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release of excitatory amino acids. Tizanidine reduces flexor reflexes and spasms and relieves pain. It appears to reduce muscle strength less than baclofen but may not result in measurably better function (see Kita and Goodkin⁹²).

Dantrolene acts within the muscles themselves to produce inhibition of the excitation-contraction coupling process, which leads to reduced muscle strength. Because of its action, it may be better suited for treatment of nonambulatory patients for whom added weakness is less likely to impair mobility. Patients receiving dantrolene should be monitored for liver function because of its potential hepatotoxicity. Benzodiazapines, such as diazepam and clonazepam, act to reduce muscle tone through three mechanisms: suppression of sensory impulses from muscles and skin receptors, postsynaptic potentiation of GABA, and inhibition of excitatory descending pathways. They are generally used in combination with baclofen or other medications.

Intramuscular injections of botulinum A toxin can be helpful, especially for patients with severe localized spasms. The chemical denervation produced by botulinum A toxin can last for up to three months. A study of nine patients with long-standing MS showed reduced spasticity and improved ease of nursing care with no adverse effects.^92,163