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 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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