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Chapter 15 — 4
confined within the solid bone of the skull, the pressure in the skull rises, further impairing
blood supply to other parts of the brain. Swelling of the brain (cerebral oedema), as well as
expansion of the nitrogen bubbles themselves, often leads to a steady worsening of this
condition.
The onset of cerebral DCS is often heralded by
headache —
probably due to
brain swelling.
Numbness
or
tingling (paraesthesiae)
,
weakness
or
paralysis
affecting a limb or one side of the body, difficulty with
speech
,
visual
disturbances,
confusion
, loss of
consciousness
or
convulsions
are all possible
presenting symptoms of this serious disorder.
The part of the brain responsible for co-ordination (the cerebellum) may also be affected
causing incoordination known as
"staggers".
The position sense and the balance organs can
also be affected.
SPINAL DCS
has a common association with DCS bubbles in the blood and lungs,
commonly known as "
chokes".
It also may be preceded by "
girdle pains
" — or pain around
the chest or abdomen. Disturbances in movement such as
weakness or paralysis
or
disturbances in sensation such as
numbness or tingling
are also common. Interference with
nerve supply to the bladder and intestines, may lead to
difficulty in passing urine, or
opening the bowel
.
Paraplegia
or
quadriplegia
may develop.
INNER EAR DCS
The cochlea (hearing) or vestibular (balance) organs may be involved. This type of DCS is
more commonly associated with
prolonged
,,
deep, repetitive, diving, breathing a helium-
oxygen mixture
.
Hearing
loss
,
ringing noises
in the ears (tinnitus), and/or
vertigo, nausea
and
vomiting
are the usual presenting features. This condition must
be distinguished from the
other major cause of these symptoms in divers – inner ear barotrauma (see Chapter 9).
LUNGS or PULMONARY DCS
Nitrogen bubbles are frequently found in the veins of divers ascending after deep dives,
without necessarily the development of overt clinical DCS. When large numbers of these
bubbles form, they may become trapped in the small vessels of the lungs, obstructing the
blood flow. If excessive bubbles occur, this leads to a disturbance of lung function and a
feeling of
breathlessness
, known as the "
chokes"
.
Clinical features also include
a tight feeling in the chest, chest pain, difficult
and
rapid
breathing
. Coughing is often observed, and may be precipitated by smoking,
hyperventilating or exercise. Frequently the symptoms come on very soon after ascent, from
relatively deep dives (over 30 metres) or after prolonged dives. Death may supervene.