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TBI AND DIVING
Divers who report a history of concussion on a dive
medical form are required to obtain clearance from a
physician. Thus, divers may withhold this information
to avoid this perceived unnecessary inconvenience. In
addition to asking about a head injury associated with
a loss of consciousness within the past five years, the
screening form asks about TBI-related symptoms that
may have been caused by a concussion.
Physicians who evaluate fitness to dive after
concussions are tasked with considering the specific
stressors inherent to diving amid a limited body of
evidence about TBI and diving. Recurrence of symptoms
such as headache and dizziness is common and may
compromise a diver’s safety. Such symptoms may also
confound the diagnosis of acute diving-related injuries
such as decompression illness (DCI).
Mood swings and mild mental-status changes are
common after TBI; these can affect a diver’s attention to
detail, interpretation of information (e.g., depth, time,
etc.), memory and interactions with the diver’s buddy,
guide or team. The recovering brain is vulnerable to
reinjury and possibly to venous gas emboli. Seizure risk
is also a concern, because seizures that occur at depth
are generally fatal.
Chronic TBI symptoms usually disqualify divers,
but there is growing pressure to lower the barriers to
participation for people who have had a mild TBI. With
a lack of definitive evidence specific to questions about
fitness to dive after TBI, we have assembled a group
of experts to provide their views on how the growing
body of TBI literature in other areas could be applied in
diving medicine.
How might a history of a head injury with loss of
consciousness in a (now-asymptomatic) diver affect
fitness to dive?
Lin Weaver:
TBI is graded at the time of injury as mild,
moderate or severe. I will mainly address mild TBI.
Equally important to the grade at the time of injury is
the potential diver’s condition at the time of the fitness-
to-dive evaluation (presumably months to years after
the injury). Twenty-two percent of patients who had a
mild TBI will have postconcussive symptoms one year
later (McMahon et al. 2014).
In general, people who had a severe TBI should not
dive. I guess there could be exceptions, made case by
case. Some people who had a moderate TBI may make
a full recovery, in which case I think it’s OK for them to
dive. If they have not recovered, then symptoms may
preclude diving, just as persistent symptoms generally
preclude diving for people who had a mild TBI. If
structural damage is apparent with CT scan or MRI,
the person probably should not dive.
A diver with a history of TBI should dive conservative
profiles that minimize risk of decompression sickness
(DCS). If the diver were to need hyperbaric oxygen
therapy, the dose of oxygen might place him or her at
an increased risk of seizure. Divers who have had a TBI
have consumed some of their cognitive reserve, and
getting DCS or arterial gas embolism (AGE) would
represent another brain injury, so the outcome would be
worse than if they had never had a TBI.
Wayne Massey:
Loss of consciousness, which is often
difficult to confirm, is cause for concern about more
serious problems that may affect the diver.
We usually want to establish diving suitability
after a mild concussion. Head injuries that involve
loss of consciousness are more worrisome than those
that do not, although getting an accurate history
from the patient, coach or family is often unreliable.
A duration of symptoms that is cause for concern is
not well defined in the literature, but all studies agree
that an early return to sports participation comes
with the risk of a second injury. Following symptom
resolution and a normal examination, individuals may
return to diving progressively except in cases in which
a seizure occurred.
Tony Alleman:
Loss of consciousness for more than
30 minutes or amnesia for longer than one hour
is considered disqualifying for commercial divers.
Returning to commercial diving after a mild TBI
is generally acceptable if no changes are present in
imaging such as an MRI or CT scan. Brain contusions,
hemorrhage and other structural abnormalities are often
associated with delayed symptoms such as seizures.
How long after a concussion should divers wait
before returning to diving?
Weaver:
With a mild TBI and a full recovery, I think
diving is OK, but I will break this down somewhat:
a.
Mild TBI and full recovery within one week:
Diving
is OK one month later, but it should be conservative
and not include decompression.
b.
Mild TBI and full recovery within one month:
The
person should not dive for six months.