Seizure Disorder
General
The tendency towards epileptic seizures is not an all or nothing phenomenon.
Most people, under certain conditions, may have a seizure if sleep deprived or
withdrawing from alcohol or benzodiazapines, especially if in addition they are
taking medications which decrease the seizure threshold (eg. Tricyclic
anti-depressants). Approximately 2% of the population will have a seizure during
their lifetime.
An adult with a single seizure has a 30 - 40% chance of recurrence. Those
with a distinct epileptiform abnormality on the EEG as opposed to non specific
abnormalities, have an increased probability of having further seizures after a
single seizure. It is therefore imperative that the diagnosis of a seizure be
correct, and the importance of a description of the
event cannot be overemphasized. Although the electroencephalogram (EEG) is
particularly useful it must be reviewed by an experienced reader to be
considered supportive of an epileptiform tendency. Individuals with epilepsy are
unfit.
Persons who have had the following types of seizures may be acceptable.
Childhood febrile seizures which are brief, not associated with neurological
deficits, and have ceased before the age of five may be considered for medical
certification. The individual must have been off all anti-epileptic medications
for at least five years and the EEG (off medication) must be normal. The
seizures of Benign Rolandic Epilepsy of Childhood usually involve the face,
tongue or hand and are often precipitated by drowsiness or sleep. The EEG shows
significant abnormalities from the Rolandic area of the brain. Individuals with
this condition may be considered for medical certification if they have been
seizure free and off medication for ten years. They must have a normal
neurological examination and EEG. A sleep deprived EEG should
also be normal.
The Single Epileptic Seizure
An individual with a single epileptic seizure is initially unfit. The case
can be reconsidered after five years if the neurological examination is normal
and repeated EEGs, including sleep deprivation and additional nasopharyngeal or
minisphenoidal electrodes, do not reveal any significant abnormalities.
Neuroimaging, preferably MRI, must first have revealed a normal brain structure.
A restricted (as or with co-pilot) medical certificate can then be granted. Such
a restriction may be removed after an additional two years. Those individuals
who have a second seizure should be considered to have epilepsy.
Five years after the event, all of the above investigations must be repeated
and found to be normal. Applicants for Category 1 medical certification should
be restricted to: “as or with copilot” for an additional two years. Those
individuals who have a second seizure should be considered to have
epilepsy.
When a single seizure was related to alcohol withdrawal, individuals may be
considered earlier if they have a normal EEG and neuroimaging and psychosocial
and biochemical evidence is presented that their alcohol abuse/dependence is in
a continuing “recovery” phase.
Those who have had a seizure while on tricyclic antidepressant drugs or other
seizure enhancing medications must be considered more prone to seizures than the
average population. They must be considered unfit for five years.
Transient Global Amnesia (TGA)
This condition is characterized by a transient loss of memory for remote
events associated with an inability to form new memories. It is an unusual
condition that usually lasts for hours. TGA is not a seizure disorder and may be
due to transient ischemia in the inferomedial parts of the temporal lobes. It is
commoner in middle aged or older people, and many individuals are hypertensive:
frequently they have been undertaking physically demanding tasks (eg. shoveling
snow) or under significant mental stress at the time of the attack.
Throughout the episode, the sufferer is socially appropriate, oriented to
person but tends to repeat the same question over and over again, this question
usually reflecting their disorientation. (eg. “What am I doing here?”) A
number of series have shown a 10 - 20% recurrence, most of which occur within
the first five years.
If there is a normal neurological examination and EEG at the time of the
event and again one year after the event, medical certification may be
considered.
Narcolepsy
Narcolepsy presents with periods of excessive daytime sleepiness not prevented by adequate nighttime
sleep and often enhanced by boredom. Excessive sleepiness may be associated with sleep
related hallucinations or paralysis and, most
importantly, it may be associated with cataplexy which is an abrupt paralysis of variable degree
precipitated by surprise or by laughter. Prophylactic medications are imperfect and may alter
performance. They include dextroamphetamine and
methylphenidate.
Narcolepsy is a lifetime illness and the sufferer is permanently unfit.
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