speech. Twins are often late talkers. Any
generalized difficulty with muscle con-
trol can affect speech production; this
may occur in children with cerebral
palsy. Damage to, or structural defects
of, the speech muscles, larynx (voice
box), or mouth may also cause speech
difficulties, as may any disorder affect-
ing the speech area of the brain (see
aphasia; dysarthria; dysphonia; speech
disorders). Delay in bladder and bowel
control have many possible causes (see
encopresis; enuresis; soiling).
A child who shows signs of develop-
mental delay should undergo a full
assessment by a paediatrician.
developmental hip dysplasiaA dis-
order present at birth in which the head
of the femur(thigh-bone) fails to fit
properly into the cup-like socket in the
pelvisto form a joint. One or both of the
hips may be affected.
The cause of developmental hip dys-
plasia is not known, although it is more
common in girls, especially babies born
by breech deliveryor following pregnan-
cies in which the amount of amniotic
fluid was abnormally small.
If dislocation is detected in early
infancy, splintsare applied to the thigh
to manoeuvre the ball of the joint into
the socket and keep it in position.
These are worn for about 3 months and
usually correct the problem. Progress
may be monitored by ultrasound scan-
ningand X-rays. Corrective surgery may
also be required.
If treatment is delayed, there may be
lifelong problems with walking. Without
treatment, the dislocation often leads
to shortening of the leg, limping, and
early osteoarthritisin the joint.
deviated nasal septumSee nasal sep-
tum.
deviation, sexualA form of sexual beha-
viour, most common in men, in which
intercourse between adults is not the
final aim. Forms of sexual deviation
include exhibitionism, fetishism, paedo-
philia, and transvestism.
dexamethasoneA corticosteroid drug
prescribed as a nasal spray to relieve
nasal congestion caused by allergic
rhinitis, as eye drops in the treatment of
iritis, and as eardrops in the treatment
of otitis externa. It is given in tablet form
or injected to treat severe asthmaand
other inflammatory disorders in order
to reduce inflammation of the brain
due, for example, to head injury. It may
be injected into an inflamed joint to
relieve the symptoms of osteoarthritis.
The nasal spray may cause nose-
bleeds; eye drops may cause irritation.
Prolonged use or high doses of tablet
may cause adverse effects common to
the corticosteroids.
dexamfetamineA central nervous sys-
tem stimulant (see amfetamine drugs;
stimulant drugs) sometimes used to treat
narcolepsy. It is also used in children
with attention deficit hyperactivity disor-
der. Because of its stimulant properties,
dexamfetamine has become a drug of
abuse. With prolonged use, the stimulant
effects lessen and a higher dose must
be taken to produce the same effect.
DEXA scanDual-energy X-ray absorp-
tiometry, a technique that measures
bone density by passing beams of low-
dose radiation through bone. DEXA scans
are used to assess the severity of osteo-
porosis. (See also densitometry.)
dextrocardiaA rare condition, present
from birth, in which the heart points to
the right-hand side of the chest instead
of the left. The heart may also be mal-
formed. Sometimes, the position of the
abdominal organs is also reversed. The
cause of dextrocardia is unknown. Sur-
gical treatment is only necessary if the
heart is malformed.
dextromethorphanA cough suppres-
sant available over the counter as an
ingredient in cough remedies.
dextromoramideAn opioid analgesic
drugrelated to opium that is used to
relieve severe pain following injury or
surgery and during long-term illnesses.
It relieves pain quickly but has only a
short duration of action. Regular use
can produce drug dependence.
dextropropoxypheneA weak opioid
analgesic drugincluded in some com-
pound analgesic preparations. It works
rapidly and relieves mild to moderate
pain for about 4 hours. Adverse effects
may include drowsiness, dizziness, nau-
sea, and vomiting.
dextroseAnother name for glucose.DEVELOPMENTAL HIP DYSPLASIA DEXTROSE
D