Glossary of Technical Terms 821
disorders, cranial nerve disorders, and cerebr al palsy affecting bulbar structures (i.e.,
lower and upper motor neuron disorders).
dyskinesia Distortion of voluntary movements with involuntary muscle activity.
dysphoria (dysphoric mood) A condition in which a person experiences intense feelings
of depression, discontent, and in some case s indifference to th e world around them.
dyssomnias Primary disorders of sleep or wakefulness characterized by INSOMNIA  or
HYPERSOMNIA  as the major presenting symptom.  Dyssomnias are disorders of the
amount, quality, or timing of sleep. Compare with PARASOMNIAS .
dysthymia Presence, while depressed, of two or more of the following: 1) poor appetite
or overeating, 2) insomnia or hypersomnia, 3) low energy or fatigue, 4) low self-esteem,
5) poor concentration or difficulty making decisions, or 6) feelings of hopelessness.
dystonia Disordered tonicity of muscles.
eccentricity Odd, unusual, or bizarre behavior , appearance, and/or speech having
strange and unpredictable thoughts; saying un usual or inappropriate things. Eccentric-
ity is a facet of the broad personality trait domain P SYCHOTICISM . 
echolalia The pathological, parrotlike, and apparently senseless repetition (echoing) of
a word or phrase just spoken by another person.
echopraxia Mimicking the movements of another.
emotional lability Instability of emotional experience s and mood; emotions that are
easily aroused, intense, and/or out of proportion to events and circumstances. Emo-
tional lability is a facet of the broad personality trait domain NEGATIVE  AFFECTIVITY .