CORTICAL EXCITABILITY AND REFRACTORY EPILEPSY: A THREE-YEAR LONGITUDINAL TRANSCRANIAL MAGNETIC STIMULATION STUDY

Fulltext embargoed for: 18 months post date of publicationTranscranial magnetic stimulation was used to study the effect of recurrent seizures on cortical excitability over time in epilepsy. 77 patients with firm diagnoses of idiopathic generalized epilepsy (IGE) or focal epilepsy were repeatedly evaluated over three years. At onset, all groups had increased cortical excitability. At the end of follow-up the refractory group was associated with a broad increase in cortical excitability. Conversely, cortical excitability decreased in all seizure free groups after introduction of an effective medication

Are Patterns of Cortical Hyperexcitability Altered in Catamenial Epilepsy?

OBJECTIVE: We used transcranial magnetic stimulation to determine menstrual cycle-related changes in cortical excitability in women with and without catamenial epilepsy and investigated whether these changes differed between ovulatory and anovulatory cohorts. METHODS: Healthy nonepilepsy women and women with generalized and focal epilepsy were investigated during ovulatory (n=11, 46, and 43, respectively) and anovulatory (n=9, 42, and 41) cycles. Patients were divided based on seizure pattern into catamenial (C1=perimenstrual, C2=periovulatory, C3=luteal seizure exacerbation), noncatamenial, and seizure free. Cortical excitability was assessed using motor threshold (MT) and paired pulse stimulation at short (2-15 milliseconds) and long (100-300 milliseconds) interstimulus intervals twice, at the (1) late follicular and (2) mid luteal phases of the menstrual cycle. RESULTS: In controls, cortical excitability was greatest in the follicular study, where intracortical facilitation was increased (p<0.05). The opposite was seen in women with epilepsy, where intracortical facilitation was greatest and intracortical inhibition was least in the luteal studies (p<0.05). There were no differences between the ovulatory and anovulatory groups in any of the cohorts. No changes were observed in MT. INTERPRETATION: Nonhormonal factors are involved in the cyclicity of cortical excitability across the menstrual cycle. Normal menstrual cycle variations in cortical excitability are altered in a similar pattern in ovulatory and anovulatory women with epilepsy regardless of seizure patterns. The underlying neural changes associated with epilepsy may alter responses to sex hormones. This may be an important underlying mechanism for catamenial seizure clustering

Headache and Epilepsy

Headache and epilepsy often co-occur. Epidemiologic studies conducted in the past few years reinforce the notion of a bi-directional association between migraine and epilepsy. Data on an association between headache (in general) and epilepsy, however, are less clear. Peri-ictal headache often presents with migraine-like symptoms and can be severe. A correct diagnosis and management are paramount. It was demonstrated that cortical hyperexcitability may underlie both epilepsy and migraine. A recent study linked spreading depolarisation, the supposed underlying pathophysiological mechanism of migraine with aura, to epilepsy. Although this study was carried out in patients who had suffered a subarachnoid haemorrhage, the finding may shed light on pathophysiological mechanisms common to epilepsy and migraine. © 2013 Springer Science+Business Media New York