A history of seizure is of great concern to aviation safety. Seizures generally occur without warning and are unpredictable. They are likely to result in total and sudden incapacitation. A pilot suffering a seizure may input the controls with erratic forces susceptible to stress the aircraft structure beyond its certificated operational limits. Rapid loss of control or in-flight destruction of the aircraft may result. Convulsive incapacitation is thus considered a higher risk than other forms of incapacitation. Some have coined the term ‘excapacitation’ for this type of event.
Very careful evaluation is necessary when dealing with any history of convulsion whether generalised or not, inclusive of febrile convulsions. It is equally important when dealing with any history of loss of consciousness to ensure that the cause was not a seizure. A careful history, preferably confirmed by witnesses, must be obtained. Copies of clinical notes from GPs, Emergency Department and specialist should also be obtained to corroborate the history. A neurologist opinion is often necessary if a clear cardio-vascular cause for an episode of altered consciousness has not been confirmed.
Anticonvulsant medications are generally not acceptable.
In the case of a traumatic brain injury a single seizure occurring within 24 hours of the injury maybe acceptable but requires careful evaluation. Early seizures after 24 hours are a risk factor for post-traumatic epilepsy. Consideration should involve the flexibility process.
Further discussion about TBI and seizure risk is outlined in Traumatic brain injuries. If in any doubt the ME should consult with CAA.
A history of alcohol or other drug withdrawal seizures is complex and a clear risk to aviation safety. Careful evaluation that AOD withdrawal was the cause of seizure(s) is important. In addition is the need for strong evidence that the applicant has a safe relationship with alcohol or other drugs. Evaluation is likely to include neurology and addiction medicine specialist reports. Some cases maybe acceptable for certification following an Accredited Medical Conclusion.
If in any doubt the ME should consult with CAA.
By definition a diagnosis of epilepsy requires two or more unprovoked seizures. A new definition has been proposed requiring the occurrence of one unprovoked seizure and a high probability of further seizures.
In general, a diagnosis of epilepsy makes someone ineligible for a medical certificate, with very few exceptions.
This is also called 'benign partial epilepsy of childhood with centrotemporal spikes'. This condition is discussed because it may in some cases be acceptable for certification following an Accredited Medical Conclusion.
This disorder represents ~15% of childhood epilepsy. Typically, seizures start at age 4 to 10, beginning during sleep and are simple partial, involving the face and tongue, but secondary generalised seizures are not uncommon. Daytime seizures occur in about one third of cases but are almost exclusively simple partial involving the face and tongue.
Rolandic epilepsy has the best prognosis of all epilepsies. The prevalence of epilepsy in adults who have suffered from Rolandic epilepsy is said to be quite similar to that of the general population. The disorder appears to have a genetic origin, with an age-related penetrance. By mid-teenage years the disorder is said to vanish in most cases. The only indicator of late resolution is an early onset of the condition. Cases of persistent epilepsy in adult appear to relate to a different epileptic syndrome. However, a frequently quoted study by Loiseau, has found that 3 out of 168 (2%) of patients with Rolandic epilepsy ultimately developed a later seizure, this is in fact higher than the general population and represents an incidence of perhaps 0.2% per annum.
The diagnosis is based on a typical history, a normal neurological examination and typical EEG with broad centrotemporal spikes. An accurate diagnosis is critical and occasionally difficult. It should involve a neurologist opinion and a detailed review of relevant information.
Someone with a history of benign Rolandic epilepsy does not meet the medical standards but flexibility may be considered.
The National Institute of Health (NHI–UK) consensus statement defines a febrile seizure as 'an event in infancy or childhood usually occurring between 3 months and 5 years of age, associated with fever but without evidence of intracranial infection or defined cause for the seizure'.
About 2–5% of all children between the ages of 3 months and 5 years will have at least one febrile seizure (Europe, USA). The peak age is 18–22 months.
Febrile seizures are classified as 'simple', being generalized tonic-clonic convulsions of less than 15 minutes duration and without recurrence within 24 hours.
Febrile seizures are classified as 'complex' (or 'complicated') if focal, lasting more than 15 minutes or occur in a cluster of 2 or more convulsions within 24 hours.
Risk factors for later epilepsy include:
In one large prospective controlled study (Dreier et al 2019), comprising 2,103,232 children, the 30-year cumulative risk for epilepsy was 2.2%. For the 75,593 children with a history of febrile seizures the cumulative risks were 6.4%, 10.8% and 15.8% after the first, second and third febrile seizure respectively. One might assume that the risk of epilepsy declines the longer someone remains free of seizure. This was not the case in this study and others. The cumulative risk after even after one seizure remained above the risk for the reference/control population up to 25-30 years later.
The probability of developing epilepsy is about 5–10% following a complex febrile episode.
Therefore, the ME should ensure that fever was present, look critically at the age of occurrence and consider other risk factors and the type, simple or complex, of the event. For instance, a history of first 'febrile' convulsion at the age of 4-5 should be looked at with caution, particularly if the temperature elevation was only moderate.
One has to be careful in accepting a history of febrile convulsion. There are a number of convulsive disorders affecting childhood starting as early as aged 2. This can lead to a mistaken diagnosis of febrile convulsions. One such disorder is Generalised Epilepsy with Febrile Seizures. This disorder is autosomal dominant with high penetrance and is caused by a defect in the neuronal voltage-gated sodium channel. In its simplest form, the children have ordinary febrile seizures that continue to an older age than usual. This is only mentioned to bring to the ME’s attention that not all febrile convulsions are equal and benign.
In summary, the ME should consider recurrent, complex or late occurring febrile convulsions with suspicion. A thorough history is essential and copies of clinical notes are necessary to assess such cases.