example, writing or reading p for q or was
for saw), most soon correct such errors.
Dyslexic children continue to confuse
these symbols. Letters are transposed
(as in pest for step) and spelling errors
are common. These children may even
be unable to read words that they can
spell correctly. It is important to recog-
nize the problem early to avoid any
added frustrations.
Specific remedial teaching can help
the child develop “tricks” to overcome
the deficit. Avoidance of pressure from
parents combined with praise for what
the child can do is equally important.
dysmenorrhoea Pain or discomfort dur-
ing or just before a period. Primary
dysmenorrhoea is common in teenage
girls and young women. It usually starts
2–3 years after menstruationbegins but
often diminishes after the age of 25. The
exact cause is unknown. One possibility
is excessive production of, or undue
sensitivity to, prostaglandins, hormone-
like substances that stimulate spasms
in the uterus. Secondary dysmenorrhoea
is due to an underlying disorder, such
as pelvic inflammatory diseaseor endo-
metriosis, and usually begins in adult life.
Cramp-like pain or discomfort in the
lower abdomen occurs, sometimes with
a dull ache in the lower back. Some
women have nausea and vomiting. Mild
primary dysmenorrhoea is often relieved
by analgesic drugs. In severe cases,
symptoms can usually be relieved with
oral contraceptivesor other hormonal
preparations that suppress ovulation.
Treatment of secondary dysmenorrhoea
depends on the cause.
dyspareuniaPainful sexual intercourse
(see intercourse, painful).
dyspepsiaThe medical term for indi-
gestion.
dysphagiaThe medical term for swal-
lowing difficulty.
dysphasiaA disturbance in the ability
to select the words with which to speak
and write and/or to understand speech
or writing. It is caused by damage to
speech and comprehension regions of
the brain. (See also aphasia.)
dysphoniaDefective production of vocal
sounds in speech, as a result of disease
or damage to the larynx (voice-box) or
to the nerve supply to the laryngeal
muscles. (See also larynx, disorders of;
speech disorders.)
dysplasiaAny abnormality of growth.
The term applies to deformities in
structures such as the skull and to
abnormalities of single cells. Abnormal
cell features include the size, shape,
and rate of multiplication of cells.
dyspnoeaThe medical term for short-
ness of breath (see breathing difficulty).
dysrhythmia, cardiacA medical term
meaning disturbance of heart rhythm,
sometimes used as an alternative to
arrhythmia (see arrhythmia, cardiac).
dystociaA term that means difficult or
abnormal labour (see childbirth). Dysto-
cia may occur, for example, if the baby
is very large, or if the mother’s pelvis is
abnormally shaped or too small for the
baby to pass through. (See also child-
birth, complications of.)
dystoniaAbnormal muscle rigidity, caus-
ing painful spasms, unusually fixed
postures, or strange movements. Dysto-
nia may affect a localized area of the
body, or may be more generalized. The
most common types of localized dysto-
nia are torticollis(painful neck spasm)
and scoliosis(abnormal sideways curva-
ture of the spine). Generalized dystonia
may be due to neurological disorders
such as Parkinson’s disease, or may also
be a side effect of antipsychotic drugs.
Dystonia may be resolved withanti-
cholinergic drugsor with benzodiazepine
drugs. In some cases, biofeedback train-
ingmay help. Injections of botulinum
toxin into the affected muscles are effect-
ive in treating some types of dystonia.
dystrophyAny disorder in which the
structure and normal activity of cells
within a tissue have been disrupted by
inadequate nutrition. The usual cause
is poor circulation of blood through the
tissue, but dystrophy can also be due to
nerve damage or deficiency of a specific
enzyme in the tissue. Examples include
muscular dystrophiesand leukodystro-
phies. Corneal dystrophies, in which
cells lining the cornea are damaged, are
a rare cause of blindness.
dysuriaThe medical term for pain, dis-
comfort, or difficulty in passing urine
(see urination, painful).DYSMENORRHOEA DYSURIA
D