongue, oral motor difficulties, and weight loss.  Muscle weakness can lead to orthopedic issues such as spinal kyphosis or scoliosis and equinus deformity of the foot. TLSO (thoracic/lumbar/sacral orthosis) and ankle orthotics may be used to prevent or reduce progression of skeletal  issues.  Oral motor limitations in (SMA I, II) can lead to gastrostomy tube placement to provide necessary nutrition.  Their cognitive development is usually normal to slightly advanced.

trekkerThere are several types of SMA classified by the age of onset of the symptoms which include Werdnig-Hoffmann (Type I), Dubowitz (Type II), Kugelberg-Welander (Type III) and Adulthood Onset (Type IV).  Werdnig-Hoffmann or infantile SMA is evident at birth or shortly thereafter with rapid death of dysfunctional neurons producing a “floppy baby syndrome” as well as respiratory compromise usually requiring tracheostomy with ventilation.

They are completely dependent in all functional tasks. Life expectancy is often very limited from a few weeks to 2 years.  However, 10% of SMA 1 with milder phenotypes and with effective respiratory support can live into adolescence or adulthood.   Type II, Dubowitz, manifests between 6 to 18 months of age with the child able to sit with or without assistance, but unable to advance much past this, with standing and walking usually unattainable.  The progression can vary.  Respiratory limitations are a concern and carefully managed per individual.  Longevity is often into adulthood.  Type III, Kugelberg-Welander usually presents about 18 months of age.

These clients are often independent in standing and walk without support to a degree.  Ambulation may deteriorate with time with client requiring wheeled mobility at some point.  Respiratory involvement is much less and life expectancy is fairly normal.  Type IV develops in adulthood near third decade of life with muscle weakness in proximal muscles of the extremities noted and possible need for wheeled mobility with progression.  Respiratory complications are rare and life expectancy is normal.

SMA I and severe cases of SMA II are much more compromised usually requiring ventilation and support for upright sitting secondary to their poor head, trunk and extremity control against gravity.  They also require tilt in space to reduce gravity’s negative impact on their weak torso, to position effectively for g-tube feedings (to prevent GERD),provide pressure relief, aid in head control and visual regard, as well as aid positioning for tracheostomy /respiratory care.

Recline can allow diaper changes without the need to transfer client with all the ventilation tubing to another surface, allow age appropriate full rest when out in the community, and aid caregiver with ventilator needs (tracheostomy changes, suctioning).

The Trekker, by Convaid, is ideal for this population with -5 to 45 degrees of adjustable tilt, up to 170 degrees of recline with angle adjustable elevating leg rests, seating that can be oriented  180 degrees reversed with client looking directly at caregiver for socialization and monitoring for medical needs, and seating options that can accommodate mild to more involved clients.  There is a depth adjustable seat pan with the option of planar or contoured cushion, as well as a height adjustable back by Convaid.

For the more complex client, back canes can be added that can accept after-market seating for more aggressive seating needs.  The Trekker has a ventilator/suction machine hard tray that is removable and mounts underneath the frame, as well as an LTV holder for ventilator mounted to side of frame for easy viewing by caregiver, IV pole with adjustable, collapsible arm for G-tube feedings, as well as a medical necessity bag or utility bag to house other ventilator accessories.   The Trekker provides all the positional changes (tilt & recline), seating options, and accommodates  ventilator and G-tube needs, while still remaining extremely lightweight, clam shell collapsible and WC-19 crash tested which allows the family and child to enjoy family activities in the home or community much easier.







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