Page 151 - ILAE_Lectures_2015

Chapter 14

Frontal lobe epilepsy

BEATE DIEHL1, SANJAY M. SISODIYA1 and MARK MANFORD2

1Institute of Neurology, University College London, National Hospital for Neurology and
Neurosurgery, Queen Square, London, and Epilepsy Society, Chalfont St Peter,
Buckinghamshire, and 2Addenbrookes Hospital, Cambridge

While frontal lobe epilepsy accounts for only 1020% of patients in surgical series, the
prevalence in non-surgical cohorts is probably higher. Frontal lobe epilepsy (FLE) probably

represents 2030% of partial seizures; calculating the prevalence of FLE in the UK from the
National Institutes of Health estimates for the USA gives a figure of about 115,000, of whom
35,000 remain refractory to medical treatment. The International League Against Epilepsy
has proposed a classification, compartmentalising different clinical manifestations into
anatomical subdivisions of the frontal lobes of which there are many, with diverse functions1.
However, FLE presents some particular diagnostic problems, both in the clinical and the
electrographic diagnosis of seizure types. The extensive anatomical connections between
subdivisions of the frontal lobe and between the frontal and other lobes blur these categories.
Seizures may, for example, spread from temporal to orbitofrontal cortex (or vice versa) within
milliseconds, giving substantial overlap between the seizure manifestations documented from
these two regions2. FLE in general has been less well studied than temporal lobe epilepsy.
Some consider that seizure freedom after surgery is the most reliable way of defining a
particular localised syndrome and thus various conceptual aspects of FLE remain poorly
understood.

Aetiology

In a large series of 250 cases operated on for FLE3:

Head injury 77
Tumour 63
Birth trauma 26
Gliosis 14
(from abscess, haematoma etc)
Encephalitis 13
Gunshot 11
Other known 17
Unknown 29

The spectrum is likely to be different for those cases not requiring surgery, e.g. fewer
tumours, but post-traumatic epilepsy is commonly frontal. Series with modern neuroimaging
data show that tumours, malformations and vascular anomalies are also not infrequently
detected. The cause in many cases remains unknown.

Clinical diagnosis

The evolution in time of frontal lobe seizures. The seizures which most of the time occur
without warning, are often short and are followed by very rapid recovery. They frequently