Focal Seizures with Visual Hallucinations

Abstract

Clinical Manifestation Epileptic visual hallucinations can be negative or positive. Negative visual hallucinations are ictal amaurosis or scotoma. Ictal amaurosis is rare and can be difficult to distinguish from postictal blindness (Anand and Geller 2000). Positive visual hallucinations are simple or complex (> Table 67-1) (Jobst et al. 2008). Simple visual hallucinations are also termed as phosphenes or elementary hallucinations, and comprise dots or simple shapes. Visual hallucinations can be colored or colorless (Williamson et al. 1992). Complex epileptic visual phenomena include visual illusions (mistaking one object for another) and hallucinations (seeing objects or scenes that are not there). Visual hallucinations are often unilateral in one visual field and seizures with visual hallucinations are often associated with other eye-related signs such as blinking or ictal nystagmus (> Table 67-2). Epileptic visual hallucinations can be quite prolonged, and in reporting a visual hallucination, there cannot be any loss of consciousness, by definition (Jobst et al. 2008) (> Fig. 67-1). Seizures with only subjective visual hallucinations can occur in isolation, or evolve into more objective seizures. These vary depending on the route of seizure propagation. Visual seizures can evolve into seizures with altered awareness, manual and oro-alimentary automatisms, if they propagate into the temporal region (> Fig. 67-2). They can also evolve into tonic seizure activity with propagation into the medial frontal regions, or with propagation to the lateral