Seizures of the posterior neocortex

Dawn Eliashiv MD (Dr. Eliashiv of the David Geffen School of Medicine at the University of California, Los Angeles, received honorariums from Eisai, Cyberonics (LivaNova Inc), Neuropace Inc, Sunovion, and UCB for consulting work.)
Jerome Engel Jr MD PhD, editor. (Dr. Engel of the David Geffen School of Medicine at the University of California, Los Angeles, has no relevant financial relationships to disclose.)
Originally released February 12, 2004; last updated July 10, 2017; expires July 10, 2020

This article includes discussion of seizures of the posterior neocortex, benign idiopathic occipital lobe seizures, focal seizures with elementary symptoms, focal seizures with experiential symptoms, occipital lobe seizures, parietal lobe seizures, and symptomatic occipital lobe epilepsy. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Occipital and parietal lobe seizures have distinct clinical characteristics. Occipital seizures mainly present with visual symptoms, whereas parietal lobe seizures can have unusual manifestations like visuospatial difficulties or ictal pain. If medical treatment with antiseizure medications fails, seizure of the posterior neocortex can be amenable to epilepsy surgery, but success rates are lower than in other epilepsy syndromes.

Key points

 

• Occipital lobe seizures present with visual symptoms, eye blinking, and nystagmus.

 

• Parietal lobe seizures may present with somatosensory symptoms, ictal pain, and visuospatial abnormalities.

 

• Occipital and parietal lobe seizures may propagate forward and mimic temporal and frontal lobe seizures.

 

• Benign occipital childhood epilepsies (Gastaut syndrome and Panayiotopoulos syndrome) present with headaches, nausea, and vomiting and visual symptoms.

Historical note and terminology

Although many other premonitory signs were recognized by the ancients, it was not until the latter half of the nineteenth century that Jackson started to add some anatomical perspective to these signal symptoms and signs (Jackson 1958). In 1879, Gowers describes visual auras in a patient with an occipital-parietal lesion (Gowers 1879). In the twentieth century, seizures of the posterior neocortex were further delineated (Penfield and Jasper 1954; Williamson et al 1992a). Seizures of the posterior neocortex can generally be divided into seizures originating from the occipital or parietal lobes. Previous seizure classifications published by the International League Against Epilepsy lists occipital and parietal lobe seizures as either “simple partial” or “complex partial seizures,” dependent on the loss of consciousness or “focal seizures with elementary symptoms” and “focal seizures with experiential symptoms” (Engel 2006). Focal seizures with elementary symptoms include seizures with elementary sensory experiences, eg, elementary visual hallucinations like flickering lights or primary sensory experiences like paresthesias. Focal seizures with experiential symptoms include more complex sensory experiences like formed visual hallucinations. A report of the Commission on Classification and Terminology recommended classifying seizures of the posterior cortex as “focal seizures with or without altered consciousness with occipital or parietal semiology” (Berg 2009; Berg 2010). The new classification of seizures by the International League Against Epilepsy 2017 classifies focal seizures according to whether awareness is intact or impaired (Fisher 2017). If associated with altered consciousness, these seizures are deemed focal dyscognitive unaware. Secondary generalized seizures are considered to be evolving focal to bilateral convulsive tonic-clonic. Specific syndromes are still classified as electroclinical syndromes (ie, Gastaut).

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