Motor cortex excitability in seizure-free STX1B mutation carriers with a history of epilepsy and febrile seizures

Objective

Mutations in STX1B encoding the presynaptic protein syntaxin-1B are associated with febrile seizures with or without epilepsy. It is unclear to what extent these mutations are linked to abnormalities of cortical glutamatergic or GABAergic neurotransmission. We explored this question using single- and paired-pulse transcranial magnetic stimulation (TMS) excitability markers.

Methods

We studied nine currently asymptomatic adult STX1B mutation carriers with history of epilepsy and febrile seizures, who had been seizure-free for at least eight years without antiepileptic drug treatment, and ten healthy age-matched controls. Resting motor threshold (RMT), and input-output curves of motor evoked potential (MEP) amplitude, short-interval intracortical inhibition (SICI, marker of GABA_Aergic excitability) and intracortical facilitation (ICF, marker of glutamatergic excitability) were tested.

Results

RMT, and input-output curves of MEP amplitude, SICI and ICF revealed no significant differences between STX1B mutation carriers and healthy controls.

Conclusions

Findings suggest normal motor cortical GABA_Aergic and glutamatergic excitability in currently asymptomatic STX1B mutation carriers.

Significance

TMS measures of motor cortical excitability show utility in demonstrating normal excitability in adult STX1B mutation carriers with history of seizures.