From the Research
Primary lateral sclerosis (PLS) typically begins with a symmetric pattern of limb involvement, most commonly starting in the lower extremities, as noted in a recent study 1. The disease usually presents with gradual onset of stiffness and weakness in the legs, causing difficulty with walking and balance. As the condition progresses, it ascends to involve the upper extremities, trunk, and eventually bulbar muscles (affecting speech and swallowing). This ascending pattern from legs to arms to bulbar regions occurs in approximately 77% of patients, though some may present with initial upper limb or bulbar symptoms. The symmetry of involvement is a distinguishing feature of PLS, unlike amyotrophic lateral sclerosis which often begins asymmetrically. Some key points to consider in the pattern of limb involvement in PLS include:
- The slow progression of the disease, typically developing over years rather than months
- The pathophysiology involves selective degeneration of upper motor neurons in the motor cortex and corticospinal tracts, leading to the characteristic spasticity, hyperreflexia, and weakness without the lower motor neuron signs seen in other motor neuron diseases
- The use of intrathecal baclofen pumps (ITB) has been shown to be effective in treating spasticity in PLS patients, as demonstrated in a study published in the Journal of the neurological sciences 2
- The importance of specialized multidisciplinary care in managing PLS, as highlighted in a practical overview of the disease 1. Overall, the pattern of limb involvement in PLS is characterized by a symmetric and gradual progression, with a focus on managing spasticity and maintaining quality of life.