Occipital lobe syndromes

see Anton syndrome.

If the lesion is partial, the patient might have hemianopsia.

Smaller lesions in the occipital lobe lead to hallucinations. Lesions in the area 17 result in hallucinations of moving lights, flashes, sparks and tongues of flame and colours. Objects become exceedingly large which is known as macropsia or exceedingly small which is known as micropsia. Objects also may be elongated or blurred in their outline. Colors might run and objects might lose colour. Lesions in the visual association areas i.e, areas 18 and 19 can produce complex visual hallucinations. These are images of men and animals. Objects and geometrical figures are seen. Micropsia and macropsia can also occur. The objects move towards the patient or recede from the patient. Complex hallucinations are fully formed and are quite real. The patient may not believe that these are hallucinations and might react to them as if they are actually present. Agnosias are the other major disorders occurring in occipital lesions. Visual objects agnosia or the inability to recognise familiar objects through sight is associated with medial occipital lesions, the patient is able to recognize the object though another sensory modality such as touch. Lesions of the left occipital lobe or disconnection of the occipital lobe from the left angular gyrus results in this agnosia. Sometimes, the patient is able to recognise the objects when the object is placed in a familiar context. The patient may be able to draw, pint or trace the object without recognizing it. The object becomes stripped of its meaning. Optic ataxia is present when the object changes its appearance or disappears while the patient is looking at it. Inability to recognise colours or colour agnosia is another condition associated with inferior bilateral occipital lesions. The patient is unable to name, match and identify colour. Prosopagnosia or the inability to recognise familiar face by sight is associated with right occipital lesions. The patient recognizes a face as a face but is unable to place as to whom it belongs. He or she may also recognize the voice without recognizing the face. The lesions are in the right occipital and temporal regions. Simultagnosia, is an inability to perceive the totality of a figure or a scene. The patient is unable to see the totality of the scene and can describe only parts of it. It is associated with difficulties in visual scanning. The ability to scan and visually explore the environment is drastically reduced. It is a beak down to perform visual serial step by step analysis. Visual attention is largely limited to the central visual field. The lesions are in the left hemisphere, or in the frontal eye fields. Bilateral superior occipital lesions can also cause this dysfunction. In some cases, the patients are unable to maintain fixation and focus on the parts of the object. This disorder is known as Balint’s syndrome. It is a strange combination of three symptoms. Oculomotor apraxia: the inability to intentionally move your eyes towards an object. Optic ataxia, the inability to accurately reach for something you're looking at and Visual simultagnosia: the inability to take in the entirety of a picture. Instead, a person sees only parts of the whole as described in the preceding portion. For example, when shown a picture of a house, someone with simultagnosia could only see a window, a door, a wall, and so on, but not the entire house ¹⁾.