Symptoms describe an individual’s experience of a medical disorder. Signs are the objective evidence of the disorder, documented, for example by physician examination, laboratory studies, or magnetic resonance images (MRI). The primary symptom of HSP is difficulty walking due to Weakness and tightness (spasticity) in the legs. Both legs are affected, usually to a relatively similar degree.
The term “paraplegia” means severe Weakness in both legs including 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).
When present, Weakness does not affect all leg muscles, but rather is most obvious in muscles of hip flexion (iliopsoas), hip abduction (gluteus medius), knee flexion (hamstrings), and foot dorsiflexsion (bending the foot back toward the shin via tibialis anterior muscle). In contrast, muscles of leg extension (quadriceps) and foot extension (gastrocnemius-soleus) usually are not affected in uncomplicated HSP.
Spasticity primarily affects muscles of leg extension (quadriceps), knee flexion (hamstrings), hip adduction (bringing the knees together, thigh adductor muscles), and muscles that extend the feet (gastrocnemius-soleus [Achilles tendon]).
Walking pattern described as “spastic gait” occurs in which the following elements are present, each to variable degree in different individuals: a) heel strike is shifted forward (landing on the mid-foot or even further forward on the balls of the feet); b) there is reduced foot dorsiflexion (not bending the toes up, but instead tending to drag the toes, often catching them on carpet or when stepping over curbs, and causing the toes of the shoes to be worn out); c) stride length may become shorter; d) there may be “circumduction” or “scissoring”, with one leg crossing into the path of the other; e) there is a tendency for the knees to be maintained flexed (not fully extended in mid-stride), f) for thighs to be close together (adductor tightness), and g) hip flexion (knee lifting) to be reduced. Balance difficulty, often worse when walking in the dark or on uneven surfaces is not uncommon in individuals with HSP.
Tightness in the legs and leg muscle spasm (often at night) are not uncommon. The consequences of abnormal walking pattern cause strain on the ankles, knees, hips, and back and often cause Pain in these areas.
Urinary urgency, the symptom of experiencing a very short interval between the sensation of need to urinate and difficulty remaining continent, is very common in HSP and occasionally may be an early symptom. Bowel urgency is less common but may occur. Medications such as oxybutynin may reduce urinary urgency. If urinary urgency is severe or accompanied by difficulty initiating urination, consultation with a urologist is recommended.
Some genetic types of HSP tend to cause only spastic Weakness in the legs and urinary urgency. These syndromes are referred to as “uncomplicated HSP”. Other genetic types of HSP tend to be associated with additional symptoms (“complicated HSP”) including difficulty with coordination (“ataxia”), impaired vision, Seizures (epilepsy), muscle atrophy, disturbance of the nerves in the arms and legs (neuropathy), and disturbance cognitive ability (intellectual impairment and dementia). Previously, it was considered that HSP caused symptoms only in the legs, and therefore, did not affect the strength or coordination of the arms and hands, or speech or swallowing. As the number of HSP types has grown, it is now recognized that the arms, hands, and speech and swallowing may be affected in some genetic types of complicated HSP
Pattern of symptom progression (course of the disorder):
When HSP begins in very early childhood (before age two years, for example), symptoms may not worsen even over many years or decades. Individuals with this “non-progressive” (non-worsening) pattern may resemble subjects with spastic cerebral palsy, a life-long disorder that also remains relatively stable. One caveat however: although early childhood-onset forms of HSP may be “non-progressive”, the degree of Spasticity may increase slowly if adequate range-of-motion is not maintained through stretching exercises and muscle Spasticity reduction.
In contrast, when HSP symptoms begin after early childhood (in adolescence or adulthood), symptoms usually worsen very slowly over a number of years. Sudden onset or rapid worsening over weeks or months is not typical of HSP and suggests an alternate disorder or co-existing condition. After a number of years of very gradual worsening, the rate of worsening appears to slow down for many (not all) subjects. These subjects seem to reach a “functional plateau” beyond which the degree of worsening seems to be similar to that expected for age and similar degrees of physical exercise. Nonetheless, not all patients reach an apparent “leveling off” or functional plateau but instead experience continuous worsening of walking ability due to very slowly progressive Muscle Weakness and tightness .
There may be significant variability in the type of symptoms and their severity. For example, symptoms may remain mild in some patients or become quite severe in others patients. This variability may occur between different genetic types of HSP as well as in between individuals with the same genetic type of HSP including family members who share not only the same genetic type of HSP but also precisely the same genetic mutation.
There is not a perfect correlation between the genetic type of HSP and the pattern of symptoms. For example, while some genetic types of HSP (e.g. dominantly inherited HSP due to SPG4/spastin mutation) usually are associated with “uncomplicated” HSP syndromes, some patients with these types of HSP develop additional neurologic symptoms. As another example, although SPG7 and SPG11 typically are associated with additional neurologic symptoms (ataxia, neuropathy, cognitive impairment, for example), some subjects with mutations in these genes have uncomplicated HSP (only spastic Weakness in the legs). There also may be variation in severity and the nature of symptoms between affected family members. Therefore, it is generally not possible to predict with certainty the severity or exact nature of symptoms associated with given genetic type of HSP. A cautious, “wait and see” approach, combined with pro-active, individualized physical therapy is recommended.
Prognosis: predicting symptoms and course of HSP As noted above, there is significant variation in HSP symptoms and their severity. This limits the certainty of making predictions. In general however, some genetic types of HSP are usually associated with only leg weakness, spasticity, and urinary urgency (“uncomplicated HSP”). Other types of HSP are usually associated with other neurologic disturbances in addition to these symptoms (“complicated HSP”). Although there are exceptions (discussed above), an individual with a genetic type of HSP usually associated with “uncomplicated” syndrome would be expected to have only spastic Weakness and urinary urgency.
Symptoms of HSP vary from mild to severe. Individuals with severe symptoms may be unable to walk independently. In general, however, HSP does not shorten lifespan.