The primary symptom of HSP is difficulty walking due to spasticity and weakness in the legs. Both legs are affected, usually to a relatively similar degree. The term “paraplegia” means severe weakness in both legs (similar to “paralysis”). “Paraparesis” indicates weakness in both legs of lesser severity than paraplegia. Although the disorder is typically referred to as hereditary spastic paraplegia, the degree of weakness is variable and ranges from no weakness (full strength) to marked weakness (paraplegia).
Spasticity primarily affects muscles of leg extension, knee flexion, hip adduction (bringing the knees together), and muscles that extend the feet.
Toe walking is often an early symptom, and the walking pattern may eventually be described as a “spastic gait.” Tightness in the legs and leg muscle spasm (often at night) are not uncommon.
Additional symptoms are variable depending on the subtype of HSP. Historically, “uncomplicated” or “pure” HSP refers to a combination of spastic weakness and urinary urgency. Many childhood-onset forms of HSP present with additional symptoms and are therefore called “complicated” or “complex” HSP. This may include developmental delays, intellectual disability, impaired speech, seizures, difficult with coordination (ataxia) or other movement disorders, and impaired vision or hearing. In some forms of HSP a small head size (microcephaly) or developmental brain malformations are common.
When HSP begins in early childhood, the initial symptoms are often non-specific. The symptoms may initially resemble the symptoms seen in cerebral palsy, a life-long disorder that remains relatively stable. It is important to recognize that HSP is different from cerebral palsy, and early genetic testing can shorten the time to a diagnosis.
