Which neuromuscular disease is listed under hypertonicity?

• A. Multiple sclerosis
• B. Muscular dystrophy
• C. Guillain-Barré syndrome
• D. Myasthenia gravis

Answer: (A)

Hypertonicity is increased muscle tone caused by disruption of the upper motor neuron pathways that normally dampen reflex activity. In multiple sclerosis, CNS lesions interfere with these inhibitory signals, leading to spasticity and higher resting tone in affected muscles. The other conditions are driven by different mechanisms: muscular dystrophy primarily causes muscle weakness with reduced or variable tone; Guillain-Barré syndrome involves peripheral nerve demyelination leading to rapid-onset weakness and decreased tone; myasthenia gravis affects the neuromuscular junction and presents with fatigable weakness rather than sustained high tone. So, the disease listed under hypertonicity is multiple sclerosis.