Dystonia affects different people in different ways. Muscle spasms might: 
Begin in a single area, such as your leg, neck or arm. Focal dystonia that begins after age 21 usually starts in the neck, arm or face. It tends to remain focal or become segmental.
Occur during a specific action, such as writing by hand.
Worsen with stress, fatigue or anxiety.
Become more noticeable over time.
 Areas of the body that can be affected include: 
Neck (cervical dystonia). Contractions cause your head to twist and turn to one side, or pull forward or backward, sometimes causing pain.
Eyelids. Rapid blinking or spasms cause your eyes to close (blepharospasms) and make it difficult for you to see. Spasms usually aren't painful but might increase when you're in bright light, reading, watching TV, under stress or interacting with people. Your eyes might feel dry, gritty or sensitive to light.
Jaw or tongue (oromandibular dystonia). You might experience slurred speech, drooling, and difficulty chewing or swallowing. Oromandibular dystonia can be painful and often occurs in combination with cervical dystonia or blepharospasm.
Voice box and vocal cords (laryngeal dystonia). You might have a tight or whispering voice.
Hand and forearm. Some types of dystonia occur only while you do a repetitive activity, such as writing (writer's dystonia) or playing a specific musical instrument (musician's dystonia). Symptoms usually don't happen when your arm is at rest.
