Vivid visual hallucinations from occipital lobe infarction

Infarction of the occipital pole causes homonymous hemianopia, and release hallucinations occasionally occur in the region of the field defect.^1,2

A 64-year-old woman developed acute right homonymous hemianopia with vivid hallucinations in the right visual field. She drew what she experienced, including colored pinwheels and lines at right angles (figure, A). Because light exacerbated the positive phenomena, she constructed a cardboard mask on her eyeglasses to minimize light entering her right visual field (figure, B). FLAIR MRI demonstrated subtle signs of ischemic infarction of the left occipital pole (figure, C). T1 imaging with gadolinium showed gyriform enhancement in the same region (figure, D). Focal hypoperfusion was evident on SPECT (figure, E). EEG was normal except for borderline slowing in the left occipital region.

Figure. (A) Patient's drawing of her experience: the dark area is intended to represent her loss of vision in the right hemifield, and bright colors represent her visual hallucinations. (Although she drew the dark area slightly across the midline, on confrontational testing the area of visual loss was restricted to the right hemifield.) (B) Photograph of patient's eyeglasses, showing the cardboard masks she constructed to minimize light stimulation of her right visual fields (arrowheads). (C) FLAIR MRI demonstrates increased signal in the gray matter of the left occipital lobe, consistent with an ischemic stroke (arrow in enlarged region of interest). (D) T1 MRI with gadolinium shows gyriform enhancement consistent with subacute infarction (arrow in enlarged region of interest). (E) SPECT scan shows a focal region of hypoperfusion in the left occipital cortex.

The positive symptoms abated over a week. The hallucinations may have resulted from infarction, with disinhibition of higher visual centers, or from simple partial seizures not detected by surface EEG. The prolonged symptoms and finding of hypoperfusion by SPECT during the phenomena argue against an epileptiform etiology.

1. Brust JC, Behrens MM. “Release hallucinations” as the major symptom of posterior cerebral artery occlusion: a report of 2 cases. Ann Neurol 1977;2:432–436.OpenUrlCrossRefPubMedWeb of Science

2. Lance JW. Simple formed hallucinations confined to the area of a specific visual field defect. Brain 1976;99:719–734.OpenUrlFREE Full Text