Medication Summary
Many symptoms that are common in people with HSP are not caused directly by HSP but are instead caused indirectly by muscle spasticity, weakness, or hyperactive reflexes. As previously mentioned, antispastic drugs may help the patient to reduce the spasticity and may allow weakened muscles to be targeted in order to improve the effectiveness of PT.[10] However, when patients are medicated to reduce stiffness, walking may become more difficult. Moreover, adverse effects from skeletal muscle relaxants can be a problem.
Skeletal muscle relaxants
Class Summary
Antispasticity medications can be useful. However, one of the drawbacks of using these agents is that some patients find that the stiffness of spasticity helps them to overcome the muscle weakness that occurs in HSP. When patients are medicated to reduce stiffness, walking may become more difficult. Adverse effects can also be a problem.
If the patient does well with the medications, however, discomfort associated with spasticity can generally be reduced, mobility can be improved, and the effectiveness of physical therapy (PT) can be enhanced. Patients in relatively early stages of the illness have achieved symptomatic improvement with oral dantrolene, as well as with oral and intrathecal baclofen.
Baclofen (Lioresal, Gablofen)
Baclofen may induce the hyperpolarization of afferent terminals and inhibit monosynaptic and polysynaptic reflexes at the spinal level.
Tizanidine (Zanaflex)
Tizanidine is a centrally acting muscle relaxant that is metabolized in the liver and excreted in urine and feces. A single oral dose of 8mg reduces muscle tone in patients with spasticity for several hours. Blood levels and the spasmolytic effect are linearly correlated.
Dantrolene sodium (Dantrium, Revonto)
Dantrolene sodium stimulates muscle relaxation by modulating skeletal muscle contractions at the site beyond the myoneural junction and acting directly on the muscle itself. Most patients respond to 400mg/day or less.
OnabotulinumtoxinA (BOTOX®)
Botulinum toxin binds to receptor sites on motor nerve terminals and inhibits the release of acetylcholine, which in turn inhibits the transmission of impulses in neuromuscular tissue. This agent is most useful for treating spasticity in the gastrocnemius and soleus muscles; it is less effective in larger muscles (eg, quadriceps). Reexamine patients 7-14 days after the initial dose to assess for their response. Treatment may be repeated every 3-4 months.
Anxiolytics, Benzodiazepines
Class Summary
These agents may act in the spinal cord to induce muscle relaxation.
Diazepam (Valium)
Diazepam depresses all levels of the central nervous system (eg, limbic and reticular formation), possibly by increasing the activity of gamma-aminobutyric acid (GABA). Individualize the dosage, and increase it cautiously to avoid adverse effects.
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