Eating-induced seizures or eating epilepsy is a rare, intriguing and heterogeneous disorder with a relatively strong genetic component.

The first systematic review of the evidence, published in the European Journal of Epilepsy, has found about 22.5% of cases worldwide had a family history of epilepsy.

Together with the young age of onset in most cases and the clustering of cases, the evidence suggests a genetic aetiology.

The Review identified 52 studies representing 378 cases from 19 countries. Most cases were reported from India (37.8%) and Sri Lanka (37.0%).

Eating epilepsy had a strong male predominance (72.0%) and mostly arose early in life with a quarter of cases recognised in the first decade (25.4%) and half in the second decade of life (51.5%).

The Review showed that just over half of seizures occurred exclusively when eating food (51.9%) while 48.1% experienced seizures both when eating and other other times.

Interestingly, the sight or smell of food could also precipitate seizures in five people and just the thought of food was associated with seizures in two cases.

Complex partial seizures (focal seizures with impaired awareness) were documented in 226 patients (59.8%), generalised tonic-clonic seizures in 70 patients (18.5 %), simple partial (focal aware) seizures in 44 patients (11.6 %), and focal seizures evolving into secondary generalisation (focal to bilateral tonic-clonic) in 34 patients (9.0 %).

Investigations showed interictal EEG abnormalities, including focal epileptiform discharges, were three times more common than ictal abnormalities.

MRI and CT imaging revealed cortical malformations and other lesions including tumours in 28.2% of patients. For some of these patients, resection resulted in a resolution of seizures.

Most patients were managed with anti-seizure medications including sodium valproate, carbamazepine, clobazam and phenobarbital.

Therapy resulted in complete resolution of eating seizures in 23.2% of cases and a good or partial response in 29.4%.

The Review, authored by a team from the UK and Australia, also found that at least 4% of patients with eating epilepsy had chromosomal conditions including Cri du chat Syndrome, MECP2 Duplication Syndrome or Rett Syndrome.

“We further identified patients who showed autosomal dominant inherited epilepsy or intellectual disability,” they said.

“These two features suggest underlying genetic aetiology such as mutations of the SYNGAP1 gene. Indeed, a recent study has shown that 25% of patients with SYNGAP1 encephalopathy experienced seizures triggered by eating.”

The study said it was possible that the genetic susceptibility lies within a central mechanism as with all other epilepsies, whilst the triggering mechanism of eating seizures is dependent on multiple stimuli.

“Dietary habits and eating behaviours, in addition to ethnic origin, could additionally play a role in the development of eating seizures. Indeed, the vast majority of cases were reported from South Asia, highlighting a potential interplay between genetic and environmental factors.”

“To continue improving our understanding of eating epilepsy, detailed clinical assessments with video EEG is needed, as is long-term follow-up to fully evaluate the efficacy of anticonvulsant treatment,” they said.

“Functional neuroimaging would also be highly beneficial to help localise generators of ictal epileptiform activity and understand the mechanisms behind seizure activity.”

Senior author Dr Udaya Seneviratne, from the department of neuroscience at Monash Medical Centre, told the limbic that while the vast majority of cases have been reported in Asian countries, eating epilepsy could be under-recognised in migrant communities in Australia and other countries.

“I think it is largely unknown to most of the medical community. These cases may come up from time to time and if you are not aware of the condition you might think this is something psychiatric or a functional neurological condition.”

“It can be misdiagnosed if you are not aware of this condition. It is a type of epilepsy so the treatment is important.”

He said the condition was variable and while affected people would not develop a seizure every time they ate, it could lead to anxiety.

Dr Seneviratne said the response to medication was variable, as with other epilepsy types.

“Some people respond well and some people don’t. Refractory cases may need some other form of treatment such as implantable devices or epilepsy surgery.”

He has also recently co-authored a case report in the journal Epileptic Disorders.