Neurosurgery notes/Functional/Seizure/Semiology/Occipital lobe epilepsies

Occipital lobe epilepsies

View Details
logo
Parent item
Semiology
  • Originate
    • Identified by the presence of visual phenomena in the early seizure symptoms.
      • Seizures arising from the medial occipital lobe, visual field deficit can be found in 20-40%.
  • Numbers
    • Uncommon (5%)
  • Clinical Features
    • The vision loss often is unnoticed by the patient, may be subtle enough to be missed on confrontational testing as part of the neurologic examination, and may require formal visual field testing to be appreciated.
    • The most common auras are simple visual hallucinations (white or colored lights that can be constant, flashing, stationary or moving).
    • Ictal blurring or amaurosis (blindness) is reported in 25-40% of case series and can be described as either a whiteout or blackout.
  • Spread
    • Infrasylvian and lateral to the temporoparietal visual association areas
      • Complex visual hallucinations and illusions (achromatopsia, micro/macropsia, metamorphopsia, micro/macroproxiopia, or palinopsia) may occur.
    • Mesial temporal lobe
      • Rising epigastric sensation, smells, and nausea and complex partial seizures.
    • Suprasylvian parietal spread
      • Somatosensory phenomena such as paresthesias and vertigo.
  • Spread from the occipital lobes may evolve to complex partial seizures typical of temporal origin with prominent oral and gestural automatisms, to lateral frontal lobe with clonic motor activity, or to mesial frontal lobe with tonic seizure manifestations typical of supplementary motor seizures.
  • Apart from focal lesions occipital seizures also occur as part of neurodegenerative disorders such as the progressive myoclonic epilepsies (LaFora body disease, ceroid lipofuscinosis), mitochondrial disorders (MERRF and MELAS) and posterior reversible leukoencephalopathy syndrome.