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allow medical certification. Thorough neurological evaluation is warranted in all individuals with a
history of seizure disorder. Additionally, recurrence risk must be assessed; if greater than one per cent
per year, medical certification is not appropriate.
The Single Seizure
When an individual suffers his or her first ever seizure, a thorough search for cause is appropriate. Risk
factors for recurrence include seizures in immediate family, a history of febrile seizures, prior acute
symptomatic seizure, remote neurological insult, abnormal neurological examination, abnormal cerebral
imaging study, and abnormal EEG. Absent these risk factors, recurrence risk is approximately 30 percent
over four years. If there is no recurrence without medication in four years, the risk may then become
acceptable for medical certification.
Operational implications:
The occurrence of a single seizure is disqualifying for all classes of medical certification.
Aeromedical implications:
Medical certification is appropriate following a single seizure when all studies are normal and there are
no risk factors for recurrence. Consideration should not be given until a four year seizure-free and
medication-free observation period has been achieved. With normal studies and no risk factors,
recurrence risk after four years approximates that of the normal population. Medical certification is
appropriate at this juncture.
The Screening EEG
The use of the EEG for screening purposes, in applicants with no relevant history, has been controversial
for many years. The United States Federal Aviation Administration and the European Joint Aviation
Authorities do not require EEG investigation, except on indication. However, some States utilize the EEG
as a risk assessment tool for potential epilepsy. As epileptiform discharges may occur in individuals who
never have a seizure, such an EEG may lead to unnecessary disqualification. ICAO medical provisions do
not require routine EEG screening and most of the major Contracting States have determined that a
screening EEG is not essential to flight safety.
CEREBROVASCULAR DISEASE
Ischaemic Stroke
Eighty-five percent of strokes are ischaemic thrombotic events, the remainder haemorrhagic. Ischaemic
strokes include large artery atherothrombotic stroke (e.g. extracranial carotid artery or intracranial middle
ICAO Preliminary Unedited Version — October 2008 III-10-9
cerebral artery) and small vessel lacunar stroke commonly seen in hypertensive individuals. Embolic
stroke (artery to artery or cardio-embolic source) must also be considered. In persons experiencing a
transient ischaemic attack (TIA), risk of subsequent stroke is approximately 30 per cent within five years.
Risk factors for stroke include hypertension, hyperlipidaemia, diabetes, tobacco use, cardiac disease,
atrial fibrillation, and asymptomatic carotid stenosis. In the young, additional factors must be considered
such as hypercoaguable states, patent foramen ovale, and arteriopathies.
The medical assessor is usually not involved in the acute evaluation or treatment of stroke, but becomes
involved when medical certification is sought. Clearly the existence of any persistent neurological deficit
must be addressed in terms of functional compromise.
Assuming absence of significant neurological deficit, risk for recurrent stroke becomes the prime
consideration in aeromedical disposition (and risk of cardiac disease in large artery stroke such as carotid
disease). Beyond the first year, recurrence risk is about four per cent per year, with some variability
depending on stroke subtype.
In considering medical certification following stroke, the medical assessor must consider stroke
mechanism, corrective measures if undertaken (e.g. carotid endarterectomy), degree of attention to risk
factors (e.g. treatment of hypertension and hyperlipidaemia), and neurological stability during a suitable
observation period.
Operational implications:
Ischaemic stroke is disqualifying for all classes of medical certification.
Aeromedical considerations:
Stroke is a heterogeneous entity with many causes, and careful individual evaluation is appropriate.
Medical certification is appropriate when cause and risk factors have been identified and addressed and
a recurrence risk has been assessed. Recurrent stroke may cause sudden incapacitation, and a recurrence
risk exceeding one per cent per year is not acceptable. A recurrence free observation period is
appropriate prior to medical certification following ischaemic stroke, and this will vary dependent upon
mechanism and risk factors. Stroke in the young with known mechanism (e.g. patent foramen ovale with
paradoxical embolism and successful closure) may allow medical certification after one year. If an
　
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本文鏈接地址：Manual of Civil Aviation Medicine 2(28)