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different therapeutic approaches, and misdiagnosis and
mistreatment could be harmful.
Headaches are a common postdive complaint, often the
result of a sinus barotrauma.
Although much rarer, another possible diagnosis was
a very bad sinus barotrauma with gas leaking into the
cranial cavity (pneumocephalus). The sudden onset of a
massive headache associated with a significant drop in
barometric pressure accompanied by nausea, vomiting and
vertigo was suggestive of such a rare diagnosis. The diver
did report some difficulties equalizing and what seemed
to have been some sinus pain during descent as well as a
sensation of pressure later during ascent. The diver’s recent
history of a cold increased the likelihood of a very bad
sinus barotrauma. Pneumocephalus is usually diagnosed
using imaging, but small amounts of gas can be reabsorbed
in a short time. Because of the relatively small window
for a positive diagnostic image and the harmful — even
fatal — nature of pneumocephalus, ruling it out should be
a priority.
The mechanism of injury is assumed to be a reverse
block of the sinuses. The presence of mucus and
inflammation of mucous membranes are the most
common causes of transient sinus blockage. These
generally pose no greater risk than inflammation in
the mucous membranes of the sinuses, but with the
ambient pressure changes involved in diving, a partial
or intermittent blockage may act as a valve that impairs
normal gas flow in the sinuses.
Gas expansion from a reverse block can be significant
enough to disrupt the thin bone walls separating the
sinuses from each other and from the cranial cavity.
When a sinus cavity suddenly relieves its pressure into
another one, this usually manifests as pain, a headache
and possibly a nose bleed. Gas leaking into the cranial
cavity (pneumocephalus), on the other hand, can result in
anything from headaches to life-threatening neurological
deficits.
Potential consequences will depend on the amount of
gas and the degree of displacement of normal anatomical
structures. This sort of injury can initially manifest as a
moderate or severe headache or, in severe cases, result in
seizures or even death. Most cases of pneumocephalus
resolve spontaneously without surgical intervention.
Management involves breathing oxygen, keeping the head
of the bed elevated, taking antibiotics (especially when
traumatic injury is involved), managing pain and performing
frequent neurologic checks and repeated CT scans.
EVALUATION AND TREATMENT
The diver’s X-rays revealed subtle signs that could indicate
pneumocephalus, which warranted admission to the
hospital. These findings, however, could not be reproduced
during a CT scan several hours later. These diagnostic
discrepancies prompted some discussions, but based on
the case history, symptom presentation and initial imaging,
the diagnosis was still thought to be pneumocephalus
following sinus barotrauma. The patient had been
breathing pure oxygen since surfacing, including during
transportation, evaluation and hospital admission, which
could have sped up the reabsorption of the gas.
In the absence of concrete evidence of pneumocephalus,
the treatment plan was for the patient to continue to
breathe oxygen, begin a course of antibiotics, undergo
repeat CT scans and be observed for no less than 48 hours.
A six-month follow-up appointment revealed the diver
had a very good outcome and had no complications during
or after her hospital stay. She has not resumed diving.
DISCUSSION
One of the first rules we learn as student divers is
to discontinue diving when we experience difficulty
equalizing. This is probably the first rule we all break.
Questions about the use of decongestants are among the
most common asked on the DAN Medical Information
Line. (Learn more about decongestants and diving at
DAN.
org/medical/FAQ
.)
With regard to barotrauma risk, the most critical
phases of a dive are the descent and ascent, during which
massive barometric changes take place. When divers have
difficulty equalizing during descent, dive leaders often go
to excessive lengths to avoid aborting a dive, encouraging
divers to try different equalization techniques and
instructing them to alternate between ascending a few feet
and trying again to descend. It is also not uncommon to
see divers pinching their nose and blowing during ascent,
presumably because they are experiencing equalization
difficulties while ascending. Both of these practices are
counterproductive and significantly increase the risk of
middle-ear, sinus and inner-ear barotrauma.
Problems with sinus inflammation and congestion may
be amplified by the sinuses’ natural responses to cold
temperature. Exposure to cold triggers a reflex to limit heat
that manifests as increased mucus production and swelling
of mucous membranes. This is known as “cold-induced
rhinitis.” Sea water can also have an irritating effect on
mucous membranes, further stimulating mucus production.
Normally this has no negative consequences other than
copious amounts of clear mucous when we surface, but
be careful when diving: If you are recovering from a cold
or have other predisposing factors such as active allergies,
gas movement between sinuses may be significantly more
difficult. If you experience mild difficulty equalizing at
the beginning of a dive, chances are the increased mucus
production and swelling of mucous membrane may make
equalizing even more difficult near the end of the dive.
Remember you can always abort a descent; aborting an
ascent is a lot more problematic.
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