Question 1 of 7: Neuromuscular Conditions — MS and Cerebral Palsy

Question 1: Neuromuscular Conditions — MS and Cerebral Palsy (20 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Multiple sclerosis (MS). MS is an autoimmune, demyelinating disease of the central nervous system: T-cell-mediated attack strips the myelin sheath from axons in the brain and spinal cord, slowing or blocking saltatory nerve conduction and eventually causing axonal loss at chronic plaque sites. The functional impairments that follow depend on which white-matter tracts are demyelinated, and typically include spasticity and weakness (corticospinal tract), ataxia and intention tremor (cerebellar tract), sensory loss/paraesthesia (dorsal columns), optic neuritis, fatigue, and bladder dysfunction. The time course is characteristically relapsing-remitting early on — discrete exacerbations over days-to-weeks followed by partial or full recovery over weeks-to-months — and in most patients converts after 10–20 years to secondary-progressive MS, a steady decline without remission. Because both the impairment pattern and its severity fluctuate and progress, rehabilitation engineering intervention is staged and re-assessed at every relapse:

• Mild (intermittent fatigue, mild foot-drop, subtle imbalance): an ankle-foot orthosis (AFO) for foot-drop, an energy-conservation program, and a lightweight rollator or single-point cane for balance insurance on bad days.
• Moderate (persistent lower-limb weakness/spasticity, impaired hand function during flares): a forearm crutch or four-wheeled walker, functional electrical stimulation (FES) of the common peroneal nerve to correct foot-drop during gait, and adaptive/ergonomic input devices (large-key keyboard, trackball) for fine-motor tasks affected by intention tremor.
• Severe (wheelchair-dependent, significant upper-limb involvement, cognitive/visual impairment common late in disease): a powered wheelchair with a pressure-relieving cushion (see Q5), an environmental control system (Q4) driven by whatever access channel remains most reliable (often a large single switch, given fluctuating hand control), and augmentative communication support if dysarthria develops.

(ii) Cerebral palsy (CP). CP is a non-progressive lesion of the immature brain (perinatal hypoxic-ischaemic injury, intraventricular haemorrhage of prematurity, or in-utero infection/malformation) that permanently disrupts the developing motor control pathways. Unlike MS, the underlying brain injury does not worsen, but the resulting musculoskeletal impairment (spasticity, contracture, scoliosis, hip subluxation) evolves and can worsen throughout growth as bones lengthen faster than spastic muscle-tendon units — so the "time course" here is a developmental one, present from infancy and requiring re-intervention at every growth spurt rather than being punctuated by remissions. Motor impairment is classified topographically (hemiplegia/diplegia/quadriplegia) and functionally (GMFCS levels I–V), which drives the choice of technology:

• Mild (GMFCS I–II, community ambulator): a hinged AFO to control equinus gait, serial casting or Botox injection to manage focal spasticity, and standard classroom seating with minor postural inserts.
• Moderate (GMFCS III, assisted ambulator): a posterior or anterior walker, solid or articulated AFOs bilaterally, and a manual wheelchair with custom seating (lateral trunk supports, pelvic belt) for community distances.
• Severe (GMFCS IV–V, non-ambulatory): a powered wheelchair with switch or head-array access adapted to the child's available voluntary movement, a fully contoured/custom-moulded seating system to manage windswept hip deformity and scoliosis (Q5), and, where speech is absent (common with associated cognitive/oromotor involvement), an AAC device (Q6).