Complex sentence: Joseph "Joey" Deacon was born with severe cerebral palsy, a neurological condition which left him with a muscular "spastic pattern", particularly arms and legs, resulting in a tendency of muscular tonus in the form of flexion of arms and extension of legs.
Split into simpler sentences: Joseph "Joey" Deacon was born with severe cerebral palsy, a neurological condition that left him with a muscular "spastic pattern" that particularly affected his arms and legs. Deacon's condition resulted in a tendency for muscular tonus in the form of flexion of arms and extension of legs.