The knowledge of encephalitis associated with antibodies targeting intracellular antigens, and neuronal surface antibody syndromes has expanded considerably in recent times.

The primary purpose of the investigators protocole is to determine the incidence of anti-neuronal antibodies (blood and CSF) in a population of patients suffering from focal epilepsy of unknown cause to guide the management of these patients.

The investigators hypothesis is that dysimmune encephalitis is more common than is suggested by the current literature, and that sometimes forms of encephalitis dysimmune "at minimum" can be observed only in the form of focal epilepsy without further manifestation associated.

Inclusion Criteria:

• Male or female 18-65 years

• Presenting focal epilepsy on the following arguments

  • Crisis with clinical symptoms indicating focal seizure
  • & / Or crisis or critical focal inter-recorded on EEG interpreted by a neurologist with expertise in the field of epilepsy.

• Having not yet received a CSF analysis

• From unknown cause:

  • No evidence of injury (excluding temporal or hyperintensity of hippocampal sclerosis) on brain MRI with focus on regions of interest cuts.
  • No discharge or generalized photosensitivity recorded over an extended interpreted by a neurologist with expertise in the field of epilepsy video-EEG.
  • No argument for metabolic or neurodegenerative genetic epilepsy.
  • Normal neurological examination.

• Epilepsy that started within a period of two years preceding the study entry (including vegetative symptoms of temporal focal seizures).

• Without treatment or as benzodiazepines or taking anti-epileptic first-line monotherapy (excluding benzodiazepines).

• Informed consent signed

• affiliated with a social security scheme

Exclusion Criteria:

• structural abnormality found in brain MRI (except temporal hyperintensity and / or sclerosis of the hippocampus).
• Background Neurological: hyperthermic seizures in childhood, neonatal distress, history of seizures related to a circumstance, inflammation or infection of the CNS.
• Taking toxic: chronic alcoholism, narcotic consumption
• The case for a genetic / metabolic neurodeg ear /: generalized EEG / photosensitivity / family history of epilepsy / autism / disorder syndrome psychomotor development / dysmorphic syndrome / extrapyramidal syndrome associated discharge
• History of thyroiditis or m. system (LEAD, SGS, PR, Sarcoidosis)
• Immunosuppression innate or acquired
• IC lumbar puncture or have already received a lumbar puncture before inclusion in the protocol.
• Person under supervision or guardianship.