Bma Illustrated Medical Dictionary

(see hypermetropia). Those that cause
divergence have a negative number and
are used to correct shortsightedness
(see myopia).
dioxinA highly toxic group of chemi-
cals. They are contaminants of some
defoliant weedkillers (see defoliant poi-
soning; Agent Orange).
diphenhydramineAn antihistamine drug
used to treat allergic disorders such as
urticariaand allergicrhinitis. It is also
used for the relief of temporary sleep
disturbance. Some cough remediescon-
tain the drug. It can cause drowsiness,
dry mouth and blurred vision.
diphenoxylateAn antidiarrhoeal drug
related to the opioid analgesic drugs. It
lessens the contractions of the muscles
in the intestinal walls, reducing the fre-
quency of bowel movements.
diphtheriaA bacterial infection that
causes a sore throat, fever, and some-
times serious or fatal complications. It is
caused by CORYNEBACTERIUM DIPHTHERAE.
During infection, the bacterium may
multiply in the throat or skin. In the
throat, bacterial multiplication gives
rise to a membrane that may cover the
tonsils and spread up over the palate or
down to the larynx and trachea, causing
breathing difficulties. Other symptoms
are enlarged lymph nodes in the neck,
increased heart rate, and fever. Some-
times, infection is confined to the skin.
Life-threatening symptoms develop only
in nonimmune people and are caused
by a toxin released by the bacterium. A
victim may collapse and die within a
day of developing throat symptoms.
More often the person is recovering from
diphtheria when heart failureor paraly-
sis of the throat or limbs develops.
Diphtheria is treated with antibiotics.
An antitoxin is also given if diphtheria
affects the throat. If severe breathing
difficulties develop, a tracheostomymay
be needed. Mass immunization has made
diphtheria rare in developed countries.
diplegiaParalysisaffecting both sides
of the body (both legs and, to a lesser
extent, both arms).
diplopiaThe medical term used to
describe double vision.
dipsomaniaA form of alcohol depen-
dencein which periods of excessive

drinking and craving for drink alternate

with periods of relative sobriety.

dipyridamoleA drug that reduces the

stickiness of platelets in the bloodand

thereby helps to prevent the formation

of abnormal blood clots within arteries.

Dipyridamole isused with aspirinor

warfarinto prevent the formation of

clots following heart-valve surgery. It

may also be given to people who have

had a recent myocardial infarctionor

undergone a coronary artery bypass.

Dipyridamole may also reduce the fre-

quency of transient ischaemic attacks.

Possible adverse may include head-

ache, flushing, and dizziness.

disabilityA physical or mental loss or

impairment that is measurable. (See

also handicap; rehabilitation.)

dischargeA visible emission of fluid

from an orifice or a break in the skin. A

discharge may be a normal occurrence,

as in some types of vaginal discharge,

but it could also be due to an infection

or inflammation.

disc, intervertebral A flat, circular,

plate-like structure containing cartilage

that lines the joints between adjacent

vertebrae(bones) in the spine. Each inter-

vertebral disc is composed of a fibrous

outer layer and a soft gelatinous core. It

acts as a shock absorber to cushion the

vertebrae during movements of the spine.

With increasing age, intervertebral discs

become less supple and more suscepti-

ble to damage from injury.

DIOXIN DISC, INTERVERTEBRAL

D

Ligaments

Vertebral

body

Fibrous covering

Gelatinous core

THORACIC VERTEBRAE

SECTION OF

INTERVERTEBRAL

DISK

Intervertebral

disk

DISC, INTERVERTEBRAL